I have a couple of questions about installing glass block windows.
I plan to replace my basement windows with glass block. This is a common practice here on the south side of Chicago to protect from breaking and entry.
All the DIY books and publications simply indicate that you install the glass block window in the opening. There is no indication that the window is anchored to the surrounding frame. I am concerned that the windows can still be kicked in from the outside. Is a standard installation sufficiently secure or should I secure it from the inside?
What kind of R factor do glass blocks have?
Some pre-assembled units include air-vents. I would like to use air vents in some of the windows because it is damp in the basement. How air tight are the vents when they are closed? How much heat do I loose?
I would appreciate any advice you can provide.
Replies
The R-value stinks. Something like 2 or 3.
If you install the blocks with mortar, there will be ladder reinforcing between the courses and tied into the window jamb.
A bigger question is getting the blocks to fit the opening ... they only come in two or three sizes, and can't be cut. You're looking at multiples of 8, 6 and 4 incehs, with 8x8 blocks being the most common.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
You can have them pre assembled w/ vents.
You may have to alter the size of the opening to fit which is no biggie.
Then frame the inside with trim strong enough to keep the window from being kicked in.
Seems to me a window on the first floor is a lot quicker way in if someone is planning on robbing you.
Be an alarm system
andy
The secret of Zen in two words is, "Not always so"!
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I don't know too much about the R-value of glass block, but I do know that what Ed said about the sizing is true. You will almost certainly have to re-size your window's rough opening to fit the blocks, because you should not cut the blocks. If you do, humidity gets inside, and mold then grows and it looks just awful. They are manufactured with a semi-vaccuum inside them to prevent this sort of thing.
For your application, you will probably be using the Mortar II system to do the installation. The sill has to be prepared to have the mortar adhere to it, then the block is laid on that. You insert reinforcing ladders every two rows, and attach the ends of each second row to the jambs with panel anchors, as well as anchoring the top row to the header the same way. Expansion strips made of foam similar to sill-seal is used to stuff the space between the blocks and the R.O. You'll need the block, spacers, foam expansion strips, ladder-style mini-rebar strips, and panel anchor strips, plus white glass block mortar. If you want the joints to look nice and clean, figure on raking them deep after the block is laid while the mortar is still wet, then filling in with sanded grout (which has a much finer aggregate than the mortar) after it all dries.
I've never heard of vented, pre-built block windows, so I can't help you there.
Don't let the lumberyard or whatever supplier you buy the block from convince you to use the silicone caulk installation method; I really don't think it will work for your application, easy though it might be to do.
Here is a link for Pittsburgh-Corning's glass block tech support; these are the people you want to talk to. This is the e-mail of the technical representative I dealt with last year on a complicated shower installation. [email protected] Talk to him or one of their other tech people. They are really good. You can download their installation technical bulletins off their website, too.
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
What are the walls? Wood frame, con block, poured...?
Good question - I realized that I omitted that info.
I have about three feet of brick sitting on an old stone foundation (It is a 1888 Victorian). The windows are in the brick and will sit on an old limestone sill.
The pre-assmbled are a good option if they are a close fit for your opening. They can be made with steel reinforcing rods embedded in the mortar. See below.
http://www.marylandglassblock.com/id10.htm
Billy