A friend's son does stonework for the National Parks Service. He mostly repairs the large stone walls at visitor's centers and along the scenic parkways. He and his wife have built their retirement from his getting transferred around the county, staying in each place long enough for them to live in "fixer-uppers," do the work, and then flip them. I never thought to ask him if he is certified to the level that he could do residential and commercial block & brick work. The pics of some of the large scale projects he's done are fascinating.
I love this guy. Fifty years experience. Uses his hands. Breaking all the rules. Gives me hope I can actually do this window.
Back to the window... Once you lay the first row of glass blocks the whole window is set in stone, literally. So where precisely do you start? In the video above Mr. Haduck keeps dry fitting 6 blocks to that measly little window. "No big deal." . But you can't dry fit a 30-block window. The granite stones used in this wall are different sizes. Once you remove all the old mortar down to the stone, the opening is not a perfect rectangle. I don't trust measuring with a tape across thin air. Apparently no one else on the whole WWW has this problem with their walls. I made a box out of 1" x 6"s. The OUTER diameter is the size of the whole chunk of glass blocks after assembly, including mortar on both sides. Squared it up, braced it, and stuck it in the opening. The box below is level and plumb, although the camera angle may not look it. Turns out there is only about a half-inch leeway sideways to place these blocks so they fit the opening all the way to the top. That's where things stood as of this afternoon.
That was smart to make the box. That's odd that the opening is no square. I guess deciding how to make the border look uniform (from the outside) is something to worry about after the blocks are installed, if if even needs it. I copied the "before" pic and zoomed in on it. Just eyeballing the gap on the left-hand side (from the outside), I bet the original was not plumb.
Imagine you have to create a stone wall with odd sized stones and with 3 windows in a row. You would spend a lifetime choosing stones so that all 3 window openings were perfect rectangles. They would have to adjust with mortar afterwards on at least some of them. When the wood window alone was removed the opening was near perfect. But you are supposed to knock off the old mortar because it's not stable. That's when it became irregular in shape. Maybe I should have decided where to put the first row of glass blocks before removing the old mortar, but I didn't think of it.
It will be fine. I am highly impressed. Starting with a clean opening is the right thing to do. I was looking at the outside photo. Between the stone facade at the upper right hand side of the stairs, the unfinished blocks below and to the left, and the stairway cutting diagonally through the center, perfection in being centered ain't a requirement. It certainly won't be noticed. It's weird how the right side (from the outside) is cut cleaner than the left side, almost like the left side was extended after the house was built.
Even when this house was built, I think they could cut granite stones fairly uniformly. There is reason to believe that the widow that owned this house originally, obtained rejects, oddball pieces, likely from Elberton, GA, just 30 miles east of town. To save money. Don't get me started. I get carried away on local history. Elberton Granite Quarry .(photo too large to post)
I read that 2/3 of all tombstones in the US are made from Elberton granite. Don't know about D.C. Maybe you're thinking of marble. Georgia has marble quarries too, north of Atlanta.
Window progress... Took out the box and added a row of thin concrete pavers on the bottom. They won't show much, if any, from outside. After those set, I put the box back and filled in around the sides with mortar. Not the top. The box is fastened together with screws from the inside. It should come out easily. Adding the mortar in the sides was a gamble, because it's very possible I measured wrong, or didn't think of something, and the opening won't fit now. Bottom line I can just knock out all the mortar and start over. With a little luck, it will work as long as I stick religiously to the spacers provided with the glass blocks. Fingers crossed. However, this project may be put on hold until they decide where Cyclone 9 is headed.
Shims??!!.. I don't need no stinkin' shims! . Dry fit first row. Perfect... The tricky part will be making sure they don't lean in or out.. I may use guitar picks.
I suppose some might wonder, as long as I'm building a box anyway, why not just build a wood frame for the blocks, and lay the blocks inside it? I ruled out using any hint of wood (to rot, warp, have to paint or repaint) anywhere close to this window. Hoping this is more maintenance free.