How to properly seal the exterior of your house with rigid foam?
 

This weekend I'll be doing a lot of work on my office remodel. I'm removing a door from an exterior wall, adding two windows in it, and will shortly after be adding cellulose insulation.

However, my question is about the exterior and how to properly seal it. The exterior sheathing on my house is wood planks. The wood plans are covered by 1/2" polystryrene XPS insulation, and then I have vinyl siding over that. I'm going to be removing the vinyl siding to install the windows and remove the door. Once things are all in place, what needs to be done to seal that XPS so that it seals the wall?

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You have to make sure it's all really air tight.

Well, this is what I have to work with. I removed the siding off the wall that I'll be working on. Some of the seams are taped with a dull grey tape that seems to still be holding well, some are taped with duct tape (some of which is falling off), and other seams are not taped at all.

Suggestions?

http://ecorenovator.org/forum/attach...1&d=1350736846


This gap is at least 1/4". I can see the boards behind the foam.
http://ecorenovator.org/forum/attach...1&d=1350736846


On the right side here you can see the dull grey tape I mentioned above. It still appears stuck quite well.
http://ecorenovator.org/forum/attach...1&d=1350736846

Foam the gaps and use a 3M tape. I forget the name. I'll get back to you on it. The problem is going to be attaching the siding. Every nail through the foam will compromise it. I'd use furring strips.

How does that work though? The furring strips need to be nailed to the studs. (Sorry, haven't had time yet to read all of the articles you posted.)

You screw then to the studs through the foam with a screw with a completely flat head that can handle the weight of the siding, foam and furring. HeadLOK® Heavy Duty Flathead Fastener - FastenMaster
This way you minimize the penetrations. You could also run a bead of foam under the strapping so the screw will pull the foam through as it goes in. It's really a conundrum.
Apparently SimpsonStrongTie is making a competitor but I haven't seen them in the lumber yards yet.

EDIT:

It's 3M 8067. You should be able to get it anywhere.

How do you seal the edges of say my bottom foam piece?

Good question. Bring the foam down below the sil an foam/tape it. There's no way these tapes and spray foams will last 100 years so I usually try to find more robust methods. Unfortunately we're dealing with foam here so tape is probably what to use. One of the reasons people use foil faced foam is that you can tale it with foil tape and it lasts a long time.

I taped most of the exposed area yesterday. There is a lot more to do...

So, I think I found a summer project. I garuentee that the whole house is missing tape completely with large gaps around the foam, or taped with duct tape... I know it will be a pain, but removing all the siding and taping everything sounds like it would REALLY help my sealing effort (which is a big problem in my old leaky house).

Up here the product you want is called tuck tape. It's red.
Amazon.com: tuck tape
It's ultra sticky and doesn't really let go unless it gets very hot or wet. I used some to patch leaks in my kids slip and slide hose over the summer. It held up to the pressure for a couple of months.