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I’m pricing some Larson storm windows for a job. One line of the Larson is recommended for enclosing porches, etc. because they are water tight. The less expensive line isn’t.
The lumberyard guy says that it is better to get the less expensive storms because, yeah, water gets in, but water also gets out. But if water is getting in and out, then isn’t air also?
So the question is…which storm should I recommend to the customer?
Rich Beckman
A high-performance single-family home builder shares tips from his early experience with two apartment buildings.
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Replies
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Rich - I am thinkin' of a conversation I had, years ago, with a friend of mine who owns the local glass shop. I was asking him about wider spacing between thermo pane units.
I think he told me at some point, like 3/4" or something, the space between the panes was so great it starts to have mini weather systems of its own, there between the panes. If what he said was accurate - and I trust that he is knowledgable about his profession - then you might be facing the same situation with truly air tight storm windows.
Seems like you would get a little infiltration around the edges or through the window jambs though. - jb
*Rich, this I can tell you: Conventional storm windows, which are typically of the double or triple-track variety should never be caulked (so they may be removed for re-painting or other window maintenance), and most importantly, the "weep holes" along the bottom frame must be left clear. In the event the lower section of the storm window is configured with the screen in place, wind-driven rain may collect on the window sill, and must be able to drain out. To a lesser degree, condensation which forms on the inner surface of the storm window during cold weather cannot drip out if the weep holes are not open. Withouit the drainage, the window sill can rot out, and the repair cost will exceed whatever energy savings the client may have enjoyed.I think the less expensive storm windows you are considering may actually be "water tight", but not vapor tight. That's OK, since as jb points out, you'll likely have some vapor leakage through the existing sashes. Sure, you'll have a little air leakage, but you won't be fighting the condensation problems which would occur if the storm sash was absolutely air-tight. The more expensive model is probably better suited to installations where it serves as the primary (singular) weather barrier between the exterior and interior of the enclosed space.Have you tried to reach the Larson people?Good luck, Steve
*I should probably include the info that the house is eighty years old with the original windows.Rich Beckman
*Dear Rich,You're a bit skimpy with the clues, but I'm going to assume that this is a cold place and the owners are tired of getting freezing drafts on them. And as you say, leaky storms are not an effective thermal protection measure.The house is question is probably under low pressure throughout when heated. Screwy ductwork can change that in a heartbeat as you'll see in the "Condensation on storm windows" thread. In any case, if you ask which rooms are drafting, you can put the tight storms in those rooms without any condensation trouble. It won't do much good for keeping those rooms warmer, but at least you'll be safe from the moisture thing.To get the windows to stop sucking air, the attic and ducts have be fixed. You knew that, but I put it in for the new readers. There's more on this in FHb #105, (Fixing a Cold, Drafty House).Feeling the first pinch of cold under the stars tonight, Fred
*jb, the literature I've been reading says the same, that beyond 3/4" you have to go to triple-pane or the r-value goes DOWN. incidentally, skylights have much worse convective loop losses than windows -- the vertical loop is shorter.
