OSB roof decking (LP TechShield Radiant Barrier)

Doing a phase inspection on a new construction.
LP TechShield Radiant Barrier roof decking was delivered.
Rained with this material stored outside.
Roofing subcontractor installed TechShield OSB roof decking
(OSB side up, thankfully)…
but it then rained on OSB for two days.
One day of no rain: 50 degree temp and 50% humidity.
Then they applied felt paper over what has still got to be wet
Even though rated as APA Exposure 1, my understanding is that
Exp 1 OSB is a bit slow to absorb moisture, but is slow to dry out.
It’s a two story, was getting dark, so I didn’t climb to try to get
through some felt with my moisture meter, but I did test some
leftover pieces of the same TechShield which had undergone the
same weather conditions…same site, same time frame.
Even painted ends were over 28% moisture.
I’m trying to contact Louisiana Pacific (manuf. of TechShield) to see
if they consider this “improper installation” and will jeapordize the new
homeowner’s warranty for this product.
Anybody got any comments?
Will this OSB dry out under felt paper and asphalt shingles?

Larry, I cannot offer any supporting technical info on this however I can tell you that my experience as a roofing contractor has forced me to do just what you are describing. It is not what you want to or know to do, simply the builders call to move on…dry in the house and shingle it (read between the lines…they get a draw after the roof is on). In anything other than new construction the place would have been dried in immediately.

I have had no problems result from wet weather application with OSB. I have seen only one occasion where the OSB had telegraphed the edges through the 3 tab shingles causing a visible defect that was visible all day, from all angles (not uncommon to see this ‘tiling’ effect in the morning light, goes away with the dew). This problem however was not a wet application, it was a product storage problem from the lumber yard.

I would pursue the manufacturers recommendations, monitor the moisture levels, make bold typed note of the condition and hope that the attic is properly ventilated. Remember a shingle roof is not water tight, it is simply designed to get the water off of the roof before it has a chance to get in. It can dry out through evaporation from the top side…ventilation from the bottom side.

Hope this offers some help.



Like any other APA Product, protection from the elements before and after installation is required.

Read the last page under installations.
Hope this helps you a little.


Thanks, y’all.
Below is the first reply from LP:

“Thank you for contacting Louisiana Pacific.
The first problem was in the delivery. The boards should not have been left exposed to the rain waiting to be installed. They should have been covered. OSB is designed to withstand weather during normal building conditions, but should be allowed to dry thoroughly before roofing is applied. If the roofing was still wet this could lead to some potential problems down the road. I would advise your friend to contact our tech line to discuss this. The number is 800-642-7881.
LP Marketing Center”

Am awaiting a return call from LP’s tech support.
My prediction is that they’ll say warranty would be null and void.
Will keep you posted.
Thanks again,

“The important thing is to not stop questioning.” — A. Einstein

I’ll be derned.
Warranty specialist for Louisiana Pacific told me that there should be no prob with warranty or any structural probs.

  1. LP’s OSB “is designed to withstand considerable water exposure during construction,” 2) “aluminumized side is purposely perforated sufficiently to allow drying through the aluminum side,” 3) “worst case: might be some ‘cosmetic’ deflections in future of asphalt shingles, but cosmetic only…not a structural problem…” However, he did advise that the OSB should dry to less than 20% moisture within a couple of weeks.
    So…I shall monitor to ensure that it does dry sufficiently…
    the OSB side of this stuff did get exposed to over 2 inches of rain.
    Cheers to all,

*“The important thing is to not stop questioning.” — A. Einstein