Since you need an answer *right now* call the Tyvek manufacturer for advice.

I called Tyvek (it isn't Tyvek it's EasyGard), but I am making the assumption that the advice would be the same. DuPont said not to install it if it is wet. Now I have to deal with the contractor and have it all taken down (this is going to be interesting).

If anyone else thinks I should leave it up, please let me know.

Thanks!

I dont think it needs to be removed, just dont install the siding. One way to let it dry out quicker would be to cut slits in the wrap in the areas of the wet to let air in and dry it out. Once dry, tape the slits up well with the approved tape for your wrap. Your installer should have the approved tape as it is necessary to tape the seams of the wrap anyhow. You also might want to be sure all your windows, doors, and any other concerns are properly flashed before the siding install.

Typar and Greenguard also say not to install some of their housewraps if the substrate is wet. Other manufacturers are silent on the issue.

If the wood is wet because they wrapped the sheathing when it was raining or the sheathing was already wet, I would err on the side of caution and wait till materials dry out.

More importantly, I would want to be sure that the siding company is providing for a gap between the siding and the housewrap by the use of furring strips. Especially if it's wood siding.

Here is a link that might be useful: Rainscreen Walls: A better way to install siding

EasyGuard is made in China and is a high-density polyethylene woven fabric coated with a low-density polyethylene coating. It may or may not be micro-perforated. This is a bottom of the barrel cheap material sometimes offered by lumberyards. If the lumberyard's name is on it that's a red flag.

It would be pointless to compare this product with Dupont's Tyvek HomeWrap which is a high-density polyethylene non-woven (spun-bonded) fabric with far superior performance.

I would ask the contractor to remove the EasyGuard and replace it with Tyvek or Typar (same as Tyvek but spun-bonded polypropylene). It would be worth an upcharge and the EasyGuard can't be worth much.

Your contractor appears to be dumb or devious in addition to being careless IMHO. The house wrap is not the place to trade performance for cost.

It's amusing to think that surface contaminants that are unlikely to exist on normal sheathing might be relied upon to correct the builder's error. And the suggestion becomes irrelevant when you consider that the ability of the type of wrap installed to prevent the passage of water is so poor that nothing is likely to be able to make it leak water any faster (see link above) They should call this stuff SleazyWrap or FilterWrap.

If this low grade porous plastic wrap is left exposed on the outside and the sheathing is exposed on the inside, the sheathing should dry out pretty rapidly in dry weather but adding finishes immediately would be taking an unnecessary risk.

I would use the contractor's mistake to help get a better performing weather barrier installed. Unfortunately, there is unlikely to be any published installation instructions for this type of wrap. Their website is in Chinese. It would be interesting to know how much (or little) money was saved by using this material.

Never heard of easygaurd, but obviously Mighty has researched it. Take his advise and insist on it's removal even if it's at your expense. It should be at the expense of your builder or split the expense between the two of you.

Paul Fisette's followup paper to the one linked by manhattan42 (I also linked to it in the other thread on this subject.) explains why house wrap should not be put on wet sheathing.

From Leaky Housewraps (linked below)

"If water gets on the wrong side of a felt-wrapped wall, the felt can absorb the water and over time allow drying to the outside of the structure. Plastic housewraps don't move water this way. Plastic wraps are non absorbent. They rely on vapor diffusion to move water that gets on the wrong side of the wrap. Diffusion is a slow and weak force."

Here is a link that might be useful: Leaky Housewraps

Considering the less than perfect detailing of house wrap applications, it's a good thing that some bricklayers still insist on using felt as well.

Paul Fissette's work at UMass is largely related to water infiltrating housewraps from without.

His work deals with surfactants and how the glues in plywoods and OSB boards actually ALLOW liquid water to penetrate housewraps from without.

Since Fissete's work is accepted in the scientific community as 'true', it should also be acceptable to determine that the reverse is also true: that when housewraps are placed over 'wet' OSB or plywood sheathings, that drying through housewraps when surfactants are present should not be a problem.

But if science and logic escapes some here, perhaps some research from Building Sciences Corporation regarding buildings 'drying to the inside' can help clear up their ignorance and confusion.

