3/28/2024 0 Comments Insulate rafters to roof tiesWhat is more cost effective depends on local cost of materials and labor and if you are DIY. If stick framing you follow IRC 2012 "Ceiling and Roofs" span tables, etc, or whatever your jurisdiction requires, or, you have cost of a PE which can be expensive.If you do so by the time you do it right and are done adding the perlins and collar ties you have a truss or close to it and probably need an internal load bearing wall if spanning over 20' tributary, 40' max total span between outer walls. The height for some mfgs can be limited by assemble jig tools and drive one into a piggy back truss or lower chord pitches and most will PE stamp the designs as part of the cost. Long story as to why I will not get into. Last one I worked in clear spanned steel 400'. You can see this in any clear span build using metal or wood. 2x2 stringers and 3/4 rigid insulation on the inside (creating a channel for soffit to ridge venting), plank/drywall the inside and blow it full of nice cheap, eco-friendly celullose insulation.įraming - Scissor trusses are by far much stronger and can span much longer distances than stick building rafters. You have built a vaulted parallel cord truss (google the pic). Instead of dimensional lumber you buy/build parallel cord trusses, to whatever width you need (mine are about 16"). Voila: no more outward push, roof load is pushed directly down on the walls. You then rest your rafters on that and on the wall. You need a single purlin at the top of the roof from one end of the house to the other (great place for a decorative log). I hit upon the perfect solution for me.It should work for you too. Then you still need occasional horizontal ties to keep your roof from pushing your walls apart We don't want to build a false roof or false ceiling, but even with 2x12 and sprayfoam (10.5" x r6) you can barely get to the r60 I need in my state, and that's outrageously expensive and heavy. The problem is the rafters are too small to get enough insulation inbetween. You're right in wanting to use rafters to create an a-frame effect inside and out (instead of those fake scissor truss cathedrals) I am mostly done building my A-frame house with a cathedral ceiling. How does one go about dense packing sawdust in a ceiling? I live in timber rich south central Kentucky and can get my hands on unlimited amounts of sawdust. I can structurally use 2圆's to frame my ceiling but something with a little more depth may be better like a 2x10, so that more insulation can be packed in, I am guessing. I have thought about many of these aspects extensively, but I can't seem to come up with a good solution.Ĭan I avoid using underlayment beneath my metal roofing with a type of rain screen? Has anyone done this and if so, how? Of course the majority of heat is lost through the roof so I want as much insulation as possible. Conventionally the easy fix is bubble wrap, felt etc, but if I can avoid that as well I will want to. I have seen first hand the amount of condensation that can happen in these types of systems when the cool air from outside meets the warm air inside and most definitely will avoid that at all costs. I have a 16x26 cinder block cottage, currently in build phase, that I would like to put an A-frame style roof on with two dormers and maybe a small loft depending on how steep I want to go with the pitch. Hopefully my subject line is fairly self explanatory.
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