![]() It's too small, it might squeek in at a 6圆. I also changed the span in the calc to 140" then entered this info assuming the same species. The fail in deflection shows it would make for a bouncy floor but a passable roof board.Ĥ0square feet of roof bearing on a purlin X 40lbs per square foot= 1600lbs load bearing on each 4圆 purlin. I looked at it as a simple beam in flatways bending Most polycarbonate roofing projects will also require battens or purlins. Common rafters are typically spaced 16-24 inches apart depending on local. ![]() They run from the ridge board at the peak of a roof down to its eaves, providing support for other structural elements such as purlins, collar ties, and ceiling joists. Batten Spacing for Polycarbonate Roofing. Common rafters are the most basic type of roof rafter and form the backbone of many roofing systems. I'd call the adjusted Fb-1125psiĪssume a 6" wide board spanning the 40"=1.66 square feet X40psf=67lbs load When installing a corrugated metal roof, battens (or purlins) should be spaced no further than 1.2m from one another for metal roofing sheets that are 0.7mm thick, and 1m for 0.5mm thick sheets. The 2×6 serves to support roofs in areas that get heavy snow loads. Wind deflection and snow load have parts to play in choosing between 2×4 or 2×6. Sometimes, you can use the 2×4 to achieve longer spans if the spacing between the rafters is less. I would bump up the Fb by 15% for short term loading(snow), 15% for repetitive member use, and you could take 15% more for flat use but I don't think I would. The 2×4 rafter goes for shorter spans, and the 2×6 goes for longer roof spans. Add 10psf for dead load so 40psf total load. Your building department can give you the snow load for your area, I'm guessing it will be 30psf. Roughly then, 4' centers on an 8/12 with 4" wide purlins is going to give a clear horizontal span of about 40". The typical spacing standards for residential and commercial buildings are about 1 to 2 feet. For heavier material such as gage steel, the metal roof purlins spacing length could go up to 4 feet. The horizontal clear span from plumb to plumb would be the way the NDS measures the span. For lighter materials such as lightweight aluminum, the common spacing length is 4 inches of the clear gap. The codebook doesn't alter sheathing, rafters or purlins based on pitch.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |