Hey y’all (with an implied “Wautch Thee-us!!):
I’ll be installing a few windows (new openings, old frame house) with glass block sidelights. Specifically, 36″x64″ fiberglass casements, 6″x8″ glass blocks forming 6″x64″ sidelights on each side. I’ll be building pine jambs between the rough opening and between the blocks & fiberglass window, and a Trex sloped sill. This will be my first glass block installation, and I’m not quite sure how to handle grouting. What I see on the Pittsburgh-Corning website involves using either plastic tracks, or foam expansion strips around the entire perimeter, with silicon caulk. On a single block width installation, that would leave me buttering just the horizontal joint between blocks with mortar, which doesn’t feel right. I’m leaning toward solid grouting all joints between the blocks & jambs, and handling expansion for the whole window/sidelight unit at the rough opening.
Thoughts? Oh yeah; this is in the Colorado high country — 120-degree annual temperature swings, lots of snow, little rain. Thanks.
}}}}
Replies
I've done glass block windows using the Pittsburg Corning installation methods on their website, but using mortar, not silicone or foam or whatever. I built a redwood jamb and sill assembly, installed that into the rough opening, and then glazed the jamb. Waterproofing is tricky and I don't remember all the details, it was 5+ years ago last time I did it.
With the mortar there is no grouting. Make sure to mix the mortar slightly fat, so that block settles into it nicely as you tap it with a rubber mallet. Putting the right amount of mortar on is critical, that way you get some squeeze-out that you can tool with a brick jointer.