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    SBI Micore-300 Mineral Fiber Board - Pack of Four

    List Price: $169.99
    Sale Price: $139.95
    You Save: $30.04 (18%)
    In Stock.
    * Usually Ships Same Business Day.
    • Micore-300 mineral fiber construction
    • Pack contains four boards
    • Board Dimensions: 48" x 24" x 1/2"
    • R value per 1/2 inch sheet of Micore is 1.04
    See complete product details >>
    Product Details
    Manufacturer: SBI
    Part Number: AC02565B
    eFireplaceStore Item Number: SBI-AC02565
    UPC: 773388155326


    • Micore-300 mineral fiber construction
    • Pack contains four boards
    • Board Dimensions: 48" x 24" x 1/2"
    • R value per 1/2 inch sheet of Micore is 1.04
    Versatile and sturdy, with a nearly endless list of applications, Fiber Board from SBI is simply peerless. This Micore-300 Fiber Board features mineral fiber construction for extra safety and durability. This pack contains four exceptionally high-quality Micore-300 boards. The boards themselves measure 48" x 24" x 1/2", and make for a splendid addition to whatever project you're using Fiber Core for. SBI's high quality materials are among the finest in the industry. You can't go wrong with this stellar Fiber Board from SBI.
    Customer Questions & Answers
    50 Questions & 58 Answers
    from Phoenix, AZ asked:
    April 17, 2018
    Can this be prepped and plastered over?
    1 Answer
    Yes it can.
    Owen O.
    on April 17, 2018

    from Vancouver, BC asked:
    April 4, 2018
    Why would I use Micore 300 over the Micore stove board? What is better for fire protection? Can I use this in the NC area?
    1 Answer
    Micore 300 has a better resistance to heat, it has a R value of 1.03. While Micore SB only has a R value of 1.47. Here is The DSS for Mircore 300 and for Micore SB
    on April 5, 2018

    from Gibson City asked:
    February 19, 2018
    After talking with Mendota about my gas fireplace, they strongly recommend this product to install in the combustible zone around the fireplace. Do you agree with this and if so, what material should I use to fasten this to the metal studs?
    1 Answer
    It is a mineral fiber board so if you use any metal fasteners you would need a washer. You can try a high heat silicone or resin. You can also try using a cement board that may work better on a wall.
    Owen O.
    on February 20, 2018

    from Lodi, CA asked:
    February 14, 2018
    At what temperature does micore 300 flash or ignite? I am using it in the "non-combustable zones" on my Mendota Full View 34 installation as face material.
    1 Answer
    Micore 300 is commonly used in construction of hearth pads and wall reduction (as per NFPA 211 fire code) and other "non- Combustible" applications. The manufacturer does not list an ignition point but Micore's melting point is rated at over 2100. You can refer to the manufacturer's Submittal Sheet for more information.
    Kevin E. - NFI Certified Fireplace Specialist
    on February 16, 2018

    Laurie V
    from Crandon, WI asked:
    January 23, 2018
    Hello, I am making a hearth pad, stove requires R-1 rating or more. Can I place ceramic tile over the Micore-300, or will I need to put cement board on top of the Micore and place the tiles on the cement board? I've heard both recommendations, and the concern is that the Micore is too soft. Thanks.
    1 Answer
    You should not adhere tile directly to the Micore and should instead secure cement board to the Micore with screws.
    Will M.
    on January 23, 2018

    Allex G.
    from Chicago, IL asked:
    January 4, 2018
    HI, We are using this product as a sub base for a fireplace harth. Please let us know what your recommended method of fastening/adhering it to the hearth structure.
    4 Answers
    Since you are using the boards forward of the fireplace in a hearth, standard mortar would work just fine for affixing the hearth finishing materials. You can simply screw the micore boards down to whatever your sub-structure is.
    Kevin E.
    on January 5, 2018
    On my personal application I used Dap High Temp 100% RTV Silicone sealant. I found it to give the adhesive quality I was looking for without fasteners. In my particular case the shear weight of the hearth material and stove put me in a position where the Micore isn’t going anywhere.
    on January 5, 2018
    from Maryland
    Hi, We used this as a sub base also and it turned out great! We laid it (unfastened) on the floor, covered it with 1/4-inch cement board, then screwed through the cement board, mineral fiber board and into the subfloor with the same screws. We used cement board screws (one brand is called durarock screws). We put screws in every 8 inches and countersunk them into the cement board. (Don't screw this mineral fiber board to the floor without the cement board on top; it's too soft and the screws just chew it up.) Then we tiled over it with porcelain tile, using thinset mortar, and set our 650-pound wood stove on it. It has held up wonderfully and we are very happy with it.
    on January 5, 2018
    from Baltimore, MD
    I used this Mineral Fiber Board and then put HardiBacker 500 (Cement) Board on top of it. HardiBacker makes a special screw which you should be able to purchase wherever you buy the board. The screws come in two lengths, I believe, so get the longer length and screw right down through the HardiBacker and the Mineral Fiber Board. You can securely fasten both boards at one time using these screws. Adhere the hearth tile of your choosing to the HardiBacker using thinset mortar and then grout between the tiles.
    on January 6, 2018
    from Linesville, PA

