Rutland Pre-Mixed Refractory Fireplace Cement - 1 Gallon Tub

The Rutland Pre-Mixed Refractory Fireplace Cement is primarily designed for masonry-to-masonry joints less than 1/4 inch thick. Since the hole in your gas fireplace log is 1/2 inch, this product would not be the ideal choice for that size repair.

However, Rutland Castable Refractory Cement is specifically formulated for filling larger, irregular holes in masonry fireboxes and can be cast into custom shapes. Gas fireplace logs are often made from ceramic refractory material, which is a type of reinforced cement, making castable refractory cement a more suitable option for repairing a 1/2-inch hole.

This castable cement requires a dry time of 24 hours, depending on thickness, humidity, and air temperature, and cures without heat. Please ensure this is only used on heavy-weight refractory cement logs and not attempted on ceramic fiber logs.

This could indeed be used for that purpose.

While this product works great for repairing existing masonry, we can't really recommend using it for creating a fireplace from the ground up. However, it is worth pointing out that currently available gas fireplaces require very minimum clearances to combustibles. As such, you can frame up an opening from standard 2x4s and install a gas fireplace therein with no concerns about heat transfer.