![]() ![]() 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. Collar ties, contrary to popular belief, do not prevent walls from spreading.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.Where they are required, they should be installed on every other rafter where rafters are on 24-inch centers.Collar ties are probably not needed if approved metal connectors were used to fasten the rafters to the ridge.InterNACHI inspectors should not call out a lack of collar ties as a defect unless they know that collar ties were required in the jurisdiction where the home is located at the time the home was built. ![]()
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