    from NE asked:
    November 13, 2017
    If I use this product to bring my wood stove to within 12" of an O.S.B. wall, can the Micore-300 be screwed to the O.S.B., or are spacers needed to have an air pocket between the Micore and O.S.B.?
    1 Answer
    You will need spacers for an air gap.
    Brennan W.
    on November 14, 2017

    from NE asked:
    November 13, 2017
    Could I use this under a wood stove? I would place tiles on these boards.
    1 Answer
    These could indeed be used under a wood stove.
    Brennan W.
    on November 14, 2017

    from NJ asked:
    November 8, 2017
    I'm installing a wood stove and the building inspector of my township requires "micore underlayment." Is this the appropriate product?
    1 Answer
    Yes, that is the exact product the inspector is asking for and it is a common practice.
    on November 8, 2017

    from NY asked:
    November 7, 2017
    Is this product good enough to apply 3/4 stone hearth to with a bonding agent?
    1 Answer
    The answer is yes, in the case of a floor application.
    on November 8, 2017

    from Los Angeles, CA asked:
    October 28, 2017
    Would this be good to use inside of a safe with thick steel walls to create a degree of fire-resistance?
    1 Answer
    Those panels provide heat resistance, so it would offer some benefit, yes.
    on October 30, 2017

    from TX asked:
    October 19, 2017
    Can this product be installed directly to the studs? Also, can drywall mud be applied directly to product and textured and painted?
    1 Answer
    This can indeed be attached to the studs and you can cover the surface of it with drywall mud.
    Brennan W.
    on October 19, 2017

    from McCormick, SC asked:
    September 17, 2017
    Can this be used as a surround for a gas fireplace requiring non-combustible materials?
    1 Answer
    Yes, this product is considered a non-combustible material.
    on September 18, 2017

    from Torrington, CT asked:
    July 30, 2017
    I'm trying to make a NFPA clearance reduction system; if I use this as "insulation board," how can I tile over it? Durock is no longer rated for high heat applications.
    1 Answer
    Standard wood screws should be used to secure any brand of cement board to the Micore prior to adhering tile or stone with Thinset.
    Will M.
    on July 31, 2017

    from Salem, SC asked:
    June 20, 2017
    Can I use this to insulate my gas grill unit in my wooden outdoor kitchen instead of using an insulated grill jacket?
    1 Answer
    As fiber board tends to retain water, we do not recomend using this product in an outdoor application. You would likely want to continue to use an insulated grill jacket.
    Brennan W.
    on June 20, 2017

    from ID asked:
    May 25, 2017
    I want to install on insulated wall behind a gas fireplace in basement and I want good heat resistance. Will it work?
    1 Answer
    Please note that this mineral fiber board may indeed be combined with other materials to create an NFPA 211-accepted method of clearance reduction or used in conjunction with other materials to create a stove board for floor protection when a hearth manufacturer calls for this material to have a certain R or K value, but this product would not be needed in the application you describe. With manufactured gas fireplaces (or wood fireplaces, for that matter), the installation instructions for framing the cavity for the firebox will have already considered the clearance requirements in these measurements, so there should not be any need to reduce heat transfer.
    Will M.
    on May 25, 2017

    from Marysville, OH asked:
    March 31, 2017
    Can this material be painted? If so, what paint is recommended? Can this material be cut with a carbide knife? What mortar is recommended to attach ceramic tile?
    1 Answer
    This material can easily be cut with a utility knife and, while you may possibly be able to paint this material, it is normally covered with cement board and the finishing material of your choosing. No mortar should be used between the Micore and tile as cement board should be screwed into the Micore with thinset being used to secure the tile to the cement board.
    Will M.
    on April 3, 2017

    from Marysville, OH asked:
    February 10, 2017
    Are these installed using refractory cement? How may they be cut? How would you attach to a ceiling?
    1 Answer
    This product should be secured using standard wood screws to cement board first, if your plan is to install tile. Adhesive will not work will due to the mineral construction of this product, so the tile or stone would then be adhered to the cement board with thinset. A utility knife may be used for cutting the mineral fiber board.
    Will M.
    on February 10, 2017

    from Northern California asked:
    December 14, 2016
    I want to use this to line the top of a see through fire pit that has a concrete top. What can I use as an adhesive?
    1 Answer
    Adhesive does not hold well to the micore board, so it is recommended that these are installed using standard wood screws.
    Brennan W.
    on December 14, 2016

    from NJ asked:
    August 25, 2016
    Can this be used outside behind a outdoor barbecue grill as a fire protection for a wall?
    1 Answer
    This product cannot be used in an outdoor installation, but clearance reduction may be reducing to 12" via 24 gauge sheet metal spaced out 1" with a layer of cement board, followed by the stone or tile of your choosing. This is only permissible when allowed by local code enforcement as they will have the final say, so I will recommend a consultation with your local office prior to completing this application.
    Will M.
    on August 26, 2016

    from Alexandria, VA asked:
    April 25, 2016
    Can this product be used to reduce the required spacing between my ceiling and a gas fireplace direct vent duct?
    1 Answer
    The manufacturer's tested and listed vent clearances with direct vent pipe may not be reduced and must be followed. The use of any clearance reduction methods will need to be approved by local code enforcement as hearth manufacturers will not approve anything that falls outside of the tested limits for heat transfer to combustible framing.
    Will M.
    on April 26, 2016

