No tyvek behind siding

Hi, Im a new inspector and could use some advice. Customer just called on a 2001 town home I inspected two weeks ago. She had heard from a neiborhood forum that some of the houses in that neighbor hood did not have any moister barrier behind the siding. She asked me if she should still buy the house if a moister barrior was not present.
I had wrote up a lot of issues with this house because it had been maintained poorly. Several contractors had been to the house to fix variouse things so far.
Furthermore I reported water seeping in on the top of the front door way , where the the front of the house is brick faced. I looked closely at the windows above on the secound floor to see if they had been channeling water Into the wall cavity. I did not see anything . I did not see anything wrong with the vinyl siding on the the back of the house. She said she was going to have a contractor come out and look to see if it had had tyvek. What is my liability if I saw no indications of it not being there? Is that considered a major defect even if no damage has occurred? Wasn’t this passed though building inspection then? It may have not been code at the time?Thanks for any advice, August P.S. I was pretty hard on this house in my report due to the poor maintaince. I’m surprised she went forward with the deal.

We find that often here, likely not required when the home was built.

I use Tyvek wrap… but what good is it when you put all those siding and trim nail holes in it anyway? I really don’t think it is much of a moisture barrier IMHO, but I still use it.

Nick, first of all, Tyvek is not a moisture barrier, it is a (WRB) Weather Resistive Barrier.
It’s primary purpose is to seal the home from the elements and hep preventmoisture from getting inside the exterior envelope of the home.

It is a nonvoven product made of polyethylene fibers and nail holes will not negate it’s function as a barrier, somewhat like a mechanically fastened EPDM roof.

Typically, Tyvek is installed on top of the wall sheathing with seams taped along with any tears to provide a safeguard against air and bulk water infiltration.
The product is not a vapor barrier but in some climates can be used in combination with.


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As mentioned WRB wasn’t required in 2001 by any national building codes, it is now.

But it has always been required by most, if not all, vinyl siding manufactures.
** How do I prepare the structure’s walls?**](

  • Apply a water-resistive barrier, such as house wrap or felt paper.

Thanks Marcel, very informative info as usual bro…



Thanks Marcel. I just can’t imagine what good it could be doing other than making the house look nice for potential buyers prior to siding. After I’m done nailing the siding and trim, the Tyvek underneath must look like Swiss cheese. I can’t say that I get it.

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If the manufacturer and building code say to wrap the house but the wrapping was not installed, then would that be written up as a major defect?

I see no one has really gotten to your original question, which is your possible liability. Could you verify the presence of Tyvek without being intrusive or doing possible damage? Yes, and no. There is a grey area there. It becomes a judgment call that you make, which is exactly what you did.

I have been expert witness in 5 cases involving moisture intrusion and tyvek all except one envolved dry set stone for exterior cladding with just one layer of tyvek and when the wall was open up mold growing galor

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It isn’t a defect. Builders choose to use it or not. You can use felt paper as well. You can also apply a layer of insulation. All choice of the builder and their approach. No siding or damaged siding…defect!

Actually I must disagree Nick as the barrier prevents wind driven moisture and when a nail is sealed it acts as a much smaller hole then if there was no Tyvek.
Surface acts as a shield to prevent moisture against the OSB or Plywood if it is done right.
There is a fair amount of training is this area to get it right and you don’t see it being applied very often.

Roofing felt seals around the nail after it heats up. Tyvek doesn’t. It might work before I hand the siding and trim… but after that, it’s Swiss cheese. I’m just not getting my head around how a piece of Tyvek full of a zillion holes does anything.

Nick you send all your product in a WRB and that stuff is strong. It does not rip open and when you put a nail through it it is still sealed. As for felt it is impossible to make it seal with proper tuk tape. If there is another method I would know about it. As for the shrinkage that is a good point, however is not the opposite possible in cold climates?
Since felt is also made with paper it becomes food for mold behind the vinyl siding and I have seen this on many occasions.
Now that being said I did point out it must be done right or it is useless to use Tyvek.

I use Tyvek because it isn’t food for mold, it keeps things dry before I hang the siding, and because I’ve always used it. Not because I can figure out how it could possibly work, 'cause I can’t.

Regardless if it is Swiss cheese, a mold incubator, or anything else. Would you note in your report if nothing was between the osb and siding? I’m not just talking about tyvek but the total absence of a any barrier. This neighborhood has already had a few house striped of thier siding to remove damaged osb and they blame it on no barrier. Its possible the damage could have been even worse with tyvek. Its mostly just bad flashing but if the flashing fails the tyvek is supposed to be a back up right? If some one decides they should have been informed about what was under the siding I need to know how to respond to that. What Im getting from ths post is that it’s not a defect so I would not even have to mention it even if I could clearly see it was missing. Knowing its not there could be a deal breaker for some perspective buyers thus making me an alarmist .

Here is a good thread on this subject.

There are only a Zillion holes if you pull them out. :wink:

No different than the installation of your vapor barrier inside your home if you have one.

Here is an article that would be benificial to read by all.

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Good point.

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