Vapor Barriers

[Kri]

I know code says one thing, but more and more I hear about those whom have installed vapor barriers as per instructions, only to experience water collection, damage, etc.  This means they've had to tear things out and start over down the line.  Any thoughts?  Recommendations?  Words of wisdom?

[glenn kangiser]

If you are talking about house wrap, the safest to use is old reliable felt, made even better if you add a rain screen wall.

[Okie_Bob]

Kri, you got it from the expert. Trust Glenn on this, he is 100% right on....as usual.
Okie Bob

[glenn kangiser]

Aw shucks, BoB

[Kri]

Thanks.  Gotcha!  What are your thoughts about adding a rain screen wall if one is using felt and building with all solid older growth/kiln dried wood?

[glenn kangiser]

It will make it that much better and last that much longer.  The space between the felt and the siding allows drainage immediately not allowing capillary action to hold moisture in there for days or weeks at a time.  Rain hits- drains and drying is started. 

Contact with especially house wraps - rain hits - is held between the siding and the house wrap by capillary action - goes out through the siding -- drains into the wall cavity through any penetration - stays in the cavity as solid water and rots or molds.  Felt will wick it out of the cavity - house wrap holds it untill it can escape as vapor -- long wet winter?   Could be next summer before it is gone - unless you drill a hole through that bubbling moldy paint on your sheetrock.

Doesn't always happen that way but if preventing it only took 3/8 or more spacers wouldn't it be worth it?

[Kri]

Oh wow.  Great info.  I get it now.  Thanks.  You guys are so terrific at this building education stuff!!!

[ScottA]

Damn, that was a good explination glenn. You should be teaching this stuff.   

[glenn kangiser]

Wow -- good idea, Scott.   What's it pay? hmm

Oh well -- I'll just remain poor and give the info away free if it helps motivated people to beat their little part of the system. 

[Kri]

This process certainly does make one want to pay it forward, if only by emphasizing the importance of managing ones own budget throughout the process.  Or to understand what, exactly, is happening and why and how, so at least there is some awareness.  It seems with any (agonizing) step I encounter, it ultimately teaches a great lesson.  Even if it's how to ((not)) do that step next time!!  All of this seemed so much easier as a child...when all I had to do was haul, pound and assemble as per someone's shouted orders.  I really should have taken photos and notes back then, too...

[glenn kangiser]

Learn it well then teach a kid who is asking questions.

That always frustrated me when I couldn't get an explanation or serious answer.  Maybe the adult I was asking didn't know what he was doing well enough to answer - probably didn't want to be or have time to be bothered.

[Kri]

Well said!