    from Greenville, SC asked:
    March 23, 2016
    What temperature is this fiber board rated to? Can it take direct flame for a Raku kiln?
    1 Answer
    This product can withstand sustained temperatures of 450 degrees Fahrenheit, but can withstand temperatures of 550 degrees Fahrenheit intermittently. For a product which can withstand being in direct contact with flame, I would suggest a product such as our SBI Vermiculite Board - Pack of Two as these are rated to withstand up to 2000 degrees Fahrenheit.
    Chris C.
    on March 23, 2016

    from GA asked:
    March 21, 2016
    What does each sheet of SBI fiber board weigh 48 x 96 x 1/2"?
    1 Answer
    This product ships with four pieces measuring 48" by 24" by 1/2", with each piece weighing in at approximately 8 pounds.
    on March 22, 2016

    from CO asked:
    February 6, 2016
    What is the total sq footage of all four boards? It's not clear to me if the dimensions listed are for each or the four boards or the total.
    1 Answer
    This pack contains a total of 4 individual boards, with each board measuring 48 inches by 24 inches.
    on February 8, 2016

    from Fairhope, AL asked:
    January 29, 2016
    Do I glue this SBI Micore-300 board to the subfloor or do I just screw it down?
    1 Answer
    This can simply be screwed down using wood screws.
    Brennan W.
    on January 29, 2016

    from Mechanicsville, VA asked:
    December 17, 2015
    I recently had a cast iron insert put into my fireplace and I thought we were in code, however we are not. I was told that I can buy micro-fiber boards to put on the cabinets closest to the insert to make sure there is no heat transfer, and this will make me in code so I can use my new unit! What other information can you give me about these boards?
    1 Answer
    This product is most commonly used beneath a finish material such as tile or granite to provide a greater R value for a stove hearth pad installation. For more detailed information, I would refer to the submittal sheet provided by USG.
    Chris C.
    on December 17, 2015

    from Brenham, TX asked:
    December 15, 2015
    We are building a home and plan on having a wood stove installed. The stove will have a corner placement and we have followed the manufacturers space recommendations. Our insurance company wants more for wall protection. We would like to create a heat shield wall using Micore covered with Metallaire (old tin ceiling squares). Is this SBI Micore-300 mineral fiber board ridged enough to stand vertically with the Metallaire? We plan to attach the panels to the wall with one inch ceramic insulators to create a free air space.
    1 Answer
    Micore has a density that is similar to drywall and should be able to serve as a backer for the metal tiles you mention, as long as they are not excessively heavy. If the tiles are 18 gauge or thinner, you will not have a problem.
    on December 16, 2015

    from Kalamazoo, MI asked:
    November 29, 2015
    Can I mortar ceramic tile directly onto this SBI Micore-300 mineral fiber board or does it need a layer of cement board first?
    1 Answer
    A cement backer board should be used first. The Micore product is not a high density material and compressibility is high enough that concentrated pressure from a stove leg or other point of contact could cause a shift or crack in the tile veneer.
    on November 30, 2015

    from AZ asked:
    October 15, 2015
    What temperatures can this SBI Micore-300 mineral fiber board withstand? Is it easily cut? Also, is it similar to all vermiculite boards?
    1 Answer
    This product can withstand sustained temperatures of 450 degrees Fahrenheit, but can withstand temperatures of 550 degree Fahrenheit intermittently. Micore will have the same consistency and feel as drywall, as such it can be easily cut with a utility knife.
    Chris C.
    on October 15, 2015

    from Blue Ridge, VA asked:
    September 10, 2015
    Will this SBI Micor-300 mineral fiber board that is covered by one layer of 1/2 inch Durock cement board and 3/8 inch porcelain tile support a 475 lb. wood stove?
    1 Answer
    With a 1/2" layer of Durock secured directly to the Micore, and then porcelain tile laid atop the Durock, the Micore will indeed support this weight. The combination of the Durock and tile allows for equal distribution of weight across the Micore.
    Chris C.
    on September 10, 2015

    from Santa Barbara, CA asked:
    May 13, 2015
    How does one cut this SBI Micore-300 mineral fiber board?
    1 Answer
    Micore can be cut with a utility knife.
    Brennan W.
    on May 13, 2015

    from San Diego, CA asked:
    January 15, 2015
    Can Micore 300 be used outdoors? I want to use it to insulate the area around a built-in outdoor gas grill and burner.
    1 Answer
    It can indeed, as long as it will be covered by a water proof material. Micore has a tendency to absorb humidity and will begin to degrade when it does. As such, a waterproof covering is absolutely necessary.
    on January 15, 2015

    from Ridgecrest, CA asked:
    December 29, 2014
    I plan to use Micore 300 for a woodburning stove hearth. Can I put granite directly on top of the Micore?
    1 Answer
    Granite can "float" directly upon the Micore product. However, if you are planning to adhere the granite permanently, a layer of cement backer board should be screwed to the Micore first, as adhesive does not hold well to the mineral construction of the Micore product.
    on December 30, 2014

