WRB both sides of sheathing
Hey all, I was reading this older post about why we caulk between top plates: https://www.greenbuildingadvisor.com/question/why-caulk-between-studs-etc
It made me think about something tuff shed does (mostly because their name is plastered all over the wrb) on their detached garage builds – WRB on both sides of sheathing.
That older post indicated that a decent amount of air leakage gets in behind the studs. I assume this is probably the studs that are on top of a joint in the sheathing, which makes sense. However, if you have another WRB between the sheathing and studs, would it not help to substantially reduce air leakage? Has anyone tried this?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
No idea why they would do that. An interior layer of house-wrap adds nothing useful to the wall. If you want to use the sheathing as your primary air-control layer then you should tape the sheathing, not rely on the WRB for that. If you want to use the WRB, use the WRB.
When they built my garage I specifically asked them not to use it on the inside but they did it anyway. I wonder if I should cut it out?
Most of their buildings never get finished, so by using it on the inside, they get their logo (which is on the wrb) plastered all over the place.
Y0u think it's problematic? I am half way through insulating the building and I haven't been cutting it out.
No, I don’t think it does any harm. I’m just puzzled as to what they think it adds?
I don't see the interior-side layer of WRB doing any harm, since it should be a vapor open material -- housewrap products are intended to block bulk water (like rain), but to allow water vapor to pass through. This would mean that the second WRB isn't a vapor barrier, so it wouldn't be causing problems trapping moisture.
There is no need for the extra layer of WRB though. As Malcolm mentioned, the exterior sheathing can be the air barrier, just tape the seams between panels, and put a bead of sealant on the perimeter framing when you put the sheathing up (I like to use polyurethane sealants for this). Do that and you'll have a good air barrier that is a lot more durable than a layer of any kind of WRB material.
Bill
Bill,
I’m really intrigued by why they do it? It’s sort of like a restaurant owner waking up one day and saying “Let’s put placemats under the tablecloths from now on”.
I'm 99% sure it's done for advertising. By using it on the inside, they can plaster their logo all over the place. Here's an example: https://cassmakeshome.com/my-backyard-tuff-shed/
I guess I'm just not pretty enough for companies to sponsor...
Someone thought "if one is good, two must be better!" Someone told me of a towing company that did that for jump starts -- used two batteries IN SERIES (for 24 volts). I can't see how that would work without frying stuff, but that's what I heard. Crazy stuff.
If you want someone to sponsor you, use pics of your projects. You do beautiful work, I always like seeing the pics of your projects that you post periodically as examples in these forums.
Bill
Bill,
Thanks for the kind words. Jokes aside, the idea of a company wanting to sponsor anyone just makes me feel old.