Originally Posted By: Amy Limbacher This post was automatically imported from our archived forum.
We are building 20 x 34’ 1 1/2 story cottage. We want to leave the area above the living room/kitchen open. It spans 18’ long by 20’ wide. Our question is about the use of rafter ties. We understand that they are neccessary to include, but we wanted to preserve as much of the open look as possible. A builder gave us the idea of using cables with turnbuckles in place of the rafter ties. These would be screweyed into the rafters and tightened by the turnbuckles. Has anyone heard of this method? What is your opinion?
Originally Posted By: jpeck This post was automatically imported from our archived forum.
First, they would not be screwed into the rafters. They would need to be through-bolted to the rafters.
Second, I would not want to use cables, if one broke (unlikely, but it could) or came loose, the cable could whip around, cutting in half anything it hit.
Solid rod would be better. I've seen that done.
That said, we have a couple of engineers here who could provide a better answer than mine. Robert?
Originally Posted By: rfarruggia This post was automatically imported from our archived forum.
I dont see a problem with using properly sized and attached (through bolted) cables. The tension exerted on each individual tie is not that great if all of them are balanced. Using turnbuckles for periodic retightening is a must. As for them breaking, well, Roebling used pot steel cables (as opposed to Bessemer process or stainless steel cables) on the Brooklyn Bridge. Seems to work O.K.
Just be sure to use at least two wire rope clips on each termination of the wire rope and use wire rope thimbles where needed.
How to apply clips:
The correct way to attach U-bolts is shown at the right, the U-section is in contact with the rope's dead end.
Apply the first clip one base width from dead end of wire rope, the next clip as near the loop as possible. Space additional clips if required equally between the first two.
Apply the initial load and retighten nuts. Rope will stretch and shrink in diameter when loads are applied. Inspect periodically and retighten.
IMPORTANT: Failure to make a termination in accordance with the instructions, or failure to periodically check and retighten to the recommended torque, will cause a reduction in efficiency rating. Never use any wire rope clips to directly connect two straight lengths of wire rope.
You aslo could used threaded steel rods with conbination turnbuckles/clevis hangers. These will probably look a hell of a lot better for an interior application. check www.clevelandcityforge.com