efficiency of storm windows?
Hi folks,
I’m contemplating putting in new storm windows in my house, and I have a few questions. My house is a 1930 craftsman in Madison WI with original double hung windows. There are currently old aluminum storm windows installed, probably circa 1975. I’m currently renting out the house while I’m living on the East Coast and the renters have complained about how cold it gets in the winter. It’s true, it can be a cold house. SO:
– is there a significant R value gain by installing good storm windows? The best ones at Home Depot (Larson Gold series) will run me about $2400.
– is it likely that a good storm window will provide any noticeable difference over old cheapies?
– do you think that good storm windows do anything to increase the resale value of a home?
Clearly, the money thing has given me pause. Going to the Larson Silver series (next one down) will cost about half as much, but I fear they will be no improvement at all over the ones in place now.
Thanks in advance,
Tom
Replies
You could probably make a big difference in the efficiency of the old storm windows by closely inspecting them for air leaks and sealing those up. Same thing goes for the old double hungs.
The double hungs are probably causing major heat loss due to the lack of insulation in the adjacent wall cavities needed for the big weights which help to raise and lower the sash.
There are several remedies for those problems. My preference is to replace old single pane, double hung units and fill in the wall cavities with foam insulation.
I did that job on my parent's 1950's SoCal stucco ranch home, using custom made insulated glass, vinyl units from http://www.milgard.com, about ten years ago. The price for sixteen replacement windows was less than three thousand dollars. They were simple to install, requiring about two hours per unit, total time, taking it easy.
The result has been dramatic in all respects. The house is much quieter inside. It uses far less energy to heat and cool. The time and expense of maintaining the painted sash has been eliminated. Oh, and the sash is easier to open and close too.
Edited 10/18/2007 4:02 pm ET by Hudson Valley Carpenter
Hi Tom,
Storms windows are going to help.
Your basic single pane glass has an R-1 value. Not much. If the outdoor temperature happens to drop down to zero and the inside temp is around 70F, then with the single pane you will have an interior glass temp of right about 16 degrees. Remember that heat goes to cold, so the window is sucking heat to it like a vacuum sucks dirt. And that heat is being drawn from anything (or anybody) who is near the window. That is why it feels so darn cold when near that window even when the heater says that the temp inside is 70 degrees.
Adding the storm brings it up to R-2 - which doesn's sound like much - but if the outdoor temperature still happens to drop down to zero and the inside temp is still around 70F, then with the single pane and storm you will have raised the interior glass temp to about 43 degrees - which is a good bit better than the 16 degrees of the single pane itself.
The key is to make sure that the original windows are tight and that all the weatherstripping is up-to-date and not all torn or missing. That way you get the advantage of both the increased glass temp plus you limit air infiltration as well.
Likely your home in Madison has very little insulation and the warm air from inside is heading outside through the attic which tends to draw colder outside air into the house thru any openings you may have - such as loose windows.
My opinion is that it is much more important to make sure that the exisiting windows are brought up to be the best they can be and then make sure that the storm windows fit perfectly and are installed correctly. Original cost is significantly less important than is application.
Does your 1930's Craftsman house have any insulation to speak of? Mine had 1" of vermiculite poured on the ceiling (well, at least in a few places) and none in the walls. Blowing in cellulose did more to warm up the house than did new windows, except for in one room that was dominated by a 5'X5' drafty casement-style window. How much storm windows will help kind of depends on where you're losing most of the heat to begin with -- windows, walls or ceiling.
Mike Hennessy
Pittsburgh, PA
Generally a storm seals much better than your classic double-hung. It's the reduced infiltration that's the major benefit, but there is also a significant increase in effective R value of the window assembly.
However, with an old double-hung, air can often get into the siding, around the outside trim, and come in through the weight pockets, bypassing the storm and any weatherstripping on the original window.
for the money, you would be better off spending on replacement windows, but if the dbl hungs are in decent shape, I wouldn't.
A lot of comments here have gone to sealing the ones you have tight. But do not seal the bottom to the sill. I see that too often, You need to have the weep drainage or moisture will build and rot out the sill.
The best gain for the dollars can come from adding interior storms which are plexiglas panels fitted in with snaps, but renters are notoriously hard on them, so....
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Thanks folks,as always, lots of good stuff to think about. I'd love to replace the windows completely, but I just don't think it's in the budget this year. Also, they're a really nice looking 3 over 1 style that may be hard to find in a replacement. Air leaking up into the attic is certainly an issue that needs to be addressed since the attic is accessed through drop down stairs. I'm sure that sucker leaks. I'll look into the plexiglass internal storms as well ... the renters I have actually would be very nice on them. The place looks better now than when I lived there! Thanks again,
Tom
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For the pull-down stairs, get some old corrugated plastic political lawn signs. Make up a box with them and maybe some 2x2s for the corners, along with some duct tape. Make the box so it fits over the top of the pull-down stairs.It's light enough that you can easily lift out of the way after pulling down the stairs, but with a little care (and possibly some extra weights on it if the 2x2s aren't enough) it will seal fairly tighly when closed.
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We live in Wisconsin for 7 years. While I was there I learned a few things about the cold. Ha Ha.
There was an interesting radio program on the public radio station. They had guest speakers from the university of Madison come on and talk about all sorts of issues.
One of them talked about storm windows and how they work. In a nutshell, the storm windows shouldn't seal that well because if they do moisture will form on the inside of them and rot out your sill. They are supposed to breath a little bit. Their primary use is to keep the wind from "washing" off heat from your windows. That was the term he used. So you want a pocket of air between your double hung and the storm but with some air turn over to let the moisture out.
You can seal up the double hung windows because they are warm and the moisture won't condense on them as much.
So buying really good storms or really well sealed storms is a waste of money. I would consider the looks of the storm to be more important. The aluminum ones look like , well, aluminum! Especially with all the screws holding them on. I guess at a certain time it was the new material and had a certain appeal. That appeal is gone for me.
But there's a difference between "shouldn't seal that well" and "shouldn't seal". You need the weep holes open, of course, and there should be a little bit of air exchange besides, but basically the only requirement is that the storm not be so much tighter than the window that moist air that gets between the two can't get out.What would actually make sense would be for the storms to have adjustable vents that you'd adjust to just the point where you occasionally got some condensation on colder days, allowing the ventillation to be "customized" for the particular window.
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I agree. I thought of the term he used and washed wasn't the term he used. It was scrubbed. So cold wind scrubs of any heated air that is near the window pane.
I like the idea of the adjustable vents but I'm not sure if they would be used by most home owners these days. People don't even take off their storms these days. They leave them on year round. The idea of living and working with the seasons in your home is disappearing. People want to buy a house that is ready to move into and has little or no maintenance so they can go do other things. Mostly working so they can service the huge mortgage they took out to buy the house.
We have aluminum storms on our house and I've never touched them. The windows on that side of the house were painted shut a long time ago. People don't even know how to paint any more.
The idea with the adjustable vents is that the tighter your windows, the tighter the storms can be without resulting in too much condensation.
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