I have a large attic and plan to stack some recently cut 8/4 lumber there to dry. Is there anything I need to watch out for? In warm weather it gets quite hot up there, though I haven't measured the temp. Can the drying wood cause any damage to my home?
(Sawing and Drying Forum)
From contributor J:
Airflow, temperature control and possibly overloading the meager ceiling joists would be my concern. Depending on when the house was built, the load rating for an unused attic might be only one quarter of the rating for occupied space, per square foot. Not saying it will collapse, but you might want to do some calculations based on the cross section of the joists and their spacing. Also, you might get a lot of degrade in the lumber. Do some research on the drying schedule for the type of wood you are considering drying. Also, air drying for a period of time prior to loading it in the attic might be a good idea.
Back in high school woodshop someone's relative died and left behind an attic filled to the roof across the length of the house with lumber. I'm talking wide walnut, wide cherry - 20" wide, some 3" thick. There were about 10 walnut boards 15" wide 5/4 with the nicest curly rope grain I've ever seen. At least 2/3 of the wood was donated to my high school, and I helped to pull a great deal of it out. The wood was up there since 1960. I don't know what the moisture content of the wood was, but the wood was very stable and has remained stable in finished products for over 5 years. Overall the wood was stickered properly, and over 1/3 of the lumber was degraded by extreme warp, twist, cupping, and cracking. I don't know if the wood was stored up there green, but I believe so.
If you air dried the wood properly elsewhere and moved the wood into the attic around 15-25% MC, it might just work. Make sure you put weights on top of your pile. Cinderblock works well.
I am worried about 8/4 weighing too much for the rafters or trusses, especially if wet. A roof is typically over-designed, just in case, but how much extra is too much? Also, 8/4 of many species must be dried slowly and an attic may dry too quickly. Also, if you have a warp prone species, you will not have the restraint that we would have in many drying situations. Finally, you may have poor air flow if the lumber is on top of the insulation. So, overall, it is probably best to air dry first. Then just put a few AD pieces in the attic to achieve the required low MC.