Here comes the old "ignorance" accusation again.

If you paid closer attention to Paul Fisette's research you would know that he spells his name with one s and that he attributes surfactants in wood clad houses to be from cedar, redwood, or stucco exterior cladding or soaps used in power washing rather than from the adhesives in structural panel sheathing. If you know of other research about sheathing adhesives you should provide it.

If you read Fisette's reports carefully you will learn that in his tests "perforated wraps leaked like sieves" If a wrap already leaked like a sieve why would it matter if a surfactant was present? If water can pass inward easily it should be able to pass back out easily too. For this reason, Fisette didn't even test the perforated wraps with soap or cedar chips in the water.

The house wrap used in the OP's house is not waterproof so it only needs to be left exposed long enough for the assembly to dry.

Mr. Fisette sums it up very well: "it is abundantly clear to me that perforated wraps, in their current state of development, can leak when placed in contact with water and/or wet wood. So why use them? You can choose a product that won't."

Since perforated wraps leak like sieves, it's likely the microperforated wrap on the OP's house will dry, exactly as the contractor says. Of course, it will be useless anyway; and, ideally, should be replaced with something else as mightyanvil suggests. But since these postings are being read by other than the OP, I quoted Fisette on, presumably, non-perforated wraps.

Incidentally, Fisette's paper is entitled: Housewraps, Felt Paper and Weather Penetration Barriers not Sufactants and Housewraps.

Mightyanvil stoops to one of his lowest levels ever in his most recent 'bait and switch' routine... by distracting from the science associated with the the argument by attacking one's spelling?

Give me a break!

The the "mightyanvil" also sets up a strawman argument by indicating how 'perforated' housewraps 'leak like a sieve' (when I never mentioned "perforated" wraps...)

And if "perforated" wraps do so well at allowing liquid water 'in'... they will also do as well in allowing liquid water 'out'....No?

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The reality here is that (non-perforated) housewraps work to keep liquid water out because of the surface tension of liquid water molecules.

In the gaseous state, water can readily penetrate these membranes...either inward or outward depending on conditions.

In water's liquid state, however, housewraps are less permeable....Not because of any inate quality of housewraps...but because liquid molecules would rather stick together than break apart.

Some research has suggested that the adhesives in OSB and plywoods can cause the forces that joins these water molecules in tight bonds to break down, and therefore cause 'leaks' in otherwise water tight housewraps.

Much like the 'surfactants' and 'soaps' in Fisette's and Building Sciences' articles.
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That said, no one has yet properly asnwered the original question:

Can one safely install housewrap over a one-time 'wet' structural plywood or OSB sheathing exterior?

The answer: YES! ABSOLUTELY!

While 'diffusion' through housewrap of liquid water may be SLOW....(as others have mentioned)....This diffusion and 'drying' to the outside through housewrap DOES OCCUR...and if no additional liquid water is introduced...should pose no long term problems at all.

And if drying to the inside is ALSO an option, drying of the temporarily wet sheathing should not even be a consideration....even when housewraps are present.

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If this were MY house, I would install the wrap...or felt...or foam insulation... and be done with it.

Knowing full well that any liquid 'water' retained by the structural sheathing will eventually be dissipated without damage any damage to the structure whatsoever.

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Sheesh...

As I said earlier, "it's likely...the house will dry exactly like the contractor said." But that's because the wrap is woven and micro-perforated.

For non-woven, non-perforated wraps such as Typar and Tyvek, the answer isn't clear at all. Indeed, that's why Tyvek's rep told the OP the opposite and Typar says not to wrap wet materials.

Indeed, Typar's surfactant resistant housewrap tested by Fisette showed "superior resistance" to surfactants.

Though surfactants are used in the manufacture of OSB, the surfactants that Fisette and Lstiburek are concerned about are those in wood siding and stucco and the soap that leaks through power-washed walls.

When I have a choice, I avoid the whole house-wrap problem and use foam sheathing and a vented wall instead. And I've still had the bricklayers insist on using felt over that, to which I accede.