    from Northport, AL asked:
    November 20, 2014
    If I'm using double wall 2100 degree pipe that requires a 61/2" clearance and a stove that requires 7 1/2" clearance, will the Micore board allow me to sit the stove any closer to the wall and if so how close?
    1 Answer
    Clearance reductions for a wood stove can be made down to 12 inches by code. When clearances for the stove are already below 12 inches, further reductions cannot be made. That being said, using the Micore as a heat barrier is always a good idea for a close clearance installation such as yours.
    on November 21, 2014

    from Wallkill , NY asked:
    November 4, 2014
    My sub floor is 3/4-inch thick plywood. Can I install 1 layer of Micore and ceramic tile directly on top of it? Will this withstand the weight of the wood stove? Also, would the Micore compress over time?
    1 Answer
    Per the manufacturer, a layer of 1/2 inch cement board should be used between the Micore and the tile. The cement board helps to both distribute the weight of the stove over the Micore and to give the tile a solid substrate to adhere to. The tile will not adhere well to Micore alone.
    on November 4, 2014

    from Saint Paul, MN asked:
    October 27, 2014
    I'm building a hearth extension and intend to use this product under a limestone slab. I'm assuming the slab will need to be supported by some rigid material on each edge (stone, steel, oak) rather than letting the slab "float" on the Micore-300 boards. My concern is that the stone slab may need some support at the center. I'm wondering at what kind of pressure (psi) the Micore-300 begins to be "crushed" and thereby loses some of its r-value. Can you help me?
    1 Answer
    I was able to speak to engineering at USG and they advised that when using a slab of material, a layer of cement board should be used between the Micore and the material being used. This will more evenly distribute the weight. Micore is fairly fragile and although the crush point is relatively high, any lateral movement of the slab could damage it. It was recommended to screw through both the cement board and Micore together, which will flatten and compress the material, eliminating the possibility of high spots that could be damaged by the limestone slab.
    on October 29, 2014

    from NH asked:
    September 2, 2014
    What is the R value of the fiber board per sheet? Can the boards be stacked to achieve higher R rating?
    1 Answer
    The R value per 1/2 inch sheet of Micore is 1.04. You can indeed layer the product to achieve a higher R value, if the manufacturer requires it.
    on September 3, 2014

    from Richmond, VT asked:
    September 2, 2014
    I am looking to build a stone wall behind my stove which is a Jotul Oslo. The manual says I need 6" clearance and I have 8" to the stud as the dry wall was removed. For added protection, I was thinking of putting a metal hat channel on the stud then Micore to gain a 1" air gap between the wall. Could I just put the Micore on the studs? Can I mortar the stone directly to the Micore or do I need to attach a concrete board like Durock next gen to the Micore first. Also, I heard that you are not supposed to use Durock next gen behind stoves anymore but I'm not sure if they mean that you can't reduce the clearance or not.
    1 Answer
    If the manual is indicating 6 inches of clearance is all that is required, anything else you are adding is simply additional protection, if you have the 8 inches you indicated. Air space beneath wall protection is only a requirement when trying to reduce clearances to a combustible wall, with the stove not currently meeting clearance requirements. In your case, the Micore can indeed be secured directly to the studs without the additional air space. The R value of the Micore alone will prevent excessive heat transfer. Veneers do not secure well to Micore, especially in vertical applications. As such, you will need to use Durock or a similar brand of cement backer board over the Micore to secure the veneer to. I honestly have not heard anything regarding changes in clearance reductions offered by Micore. The product has consistently offered the same R value for some time now and still meets all UL requirements to be used as a floor or wall protector.
    on September 3, 2014

    from Ohio asked:
    August 7, 2014
    I have a couple of questions. If my husband builds a hearth platform out of wood topped with plywood, can I use a combination of micore board and durock on top of the plywood to get to the desired R-value of 2.0 before adding slate tile on top? Secondly, if we have fire-resistant drywall behind the wood stove, what is the best way to finish that out to make sure it has the appropriate heat protection (or should we have cement board instead of drywall on the studs)? I've seen a lot of reference to ceramic spacers and 24 gauge sheet metal, but (not to sound stupid) do you fasten the spacers straight to the drywall or does something need to go on top of the drywall? I realize maybe I shouldn't be asking part of this questions here, but I have been looking online for hours and can't find answers.
    1 Answer
    The short answer to your initial question is yes. As long as enough Micore and cement board is used to achieve the required R value (2.0 in your case), the platform beneath can be fully combustible. The slate tile can be applied directly to the cement backer board. The tile itself will have its own R value, but I don't recommend factoring that in, as the porosity and density of the slate will vary. As for the second question, the appropriate material to use will actually depend on how close the stove will be to the wall. If the stove is positioned so that it meets minimum required clearances to the wall, standard drywall could be used. Cement board, sheet metal, or any other wall protection would only be needed if clearances need to be reduced even further. If you would like to provide the model of stove you have, whether you are using single or double wall stovepipe, and the intended proximity to the wall, I will be happy to advise further.
    on August 8, 2014

