Grinding Down Brick

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Well-Known Member
Nov 2, 2022
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Cleveland, OH
I want to install glass block windows in my basement but the rough opening is just a hair (1/2") too small to fit the standard sizes available at the big box store. What is the best way to remove a small amount of material from the horizontal window sill that's there now? Angle grinder? Chisel? I found many tutorials about cutting bricks in half but can't seem to find anything about grinding them.

Glass Block Window.jpg
Is it a sill proper with sloping bricks or just an opening in a brick wall? I've seen bricks sawn with a masonry saw but am not sure how that might work for your application. Since I have never done it I am just speculating what I might attempt. One approach might be multiple cuts with an angle grinder (or sawzall with Spyder masonry blade) and carefully removing material between scores with hammer and chisel (much like sawing and cleaning a dado in woodworking). Maybe someone with actual experience will jump in.
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Here are a cpl. of commonly employed options;
DIABLO 4-1/2 in. Diamond Turbo Masonry Cut Off DDD045TUR101C - The Home Depot
Both demand several pieces of safety equip and clothing.

Both are less costly from AMAZON.

As you can see the depth-of-cut, of the 1st, will require several different approaches and some chiseling out for removal of material, and the 2nd is several times the mess, but maybe will suffice.
As an observation, many basements are used as bedrooms, IE, sleeping quarters, which require 2 forms of egress, so if this is, in your case, such a use, that window may be required to remain, in a serviceable condition.
Another observation; As often as not, folks will return with comments re: their repairs and discuss the cures, successes and failures, as well as the methods that they found most effective, as incite to future inquisitors.
Thanks for the comments! I do have an angle grinder and this was my first thought at tackling this using a diamond grinding wheel. Also, the bricks are not sloped, it's just a straight edged hole in the wall. I will post back how I end up doing!
If you grind or saw masonry, remember to wear appropriate breathing protection. Silicosis is a very damaging disease.

Plain, cheap composite, masonry grinding wheels work well. If you can have a helper trickle water on the area, the dust will be far less. Remember to change your furnace filter when done. Dust will find its way there.

Plan B: The Easier Way...
We faced the same situation as you're facing- pre-made would not fit some of our openings.
I bought individual blocks at a big box store and mortared them in. By cheating a tiny bit on each mortar joint, I made up the 1/2" the opening was short.

I also was able to put in vents & those tilt-up windows where we wanted them. There is white "Glass Block" mortar available, but I used white thinset. I added a dryer vent port in a workshop window to connect an exhaust fan.

Actually, building the windows block-by-block was a whole lot easier than installing the pre-made ones. They are heavy and hard to make level and plumb at the same time. Also, after a few years, the mortared ones look cleaner than the pre-made ones that are siliconed together. (In my opinion, anyway. I like the white mortar joint versus the "used to be clear" silicone joints.)

Which every way you choose, be sure to enjoy your project and your new windows!