New windows for an old (structural) masonry house?

staceyneilMarch 22, 2010


We have a 1956 ranch house. It's built of cement block shaped and colored to look like brick. It's structural: walls are about 9" thick.

We need to replace three windows. One is simply glass block mortared in place. Two are cheap vinyl replacement windows set into the old wood frames.

From tearing out some other windows, we know how the original frames were installed: they were added as the masonry walls were built, so the nail heads are stuck IN the brick wall, and the nail points stick into the wood frames. REmoving those frames required tearing the frames out and cutting off the nails that were left sticking out of the masonry openings.

We'd like to replace these windows with double-hungs. We'd also like to maximize the glass area, so using new construction windows sounds better. Would we simply shim these in the masonry rough opening and fasten with Tapcon or similar... and caulk the gap or cover with small wood trim on the outside?

One problem is that two of the windows flank the front door and should be symmetrical.... but the ROs are slightly different: off by an inch or two. Looks we'd need to frame out the larger opening in order to have matching-sized windows. Would we need to use PT lumber for framing that out? If that one has to have a frame, would it look better if the other one did as well, albeit a smaller frame, with like-sized windows?

Any other advice for this difficult scenario?

Would photos help?

(Interior retrimming is a non-issue as it's all gutted anyway!)

Finally, what is the most cost effective place to get windows for this project? I priced Andersons, which is the look/quality we want, but we can't get custom sizes there.

Thanks for your input!


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Good morning Stacy. The situation you have is pretty common within our industry. I own a business in western PA that has been distributing and installing windows and doors for residential and commercial projects for 74 years. Based upon your comments I would suggest that you go with Eagle or Marvin windows for this project. They both are very similar. Extruded aluminum exteriors and wood interiors. Eagle offers more options and is typically less costly. That said, eagle would be my first choice. Secondly, I would add masonry to your openings to correct the difference in symmetry, in lieu of wood of any type. Wood trim inside is ok.

The installation method we would use is a Tapcon type fastener. We would take the window apart during installation so as to hide all of the fasteners. This is a simple and typical process in this type of installation. Furthermore, I would recommend buying the sealant from a glass company for the exterior. You should also ask for a non gassing backer rod to support the sealant. From the existing masonry to the window frame should be a 1/4' gap. We would fill the gap with fiberglass insulation being careful in the installation not to distort the jamb inward. We shy away from any spray in foam insulation. It's messy and can create problems. Then we would apply the backer rod at a 1/4' depth. You would than have a 1/4' deep and a 1/4' wide void. This is the ideal scenario for sealants. Expect to pay about $7.00 to 10.00 per tube for a good urethane or structural silicone sealant. These types are not available to the public in home centers. I hope this helps you.

Here is a link that might be useful: Eagle

    Bookmark   March 23, 2010 at 10:09AM
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Rather than disassemble the window to find a place to hide your tapcon anchors............ask about masonary clips that provide an inward flange of sorts so you don't need to go thru the windows frame. All wood window companies like Eagle or Marvin have these available.

I have installed many windows by hiding screws behind the jamb liners, but since the inside is gutted there is no problem hiding your fasteners that attach a clip to the wall.

    Bookmark   March 24, 2010 at 8:46AM
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