    from St. Louis, MO asked:
    June 28, 2014
    Is your mineral board similar or the same as vermiculite board? I am looking for something rigid and easily cut. I will be using it at a temp of approx 1600 degrees
    6 Answers
    The fibrous board is not the same as vermiculite. It is designed to be used as an insulating barrier behind noncombustible material or in place of combustible drywall behind a stove. It is not rated for the temperatures you expect for your application. The SBI Vermiculite Board - Pack of Two can be cut to size and is rated for direct contact with flame. This product is commonly used to replace baffles in high efficiency wood burning appliances.
    on June 30, 2014
    They are similar in that they are both light weight, but I'm not familiar with the heat tolerance and R value of vermiculite board. When researching materials to use for our fireplace pad, the micore 300 seemed the best choice. With the other material we put with the micore we achieved the R value of 1.5 required for our stove. The Micore was more expensive but now that we have it built I'm glad we went with it. I feel confident that we wont have a fire.
    on July 9, 2014
    from Boise, ID
    It is nothing like vermiculite. It is lightweight and easily cut. As far as the temperature rating, that would have to be researched
    on July 9, 2014
    from East Lansing, MI
    I chose Micore-300 (capped with a layer of Durock), because it allowed me to achieve the required R-value for my wood stove hearth, using the shortest height possible. There are other materials you can use, but I wanted to keep the overall height of the hearth (including tile) to under 1.5 inches. Every other material I researched would have pushed my hearth thickness to well over 2 inches. If finished hearth height is not an issue, go with something else. I know the Micore is pricey (and difficut to locate), but it is the best material currently available.
    on July 9, 2014
    from Newton, NJ
    I'm not familiar with vermiculite board, so I can't comment. But Micore is the same stuff that is in the pre-made hearth boards they sell at Lowes. It is rather soft, so it's easy to work with, though it tends to be a bit crumbly.
    on July 10, 2014
    from Virginia
    I used this under a raised fireplace hearth and it worked perfectly. I needed it to meet the heat transfer requirements protecting the framing underneath. Under normal circumstances, it sees no more heat than what is radiated from the fireplace warming the stone on top of it. I have 2" blue stone on top of it which is heavy but spread evenly. It cuts very easily with a utility knife and will probably compress if a lot of weight is placed in small spot. In terms of durability I would compare it to a ceiling tile.
    on July 10, 2014
    from Pennsylvania

    from Nobleboro, Maine asked:
    December 11, 2013
    I want to use Micore 300 in a hearth and I assume I can tile directly on top of it. Do you know? In addition, I want to use it in the wall behind the stove as fire protection. If I did, could I use it as the substrate for tile in the wall?
    1 Answer
    The manufacturer advises that the Micore board can be used as a thermal backer, but tile should only be applied upon a layer of cement board that should be screwed down to the Micore. The Micore does not lend itself as a good backer material to tile upon directly, as it is not dense enough.
    Collin C. - NFI Master Hearth Professional
    on December 12, 2013

    from Hedgesville, WV asked:
    October 19, 2013
    My insert manufacturer specifies a 1/2 inch Micore board and 24 gauge steel sheet for floor protection. They don't say which goes on top and which is the bottom next to the floor, or how to fasten it down. What is your recommendation?
    1 Answer
    The 1/2 Micore board should be used as the substrate with the steel sheet placed over the top of the Micore for additional protection and finishing. If the Micore is upon a combustible surface, wood screws should be used every 6 to 8 inches to secure the Micore to the floor. The 24 gauge steel can then be secured to the Micore using construction adhesive.
    Collin C. - NFI Master Hearth Professional
    on October 21, 2013

    from Walla Walla, WA asked:
    October 13, 2013
    In an earlier answer you indicated that one should screw the micore directly to the sub-floor. Then use thin set with a cement board over that. Then thin set with tile on the top. My question is regarding securing the cement board. Usually when installing the cement board to the sub-floor, I use thin set and then screw it down. But my guess is that the screws will have nothing really to grab when they get to the micore. So do I just use really big screws to get all the way to the sub-floor, or do I skip the screws for the cement board?
    1 Answer
    We usually recommend skipping the screws as a rule, but it really depends on the application. In many cases, a stove will require some sort of R-value for the floor protector. Using screws through the cement board will allow heat to be easily conducted down the screws to the sub floor, potentially causing scorching to the floor over time. If the stove is insulated well enough that it does not require the floor protector to have an R-value, this is not a problem. However, the thin layer of tile would not insulate well enough for a stove that does require a listed R-value and screws that penetrate to the floor should be avoided in that case.
    Collin C. - NFI Master Hearth Professional
    on October 14, 2013

    from Hartford, CT asked:
    September 26, 2013
    I am debating whether or not I can, and should, tile directly over this product for use as a wood stove hearth. I read in your FAQ section that this can be done, however, I've also read in my research that it is not strong enough to hold a wood stove. Could you shed some light on your experience with this?
    1 Answer
    Both pieces of information are true. This item can be tiled directly over, but that is only recommended for a wall application. Furthermore, it is better to use a layer of cement backer board over the Micore before tiling. The backer board is a better material for the tile to adhere to. The Micore is definitely not strong enough to be used on its own as a hearth. While it is a dense material, the weight of the stove legs will cause it to compress and indent. Manufactured hearth boards use Micore, but it is usually layered between sheets of steel or cement board. As such, you can use the layer of Micore as a base, then cover it with cement board, then apply your tile.
    Collin C. - NFI Master Hearth Professional
    on September 26, 2013