*For Freddy's line of business of course, a pinch of cold means a pinch of gold, no?Note that he's citing himself now, the second published author hereabouts.jealously, ad
*Fred, sorry about the skimpy details. This is central Indiana. She just bought the house this summer, so she hasn't been through a heating season yet. The house is two story brick with a full basement. The second story has sloped ceilings only at the edges of the room (I don't know the terminology for that). The attic is not accessible from inside the house. There are a couple of gable vents beyond the reach of the ladder I had with me, but they look awful small (and I am skinny).The heat is gas forced air in the basement. There is one duct that runs into the next door room in the basement (where there is a shower, washer and dryer), but I saw no corresponding return. The basement has steps up to the first floor and also steps up to an exterior door, the second stairway is "open" to the first floor. We have been in a drought all summer, so she doesn't know if the basement gets water or not. The only evidence of water is from a basement window.She has been told that the fireplace chimney has been sealed. There are several spalled bricks in the top foot or so of the chimney. Not clear if the spalling was before or after the sealing. Going to try and find out.There is a separate chimney for the furnace.The customer called me wanting to put in new windows. The existing windows are sound, needing just a bit of work here and there, and the top sashes have four lites, each full height, a detail that I bet would be expensive to reproduce. So I suggested storms instead of new windows. Some windows have storms.There is also a marvelous enclosed porch on the east side of the house. Concrete floor, brick walls, fully under the roof, LOTS of screens. She wants to put real windows in place of the screens (not the storm windows, Anderson casements).Rich Beckman
*Dear Rich,Often I find myself speaking to a potential client who will ask about a specific renovation measure. It could be a new roof or insulation or new windows. After they tell me what they want, I invariably ask them why they want it. About half the time, this begins a discussion leading to the conclusion that they really don't want the original thing. With new homeowners, the process is more difficult because they bring so few facts. So as a renovator, I've learned to test and observe the buildings themselves to make up for the lack of occupant participation.In your case, I would want to know what the client expects to receive from the storm windows in terms of tangible benefits. And then, since she can't provide clues about the building behavior, I would stress the building to learn about how it behaves in extreme weather. From that information, you can pick the right model or do something else to create some real value and give her a fair deal.Fairly, Fred
*Fred,At the time I wasn't aware that the storm window choice was so complicated. She wanted new windows because she wants to be warm in the winter and her eighty year old single pane windows, although beautiful, didn't look very warm to her (or to me either). From months of reading this board, I understand that new windows are expensive and often fail to ever pay for themselves in reduced energy usage, so I suggested storms. At the lumberyard, I was assuming that the weather tight storm was the better choice until the guy told me otherwise. So I came here to ask if he was right. Up until your response above (#4), I assumed that most of your usual concerns required fixing the ducts, sealing the attic floor, etc. I don't recall the storm choice ever being a factor. So I didn't know. But even above you seem to imply that the other fixes are better and that the choice of storm wouldn't be relevent if the other fixes are made.>From that information, you can pick the right model or do something else to create some real value and give her a fair deal. "Do something else..." Are you implying that the storms might actually be a complete waste of money? With all the threads on replacement and new windows in the past eight months and the number of times that storms have been recommended over new windows, why has this never come up? This I don't understand.Rich Beckman
*One of the most important revelations for me that I've gleaned form this forum is building envelope performance. In the past, the typical response has always been to treat the symptoms instead of killing the virus.The awareness I now have in basement/crawl space/duct performance, etc, is much greater than it previously was. Fix the envelope and often times issues with interior climate discomfort are reduced or eliminated. I don't do much reno work, mostly all new construction.I'm still absorbing info on these topics. For me, they're probably the biggest change in how I do business.Example: Last year my sister was going to replace all her windows with replacement windows due to condensation and winter chills. Her cost estimates were astronomical. With the exception of being taken by a ripoff artist I normally wouldn't have been too concerned. However, I flew over to see her and did a little house inspection. We did some work in the basement, tightened up the duct work, did a little foam/caulk work. She rode out the next winter with no condensation on the windows and with a slightly lower fuel use bill. The exterior look of the house wasn't compromised by ill-blended replacements, and she avoided the possibility of paying good money for bad work and inferior merchandise.If you can't or the owner isn't willing to treat the problems, I think "tight" stroms would do more damage than good. With moisture-laden vapor passing through the interior windows and condensing on the storm, no weep holes would equate to future rot problems.Now, Fred et al are a heckuva lot more knowledgeable about these subjects than I, but I thought I'd toss out one case where I saved my big sis a stash of cash and gave her a "better performing" home for a few dollars in materials and a bit of time. Forever learning, Mongo
