![]() ![]() Resistance to expansion and contraction: Another reason screws are a better fit for metal roof nailing is that screws withstand metal roof expansion and contraction better.On the other hand, nails have smooth shafts that are more likely to pull out. The threads on screw shafts allow screws to hold onto wood for much longer. Holding strength: The first main reason screws work better for metal roofing projects is that screws hold for much longer.Though nails are more common in metal roofing projects, screws offer plenty of advantages. Generally, many roof experts prefer screws to nails. The idea is to place the screws close enough to ensure a firm roof installation and far enough not to distort or tear the roofing material. Alternatively, make sure that every third corrugation has a screw, including both sides of the panel side lap. Generally, itβs best to place roofing screws one and a half to two feet apart. Above all, an appealing screwing/nailing pattern makes your roof more and the home, in general, more beautiful. Correct spacing is also critical to ensuring a level roof. The correct nail spacing holds the roofing sheets more firmly in position. I usually give them the table number in my submittal to make it faster for them.One of the most important factors in a proper roof installation is screw (or nail) spacing. During plan review, they look at the tables to see if you are correct. They are familiar with it and it will facilitate the permit process. If you figure it out correctly and your jurisdiction requires a permit, you can provide the information to the building department. Nothing against beer drinkers, I just don't let them design my buildings. Don't guess and don't let someone with a beer in one hand and a framing square in the other give you advice. If the person is not licensed and providing a professional stamp, I want to check the calculations myself. ![]() They usually do not have a licensed engineer on staff, just someone who is used to looking at span tables. They might have someone who can figure it out for you, but I always check it myself. No sense looking at a table for a species not available to you. I would start by calling a few local lumber suppliers and asking them what grade/species they carry in the length and potential sizes you might be selecting. Prices and availability of species vary from region to region, so you can figure out a few alternatives and price them out to get the most cost effective selection. Use a rafter span table for L= 1/180 (I won't explain that, but you should see it at the top of the table). That is what an engineer would do but you can do it yourself. ![]() It takes a little head scratching with a table to figure out what size, the grade/species, and the spacing. The beam holding several has to be upsized, consist of more boards, and/or have diagonal bracing to reduce the span. Remember that if it calls for 2x8 rafters, you cannot put 3 of those 2x8s on top of a beam consisting of 2 2x8s. Your beam from post to post has to be sized properly, too. For a given species, if it needs 2x8 members on 2 foot centers it might be acceptable to have 2ε members on 16 inch centers. For example, #2 SPF (spruce/pine/fir) is not as strong as #1 Douglas fir. It also depends on light or heavy weight roofing, but your example has light weight roofing. It all depends on the spacing of the rafters, the pitch of the roof and the species/grade of lumber. Most building codes are available online and they have span tables for rafters. I have attached a picture of my current pole barn. I just ran across this website/forum, I have a feeling I will be spending some time here-it's great! Thanks in advance!! Any advice or pictures would be very much appreciated. I'm sure I will run into more hurdles, but something I would really like to try on my own. I will plan to have a metal roof put on with 2x4's (2' o.c.) ran across the top of the rafters to Install the metal too. I am not sure what size rafters I would use for the 16' span, nor the spacing? Any advice on laying out the pitch would be greatly appreciated. I was wondering if this sounds accurate? I was planning on running rafters off this board and out to 6ε posts (8' on center) with 2x8's sandwiching the 6ε posts. I have been told I can cut the metal at the top of the wall and run a 2x10 down the span of the wall and run the new metal roof on the underneath of the existing roof. I do live in Northwest Indiana and experience Lake Effect Snow, so will need to take snow load into consideration. I have 14' walls currently and would like to tie Into the existing roof to keep as much height as I can. I have a travel travel and some tractor implements I would like to store here. Ideally I would like to go 16' out from the side and span it the length of the building. I currently have a 36'x56' pole barn and would like to add a lean to to the right side.
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