Now it's nice and toasty...PM is very concerned about the moisture level of the roof sheathing. He's afraid with the closed cell foam with the Grace will trap moisture and rot the sheathing.

We pretty much just rolled our eyes yesterday, but we went through the motions by getting a moisture meter (anyone know the proper moisture of OSB?...we don't)....anyway, after 12-15 hours of heat, we came in today and found a good amount of condensation on the bottom of the roof.

We pretty much determined the condensation is from the moisture evaporating from what's already inside the house.....

Typically, we wouldn't pay much attention to the moisture level of the framing, we just crank the heat until we're ready to hang board and keep an eye on the sub-floor.

PM wants us to wait to insulate (1st phase) until all levels of moisture are consistant....who knows how long that may take???

I guess the question is....what level of moisture is OK to foam over, and what's the best way to dry out a frame?....right now we have fans and the furnace running 'til atleast Tuesday when the Insulater is scheduled to spray?

Sorry for the long post/s....

 

My first question is, what are you heating with? Propane will dump more humidity into the house. I believe Kerosene will as well. I'd suggest dehumidifiers if you want to pull the moisture level down.

 

We were using propane until our gas furnace was installed. We still were using the heaters for ourselves, but now it's the weekend.....The furnace is running as we speak, along with fans (no propane) and nothing will change for 72 hours....A lot will be riding on the conditions Tuesday.

 

I think you want your building materials near 12% moisture content.

I would use portable electric furnaces and a big commercial dehumidifier.

 

Tuesday may be too soon.

 

Thanks!....you're starting to narrow down my questions, I wasn't sure what to ask at first...

We're only spraying the roof system....would you be concerned about the roof sheathing not drying, or rotting if we sprayed before it reached the optimum moisture level?

IMO, as long as we get the roof to stop condensating we should be okay to insulate (partially)....waiting until the roof is the same as the subfloor for hardwood seems completely ridiculous....EDIT(unnecessary)

 

I think I'd wait to get it down to where the roof deck is giving readings that the insulation contractor is comfortable with for spraying. I don't know much about the Grace I&W product or spray-foam insulation, so I can only guess the outcome of applying foam in less than suitable conditions. If it was felt on the roof and the sheathing was spaced, I'd be more inclined to push the issue with the IC, but with I&W, trapped moisture will definitely cause problems, so I would value his professional opinion.:thumbsup:

 

lots of heat being electric, a few dehumidifiers and a few very large fans, keep the air moving so that the building will dry ouit quicker and reduce the chance of mold

 

OSB isn't very good for letting water vapor through, it's technically not a vapor barrier, vapor passes through it just not very much. That's what Zip System sheathing panels are for, they allow more water vapor to pass through than OSB allows. That's probably why you're seeing condensation on the OSB, if the house was wet then that partial vapor barrier in OSB will catch some of that condensation.

I don't think it's a big deal, just get a dehumidifier in there and give it time to dry out. And I believe 15% moisture or lower is good for framing, I am not sure though.

 

12% would be a real nice number, 13-14% may be more realistic, but I would be concerned about making a high moisture sandwich: with Grace on one side and foam on the other, the only point for moisture to escape would be the ends (eaves). If it's open cell (I'm not knowledgable enough on this...) the moisture may be able to escape-someone correct me.

I wonder if you'll need to get the snow off the roof to help w/ the condensation issue (?)

 

I wonder if you'll need to get the snow off the roof to help w/ the condensation issue (?)

With the current cold and windy weather, I'd think snow on the roof would actually help keep it a bit warmer.

WNY, like many I have no experience with your particular scenario. But considering what you have riding on this, I'd definitely want the insulation guy to be happy (and taking the responsibility) with the moisture level.

 

Thanks for the input!

The foreman is going in Mon. to asses the situation, I'm guessing we'll probably put off insulation for another week and bring in a dehumidifier.

One of the problems we were having was getting an accurate reading from the meter....Knowing what % moisture we needed didn't help. We had to program 'species', 'temperature'....(neither I nor the Foreman really knows how to use a moisture meter:sad

My best guess was to set the meter for SPF, and we guessed the temperature.....yesterday afternoon the air temp we figured indoors was 45*. we were looking for a constant to compare to, so we probed a recent delivery of 7/16....6, Then we checked the sip sheathing, 26, then the framing, 18, the roof deck was 36, and the subfloor @the entry was 76 LOL....each of which we guessed the temperature.

We generally only use a meter for the hardwood flooring that has been acclimating for a couple weeks in a dry house at 60-65*...

Any advice as to how we should calibrate the meter to actually understand what the differences in moisture content is in our building materials?

 

As I said, you're in a situation I haven't had to deal with (thenk yew!). But it seems obvious that your first step in "calibrating" is to know for sure what temperatures you're dealing with. That I could do--I always carry a $10 digital thermometer so I can tell just how miserable I am. :laughing:

Sorry I can't help with the meter, but if your WAG method is anywhere near accurate, 6x the moisture in a recent delivery does sound like you have some serious drying to do. :sad:

 

That Grace sounds like
a real problem for you.
You have effectively put
a vapor barrier on the wrong side
of the OSB, and saturated
the other side with condensate.
I would want to give it as long
as it takes to come down to 12-14%.
Once you spray the closed cell
with the Grace on top there is
no where for the water to go.....

 

When you get the dehumidifierS working you will be amazed how much water you haul out of that house.

I'll start the pool at 32 gallons.

 

When you get the dehumidifierS working you will be amazed how much water you haul out of that house.

I'll start the pool at 32 gallons.

I say 25:thumbsup:

 

Oh don't we love winter construction in the North.......
We've used closed cell PU foam with many of our projects.
I wouldn't try to guess on this one.

If you have a fire and water damage restoration outfit nearby, I would call on them to set you up with the proper equipment to dry out that roof.

They do it all the time and have calibrated moisture meters so they can assure you and the insulators that the foam can be applied without causing future damage to the structure.

Be safe with this one:thumbsup:

 

Oh don't we love winter construction in the North.......
We've used closed cell PU foam with many of our projects.
I wouldn't try to guess on this one.

If you have a fire and water damage restoration outfit nearby, I would call on them to set you up with the proper equipment to dry out that roof.

They do it all the time and have calibrated moisture meters so they can assure you and the insulators that the foam can be applied without causing future damage to the structure.

Be safe with this one:thumbsup:

That's a good eye deer:thumbsup:

 

What would be better....(we haven't set any windows yet)....

to frame in a box fan @ the 2nd floor window RO blowing out and knocking out some of the rafter bay blocking with the furnace running in the basement. That way the hot moist air gets sucked out and venting? Or keeping the structure tight and just using dehumidifiers?

The house is already 75* insulated. ICF foundation, SIP panels. Only the rims joists and rafters are left.

Our original thinking was to hurry and get the structure sealed so it can dry out. Now I'm thinking (because it's already a tight house), we need to let the place vent.

 

What would be better....(we haven't set any windows yet)....

to frame in a box fan @ the 2nd floor window RO blowing out and knocking out some of the rafter bay blocking with the furnace running in the basement. That way the hot moist air gets sucked out and venting? Or keeping the structure tight and just using dehumidifiers?

The house is already 75* insulated. ICF foundation, SIP panels. Only the rims joists and rafters are left.

Our original thinking was to hurry and get the structure sealed so it can dry out. Now I'm thinking (because it's already a tight house), we need to let the place vent.

In my opinion, I would keep the place closed up to retain heat, but dehumidification is paramount.

 

warm air will carry more moisture,
then the dehumidifiers can wring it out. :thumbsup:

 

I worked on a job that developed mold during framing.

The HO freaked out so the contractor brought in a mold remediation co. to dry it out.

From what I can remember they pumped super dry air into the house,
the dry air would absorb the moisture before venting out.

It was really expensive and quite a process but it worked.

It was a condo project, so after that happened all the other HO's wanted their's dried out too.

 

installing a cieling fan or two would be nice to pull the air up and move it around.

working on a project right now that is an insurance water damage deal, every week a guy comes by from the fire water restoration company and checks the humidity of the house and records it. The insulation and drywall cannot be installed unless he says it's ok.

ps. I don't miss working in humidity of ny.

 

installing a cieling fan or two would be nice to pull the air up and move it around.

Yep. I do that just to alleviate the 20° temp difference from high to low.

 

if you have a temp heat co call them they can heat it with dry air and be done in less then 3 day. call a com contractor to find out who they use.
you might talk to your insulation guy about doing one inch of open cell to start with.

 

Id install a fan or hang a box fan i never thought of that and get a few dehumidifiers running give it a few days and shell be nice and dry... Also keep it sealed tight for heating purposes

 

Thanks to all!

I think the foreman and I just had this game plan in mind....The closed cell foam is an area that is relatively new to us and we're not as educated about building systems as we like to think.

We've been battling set backs, budget constraints, and scheduling all the while, so we were a little aggravated by yet another obstacle.

With 6' of snow since the beginning of Dec., and temps not getting above 25* in as long, we really were looking forward to having indoor work....and having work when the weather gets inefficient.we're forced to send guys home.:sad:

I appreciate all the input. We just need to be patient....We still have ALL the mechanicals to rough in (subbed), a lower roof to frame, windows, ext. trim and siding.

It's not like we don't have work, we just have to switch gears!

If our Insulation contractor can spray 1" open celled we'd be back on track! This project has been a great learning experience on many different levels!

 

Thanks to all!

This project has been a great learning experience on many different levels!

For the majority of us as well.:thumbsup:

 

I believe the condesation on the bottom of the sheathing is caused by the warm inside air coming in contact with the cold surface and reaching the dew point. I always ice and water my entire roofs, usually with grace, but I always have soffit and ridge ventalition. The sheathing needs to be able to dry to one side or another. I good book to look at for advice is called "The Moisture Control Handbook".

 

When we showed up today things had dried out remarkably well....No condensation, and the powers that be OKed us to spray tomorrow.

We didn't test the roof deck, so I suppose i'ts arguable whether we're doing the right thing, but thanks again.

 

If you still need help, let me know.

It sounds like you have all types of structural drying issues, which without proper drying will lead to dry rot, mold, an unclean breathing environment and unnecessary demo and rebuild.

I have 16 years of restoration and insurance adjusting experience. Structural drying, including new construction, is a specialized field.

All framing needs to be properly dried and the Relative Humidity needs to brought to an acceptable level before any more construction is done.

There are issues with the OSB, the GRACE I&W, sheathing, wall framing and any sub floors.

If you still need help, let me know by e-mail or phone, and I will try to get you someone in your area ASAP.

I am currently in SW Florida, but I have contacts all over the country. Without proper drying methods, this structure has the potential to turn into a real headache.

Mark
210-823-3864

 

FYI: Quoted from Fundementals of Building Construction Fourth Edition,

"The Moisture percentage at which wood will begin to mold or is capable of supporting mold growth is 19%... ideal moisture percentages for rough framing prior to finishing 7-9%... ideal moisture percentage for millwork, cabinetry, trim, prior to installation- 5% or less."