    from CT asked:
    August 21, 2013
    What is the value of one sheet of Micore?
    1 Answer
    The R-value of the Micore board is 1.03 for every 1/2 inch of board that is used.
    Collin C. - NFI Master Hearth Professional
    on August 21, 2013

    from Port Austin, MI asked:
    April 23, 2013
    I want to apply ceramic tiles to the Micore-300, how would I do that? Would I first put down a coating of thin set, then place the Micore on top when installing this over 3/4" plywood? What screw spacing would you recommend?
    1 Answer
    Per the manufacturer, no thin set is needed between the Micore board and the plywood. The Micore can be secured directly to the plywood with coarse thread wood screws, spaced 12 to 18 inches apart.
    Collin C. - NFI Master Hearth Professional
    on April 24, 2013

    from San Jose, CA asked:
    January 26, 2013
    Could I place a granite slab on top of the Micore 300 board?
    1 Answer
    The Micore 300 product is indeed dense enough for granite or stone to be placed on top of it. Most installations will require two layers of Micore to achieve the minimum required R value.
    Collin C. - NFI Master Hearth Professional
    on January 28, 2013

    from Cornwallville, NY asked:
    December 5, 2012
    If you cut the Micore 300 into 2' x 4' pieces for wall application, does this compromise the thermal resistance of the board?
    1 Answer
    Cutting the Micore board will not compromise its R-value. As long as the thickness of the board is not changed in any way, the product will meet the same listed values outlined on the data sheet.
    Collin C. - NFI Master Hearth Professional
    on December 5, 2012

    from Dallas asked:
    December 5, 2012
    Is this a good product to use as a sub-floor in front of the fireplace, to be covered with tile?
    1 Answer
    This product was recently revised with increased density that would make it ideal for this type of application. Its superior R-value over concrete board makes it an excellent substrate to be used for hearth extensions and hearth boards/pads.
    Collin C. - NFI Master Hearth Professional
    on December 5, 2012

    from Cornwallville, NY asked:
    November 27, 2012
    Can you apply ceramic tiles directly to this board with thin set mortar? Also, I thought USG manufactured Micore 300? Is this a less reliable copy?
    1 Answer
    You can indeed apply ceramic tile directly to this product, but for better results it is recommended to use a layer of cement backer board over the Micore. This Micore 300 board is manufactured by USG. It is simply purchased from them and sold through the manufacturer SBI, hence the use of their name in the product description, even though they do not actually make it.
    Collin C. - NFI Master Hearth Professional
    on November 28, 2012

