![]() (the tables permit a bearing length of up to 3. I'll try to attach a couple recent photos of a home I framed with my son's business.this photo does'nt have the back framing completed yet, as I described it, but you can see the hangers before the blocking is put in.works for me anyway. Table 9.1 in Span Tables for Joists and Rafters (Figure 5) gives a required compression value of 237 psi for a span of 16 feet and bearing length of 1.5 inches. As for the underside, the boarders attach a 12' creased sheet of tin to length and that determines where the two slopes meet. Personally, rather than wrap the hanger onto the filled TJI, I like to put a 2X8 block between the roof joist and nail the free hanging wing of the hanger, onto that. Basically all you need is the proper plumb cut and the hanger wraps onto that and hangs from one side onto the valley beam. Just to repeat, I have checked span tables based on my type of lumber and size. Permissible Clear Spans for Rafters (to BS 5268-7. I just don't like to cut into an engineered beam, other than to length.Īnyway I like to use the simpson hanger designed for that, simply because that's what it's made for. Because of the angle, the extra length will be longer than the horizontal distance of the overhang. When ordering rafters make sure to add the overhang length. The table only uses the unsupported distance between the ridge board and the wall. OK if you use good filler material I guess and not OSB. Rafter span tables do not include the length that extends outside the walls. For valley framing, I've seen guys actually shape the underside of the valley beam to pitch, and use fillers and combination cuts, doing away with the hangers provided. Hello I've worked on that type of framing with large and small crews, and I've seen different carpenters doing it differently. I would use I-joists again in a heartbeat. Span Tables for Rafters (to BS 5268-7.5) Imposed loads of 0.75 kN/m² snow load are applicable to most areas where the altitude does not exceed 100 metres (refer to BS 6399-3) Imposed loads of 1 kN/m² snow load are applicable to most areas where the altitude exceeds 100 metres but does not exceed 200 metres, but excluding parts of Scotland. It doesn't take long with a table saw and it saves a lot of time with webstiffeners. On both roofs I ripped beveled pieces of 2x and nailed them to the topplates so I didn't have to cut a birdsmouth. What I did was lower that rafter so the lookouts could run over the top One detail that is goofy is the gable overhangs. I've used 30' 2x12 before (a fair amount of 28' last spring) and I'd always go with I-joists if I can. What I loved is that they are much lighter thand dimensional. I'm going to post links to photo galleries. I drew up the roofs both in Autocad (not very well, but well enough) and then had the supplier do a real drawing with the specs. I'd try and design around that if I did that again. ![]() One of them we used skewed hangers at the valleys and they were about $50/pc. Note that these are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction.I've framed two roofs with I-joists and loved them both. applications according to the 2018 International Residential Code. This is the right way to fix truss clips connecting the rafter and wall plate. These rafter span tables provide the best reference to quickly and easily determine the maximum span for all grades of southern pine according to the 2018 International Residential Code. Vertical strapping at eaves pitched roofsĪt eaves level, vertical straps 1m long should be fixed as shown in the diagram opposite at a maximum of 2m centres. Effective strapping at gable wallĮach strap should be fixed as shown in the diagram opposite with noggins between the rafters to support the metal strap along its whole length. SPAN TABLES FOR JOISTS AND RAFTERS 3 AMERICAN FOREST & PAPER ASSOCIATION Table 9.1 Required compression perpendicular to grain design values (F c) in pounds per square inch for simple span joists and rafters with uniform load. Gable walls need to be strapped to the roof at the maximum 2m centres using 30 x 5m galvanised mild steel straps. This diagram illustrates the typical arrangement of a rafter and purlin roof and shows the dimensions referred to in the tables above. Roof pitch between 30 and 45 degrees strength class C24 Size of purlins in mm
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