Trapping Moisture With House Wraps And Vinyl.

GiantScale

After doing a bit of research about different house wraps, Im a bit concerned with my plans and my 70's existing wall system. I have poly under my drywall. And when I install typar or tyvek before my vinyl, Will I trap moist Iowa air inside my wall?

I do plan on installing a rain screen of some sort (home slicker or vertical furring strips) to keep the vinyl off the house about 1/4". But Im tempted to omit the house wrap since my old T-111 is painted. Any advice?

RJS

House wrap is designed to allow moisture out...dont think that would be a problem.
R

GiantScale

After talking to a local inspector it turns out poly on the inside warm side is still required by code here in iowa. So Im not alone. I just hope my paint problem was due only to UV.

Looks like tyvek has the highest perm rate. I think I might try plastic mesh used by E.I.F.S. installers on first. Then tyvek, furring then vinyl siding and hope that the wall can breath enough.

Grumpy

House wrap is designed to be a one way vapor barrier. If you were to make a bowl of the house wrap and fill it with water, one way it would allow very little water to pass though. Turn it over and the water will freely flow through. DOn't ask me how the genuises though it up but it works.

Compare it to your own skin. It keeps the water out but allows perspiration to exit.

I always compare features of the house to the human body because so many people just can't understand building concepts but do understand their own bodies.

red_cedar

Actually a persons skin is very porus and does absorb alot of moisture...
keep your hands in water and watch them wrinkle up from moisture absorbtion

But your point was understood

TimNJ

[QUOTE=GiantScale]After talking to a local inspector it turns out poly on the inside warm side is still required by code here in iowa. So Im not alone. I just hope my paint problem was due only to UV.

If you have a lot of strong southern or southwestern exposure that would kill the paint. I have T&G cedar on my house and the clerestory area with southern exposure gets KILLED by the sun. I use Benjamin-Moore stain and it still can't take it. All the other walls exposure...no problem.

747

I don't understand. My house was just vinyl sided 9 months ago. They took all the old clapboards off installed tyvek than vinyl sided over the tyvek. I ask the GC about doing it the other way meaning the insulating panels over the existing clapboards than vinyl over that. He said i don't like the way that looks because the vinyl will be flush or over the windows alittle bit. I didn't understand what he ment at the time. Then i looked at my neighbors house and i see exactly what he ment. My house looks better because all of the windows are sticking out pass the vinyl. What is T-111 clapboards i'm assuming i have never heard of that before. I also don't understand the purpose of putting furring strips to keep vinyl off of house. Somebody explain. Its my understanding the Gc who did my vinyl did it the best way.

TimNJ

T-111 is plywood used for siding. it has vertical grooves cut in it. 747, your siders went through a lot of extra work to strip off the old siding, but you answered your own question, because you say your house looks better than your neighbors siding job. :Thumbs:

Tom R

I never, ever leave the window casings in deeper than the 'plane' of the siding, - - it doesn't take but a few minutes to fur out the casings, - - and leaving the window casings 'inset' not only looks cheap as hell, - - it creates an unwanted 'water-catch'.

__________________
http://www.tr-built.com

747

That is exactly the way my neighbors house looks. If you look at the windows on his garage they look suken in compared to my windows. I seen this other house was being vinyl sided when i was home. He had windows on his house that looked the same way. My guy wasn't a vinyl man he was a do it all carpenter. :Thumbs:

TimNJ

Yeah that really burns me up when I have to yank out a capped door or window and they just lay the coil over the old siding and then put their J- channel over the coil and run the new siding over the coil

housedocs

well said I totally agree

__________________
"All you need in this life is ignorance and confidence, and then success is sure". -Mark Twain

mighty anvil

The underlayment (Tyvek or building paper) should go directly over the sheathing (T1-11 in this case), then install either mesh or vertical strapping (but not both). The mesh or the strapping will create a "drainage plane" so that any moisture that penetrates the siding can drop and exit the wall at the bottom. I'm not sure the drainage plane is really necessary with vinyl siding (like it is with wood siding) but it can't hurt. You might consider Dupont's StuccoWrap because it is essentially wrinkled Tyvek and acts as an underlayment and as a drainage plane.

The underlayments mentioned above are vapor permeable and will not act as vapor barriers.