![]() And a guy could certainly add one on every rafter section too for that HD upgrade. I suppose this would vary depending on snow and wind loads too. # Posted: 13 Mar 2016 13:12 - Edited by: toyota_mdt_techĪlso, a added note, in my cabin, a collar tie was on every 3rd rafter (with 16" OC spans) and if you have a 24" centers, every other one. In terms of my last point, I'm not sure why this seems so rare in my searches. In terms of eliminating both collar ties and ceiling joists or mostly eliminating them the collar ties, (which I want to do in removing a cabin's ceiling) rare are the photos of 3 beams - a ridge beam with two outlying beams, one on either side midway up each side. I also see larger beams going from wall to ridge, spmetimes with a large exposed ridge beam, sometimes not. However, in searching google images of open beam and cathedral ceilings, I see lots of photos of ceilings where the ties appear to sit about half way down and there are no ceiling joists/rafter ties. Stud grade lumber has the least resistance to bending of all the commonly used lumber grades. If there is a kneewall with rafter loads being applied above the loft floor wind forces may total up to exceed the carrying ability of wall studs. Wall studs are meant to support axial loads, top to bottom, as well as wind forces against the wall. The so called kneewall above the loft floor results in increased side forces on the side walls. Loft floor joists across the walls that are below the side wall top plate do not count as rafter ties. This will sometimes result in requiring a larger size rafter. When rafter ties are raised to increase headroom corrections must be applied to the rafters. Rafter span tables are calculated assuming the rafter ties are located at the bottom across the wall tops in other words. With a pitch of 12:12 the downwards and the outwards forces are equal. The lower the pitch the greater the outward horizontal force. Some of that force is down the wall and some horizontally outward. Loads on the roof, snow, wind, rain are transfered by the rafters to the wall top. Rafter ties keep the wall tops from spreading apart. Rafter ties are located in the lower third. Collar ties keep the peak together, metal hurricane ties keep the eves connected to the walls. ![]() High winds blowing over a roof up to the ridge can act like an airfoil, causing lift forces. The collar ties help keep the roof together at the peak. That should be self explanatory, but take note that the collar tie is in the top third of the space. ![]() Thay are not the same, they are not interchangeable. I have found some confusion out there when it comes to these two vital gable roof components. This discussion/tip concerns gable roofs and their collar ties and rafter ties. Small Cabin Forum / Cabin Construction / Collar ties vs rafter ties Forums - Register/Sign Up - Reply - Search - Statistics. ![]()
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