What is the best way to temporarily remove rafter ties (attic joists) to replace them
SLCraftsman
| Posted in General Questions on
I am getting ready to upsize my attic joists and I would love to be able to remove everything and get all of the demo done and have everything open before installing the new joists and supporting walls below, but I don’t want my walls to push out in the process. The house is 22’ x 28’ and there is no ridge beam. The rafters are all 2×6 and the pitch is 12/12. The new joists would be installed within a day or two of removing the old joists and there won’t be any live loads or snow loads on the roof.
What would be the most efficient way to get the old stuff out while still keeping the structure from being affected?
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Replies
Generally, the old joist remains in place and the new taller joists just sit next to the old ones. This is the safest plan as the building is only made stronger.
Assuming the ceiling is down and the old wiring has been removed fitting them in should not be that hard.
Walta
SLCraftsman,
You definitely need to temporarily support the roof if you want to remove the rafter ties. The two solutions I can think of are:
- Provide support for the ridge board - either posts or a stud wall. These need to bear on existing parts of the structure that can carry the loading down to the foundation. The attachment of the existing roof rafters to the ridge board may need to be beefed up too.
- Remove every second rafter tie and replace, then repeat the process.
I don't see any scenario where you can entirely clear out the existing ties and assume the roof diaphragm will be sufficient to guarantee the walls won't spread.
One at a time -- one out, one in. Measure the distance precisely, if it changes use a come-along to pull everything back together.
I've used tensioned chains for this in the past, but it's a hassle. It's easier to do it the way DC mentioned, going one at a time down the line and being careful that nothing bows out too much with each one. Normally I just sister things in place though, which avoids the issue entirely. If that's not an option for you here, then I'd try the 'one at a time' method. The tensioned chain way it complicated, gets in the way, and needs STRONG fasteners at the end -- much more than just your usual eyebolt with a lag screw thread on the end. You need bracing at the tie points too. You're well into engineer territory at that point.
Bill