It is my understanding that in situations like the one I am about to describe, the savings in labor / current state of the supply of materials may make a roof truss become the most applicable option. Or there's a lot of extra bracing required.Good afternoon everyone, I was hoping for a discussion on the expertise / applicability of choosing a roof system based on structural serviceability. Yea that's my plan “B” if the architect wants to much. I would be more inclined to just insulate between the rafters and fasten the sheathing to the bottom of them. I would more than likely be coming off several different roof rafters to support each ceiling rafter and the job could probably be done with standard 8' lumber & plywood gussets. My brothers friend said the same thing! In-fact he pointed out that because of the way a hip roof comes to a point. In fact- I can almost guarantee that most of them would default to a spliced bottom chord - 2 8' or one 6' + one 10' -because shorter lumber is cheaper than longer. The way he explained him to me is: This guy works for a large company in commercial design, But he works on small home improvement type jobs from his home for several home improvement contractors & he's very reasonable. He gave me the name & phone # of an architect that he uses if anythings out of the normal and needs to be designed. I talked to a friend of my brother that's in carpentry (mainly porches & decks) and he also thinks it would be best to have it designed correctly. Nailing to the side of the rafter instead of sitting on the wall is not really significant.ĭoug ought to consult an engineer if he wishes to tie in ceiling rafters to the existing roof joists though. Having an engineer design it would probably be best but$$$? You could also say "the heck with all this noise" and use 2x8 #1 for the bottom chord, and 2x4 STUD for the webs and have no worries.ġ6' is far too great a span for 2 x 6 materials unless the structure is aproperly designed truss. You can also look up on-line any number of standard, simple, truss designs that will take into account your location. This also has the benefit of letting you know the proper grade of material - I'd think that, if anything, you and I would likely tend to under-spec the bottom chord grade, and over-spec the web grade. Especially if you tell them you want to buy the all the lumber and hardware from them - its not like the truss suppliers and building supply houses are exactly overwhemled with work in SE Michigan these days :D. If you went to a builder's supply place that sells engineered roof trusses, I think that - for a nominal fee - they could get the whole thing designed for you - it would take maybe 30 minutes on the modern design software their truss supplier uses. But in a DIY situation, pounding in large nail plates is a thankless task, so I personally would go with the longer board. In fact - I can almost guarantee that most of them would default to a spliced bottom chord - 2 8' or one 6' + one 10' - because shorter lumber is cheaper than longer. In fact, I'd guess the engineering design software would actually come out with 2x4 top chords and 2x3 webs including the weight and snow load issues you correctly pointed out - but your're not about to replace the top chords. In a truss, 2 x 6 top chords and 2圆 bottom chord with 2x4 webs would easily handle a 16' span. You need to consider the weight of the wood and finishing materials being added to your existing rafters with the anticipated snow load the roof may see. The new ceiling joists will be running from side to side same as the old collar ties, However the new ceiling joists will be coming from the roof's rafters instead of the walls sill plates.ġ6' is far too great a span for 2 x 6 materials unless the structure is a properly designed truss. All framing including the walls is 24” O/C.Īre you going to run the new ceiling rafters in the same direction as the existing ceiling joists / collar ties? Currently there are no ceiling joists just the two collar ties I mentioned before. There are 8 common rafters 2X6's at about 11' 6” each, (three on each side of the ridge board & one at either end) The rest of the framing is 2X6 jack rafters from the hip beams to the walls. The ridge board is a 2X8 & just over 4' long. The 4 hip beams are 2X8's and about 16' long. What is the size of the existing roof rafters? There's only one long 2X4 running from the top of the of the front door header to the back common rafter just above the back wall. Does the garage have existing ceiling joists or collar ties connecting the top plate of the walls to each other? No ceiling joists, Just two 20' 2X4's running from side wall to side wall.
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