August 4, 2021 - Faberlic-zp

Installing Glass Block – Tricks of the Tradesman

You can install glass block!

It’s not the easiest do it yourself project out there, but it will be perhaps the most rewarding, because it can be challenging and it will impress everyone–especially you! I have discovered the following tricks over the last eight years while building a successful glass block installation company in Palm Coast, Florida. You will not find them on any installation guide out there, because installers don’t write the guides!

Start with the fun stuff–design the window. There are only a few manufacturers of glass block–Pittsburgh Corning (distributed by Home Depot and Lowe’s, to name a few), Weck, and Mulia. Personally I prefer Mulia–the price point is usually lower, the block meets the same design standards (all 4 inch deep block meets the Florida hurricane codes–the toughest standards in the country), and Mulia paints the interior edge of the block, which makes a nicer detail when the window is finished. All three make similar sizes and patterns. Design with the opening in mind–Pittsburgh Corning has a great guide on their website for planning out the project. Whichever block you choose, you can use this site for a planning tool. Just be sure and plan for a masonry installation–it is the most cost effective, easiest to finish, and best looking. Follow that guide for a materials list: glass block, spacers, glass block mortar, panel anchors, reinforcing, and expansion joint. Don’t use channels; they complicate the project with no added benefit and less visual appeal.

Tip #1–The rough opening size

You want the rough opening to be one inch over the nominal dimension of the window. Simply put, if you want a window six blocks wide by six blocks high, using eight inch block (the standard size) your nominal dimension will be 6 block x 8 inches = 48 inches + 1 inch = 49 inches. Now that you know the standard, know the tolerance. The actual size of the glass block window will only be 47 3/4 inches x 47 3/4 inches. That 49 inch opening you are shooting for can vary up to an inch, and you can still make the window fit. So don’t split hairs.

Tip #2–The bed joint

The bed joint is the foundation–it is a layer of mortar set on the window sill. If you have a true one inch over the nominal size,split it and make a half inch bed joint. You can guesstimate this, just check the opening after the bed joint is down to insure that you have enough room for the glass block. The secret to a window that lays itself is the bed joint. Put down the mortar (made the consistency of home made mashed potatoes), then dust it liberally with dry mortar. This will allow you to level this bed without the level sticking to it. If you start with a firm, level bed, you will seldom have to make any adjustments as you go up. Using your …