    Customer Reviews
    33 Reviews
    79% (26)
    18% (6)
    0% (0)
    0% (0)
    3% (1)
    97% Recommend this product (32 of 33 responses)
    By Mark from TX on February 28, 2018
    I would recommend this item to a friend.
    Great service
    The store had what i wanted and it shipped quickly and arrived in perfect condition.
    By Patrick G from Smithtown, NY on February 20, 2018
    I would recommend this item to a friend.
    Impossible to find Except here.
    My wife and I purchased a new Medota gas fireplace and we're having a granite hearth installed which required a half inch fiberboard with an R-factor that was at least 1 or higher. I researched and found that Micore Mineral Fiberboard 300 was exactly what I needed but no one on Long Island, New York sold it. I found a hardware store in Ohio that would ship me a pallet with 75 pieces and I only needed one. Then I found the e-fireplace store that shipped me a package of 4 with no shipping charge for $125. The package arrived in 3 days and our hearth was installed that same day. We are now enjoying our new fireplace thanks E-Fireplace Store.
    By KF from Long Island, NY on October 30, 2017
    I would recommend this item to a friend.
    As Advertised
    Four micore boards showed up at my door!
    By Sam from Linesville, PA on October 25, 2017
    I would recommend this item to a friend.
    Glad I Found This Product!
    I am so glad I found this product. My wood burning stove requires a hearth with an R-value of 1.2. I couldn't find any way to make that happen until I stumbled across this mineral board. I put this down and then applied a 1/2" thick cement board on top of it and then set porcelain tile using thin set mortar and grout. I ended up with a beautiful hearth that exceeds requirements.
    ProsLightweight Easy to work with the product High R-value
    ConsEasily damaged if dropped on corners. My box was apparently dropped on a corner during transit. I was able to cut off the damaged areas and still had plenty to complete my project. It would be nice if the packaging could be strengthened at the corners to prevent damage during shipment.
    By Keith from VA on September 14, 2017
    I would recommend this item to a friend.
    Too Much Product
    I only needed a 20" x 22" piece; and, now what do I do with all the rest?
    ProsIt was easy to cut the small piece I needed.
    By Talina from ID on March 18, 2017
    I would recommend this item to a friend.
    Micore Fiber Board
    We tried finding this fireproof board locally with no luck. I ordered it from eFireplaceStore and had in two days at a reasonable cost.
    By Greg from San Rafael, CA on March 10, 2017
    I would recommend this item to a friend.
    Micore Mineral Fiber Board
    Great material to work with.. Used it for a new gas fireplace surround.
    By James from PHILADELPHIA on February 3, 2017
    I would recommend this item to a friend.
    amazing product
    I purchased this for our fireplace facing the area above a gas fireplace that prevents heat from transfer and combustion of regular drywall materials. The fireplace was installed by someone else and was too close to tv and also too large of a unit. We had hardi board but that was heating and retaining heat. We used micore 300 and finished with wire mesh and durabond spackle, came out great heats about 40-50% less than cement board. One note if not going to install cement board on face of micore 300, and going to use as finished wall surface prime the board first. Original fireplace came with 5" of "non combustible facing" but was unable to order more this actaully worked out for me getting almost 18" of micore 300 instead of 5" that came with.
    Proslight weight withstands high heat low thermal transfer
    Consonly con and mostly because i am using as a finished wall surface is needs to be primed prior to spackle ( not exactly a con just using in ways different than intended)
    By Neil from San Jose on January 17, 2017
    I would recommend this item to a friend.
    As advertised
    Nice to find a source for this product online; none of the local big box stores carries this type of product. Shipping was quick and product was in good shape. Satisfied customer.
    By Kim from Hayward, California on January 2, 2017
    I would recommend this item to a friend.
    Cool top!
    We installed this over a custom fire pit to keep the granite top cool. It really works!!!
    By Steven from Iron Mountain on November 25, 2016
    I would recommend this item to a friend.
    Micore 300
    Have not installed yet, product arrived well packaged and undamaged.
    By Matt from Shepherdstown on October 19, 2016
    I would recommend this item to a friend.
    Price is right!
    Good product/quantity for price.
    By JESSE from ATHOL,ID on September 5, 2016
    I would recommend this item to a friend.
    Awesome product .excellent shipping thank you efireplacestore you guys are the best
    It's very hard to find this product ..The family is excited we needed this for are hearth pad ,and thanks to efireplacestore are dreams have came a reality if it wasent for these guys we would be up a creek with no paddle .Thank you folks, much appreciated.
    ProsExcellent service,excellent product.
    ConsNo cons.
    By Marty from NC on January 27, 2016
    I would recommend this item to a friend.
    building code
    great way to meet/exceed the NC building code for a fireplace hearth
    By Amy from Lake Village, Indiana on January 12, 2016
    I would recommend this item to a friend.
    Amazing Product
    We noticed that the wall behind our stove pipe was incredibly hot, so we purchased this product to hopefully eliminate this problem. It has worked amazingly well, drastically reducing the wall temperature!! Ordering was easy and product showed up as promised. Installation was a breeze!!! Thank you efireplace store!!!! Looking forward to working with your store in the future!
    By Erika from Kentucky on December 17, 2015
    I would recommend this item to a friend.
    No hassle company
    I have purchased SBI Micore from this company twice now. Each time it was a painless experience. And both times the product shipped quickly, without damage and arrived ahead of the date promised! Personally, I wouldn't hesitated to buy from efireplacestore in the future.
    ProsQuality product Fast shipping
    By Terry A from Shelburne Falls on November 28, 2015
    I would recommend this item to a friend.
    Great product, solves problems
    Micore 300 solves building code problems with fire separation with minimum of thickness and cost. It is easy to work with and arrives from eFireplaceStore within a day or two. Great product that is hard to find elsewhere.
    By Matthew Morrison from Big Sandy TN on October 29, 2015
    I would recommend this item to a friend.
    Great Price, Great Product
    The only problem I had with the purchase was that the estimated delivery time was wildly inaccurate. I talked to customer service and the next day i got an e-mail that it had shipped. The product ended up being shipped from the manufacturer in Canada. This held up my hearth project for a while but all's well that ends well.
    By Rick from Linden Az on October 26, 2015
    I would recommend this item to a friend.
    SBI Micore-300
    I am using this "stove board" as a heat berrier between the roof of my porch and a patiio heater. Not enough space to feel safe without shield The patio heater puts out 36000 btu on high. I had only apx. 10" or so between the roof and top of heater. So, I ordered this Fiber Board and put it between two pieces of sheet metal.Added a few nuts and bolts to keep it in place and have had good results. This heat shield fits above the heater apx.6"-8 " and between the rafters. I can hold my hand above the shield with heater on high. I have heat resistant paint on the sheet metal and the paint did not peel or burn off. I did not cut the board. Used 24x48 piece since my rafters were 24" on center. So far so good. The product works.
