Tyvek Under 1/4in Foam For Vinyl Siding?

Tom Struble

if you tyvek first how do you cut your foam to fit tite without cutting the tyvek?

Grumpy

Cut it away from the wall?

easy sider

Vinyl siding must be applied over a rigid sheathing that provides a smooth flat surface or an underlayment (such as wood. wood composition, rigid foam or fiber sheathing ) that is no more than 1 inch thick.

Vinyl siding is an exterior clading, it is not a complete weather resistant barrier. Before applying siding, make certain the substrate is watertight.

V.S.I.
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T-yvek and most other modern T-Vek type barriers are not water tight barriers. Felt is a water tight barrier and can be used as a weather barrier with foam sheathing over the top.

House wraps are far more convienent to use than felt and are meant to controll air infiltration and while it does provide some water protection, house wraps are not water tight. The foam sheathing would be applied over the house wrap with any wood or composite types of siding.

In some areas of the United States, solid foam sheathing should not be used as it can cause moisture problems in the wall. Foam under-layment with air holes should be used in locations of high humidity.

Tom Struble

this is from the tyvek web site number 18 suggest over foam

15. Can I tape sheathing board seams?
Taping sheathing board seams creates a continuous vapor barrier, so moisture vapor would have no where to escape. Adhesion of tape to foam and wood would also be temporary, due to thermal expansion and contraction of the wall assembly. A more effective and efficient means to provide air infiltration resistance and bulk water holdout is to properly install DuPont™ Tyvek® using our best practice guidelines. Since DuPont™ Tyvek® flexible, it will continue to provide protection to the sheathing when undergoing thermal expansion and contraction.
16. Doesn’t housewrap make a house too tight?
With more energy efficient construction, “building tight; ventilating right” is the best practice. Mechanical ventilation is more important with today’s sophisticated energy saving home features. However, blower door testing on homes wrapped with DuPont™ Tyvek® show natural air exchange rates per hour that are well within acceptable guidelines per ASHRAE Standard 62.
17. Why should I tape seams in the DuPont™ Tyvek®?
Taping the seams with DuPont™ Tyvek® Tape gives you the best Tyvek®-to-Tyvek® adhesion, optimal protection against air and bulk water penetration, and extra durability protection during the building’s construction phase.
18. Is DuPont™ Tyvek® necessary over foam board?
DuPont™ Tyvek® adds considerable protection against leaky seams in foam board, similar to the protection provided over wood sheathing. Foam boards alone, even interlocking foam boards, do not adequately stop air leakage due to wall movement from settling and thermal expansion and contraction.

i dont know how everybody eles cuts and installs foam but to get the tightest fit I usually cut it on the wall

Grumpy

That's the exact reason we tried it, and just didn't like it.

TTR

Go to buildingscience.com

There are many articles that will answer many of your questions and provided cases specific to different parts of the country.

kansas-builder

What you are trying to build is called a rain wall - and it is a good idea and should be required in my opinion.
#4 below is my method.

I am using "tyvek" as a name for any sort of wrap and "tyvek-drain" as a product or technique (vertical pvc bats attached to studs outside foam) that allows vertical water flow between layers.


1) Stud, tyvek, foam, tyvek-drain, window, siding
2a) Stud, tyvek, OSB, tyvek-drain, window, siding
2b) Stud, OSB, tyvek, tyvek-drain, window, siding
3) Stud, tyvek, OSB, foam, tyvek-drain, window, siding or
4) Stud, OSB, tyvek, foam, tyvek-drain, window, siding

Since I build walls with them laying down on the deck #4 is pretty easy.
Putting the tyvek on top of the OSB minimizes damage until foam is placed.
The thermal break from the foam and the extra moisture protection is easily worth the extra work and $$s. I can't guarantee water will never damage any of my houses but I sure want to come look if it does.

JMD Home Repair

I like all the information that has been shared. I still have a question, though. When doing a remodel and putting up wrap and foam board what do you do around the windows? You have increased the thickness of the wall relative to brick moulding and then the J-channel sticks out beyond the brick mould. I want to remove old brick mould and put on new PVC style brick mould, This takes care of more maintenance up keep.

CharlesD

I'm not following exactly what the discussion is about.
Are you all discussing tyvek over foam sheeting like is used on a new wall instead of OSB or plywood or foam over an existing wood sided wall as in a reside job?
I think #18 above is talking about using Tyvek over foam in new construction, not resides.

LetItBeLEED

Re Grumpy's post #6, somewhere or other I read that the thermal benefit of 1/4" foam board was achieved primarily by reducing air leakage and by providing a thermal break, and not its (trivial) Rvalue.

(I read it, so it must be true)

Steve

Tom Struble

my feeling on this and i know it can get complicated sometime is i like to consider any foam underlayment as a ''sheathing extenstion'' and the windows should be packed out the foam thickness then the wrb installed,
I realize its hard to do this unless your changing out the windows and it usually requires an extension on the jambs but I feel it puts the drainage plane in the proper place

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Tom

mattp

They should make and insulation board with tapered edges. So you can overlap the top and bottom then tape the seams, instead of butting them tight together. Or do they already?

Tom Struble

some have a shiplap some have a t&g

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Tom

Tom Struble

saw the pics of your jobs i for one wasn't that impressed i don't think you have any standing saying who should or shouldn't be doing siding

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Tom

Tom Struble

im talking more about you than your reports

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Tom

Tom Struble

for sure im just a lowly stupid siding guy

thankyou Mr.Scientist

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Tom

loneframer

If vinyl drains all of the moisture then why is this house wrap all wrinkled from the moisture?
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I don't have alot of experience with Tyvek because I was extremely dissappointed in it 20 years or so ago. That is neither here nor there. If Tyvek is not Hygroexpansive, why would it wrinkle from moisture? That being said, wouldn't the wrinkles in theory provide the drainage plane you tout to be so important? I'm not being argumentative, I'm being inquisitive.

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nEighter

spoke with a H/O tonight that just had his house Vinyled 2 yrs ago. They didn't use tyvek on it. And from the jobs I have seen around here, no tyvek is used. Just puttting the foam right over whatever sheeting is there and away they go.

nEighter

had a tyvek rep come out to a house we were framing YEARS ago. It was a cold morning and he had a styrofoam cup of coffee. He put the tyvek word side down on the coffee.. nothing happened. He turned it around (words facing up) and the steam was coming through it.. probably has nothing to do with this discussion but thought I would share

loneframer

Lets talk moisture management after you all read the report. Give me your honest feedback about it.[/quote]
I read the report. Reminded me of Ross Perots run for president.
Let's face it, every type of siding and every type of moisture barrier has pros and cons. One will do well in one test, another in a different test. I know that moisture will form on the backside of vinyl even if it hasn't rained. I've seen it. I know that the sun can drive that moisture through the moisture barrier into the wall assembly. Once the moisture is there, it needs to get back out. That is the primary reason I prefer #30 asphalt saturated felt. You can plead your case for your rain wall or whatever you want to call it, but I will stick to what I have had excellent results with, until it proves to be defective. As for moisture management, proper flashing details and attention to detail have proven effective for me. Water will obviously gain entry at windows, corners, roof intersections and siding laps. Good flashing details will force that water away from the wall. That is what I refer to as "My Best Practices."

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"Walking the fine line between production and perfection"



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