Raise the Roof

[Robert_in_NY]

By doing what you suggest the roof will be off 1/10 of an inch which isn't much but by the time the other side is raised the roof will be off at least .2". This puts addes stress on the jacks from the roof moving. It doesn't seem like much as the roof is only 20' but the majority of the weight will be on the lower side as soon as you start jacking it up. Then any twisting that happened when you raised the first side will transfer to the second side as soon as you clear the existing wall. So if it wants to kick it will do so right then. The other issue is bracing the stub wall, you will need the stub wall that was built to hold the first side up braced well otherwise as soon as the lower side is free and starts moving you have to worry about the stub wall moving. It can be done but in my experience it would be wiser and safer to raise the entire roof at once and build the wall out of block as you go. Then every 8" you raise you block the wall up and it is finished.

An 8" block gives you more surface area on top of the wall then a 2x4 wall will and is more stable then a stub wall so if something did drop it would be ok.

As for the roof that shifted, it is not that different. The roof still needed to be raised and if anything it was a much more difficult job. Cranes can tip but people fall off roofs every day. In my experience I have raised a lot of houses, replaced lots of broken beams in crawl spaces and jacked up a few roofs. I have a lot of experience with jacks and have had jacks kick out because of stress. While raising one side can work it is not the safest route and not something we would do on our jobsite. And I would much rather raise this roof if it is in good condition then to tear it all down and have to rebuild it. Anything can happen when you are working trying to remove plywood and trusses as well as resetting the trusses.

 

[Henro]

Robert,

I would certainly suggest that anyone reading this thread follow your advice, as I value your experience more than my "out of the box" analytical solution to the question... /forums/images/graemlins/smile.gif I am sincere in saying this.

One small, but interesting point. As the roof is jacked up, the weight felt by the wall that is still supporting it would likely drop a bit, and not increase. This is because the jacks supporting the roof, if they were inside the building, would carry half the weight of the roof section that was between them and the other wall, and all of the weight of the roof section that was on the other side of the jacks, hanging above the wall the roof was lifted off.

So it looks like as the roof started upwards, the weight on the wall opposite the jacks would drop, then natually start to increase again with angle change...

None of it really matters much, just a point of discussioin. Doubt anyone will try the "hinged roof raising method" anyway... /forums/images/graemlins/grin.gif

 

[Robert_in_NY]

You are right that the weight would initially drop on the hinge wall but only for a few inches depending on the distance the jacks are from the wall. Ideally the jacks will be as close to the wall as possible so you will be lifting the roof from the strongest part of the truss that you can.

Also, I didn't mean to come out and dismiss your idea as harsh as I sounded but it is my experience in this situation and I have tried a lot of different ways of doing things. Heck, I just jacked up two different porch roofs last week to replace the floors under them. One was 10'x32' and the other 9'x25'. I have one more small porch replacement to do this year. Porch roofs are a hinge roof lift /forums/images/graemlins/grin.gif Later.