    ProsSo far pruduct performs as claimed. Works well for my application. Reduces space needed between heater/stove and in my case roof boards.
    ConsWill soak up moisture. For my outdoor use wish it was more "outdoor" usefull. I painted over it to hopefully seal it better.Yes, using hi-temp paint.
    By Pam from central Wisconsin on October 6, 2015
    I would recommend this item to a friend.
    Micore for a woodburner hearth pad
    I have not installed this item yet but am so happy to have found it. I asked at a woodburning stove sales shop what insulating board to use for a hearth pad. They recommended Micore Fiber Board and since I had heard of it I welcomed the endorsement as I was already leaning that way. However, they said it was readily available at home improvement stores but I found that is not the case. Thanks to this seller for carrying it!
    By Jim from Southwest, VA on April 7, 2015
    I would recommend this item to a friend.
    The only insulating board I have found for making a stove board.
    I have had no success in finding suitable stove boards at a reasonable price, so I decided to make my own. I previously purchased Micore 300 to make a stove board for the wood stove at my hunting cabin. I had a local sheet metal shop make me a 44" square pan, 1" deep. Painted it black and turned it upside down on 2 layers of Micore, and I had a reasonably priced stove board with an R factor of 2.06. I used 14 gauge metal, which spread the weight out enough for the Micore to be able to support my stove (350#). I am putting another stove in an addition at my house, so I am doing another homemade stove board. I have no doubt it will work out just as good as my first one.
    ProsReasonable price, quick shipping, sturdy product.
    ConsA little damage to the edges in shipping. Not really a problem for me because I had to trim the pieces anyway.
    By Paul G from Cleveland Oh. suburbs on March 29, 2015
    Micore 300 was not the easiest stuff to find, and it is pricey, but you get what you pay for! It allows you to make a fireplace hearth that is a lot thinner, rather than using thicker materials, to obtain the ''R'' required. This seller is one of the few places I found that carry Micore, and their shipping was super fast!! I sandwiched the micore between two 1/2'' sheets of Durock next generation cement board, and then finished with multi color slate tile cemented on top. Looks fantastic, and is more protective than the 1.2 R factor that my stove required..
    Prosgreat insulator
    Conskind of pricey
    By Opie from Ronkonkoma, New York on December 26, 2014
    I would recommend this item to a friend.
    A product that is easy to install..and works
    I had a problem with my ceiling for a number of years now and went to a store that sells stoves and asked him about my problem which was paint flaking off my ceiling. I have repaired it many times but to no avail. The man in the store stated that my smoke pipe is too close to your ceiling and then i asked him what he would put on the ceiling..he said Micore-300 Mineral Fiber Board.! and so i ordered it and installed it over my ceiling with screws going into the ceiling joists...
    ProsI was told that this item is put into the backs of stoves
    By Brad from Vermont on October 10, 2014
    I would recommend this item to a friend.
    Just what I needed for custom hearth pad, best price, no problems.
    By Denis Lee from PA, United States on September 12, 2014
    I would recommend this item to a friend.
    Good price for hard to find Item
    I was installing a slate pad for under a wood stove and wanted to protect the original hard wood floors, century and a half old house. In my area this product is not carried in the hardware stores. They could order it for me but I would have to wait for the next USG shipment of drywall, maybe weeks. Both price with shipping and timing were better than any local store offered me. Very happy , pad and stove installed.
    ProsThe product is a heat barrier, it preforms as described. The time to delivery and price were what was exceptional.
    ConsNo cons.
    By Chris from Willsboro, New York on August 13, 2014
    I would recommend this item to a friend.
    Great product, Great Price
    I was already aware of the benefits of Micore for building my hearth but I was surprised to find it here for less than Amazon and the shipping was fast.
    ProsGood product
    ConsYou can't buy one sheet.
    By Theresa from Boise, ID on June 17, 2014
    I would recommend this item to a friend.
    High R value, light weight and easy to use.
    We installed a wood burning stove over hardwood floors in a house with a basement. Because of the weight of the stove we didn't want to add a lot more weight in the floor pad. It needed an R value of 1.5. By using the Micore 300 in place of many layers of durarock we achieved the R value we wanted without it weighing a ton. We used 1/4 " plywood and the Micore was sandwiched between the durarock. On top is ceramic floor tile. The Micore was easy to cut and light weight. I only gave it 4 stars because I thought it was pricy.
    By Dean Selzer from Valley Lee, MD on May 5, 2014
    I would recommend this item to a friend.
    Awesome Product and Fast Free Shipping!
    Micore board was exactly what I needed for my hearth!
    ProsR-value and Free shipping!!!
    By cody from mi on December 16, 2013
    I would recommend this item to a friend.
    Great Product
    Exactly what I needed for my custom hearth pad and hard to find .
    By DW from MA on October 30, 2013
    I would recommend this item to a friend.
    Exactly What I Needed
    This product is fairly hard to find, but FS had it shipped to my door very quickly. My only caveat is that it comes in a large quantity. If it came in a package with half the coverage I would have given it 5 stars.
    By Kurt from Mt. Holly, NJ on October 12, 2013
    I would recommend this item to a friend.
    Great product
    If you need R value this is the product. Sandwich between two sheet of 1/2 Durarock and you can put any stove on it.
    ProsCan be shipped anyware
    ConsWould be nice to have a larger sheets.
    By Renee from Aztec, New Mexico on April 15, 2013
    I would recommend this item to a friend.
    Micore-300 Mineral Fiber Board completed our Wood Stove
    The product was easy to use and just what wee needed to complete our hearth for our wood stove. We had to abide by the codes since we put it into our manufactured home. I would recommend this product to others. The price was also in our budget.
    ProsIn our budget easy to use
    By Robert from (S. Indiana/Louisville, Kentucky on February 4, 2013
    I would recommend this item to a friend.
    A Complete Minimum Clearance Solution
    I bought this product so I could comply with my wife's request that our new wood stove be placed closely as possible against the wall and without a raised hearth. This product solved all of our clearance issues in as much as a one half inch thick sheet has the heat transference protection of nearly six inches of concrete!
    ProsGreat product with excellent heat transfer retardancy values.
    ConsThere was nothing that I disliked about the product itself. I was simply surprised that it was so difficult to locate. In that regard, I am especially grateful to this store for including it in its inventory of wonderful products.

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