question for guy re insulation around windows

16 years ago

I am in the process of having siding and windows replaced. After looking at several brands and types we decided to go with Marvin Integrity after the lumber yard guy told us they could fit our windows but that the middle stile between the 2 casement sections would be enlarged to make them fit properly. He came out twice to measure and stated that twice. Great, because we really preferred intgrety to vinyl and the regular Marvins were too expensive for this modest lakehouse.

Fast forward to installation. The windows are smaller than the opening left by the older windows because, surprise, surprise,there was no wider stile. Guess we should have asked more questions after the company that we used previously(very good and hoped to use again) told us Integrity wouldn't work in that app. Apparently they know more than the guy who is supposed to know!

But my question is about filling the gaps. The contractor seems very careful and has cut wood to size up the opening. Careful about leveling and flashing around the windows and tyvek. But he is using fiberglass to stuff the remaining cracks rather than nonexpanding foam. When I asked about that he stated you never want to use expanding foam and although he has used the other type, he feels fiberglass will do a good job without potential problems of getting the window out of shape. I wonder about the small gaps that have no builder board( where there will be only fiberglass, then tyvek, then hardiplank). Am I going to have cold spots or moisture? Is his approach ok? I know there is not always just one acceptable installation method so would like your input.

Darn, I'm miffed because not only do I have that issue ,but will have to do some repainting and deal with drywall dust where the contractor has to patch. (I will request free paint from the building supply center--that seems the least they can do).

Thanks

Sort by:Oldest

Comment (1)

guy_exterior_man
16 years ago
last modified: 9 years ago
mnzinnia, I'm a bit baffled at Marvin making a window smaller than what you needed for your opening. Marvin has always been really good at making windows to the specs we require. The only time they can't meet these needs is when we push the over-sized units. Otherwise they've always come within a fraction of an inch of what we need. In your case the person that measured told you the "vertical style", or the proper term being the "Center Mullion or MULL", would be spread to fit. This is a very common practice in the industry used everywhere. We call it a "Spread Mull" when we order a product needing a special sizing. We use it when ordering custom sized doors with side-lights all the time.

If your windows didn't come with the spread mull done properly your installer should have sent them back to be done to the right size. We would have never installed these windows if they were to small unless the customer gave us the go ahead to downsize the opening. One thing I've seen lately are the outstate contractors still do things the old school way. Their continuing education on the changes in our installation practices always seems to be light years behind. One thing the installer has to be aware of is the new building codes from 2006 have specifically stated that the manufacturers installation instructions for windows and doors become code. This means every installer must know and understand the application instructions of each product they install or they will void the manufacturers warranty. In your case there's no problem because Marvin's insructions only state that "If You Desire" you can use a low-expansion foam sealant around their window next to the nailing fin. In todays practice we are using a low-expansion foam all the time during our installations. We have also been using the stuff in fiberglass combined with the low expansion foam. We spray the foam in first against the nail fin and then use the stuff in fiberglass behind the foam. The main reason being it stops the expanding foam from oozing out of the opening and making a mess. The use of low-expansion foam properly will eliminate any "Air Infiltration" from around the window. Fiberglass insulation is really made to be most effective at it's expanded 3-1/2" or more. When the fiberglass is compacted around a window in that tiny gap it's air infiltration impedance is nothing. So any air leaking in past the nail fin will find it's way into the home. The low expansion foam forms a barrier that stops air infiltration from entering the home. It will fill the little voids and cracks that the stuff in fiberglass won't. The positive feature of low-expansion foam is it stops water from entering the cavity. If water happens to get past the exterior barriers the foam will act as a watershed and keep the water from penetrating. The stuffed in fiberglass will soak the water up like a sponge and start to break down or sink in the cavity it's suppose to protect. When this happens you get an opening to possible mold & mildew issues that I'm not even going to think about getting into.

Just to make you feel a little better about things and I don't send you into a panic attack. The worst case scenario of leaking water and air threatening your lake home is very small. Since it sounds like your completely overhauling the exterior of the lake home you have a couple barriers that will more than likely stop anything before it gets to the window cavity. You've already told me the home was wrapped with Tyvek and flashing was done around the outside of the windows. Hopefully the installers used a nail-fin application that was back caulked before anchoring. If all these items were done properly and drip caps were installed above each window with the Hardiplank siding finishing it off. Your probably going to be just fine. Just make sure all the windows are caulked and sealed to the Hardiplank to form that first coat of armor. In other words I think you'll be just fine and dandy down the road. Sounds to me like your only problem will be that sheetrock dust and touch-up painting. I wish you well in the final moments of your project. Then you can sit back and enjoy the great Summer Minnesota has for us every year!! Good Luck!!!
Related Discussions
Two unusual questions re spray foam insulation
Q
Comments (10)
I don't know why anyone would be spraying foam on the outside of a barn but foam hits a surface as a liquid and then immediately turns into a foam. Very little of the liquid is likely to adhere to the bicycle so the foam would expand from the wall surface outward and begin to envelop the bicycle and it would become firmly adhered to the wall if the foam is thick enough. But that much foam requires multiple passes and would be unlikely to be used for insulation purposes. Open celled foam often has a soft matte surface and closed cell foam has a harder surface with a slight sheen. Foam insulations stick to everything and are very difficult to remove. There are many videos of foam installations on YouTube. Here is a link that might be useful: foam video
...See More
Re-insulating around windows
Q
Comments (4)
Don't bother with removing those additional pieces unless they are covering some large void. Even in that case, you can drill a hole and fill (don't overfill) that section. Shop vac out all the old fiberglass that you can readily get to. The issue is not insulation as much as it is stopping the air (as you noted). That being the case, a small skim layer to seal the envelope would accomplish about 85-90% of the value of the retrofit. Do yourself a favor and get a foam gun. Don't bother with the straw stuff. It is more cumbersome and less controllable. Make sure the can is warm and slightly mist the area that you are going to apply the foam to. These low pressure foam are water based cures. Don't worry about making the substrates super clean. Once you work with the foam, you will quickly realize that it sticks to everything.....trust me. Do not try to fill the larger void in one pass. You will get over expansion and leave yourself with a mess inside, outside, or both. Fill the gaps with multiple passes of the foam if they require a larger fill. Get some disposable tips for the gun and don't remove the can from the gun unless you have another can going on the gun. This will prevent the foam from curing in the gun barrel. Thankfully these guns will still be available after the Executive orders. Good luck.
...See More
Insulate around replacement windows
Q
Comments (10)
You can still feel cold are blowing in around the case molding. I could put some foam between the case molding and the wall, but that would probably just direct the air elsewhere. I wonder if it would be best to have insulation blown into the weight pockets from the outside. The bozos who did the windows left the darn weights in the pockets. In the downstairs we have double windows. I was able to pull the center panel and insulate the weight pockets with rigid foam and seal it up with expanding foam. I wish I didn't have to pull antique molding and cut plaster to get to the weight pockets on the single windows :).
...See More
Question re: insulating cement ceiling of a crawlspace
Q
Comments (6)
You can do what you are thinking but the difference it make's will not be worth the effort. Two things to consider, #1 masonary is a poor conductor which in it's self make's it a pretty good insulator. If one disagree's,just feel the outside of a brick chimmney while a roaring fire send's heat through inside. #2 heat rises,therfore cold settle's below. What that tell's us is that what little heat conduct's through floor will stratify against the ceiling of crawl space ( unless wind blow's through ). Anything blocking wind from crawl space would do more good. I'll wager there are other things you can do around the place that will save more energy.
...See More

question for guy re insulation around windows

Comment (1)

guy_exterior_man

Related Discussions

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US