Why is there moisture in the walls of my REMOTE wall construction?
Hello
I finally built my shop! The final construction is gyproc, furring, r15 batts, 2x6, osb 1/2, membrane blueskin vp160, 2 sheets of 4inch EPS foam (total of 8 inch), furring, siding.
I put Lunos for air exchanger.
But I noticed some issues lately. I checked the osb under the batts and in some areas, it is humid. I checked the humidity level of the room and it is high (around 60%).
For context, I started the glycol heating around 2 weeks ago and the air exchanger just 2 days ago. I am hoping to decrease the level of humidity with the Lunos and I will add a dehumidifier also.
My plan is as follow: I will try to decrease the humidity level of the room to an acceptable level (like 40%) and see the effect on the osb. If it is still a problem, I will remove the batts and live with only the foam insulation outside.
I would like to know what you think about all that.
All the best
David
What you describe sounds like a sensible wall assembly, seems like a great air barrier, no thermal bridging and you have 2 thirds of your insulation outside the vapor barrier. For sure 60% RH is too high and lowering it may help.
Given what you describe, my first guess to the source of moisture would be the studs. How long has it been standing, and how wet was the lumber when you framed it? It is not unusual to see moisture inside newly built walls, and especially if lumber was wet and you moved quickly to get insulation in the cavities.
Lowering the humidity will help, and to pinpoint the exact problem I would suggest you pick up a cheap moisture meter and check the content of your studs. The moisture content of a framed wall should not exceed 19% when its being closed. It its much over that I think you hae found your problem, and as unappealing an idea as it may be, pulling the batts to let it dry may be a wise move. And I would put them back after too, they would not be the source of moisture. You already spent the money on the batts, so if the lumber is the issue and you let it dry, then stick the batts back in after. I hope that's the solution, let us know how it works out.
Hello Mike
thank you for your response. I think I actually solved it. It was the concrete slab! I asked around and also read it that it can take up to 2 years for concrete to dry. My slab is super insulated under and also on the sides so the only way out for the water is on top. When I started the radiated floor, I think it increase the evaporation rate.
So I left the dehumidifier on 24/7 for months and it stabilized everything. I will continu to monitor everything but it should be under control.
I wish I had known this before ...but now I know!
I hope this can help someone else in the future.
Thank you
David
HI David
That makes sense. Glad to hear you solved it and thanks for sharing. Good luck with the rest of your build!
Thank you!
Also, I made something pretty cool to be able to attach some Finex panels on the foam that is around the slab. The challenge is to keep the foam (2x4 inches) and the Finex panel tight to the concrete slab.
Let me know if you are interested in the way I made it. I have pictures.
Best regards
David