*First, thank-you to Jim, Steve, Mongo, Andrew, and esp. Fred. I appreciate the time it takes to type these posts. OK. It does sound like the tight storms would be the wrong choice (and more expensive too!). But now my question is: Given that the existing windows are single pane, is it possible that buying storm windows might be a complete waste (or almost so)? If the forced air is all balanced, and the attic floor is sealed, and moisture from the basement dealt with as much as possible...are the storms completely superfluous?Inquiring minds want to know!Rich Beckman
*Rich, I'm wondering if REPLACEMENT SASHES might be a part of the overall program for this house. After addressing the major items Fred has mentioned, you might find that replacement window sashes, which include new jamb liners, would preserve the architectural integrity of the building, and provide the draft-free/insulated glass features which would match that of the storm windows. Among others, Caradco and Marvin offer replacement sash kits. Caradco, at least, can provide "simulated divided lites" which are very realistic, and are available in aluminum cladding. These kits are easily installed, and won't cheapen the house like vinyl replacement window 'boxes". You will, however, want to make sure the existing jambs and sills are in good shape.What part of Indiana are you in?Ex-Hoosier, currently bracing for Hurricane Floyd, Steve
*Steve, Rich, I'll tell you what I did several years ago on my old lakehouse up in Wisco...The place has great windows. Terrific muntin arrangement, etc. The glass is gorgeous, slightly wavey due to age. As far as thermal performance, the windows rattled in the sashes, the sashes rattled in the jambs, the windows were noticeably breezy on Wisco winter nights. Some rotted wood on the edges of the sashes as well.The price to replicate the sashes was phenomenal, plus I would have lost the attraction of the old glass. Having a shop build new sashes and using the old glass was too pricey as well.I contacted a Marvin rep and ended up buying the jamb liners off them. They also sold me the small metal clips that are on the sash sides of Marvin windows. They were hesitant, I was persistent. The clips mate into the jamb liners. I ended up ripping about 3/4 to 1" off three edges of all the damaged sashes. I then added about the same thickness of new wood, adjusted for the jamb liners. I milled the sides to mate in the liners and tried the fit. It took a few tries to get the correct offset, but finally got it to fit. I then used that "offset" to add wood to make all the other windows the proper width.Scraped to thickness, is was a nice match. I milled the sides of the sashes for the "marvin groove" that would mate with the jamb liners, then attached the metal clips. Primed, painted, and popped them in.The "new" old windows were tight. Helped the house so much. It was a bit of work, but I essentially preserved the old sashes, the old glass, and with the exception of my labor I only had to purchase the jamb liners, clips, and wood to add to the sashes. This still left me with single-pane windows, but my major concern was not losing the architectural detailing of the old windows and the charm of the glass.May not be practical in your application, but thought I'd toss another log on the fire...Mongo
*I'm in Marion, halfway between Indianapolis and Fort Wayne.Rich Beckman
*I looked at Marvin tilt-in replacement sashes and nixed them because a full window, flat casing amd all, was literally only $35 more. Also, they reduce the glass area a couple of inches in each dimension and must be customized to whatever (probably inadequate) sill angle the original frame has. They don't address sill/jamb water leakage and other old-window defects, but do get rid of those (*&^%(^ counterweights.The big difference is labor -- you can put the sashes is for maybe $50 vs. maybe $300 for a full window. I was DIY, so... The Marvin jamb liners are nice and tough, as Mongo relates; he was clever to think of adapting them to existing sash. Of course, this is again the high-labor approach.Marvin has true divided light windows, which look oh-so-much-more-real than the clip-ons, and significantly better that the glue-ons. They also offer cheap "energy pane" storm window panels that clip within each sash -- subtle and useful year-round.From a strictly frugal point of view, I'd look at the diddling with rest of the house and spend a relatively small amount of time weatherstripped a few of the windows. If they can't be weatherstripped to satisfaction, talk replacement or storms. The storms do give you an extra "R" or two, and they do keep some of the winter rainwater away from the sill. But they then trap water & condensation when (not if) the weep holes clog, they are ugly, limits use of the window and quickly going out of style. They would be my last choice with the better alternatives out there. If the customer WANTS to reason the problem through, she can spend less money, get more, AND give you a better profit (more labor, less materials).We've been Floyd'ed in D.C., not too bad. Now, what about Gert?
