Raise the Roof

[MarkV]

Any thoughts out there as to how to Raise the Roof on my out building? The place we bought came with an existing out building that is block construction and measures 19’ 6” x 38’ on the exterior. The roof framing is trusses with a 4/12 pitch on 16” centers with ply sheathing and a shingle roof. The problem is that the interior height is only 8’ which is too low for my needs.

I am trying to figure a reasonable way to add another 2’ of height to the building short of tearing everything off. The thought I have had would be to cut through the roofing between each truss or every other truss and jack up about 2’ adding a 2’ high framed wall between the block and trusses. If I can get the whole thing raised I would then add purlins and metal roofing.

So, what kind of problems do you see with the plan and any suggestions on how to do the jacking? No snow load worries here in Georgia.

MarkV

 

[RobS]

Why cut through the roofing? Could you build/borrow/rent some long beams to put under the trusses along each eave. Put them just inside the wall and lift the whole roof straight up. Build a short wall section on top of the block wall (2X4 conventional framing) then lower the roof back down.

I have no experience with this but it would be something I'd try if I were in your situation /forums/images/graemlins/smile.gif

 

[MarkV]

Thanks Rob,

I had thought of the same plan but just could not figure out how to jack up 40’ of roof at one time without having to buy some expensive equipment I would never use again. I’m not even sure how to jack smaller sections 2' without special equipment.

MarkV

 

[Kevin_in_VA]

At almost 20' by 40' that is an awful big roof to try and jack up.

One solution would be to convert each truss to kind of a modified scissor truss with the roof in place and remove the lower rafters. This would open up the ceiling quite a bit.

Another solution would be to re-inforce the trusses further up by adding a second rafter at the proper level, perhaps at the peak as well along the entire length of the roof, in effect adding a ridge-beam to the interior of the roof and then removing the original rafters.

The benefit of these two plans is that all of the work could be done inside, weather would not be an issue.

Kevin

 

[RobS]

Ever seen a house moved? It's amazingly low tech. You're looking at the same thing except you're only going up, not down the street. With steel prices the way they are, you could probably buy some beams, use them and resell them later for more than you paid /forums/images/graemlins/shocked.gif

For lifting, I'd build up some platforms in each corner and in the middle of each eave wall. House movers use timber cribbing which is easy and strong. It would take a lot of it but maybe rental/borrowing is possible? Actual jacking is remarkably easy. I've seen entire houses raised with just a couple of 50 ton bottle jacks. The key is to to it a little at a time. That's where the cribbing comes in. Raise one side four inches, insert new cribbing and lower. Use the same jacks to do the other side. Repeat until you're high enough.

Come to think of it, sounds like a great TBN get-together project! Where are you located /forums/images/graemlins/smile.gif

 

[MarkV]

Kevin, fortunately here in Georgia we can work outside year around for the most part and even if opened up it would not be a big problem if things got a little wet. I understand your suggestions but I don’t think that would solve all the height problems I have. If I was going that far I would most likely take the whole thing down and reuse the trusses.

Rob, you or anyone else is welcome to make this a TBN project. I have a feeling that Michigan to Georgia is more than you might want to do. On the other hand if I do it in January our weather compared to yours might make it seem close enough to entice you down this way.

Thanks for the suggestions.

MarkV

 

[bczoom]

MarkV,

IMHO, personally, I'd do something like what Kevin and Rob are suggesting.

In your original post, you said "If I can get the whole thing raised I would then add purlins and metal roofing." Was this an intent (replacing the existing shingled roof)? If so this may change things. You just rip off the plywood, remove (and save your trusses (take off the roof or move all to one end), build your 2' up, put trusses on then continue with purlins and metal roof. Even if a couple trusses get destroyed, with no snow load and metal roof, you could probably re-install the trusses 2' on center.

 

[Currmudgeon]

About 20 years ago, we dormered a f(r)iend's house, raising about a 20 foot section of roof. We used two hi-lift jacks and a bunch of 2x4 struts. We just walked them, at a constantly steepening angle, across the floor, and anchored them with temporary 1x4 cleats.

I think you could do the same thing with your outbuilding. Cut the roof trusses loose from the walls, and use jacks. Lift a little at a time, and keep adjusting your struts. A timber structure like that is pretty flexible, just stop jacking when it creaks too much, brace, and shift the jack to the next point.

For something your size, I think I'd use some doubled 2x12 beams to jack from and slowly walk the thing up, then put in prefabricated knee walls.

I think I'd invest in a couple of come-alongs to be used to hold the roof down. If an unexpected wind comes up, you don't ant to be chasing your roof across the County. /forums/images/graemlins/blush.gif

 

[chucko]

I have seen whole roofs biger than that set at one piece with a crane

in the lower section of this you can see some lite gage steel trusses about to be set
http://www.alpeng.com/testimonials.html?todo=item&id=22

 

[Bob_Skurka]

MarkV . . . there are companies that do nothing but jack up buildings or parts of buildings. I just watched an episode of THIS OLD HOUSE and they jacked up an entire barn, put a new foundation and floor in, changed a few other things around and then lowered the whole thing back down. I would not try to do it myself, but it sure was fast and amazing to watch on TV. They crew came in built some interior frame work, tied everything in structurally, and used some well spaced hydraulic jacks and a HUGE pump in the rear of a truck.

I think you might want to call around and see if there is someone like that in your area. If there is, they can come out and lift your roof 2.5' so you can build a 2' wall, then they come back and lower it down onto the new wall. The entire roof and structure would be reused and you would not even have to reshingle.