Spf rafter span table3/20/2024 Please contact your representative to determine quantities. Refer to appropriate sections of the Specifier Guide for installation guidelines and construction details.The subfloor must be glued as per APA Specification AFG-01 or ASTM D3498 and nailed as per NDS, ICC IBC/IRC code. and is a “24 oc APA rated panel” for joist’s spacing of 24″ o.c. The considered subfloor is a “20 oc APA rated panel” for joist’s spacing of 12″, 16″ and 19.2″ o.c.Rafter spacing is the distance between the centers of two consecutive parallel rafters. Roof Rafter Spacing, Span, and Sizing Requirements. The indicated spans are based on the Allowable Stress Design method as per NDS, ICC IBC/IRC code. For a particular span, rafter spacing distance can vary based on the species of lumber, grade, and load conditions.Live Load deflection is limited to L/480.Total Load deflection is limited to L/240.Maximum spans are measured centerline to centerline of bearing and are based on uniformly loaded joists.Minimum end bearing length is 1½”, spans in bold require web stiffeners at OSB end panel.If the re-engineering is correct, the floors and roof will be fine with SPF. SPF cannot span the same distance as SYP, so you must have closer spacing, larger sized pieces (2x10 instead of 2x8, for example), etc. If it is for joists and rafters, big difference. The indicated spans are based on simple span joists. If it is for the studs in the walls, no problem.If your build has a permit inspector, then the first thing to do is check with that office and verify that your plan change is allowable.Live load: 100 psf / Dead Load: 15 psf / Depth: 16″ – Span table Live load If your porch is bigger or you have more snow in the area then a bigger beam or better quality wood will be required. Based on my assumptions and further assuming all my calculations are correct, it looks like a 4x10 will be adequate for that span. Your architect designed for the specific values for your area and those should be noted within the design documents. For a porch 8' deep and a beam span of 16', that equates to a design load for the beam of 1920 lbs. Assuming 10 psf and 20 psf respectively, that is 30 lbs per square foot. Multiply that by the design load, which is the sum of the dead load and live or snow load. Multiply half the porch depth by the beam span to get the area. The house is holding up half of the porch roof, and the beam the other half. The load that the beam must carry is determined by the depth of your porch and the design load for your area. BOXSPAN® Residential Span Tables Non Cyclonic up to N3 Wind Class Joists I Bearers I Rafters I Lintels I Roof beams Residential Guide.indd 1 4:59 pm. Using that value and a width of 6" and a depth of 10", the max load is 3140 lbs.įor reference, a 4x8 beam of EWP #2 spanning 90" like in the original design has a max load of 2840 lbs. A 6x10 beam consisting of three 2x10 nailed together has Fb of 727.35 psi. Using a built-up beam of three or more stringers nailed together allows a 15% increase in the bending fiberstress. Using that and a depth of 12" the maximum load for the beam is 2610 lbs. Download the free PDF guide and get started today. Going through the same process you will find that the maximum load for the 4x10 is 1970 lbs.įor a 4x12 beam the shape factor is 1.1, resulting in a Fb of 632.5 psi. Learn how to design wood joists and rafters with the latest span tables from the American Wood Council. Update that value in the calculator, and set the beam depth to 10". The loads are based on adjusted roof snow loads from the governing building code. You will soon arrive at the max load for the beam of 1375 lbs.įor a 4x10 beam of #2 EWP apply the size factor of 1.2 to arrive at a Fb of 690 psi. Rafter spans are tabulated for the most common roof loads. Add 100 lbs to the load and click Show Result. Now input a load of 1000 lbs in the top field and click Show Result. Input these values and keep them constant: Span 186", width 4", depth 8", fiberstress in bending 747.5 psi, modulus of elasticity 1,1 million psi, and allowable shear 135 psi. Now go to the beam calculator and plug in the relevant numbers. For a 4x8 beam (assuming rough cut so using full 4" x 8") the F b size factor is 1.3. Table 4A in the NDS Supplement has adjustment factors that need to be considered. These are base numbers that we may need to modify depending on the manner of beam chosen. For EWP #2 those values are 575 psi, 1.1 million psi, and 135 psi. The values we need to know are for Fiber stress in bending (F b), modulus of elasticity (E) and allowable horizontal shear (F v). Table 4A gives the reference design values for Eastern White Pine. The engineering properties for graded lumber species are codified by the American Wood Council.
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