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Wet plywood during construction

kalia's picture

Hi all,

I'm new to the discussion forum here. I'm a furniture and cabinet maker in California, and have a construction project going on that I wanted to ask some questions about. The project is a second-story addition over our garage -- I'm not building it, just to clarify, we've got a contractor doing the work.

So here's the issue: We got caught by a series of rainstorms before we could get the roof finished, and despite the contractor's assurance before we started the job that he'd be able to tarp and protect the job in case of bad weather ("Don't worry, it'll be fine"), the roof sheathing and second-story subfloor got soaked by several storms. Leaving aside our irritation with the contractor about not tarping the job, where does this leave us with regard to continuing work?

There are two issues here. The first, and most pressing, is the roof. We'd obviously love to get that roof papered and closed up ASAP, but not until it's actually dry. The contractor wants to get a crew out here Friday (the day after the next set of storms is due, btw), which would mean papering over really wet wood. Just how common is this, and just how bad is this? To me, this seems like a major invitation to mold and rot. Would letting the roof dry before finishing be sufficient, or is the plywood, once soaked, unusable and in need of replacement?

Issue number two: the floor. The flooring that will be going over this subfloor is 1" thick VG Doug fir (roughly 4" wide t&g). This is intended as a dance floor, so the floor needs to be _really_ sound, no bumps or squeaks or wierdness. At this point, due to the fact that there have been standing puddles of water on the subfloor, there are pockets of de-lamination all over the place. We could, once the roof is complete and the building is closed in, get a de-humidifier in there and really cook the place dry before installing the flooring, but what about all those plywood bubbles? And in case you're wondering, yes, the I-joists holding up the subfloor also got wet (primarily the plywood caps, not so much the OSB ribs). Oy.

What are the industry standards about plywood getting wet? I'm interested in hearing both the "here's what folks usually do" and the "here's what the manufacturers tell you" side of things. At this point, all I'm hearing is what my contractor is telling us, which I suspect is motivated by a desire to close this job up and flee.

I look forward to hearing from all you buildy-types out there.

Many thanks,

Kalia

(post #96447, reply #1 of 9)

I'm not a builder by living, but in it enough.


I think your stuff is fine.  Roofing over wet plywood?  No problem.  It will dry to the inside.  Subfloor delaminated - should have use Advantech, but you are beyond that now.  But really, I don't think it's a big deal, just get a dag-gone roof on the thing, get closed in and get some heat / dehumidifier rolling in there.  Don't interior finish until the moisture in the wood has stabilized!  Get a moisture meter and keep an eye on it.  It shouldn't take long once you cut off the rain.


Houses under construction get rained on all the time.  If you are worried about your floor, lay some 1/2" plywood over the subfloor (after dried-in) and then finish floor over that.


 


MERC.

(post #96447, reply #2 of 9)

look at the stamp on the plywood. If it says "exposure 1" it should not delaminate under wet building conditions.


If it is in fact delaminating you either have the wrong exposure rated plywood or a warrantee claim

(post #96447, reply #3 of 9)

Kalia, as already noted, the roof will dry out ...its not a problem. The bigger problem is slipperyness and the roofers are used to that.


The subfloor sounds like warranty issues, as already noted.  All subfloors are made with exterior glue. They anticipate a good drenching or two. I've seen subfloors that were exposed to the elements for more than a year perform perfectly. It get gray...but it still holds together. You lumber dealer will re-imburse the contractor for materials, but they might fight paying for labor. I have been payed for labor however.


The puddling is normal....but I would not be happy if the floor had more than 1/4...maybe 3/8" deep puddles. I actually like a good rain after the subfloor is down because it confirms our plane or exposes our low spots.


Don't look to unfavorably on the contractor because of the rain hitting the lumber....it won't hurt it....the lumber has been outside for the last 30 to 80 years....and it knows how to handle the elements. Possibly, a bear might have even urinated on that stud.....


blue


If you want to read a fancy personal signature...  go read someone else's post.

"...

keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #96447, reply #4 of 9)

Too tired to read your whole post so all I can say is in the future use Advantech....#### product!

Be wet : )~

andy

The secret of Zen in two words is, "Not always so"!




http://CLIFFORDRENOVATIONS.COM

(post #96447, reply #5 of 9)

 


K,


Building in the NW...do you think it never gets wet? (Where I live) Don't worry...I think you'll be just fine once it gets dried in. You also have one inch flooring going in...quit stressin'.


Peace

(post #96447, reply #6 of 9)

Kalia,


Those pockets of delamination will give you grief as it will be impooisble to get the finished floor tight and level and you really don't want that bouncy poppoing weirdness going on under all those toes.


The low spots where the puddles were. Just how deep were they? Anything over 1/32" will be noticable to the foot at times.


http://www.eijkhout.net/rad/data/dancefloor.html


Din standards


http://www.findarticles.com/p/articles/mi_m1083/is_6_76/ai_87022591


Dance floor construction is a specialty as much as cabinet making. You would not ask just any old framer to build cabinets.


Has your GC any previous experience with dance floors? Did you tell him that dance floor construction was special? Did you know that?


It might be time for a serious sit down with him.


 


Samt


Change The Equation!


47807.1 


SamT
A Pragmatic Classical Liberal, aka Libertarian.

I'm always right!
Except when I'm not.

(post #96447, reply #7 of 9)

Visit the APA website to see how exterior plywood is rated. It's allowed a certain number of wet/dry cycles... I forget how many. Here in WA the subfloor will almost certainly get wet during building, but it's normal and won't cause delamination. As you described it there are serious problems with the plywood... either what was used or how it was treated. Pockets of delamination all over the place??? Ugh.

(post #96447, reply #8 of 9)

Good advice David....and I agree Ugh!


One other thing....maybe the installer pounded all the joints too tight. I'm amazed at how many carpenters neglect to allow expansion spaces on t&g flooring!


blue


If you want to read a fancy personal signature...  go read someone else's post.

"...

keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #96447, reply #9 of 9)

On a dies note... not about delamination but applies to wet plywood situation...


What about the growth of mold on the plywood... Can or should anything be done about it if it starts growing mold?