High moisture in subfloor - Contractor Talk - Professional Construction and Remodeling Forum

RJ Tile · 06-03-2009, 12:28 AM

I am installing 3/4" prefinished hickory over 1-1/8" plywood floor decking in new construction. Two weeks ago the moisture in the subfloor was 22%; a week ago it was down to 12% or 14% depending where you checked. Today it was at 12% or 14% still. I'm using a pin tester and checking at a depth of 1/8" to 1/4". Closer to the surface it is a lot lower, around 6% to 10%. Air humidity was around 40% to 50% most of the 2 weeks, but jumped to around 70% the last few days. Humidity in the crawlspace is lower 35% 45%. There is no air conditioning. We have fans inside house and in crawl space to circulate the air.

Here is the dilemma.

I told the home owner that we needed to get the subfloor and wood to within 4% before we install. The supplier of the subfloor told the home owner that the plywood was at 14% at the warehouse and went to 22% from the rain during framing, but won't drop back much below 14% because that is what it normally is. The hickory was at 6% at time of delivery last week and is still at 6% a week later. I told the home owner having the AC hooked up will help; she doesn't want to have it done yet, no idea why. They are going to get dehumidifiers in the house now that the humidity jumped up. But they want me to get started right away if the moisture content doesn't start dropping soon. So I told the home owner we need to get the subfloor to 10% or she needs to sign a warranty waiver.

Here is the question...

What else can I do? How do I lower the moisture content?

Thanks, RJ

Morning Wood · 06-03-2009, 05:15 AM

dehumidifiers will help alot. just get her to sign that waiver if it comes down to it.

Floordude · 06-03-2009, 10:31 AM

First off, it sounds like someone else is in total control of your job!!

You need to take the bull by the horns and man up. Do you have any documentation to get the point across and how important this is. Do you have the NWFA Technical manual? That one bible, will set you free!

At this point what I would do, is to compose a very specific well worded waiver of liability. In it, state what they want done. the conditions they want it installed as, what the standards and guidelines state. State what is going to happen if it is installed like they wish. Then in BOLD TYPE, State, " This installation is only meant to be a temporary installation, as the understanding has been met and agreed, with all parties involved with this contract, that this installation as specified by ___________is prone to fail, by not following documented industry standards. Any corrections or replacement after installation is complete, will be billed and charged per our most recent price list. Then get the person you have a contract with, to sign it. If you are subcontracting through a GC, get both the home owner and GC to sign it, or walk away from the project.

This jobsite is not even ready to start acclimation, much less a full installation.

Use the long probes on your moisture meter, or some finish nails to drive into the subfloor in depth increments. You want to see if the deeper you go into the subfloor, the moisture % does not keep rising.

From what I hear from your post, the floor is going to cup severely, it may even buckle. When that happens, your looking at some expensive firewood, that does not taste any better eating it, even with a little salt & pepper.

Floordude · 06-03-2009, 10:39 AM

Quote:

Originally Posted by Morning Wood

dehumidifiers will help alot. just get her to sign that waiver if it comes down to it.

And as soon as the floor is installed who is in control of the dehumidifiers, especially in the sealed crawl space?

That floor is going to buckle as soon as they turn them off after the install and they don't have the HVAC installed, and it is going to cup as soon as the crawl space dehumidifiers are removed.

How much plastic is installed in the crawl space, to cover the ground soil?

What is keeping roof run off from seeping into the crawl space?

Floordude · 06-03-2009, 10:46 AM

Quote:

Originally Posted by RJ Tile

The supplier of the subfloor told the home owner that the plywood was at 14% at the warehouse and went to 22% from the rain during framing, but won't drop back much below 14% because that is what it normally is.

Thanks, RJ

The supplier is BSing the homeowner, or is totally clueless about woods moisture content, in relation to humidity. I guaranty I can get the subfloor material below 14%! Give me a piece and let me stick it in an oven set at 200º for an hour and recheck moisture content!!
There are some crooks out there that will say anything to cover their lame stupid butts.

Darwin · 06-03-2009, 11:14 AM

Thick plastic sheeting covering the entire crawlspace will lower the humidity. Once this is done, make sure adequate ventilation is reaching the crawlspace--via cross ventilation from the vents on the opposite sides of house.

Good Luck.

jaros bros. · 06-03-2009, 12:53 PM

The first post said it all. Who is really in charge of your jobsite? The HVAC needs to be running. Sounds like a disaster waiting to happen.

drive55cat · 06-03-2009, 03:36 PM

Get the waiver signed or run away. d55

Jerry T · 06-19-2009, 05:37 AM

How wide is the hickory? Does your meter self calibrate to selected species, or do you need to manually convert the readings using a species correction chart? Both the subfloor and the wood have to be species corrected.

You may be alot farther off than you realize at this point....

On new construction the HVAC should be up and running set to lived in conditions 10-14 days before any wood is brought in.