I am remodeling a bathroom in Western PA, and another part time contractor is installing a glass block window in an existing wood window frame. He prefabricated the window and set it into place and informed me that he is going to seal the window in place with liquid nails. Also the block has silicone in the joints in place of mortar. I think the silicone may break down in a few years along with the liquid nails holding the window in place.
Any advice.
Jerry
Replies
Hi Bear.
You can order glass block windows pre made from the manufacturer and specify that the windows be made with either mortar between the joints, or silicone. I'm telling you this to emphasize the point that silicone joints are perfectly acceptable, and in my book, perferred.
I think ( actually, I know) that a silicone window is stronger than a mortared one. Mortared glass block windows can easily break apart. Mortar really doesn't adhere well to glass anyway, which is why glass block has their edges roughed up specially so to help the mortar stick to it. Silicone sticks to practically anything, stands up to great temperature extremes, is 100% waterproof, and much more flexible...all great attributes...which is why I always specify silicone for large glass block windows. The last 4 I just installed 3 weeks ago measured 5 feet tall and 40 inches wide....everyone was siliconed. Also, silicone gives the block a more "glassy look" you dont notice the joint lines like you do in a mortared job.
AS for securing the window by glueing the unit in place with liquid nails...throw the bum out! No way, no how. There are several methods that could be used, but liquid nails is not one of them.
They make and sell glass block framework that can be screwed into wood, and then the block inserted into the frame. The frame acts as a "stop." Instead of using the store-bought frame, you could actually install wooden stops both on the inside and exterior side of the wood work. The stops would be screwed to the wooden frame and hold the window in place.
More commonly, wooden or plastic shims are driven between the glass block and the wood frame work. These shims are driven tight so as to wedge the window unit in place. Then the shims are nailed in place with a finish nail to keep from loosening up. Then the shims are scored , excess snapped off, and the gap between block and frame is either sealed with mortar, or if the joint is less than 1/2 inch wide, a urethane caulk can be used. This caulk is waterproof, UV proof, and in general, a lot tougher than the silicone caulks.
On another note, some people ( myself included) have on occaision used triple expanding spray foam in this gap, and then used the urethane caulk. I would advise against using the expanded foam unless you know how to use this stuff. It will hold the block tightly ( which I like) but you have to be careful. The foam will break down in sunlight so it has to be covered over.
Shims and mortar are the way to go and is the "tried and true" method. Liquid nails won't survive 1 year.
Just my humble opinion..
Davo
Davo:
Thanks for the advice, I did not think that liquid nails was a good idea, I beleive you should need a license to buy it so you don't use it on things like ceramic, glass, among others I have seen used improperly.
The Baer