basement windows in cinder block foundation


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Old 11-14-10, 02:12 PM
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basement windows in cinder block foundation

Hello,

I am new to the forum and neither a pro nor a very experienced DIY-er. However, I am badly in need of advice, and was hoping someone could help me out.

Here is my problem:

I wanted a block-to-block basement window installation (for light, water and air-tightness, and because the wooden frames in place now are 50 yrs old). The window sales people want to do a retrofit (one's telling me the old cinder block will fall apart if they try to remove old frames).


The frames now in place were part of the original wood hopper windows (2 are still in place). The frames run to the brick on the sides, are slightly raised on the bottom where a cement slope was formed both inside and outside, and appear to have a gap on the top between the wood and metal or cement plate above them. (I have included some photos, to show the detail).

I don’t know what those frames are made of. I am pretty sure there is no moisture barrier of any type between the frame and the concrete wall, as there is none between the concrete floor and the interior wall framing. The wood is weathered on the outside, but I don’t recall seeing active rot. Numerous stains show history of water ingression through the windows (can’t tell if the water gets in around the old frames as well, but, they may have been repeatedly soaked). The inside concrete slope shows damage in some areas (cracks, crumbling).

This type of home is referred to as “brick on block” construction, with a 1” gap between them providing the only insulation.

What would you advise? Should I insist on a total rip-out and replacement? If so, how should it be done? Should it even be attempted in the winter?


Please see photos below and let me know if I can provide any more information.



window from outside

original hoper seen from outside

small hoper seen from inside

detail of bottom edge of the original frame with replacement alum window

top of the frame )some insulation sticking out of the gap between the frame and the metal of concrete plate (red edge)

detail showing the side of the same window

a window with cracks in cinder block and cement slope (notice gap between the right side of the frame and the wall)
 
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Old 11-14-10, 02:37 PM
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It's hard to give you specific advice, but from the looks of it, I wouldn't be afraid of tearing out the wood frame, and installing a new window in the masonry opening. Once the old window is out, I'd probably suggest removing any mortar that has been parged onto the interior side of the wall. Your new window would be sized about 1/2" smaller than the interior size of the (cleaned out) masonry opening. This way you'd have about 1/4" of space on each side to shim and square the window. It would get attached to the masonry opening with tapcons, then sealed with Vulkem or Quad, or any other high quality polyurethane sealant. If needed, you'd parge new mortar on the perimeter of the window to "trim" the opening.

If the wood has been parged with cement on the exterior side of the window, then there will be some damage to the exterior cement surface when the wood frame is removed. But it's nothing that can't be repaired- it's just that the repair might stick out like a sore thumb in contrast to the old cement finish.
 
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Old 11-15-10, 07:27 AM
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Thank you for your advice sleeper.
So, no need for buck construction? Would one need to use a vapor barrier, or expanding foam? If yes, where would these go?

Originally Posted by XSleeper
It's hard to give you specific advice, but from the looks of it, I wouldn't be afraid of tearing out the wood frame, and installing a new window in the masonry opening. Once the old window is out, I'd probably suggest removing any mortar that has been parged onto the interior side of the wall. Your new window would be sized about 1/2" smaller than the interior size of the (cleaned out) masonry opening. This way you'd have about 1/4" of space on each side to shim and square the window. It would get attached to the masonry opening with tapcons, then sealed with Vulkem or Quad, or any other high quality polyurethane sealant. If needed, you'd parge new mortar on the perimeter of the window to "trim" the opening.

If the wood has been parged with cement on the exterior side of the window, then there will be some damage to the exterior cement surface when the wood frame is removed. But it's nothing that can't be repaired- it's just that the repair might stick out like a sore thumb in contrast to the old cement finish.
 
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Old 11-15-10, 08:55 AM
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You would be wise to use a low expanding foam such as Dap latex door and window foam around the perimeter of the window (between the window and the masonry opening). But take care not to overfill the cavity. A bead of polyurethane sealant on each side of the window (inside and out) will also provide an air seal. If you parge cement onto the window perimeter (inside or out) it will only be for appearance sake, to repair anything that cracked or looks bad. Do not rely on cement to air seal a vinyl window.

I think a wood buck is pointless since the windows are pretty small and the basement appears to be unfinished. If the basement is ever finished in the future, the wall framing will provide a surface to nail a jamb and trim to.

You can install a wood buck,for instance if you want to install a window with a nailing flange, but keep in mind that the wood buck will reduce the window size even farther (vinyl windows have 2-3" of frame around them already which reduces the glass size dramatically on small windows). Plus you need to attach the wood to the cement, then the window to the wood, and seal up each layer. To me, it's often better to just pop a pocket window into a finished masonry opening and caulk it. In some cases, you need to repair/replace the sloped sill under the window to provide a drainage plane. This can often be done after the window is installed if you shim it up during installation. Then you just need to remember to let the cement cure before you caulk the window to the new cement sill.
 
 

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