Hey all. I’m getting ready to reside my house as part of a roof raise. All the existing siding has been stripped and the sheathing is covered with 15# felt. I’m using vinyl siding and want to put extruded foam on the walls first like you would when you reside over old siding to get the added R value. The windows I installed come with an integral j channel which is not deep enough to recieve both the foam and the siding so I’ll be J channeling around the windows with the siding j channel. My only concern is water getting behind the siding and (especially around the windows) getting behind the foam. The foams back is smooth so it would be tight to the tar paper. Is this a real concern or should I not worry about it? If it is a concern, what’s the best remedy other than furring out all the foam?
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We just finished a house 2 weeks ago with your senario. We furred the new windows out by putting strapping under the brick mold. The level wall then butts up to the strapping leaving the J open for the siding. As the level wall is put around the windows we tape using a poduct called blue skin. Real sticky on one side and a vinyl type coating on the outside. There are tons of different brand names out there. I use the blue skin. Similar in use to windows and doors as ice and water shield is to roofing. Seals stuff up tighter than a ducks butt and thats water tight.
Some guys prefer to use it only on the sides and tops and leave the bottom open for any drainage. I'm not one of those guys. I don't like to think my installations are going to need a plan B for anticipated leaks. Done right they will remain water tight.
Works for me and good luck with your job.
Gary
Should add. The tape comes in many different widths..
Edited 8/23/2008 9:49 am ET by hartlandboy
I have a basic problem using extruded foam, I would use expanded foam. I know it has a slightly lower R-value but extruded can be used as a vapour barrier whereas expanded will let the moisture out.
Just my 2 cents,
Bagtown
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I was now thinking of running the foam into the channels of the windows and then, starting at the bottom, running 6 inch wide pieces of aluminum around the windows tight to the windows and let into the foam above the windows. I would caulk this to the window and then run the j channel and siding. Any water that gets around the windows would hit the aluminum and run down staying on top of the foam and harmlessly running down behind the siding and exitting or evaporating. What do u guys think? Also, the tar paper has been on the walls about 1 1/2 months. Is it still effectve as a weather barrier or should I put a second layer over it? Thanks.