*Rich, I was born and raised in Muncie. Not a Bearcat ... went to Burris (Lab school at BSU). Marion always was a nice place, and hope you're happy there. Now living in Williamsburg VA, having just experienced 17 inches of rain, with 1/3 the local population without power and most of those withhout phones. Most utilities are now functioning. Saw several utility trucks from Toledo Edison (Toledo, Ohio)! Seriously! I talked to some of the guys and thanked them for their efforts. Imagine, coming all the way from Toledo to Virginia to help restore our power ... I'll bet there's similar stories from all along the Carolinas and up through the Delmarva peninsula.Steve
*Mongo: What an elegant way to save those beautiful old sashes! I routinely replace old beat-up aluminum jamb liners or broken vinly ones with new vinyl units when we retain sashes during remodeling. I get them in two profiles from our (true) building supply house. I'm gonna keep your solution in mind for some of those older homes.Regards, Steve
*Steve,Sure, I am happy here, but the city of Marion doesn't have much to do with it. I live out in the county with an incredible woman as my wife. THAT is why I am happy.Williamsburg...I always say I am not ready for Williamsburg, but I think it goes over the head of a lot of people.Rich Beckman
*In response to the appearance issue, I'm removing all the old and falling apart triple tracks and replacing with Marvin Wood Combination Storms. Appearance is close to original wood storms and screens but have convenience of self storing the bottom storm panel. According to Marvin data - single pane sash with these storms is slightly better r-value than double pane.
*i ". . . single pane sash with these storms is slightly better r-value than double pane."I think that's actually universal data. I had a chart that I've been trying to find that gave the R value for single, thermo, triple thermo, and single with storm, and single with storm was even slightly better that triple thermo. . . regrettably we're still talking about fairly negligible R values when compared to wall and roof insul. -pm
*Welcome back, Bill. Good to see your name back on the screen.
*It seems that Bill HAS a life. Sigh.
*Bill, Andrew, et al,Any thoughts on single-pane prime coupled with double-pane storms? Seems to me you would get the higher R associated with the greater space between prime and storm, plus you would get less chance of condensation on the storm, even with a loose prime window, because of the warmer inner pane of the double-pane storm.I was thinking of making something with 1 over 1 double-panes that had a removable lower glazing that could be replaced with a screen come summer.Steve
*I doubt it would get you a whole lot of benefit for the trouble. The double-glazing is expensive and heavy. Also, the higher R between the storm and window is only a hair higher -- there's that 3/4" max air gap where the benefits taper off. A really good sealing job on the primary window would be the best thing. I've been so happy to throw away our old finger-crunching triple-track storms for double-glazed double-hungs (can I call those DGDH for short?).I forget your latitude -- you're not in an extreme climate are you?
*Steve - I think if you pay yourself anything greater than $2.50/hour those 1/1 double glazed storms will never pay back. Buy the Marvins or similar by Midwest - mine were $75-80 per window.
*...and, if you can find enough things wrong with the window (such as being nothing-special, leaky, lead paint encrusted, counterweights broken -- I had all there) replace a few with new units for another $200 each. I really really love the new unit -- it is bigger and just plain nicer than the old. It works right, there are no dings from the sash lock, there's no storm to struggle with, you can use both sash, etc. Oh yeah, it maybe saves energy, too. :)
*Hi Bill and Andrew,Bill, yes I know that building them myself is not worth the time. I was thinking of buying Midwest's product with the single-glazed removable storm insert and making the rabbet deep enough to take a double glazed section.Part of my problem is that my primes are pretty leaky, but I want to preserve them.Andrew, as a restoration carpenter and lover of patina, I can't bring myself to ditch the circa 1865 6 over 6 sash with old wavy glass. I've spent many hours reconditioning them, but they are still going to be leaky because the design is such that it is nearly impossible to get a good seal at the meeting rails. That's why I'm thinking of going with double-glazed storms, essenially making my prime sash large decorative.Steve
*Yeah, your sash don't meet the "nothing-special" criterion. Ours do. It's a shame to hide nice windows behind storms. The Marvin "Combination Window" doesn't look so bad. Mongo's approach is interesting -- the Marvin jamb liners do seem to work well.The meeting rail can't be sealed with bronze V-strip or equiv.? It seems they have a weatherstripping product for every conceivable application. I'm thinking of Resource Conservation Int'l in Baltimore -- EPDM galore. Air leakage is a much bigger source of cold than R-value...
*Hi Andrew,The problem with the meeting rails is that they dont stand off from the window enough. I tried a v-strip, but it hangs up on the other sash when they glide against each other. The parting strip is 3/8 inch.Maybe an epdm strip down low on the meeting rail would work. I have to monkey with em some more.Steve