Proper way to install new windows

I am going to install new construction windows in my home. they are double hung andersen 400 series tiltwash. I have talked to some contractors and they told that they would cut closely around the windows and not disturb the siding and replace the existing window and then use caulk to seal the windows without using the storm flaps. my idea was to cut a 2 or 2 1 /4 channel around the old windows and replace the windows with the storm flaps to stop air infiltration and put brick mould around the windows.. which method do you think is the best for protectiion against air infiltration and asthetics? thanks for any help.

frankk

 

It would have helped to tell us what the siding is, but you definitely do not want to cut the nailing fins off. Cut the siding back and install brickmould or similar. I have found that cutting twice gives the best results. First, cut back about 1 1/2"... enough to get the window to fit. Then once you have it plumbed up, shimmed in and set where it is finally going to go, the measure 2 1/8" away from the window and cut it again. Be sure you put a drip cap (z-flashing) over the top piece of trim.

With the tilt wash windows, it is incredibly important that the windows do not get spread or twisted on the sides (at the center where the sashes meet) so you will want to measure the sides for parallel on both the inside and out, and shim according to the mfg's instructions.

 

the siding is steel and I thought the idea you suggested to be correct but was just checking. thanks for the additional information as to how to cut the siding. thanks again the installation instructions say 1/8 inch parallell and it also says to use low expansion foam. what do you think of that for on the bottom of the window or would you use regular fiberglass insulation?

 

There called nailing fins, not storm flaps.
Cut them off and those windows are going to leak and there's nothing left to attach the window to the wall, I've seen it way to many times.
I never use fiberglass to fill the gaps, compressed insulation has little R value.

 

what product do you use to fill the gaps? type, brand name anything to point me in the right direction. just trying to get this done right, I am not trying to pester you. thanks

frank

 

Great stuff door and window foam is one brand. Blue can, not red can. DAP latex is another... completely different kind of foam though. Its more expensive and is better in tight gaps (around 1/4"). Great stuff is best in larger gaps.

When you cut that steel siding, a 1/16" metal blade in an angle grinder works best. You will want to slip a little housewrap behind the siding where your blade scores the house. And you will need to slip a siding j-channel around the siding after you make your final cut too.

 

Funny, I am in the same situation as Frank, 12 New Construction windows (Andersen Woodwrights) to be installed in my 1996 House. The House has existing vinyl siding and my contractor said basically the same thing:

"We will pop off the existing brick molding, remove the old windows, then install the new window, flash it, trim it & caulk it WITHOUT disturbing/removing the existing J-channel / vinyl siding. If we have to peel back the siding then it will take more time" (Which means more money to install the windows)

My thought to myself was, if he does that how can he get a good seal when installing the flashing tape OVER the nailing fin???

He wanted me to measure the inside distance between the J-channels and he said if need be he will cut the nailing fin to fit... (cut meaning trim it not remove it completely from window)

But after reading this post - I like XSleeper's Post#2. If needed have him cut the siding, install the window, cut the siding again. Re-install J-Channel and then trim out the window.

I like this method as I feel that it will also give the Contractor a better surface to use the flashing tape on.

Your thoughts?

 

When we install windows where there is vinyl siding it all comes down to a point where we can work without being slapped in the face with the siding. It is easy to unzip and remove from the nail heads. Leave the nails in the underlayment so you will have a pre prescribed place to put them back and keep them level. I number all the pieces according to the run they are in from left to right so I can put them back in the right order.

Once your windows are installed, flashed and taped, you can install your siding into the built in j channel, cutting it as necessary for a good fit.

 

I think with vinyl removing the siding would be something to think about , but with steel everyone I talk to says it will get ruined in the removal. I have not started with my windows yet as I live in Iowa and am waiting for the weather to straighten out. but his no.2 post got me going in the right direction.

 

Sorry frank, my response was to the poster just prior to mine who had vinyl siding. Yeah, I agree the metal siding would leave no avenue for removal, so follow what XSleeper is advising.

 

well I installed the windows, cut around them with a .040 steel cutting blade and used ice and water barrier around the old frame work to protect from moisture. used silicone caulk under the nail fins and then nailed it, trimmed it out with vinyl brick mold it turned out nice, I am happy with it. now I am on the inside of the house and starting to finish the windows and am questioning the old foam or fiberglass question? the top has about a 3/4 inch gap, sides 1/4 inch on one side flush on the other, the bottom has a pretty good gap of various sizes. what do you suggest? I bought a can of the blue low expansion foam and was reading it. it seems pretty straight forward. if it was you what would you use and for what reason. is there any chance the foam could bow the jambs? thanks

frank

 

Use foam, not fiberglas. Fiberglas can't be compressed and afford insulation. The Dap product is water soluable, but can be finicky to apply. Low expansion foam is preferred/required for windows to keep the frames from warping. The can will say "low expansion" or words to that effect.

 

I used the great stuff low expansion foam and it worked out great. will be using it again in future projects. thanks to all you guys for you help and suggestions. thanks again.

frank