My friend is sawing some SYP for paneling a room in his home.It will be installed with black roofing paper behind it so a small gap will not be a problem.It will not be tongue and groove or lapped .It will be air dried inside with a fan .What moisture can we get away with.I was thinking around 12% .It will be 1x10's.Thanks al
If you plan on air-drying pine inside, you had better have some serious ventilation. Green pine contains a tremendous amount of moisture, and if it doesn't have somewhere to go, you will have a moldy mess on your hands. It sound like your friend is going for a very rustic look with no T&G, lap, or battens, so 12% would be fine. Equilibrium MC will get up to around 10% inside during the spring and fall in Georgia.
Thanks Dodgy,He is going for that look.He was going inside with fans to avoid a mold problem.We were thinking because it"s been so wet this winter that inside with a fan would be better.
It would work better if he had a way to vent the moist air from the fans out of the room/building and if he does not go light on the fans.
This pine paneling was air dried outside, milled, then installed on the exterior walls of a mobile home. Unfinished, worked just fine.
(https://forestryforum.com/gallery/albums/userpics/14000/1570/wall-panel.jpg)
As a point of reference, a 10" piece of pine will move (in this case, shrink) 1% in width (that is shrink 1/10") for each 4% MC loss. In the wintertime, the house interior can be around 6% EMC, so that means (if you started at 12.0% MC) about 0.15" (over 1/8") gap between each piece is possible. Sometimes two pieces will stick together and so the gap will then be over 1/4" and then nothing and then another 1/4", etc. I think that most foks will be unhappy with such gaps. A house int he summertime may be 10% EMC, so the gaps will close almost all the way. Note that 12% MC, is usually a ballpark estimate, so you might have some pieces that are wetter and that means an even bigger gap will develop. Because of these gaps, most people use shiplap or t&g with a long tongue.
I just made some barn doors with V-Groove SYP. My issue was not shrinkage, but swelling as I kiln dried the boards to below 10% moisture content. With the outside humidity and rain blowing on the doors, I had to engineer the doors so that the boards could swell just a bit. I used the shrinkage calculator to determine the likely amount of movement between about 10% and 15% moisture content, and made allowances for just under 1/2" of movement for every 35" of door panel. The door panels float in an 8' x 8' frame with a middle style, leaving two panels in each 8' x 8' door.
Danny, your just so darn smart! ;D
Ellmo old Danny is not only smart he can play one more mean guitar .
(https://forestryforum.com/gallery/albums/userpics/14302/001%7E16.JPG)
It will really help if you can put a water repellant coating on the doors to keep the rain off. Without that coating, the pieces can exceed 15% MC easily when raining and will swell more.
That is a very good suggestion, and one that I will definitely take you up on.
Man, it was hot that night :).