In other words, don't even start if it doesn't give easy. The walls might not want to move and you could splinter a rafter trying. Cut the lengths and rig up the turnbuckles before you go up in the attic.Ĭheck ceiling edges before pulling the walls in. Too hard to work with.Ĭutting cable up in the attic with an angle cutter could start a fire up there. 'Strawline' is heavier but will not dig in. Or use a short loop of cable and clamps to attach the turnbuckle.įor cable strength, 'airline' cable, the type you might use on an electric winch, could be good, but it will cut in to the wood, unless you lined the hole with a piece of pipe. At the other end you could bolt the turnbuckle but it will pull sideways, unless you add a horseshoe-shaped strap like a yoke. If the wood is soft you may need to install brackets instead held with several thru-bolts. The hole should be as close as possible to the outer edge, the sheathed side. The attachment could be simply a hole in the rafter with cable threaded thru it and secured back to itself with at least two cable clamps. I am not an engineer and this is no substitute for an engineered design. So, I want to know how strong a cable to buy and if a single attachment point to the rafters is adequate.ġ4 rafters (not including the gable rafters), 24" oc 2圆 This site formula gave me thrust of 1250 I have a bad back and cable is so much lighter too. One would be easy, more requires a special designed fastener.Īnother reason for not using wood rafter ties is that I would need to cut each rafter into three pieces to get them thur the attic access hole. Now, Im not sure how many that i need to connect the cable to the rafters. Using enough fasteners to hold it secure. Can someone help?Īlso, many sites discuss the number of nails/screws/bolts that are needed to fasten wood rafter ties. I have spent many hours trying to figure this out. Its most likely because I am using the formulas incorrectly. I have found several formulas on the net on figuring side thrust, but each i use gives different results. I have two unresolved questions concerning using cable. I do not plan on trying to take out all the sag (3'), just a little to remove some existing pressure on the side walls. I have a string pulled straight across the ridge inside the attic. Cable is stronger and will allow me to remove some of the pressure on the side walls, using a turn buckle I can pull up the roof slightly. In my research, I have discovered the idea of using cable instead of wood for the rafter ties. So, I decided to add the rafter and collar ties too. Vertical rafter supports and then a new roof cover too. However, Im adding hurricane straps, supports for the gable ends, and extra fasteners to hold the roof planking to the rafters. The roof does not have much sag and the walls have no apparent bow. The ceiling joists run parallel to the roof ridge. Every time Im in the attic and look around, I wonder what holds up my roof. Im planning on installing rafter ties in my 1952 cinder block home.
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