I'm working on finishing my atticMy house was built in 1932 and is located in Michigan.The attic space is approximately 24'x24'The rafters are 2quot;x6quot;, 16quot; OC, 13'6quot; in length from bottom to peak, at an angle of 33 degrees.My question is: can I install 7/16quot; osb sheathing on the bottom of the rafters to use for a ceiling? Will the dead load be too great?There would be about 9+ sheets of 4'x8' osb on each side, and the rafters already show normal slight sag, from the weight the roof, and live loads each winter.I'm interested in using the osb, because I have thin tongue-and-groove pine which is flimsy on it's ownI believe the 7/16quot; osb 4'x8' sheathing would provide good backing.
natural fibers have pours and the synthetic are made of plastic?
natural fibers are way more absorbant than synthetic ones, they hold the dye better
OSB is not that great of a productIt will swell if it gets damp and it doesn't have very good nail holding ability and it will sag between the rafters.not stay flatAs for the weight load, that will be iffyRafters are designed for snow load, but not additional weight beyond thatOn the other hand, people close off attics all the time and don't think about the weight factorIt would be similar to putting 2 or 3 layers of shingles on the outside, which people do, tooSo, unless you get an official okay from an engineer, everybody else will just give you advice I would tend to go with 3/8 plywood or maybe even 1/4, but that would be pretty thinEither would hold the nails for your pine T GMost important, thought, is to insulate the space between the rafters, but first put in the styrofoam vents from the bottom to the top to allow air movement above your closed off ceilingThis is the most neglected step, which leads to rotted out roofsAlong with the styrofoam vents, you need to make sure there are soffit vents and ridge vents so you get the proper air flowEven if you live in a warm climate, you will want insulation between the living area and the under side of the roof, because that roof will get super hot in summer.
