3/1/2023 0 Comments Roof rafter brackets![]() ![]() I know you can get a spec supplied by the manufacturer, but this is based on coach screws to the topplate, but no accounting for fixing with bolts to a beam instead of coach screws to a standard topplate.Īs I understand it the uplift force is determined by the top-plate to stud connection and the rafter to top-plate connection which in an old house like ours was 2 rusted old skew nails so the rating is conservative and therefore spacing not really determined by beam size. The center bracket has 6 cleats each 21/4' wide. Love to know more about the engineering criteria for these things. Ensure uppermost hole is inset enough to allow for upper hip plumb cut setback. But the typical metal flyovers are spec'd with posts of limited bracing, and several extenda's! With wind loads of say N3-4 regions, I don't see a lot of resistance to racking, no matter the number of extendas used. A rafter may only be 90mm and bolting to such might be a bit challenging (to insert the bolt away from the rafter's edge). Then I wonder about bracing, and I know there has been argument before about the level of bracing required for flyover roofs. Would like an understanding of the calculation and alternatively, if the extenda is bolted through a hefty beam (in lieu of a standard topplate) then the uplift would have no chance of pulling the extenda off, and seemingly just two of these would be enough, rather than many. ![]() I wonder why many are spec'd or if it's simply only because these are coach screwed to the topplate. Finally, use a handsaw or circular saw to cut along the plumb cut, birdsmouth, and tail cut lines.I have found that specs for roof extendas typically are in line with spaced every second rafter, no matter the roof area. Then, trace the short side of the framing square with a pencil to mark the tail cut. After you’ve done that, rotate your framing square 180 degrees so that the 8-inch mark on the long side of the framing square intersects the line for the tail cut. Make sure the other stair gauge is resting against the rafter and use your pencil to trace the length of the tongue. Then, reposition your framing square so that the stair gauge of the tongue is on the pencil mark you made to indicate the full diagonal length of the rafter. Once you’ve marked the lines, use your pencil to draw the diagonal length on the rafter. ![]() Next, set the framing square on top of the rafter beam and use a pencil to trace the outside edge of the framing square’s tongue. To cut roof rafters, start by fixing the stair gauges on your framing square to the dimensions of your pitch. The calculator (or math equation, if you’re writing it out longhand) will only calculate the diagonal measurement to the edge of the building.
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