Sealing kiln ceilings

What's the best material for sealing a kiln interior? July 18, 2000

The vapor barrier in our kilns has broken down and our plywood ceiling is falling. I am looking at replacing the ceiling and want to add a good vapor barrier as well as a seal over the plywood.

I have heard that some kilns use foundation coating or 'silver coating.' What has been your experience, how is it applied, and what's the frequency for reapplying?
The product is called Silver Liner, and it is made by Pace Products in Overland Park, KS. It works.
Gene Wengert, forum moderator

Many people in this area use mobile home roof coating, available at your local hardware store. I know one guy that put Gyprok [wallboard, drywall, etc.] in his kiln and coated it with this product. The Gyprok stayed at the ceiling and walls for the five years that he operated the kiln. After that time the Gyprok was still in excellent shape.

Pace Products is the maker of mobile home coatings, too! That was one of their main business lines, then they found out it worked on kilns! It is expensive; more expensive than the black, tar-like coatings.

Aluminum fiberated roof coating works very well. Buy the one with the most aluminum and fibers in it (is the difference in good roof coating). The best place to buy is a roofing material wholesaler.

After 30 years in the roofing trades, I know that just coating your plywood will not stop moisture from getting into it. You have to tape the joints. Use 4-inch cotton fabric that has been coated with tar (available at any roofing wholesaler) and follow these steps:

1) Coat your plywood and let it dry for two days (use fans).
2) Coat the joints and embed the fabric, then do a light coat over the fabric.
3) Apply the second coat over the plywood and joints.