Need to demo a roof for an add a level. 7:12, 30 foot span, all 2×6 commons 1×4 sheathing with 1 layer of asphalt 3 tabs. Thinking about running a circular saw downhill between the rafters then cutting across and finishing with a sawzall into small/manageable chunks. Any problems with this? Would it be wise to put temp kneewalls midspan for support? Is there a better way? There is a better than even chance I’ll be doing this solo. Anyone done this sort of thing alone?
Thanks.
Jim
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Replies
I think I'd strip the shingles first to make cutting easier. If you can access the sheathing from the attic it might be easier to pry the boards up after making cuts at 8' or so. If you need to protect the inside from the elements and are working solo, I'd mentally break it into chunks that can be covered quickly.
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I just did almost exactly that, the only difference being this was a small barn and we flattened it first. However, the roof was 12:12, 2x4 on 24 centers, 1x4 skip spaced about 2" apart, no nail pulling possible due to the crystallization of the fir sap.
Using a chainsaw I cut vertically thru the skip, cutting the roof into 6' x 14' chunks (3 rafters + 1 foot of skip on each end). It was very quick and totalled my chain, but I sharpened it. My helper and I then lifted and stacked the 'panels'.
In your case you'll need to get them down on the ground. You could cut the nails at the ridge board and then attempt to pivot a 2- or 3-rafter section up and off the roof wall plate, but it may fall uncontrolled. Maybe the best approach would be to cut the skip between every rafter--that way you can lift the section and throw it.
The easiest way might be to get a boom truck and have them pick each panel as you cut it, and you could go with 10' sections that way. Save your back...
I like the idea of pivoting them over the side. I forgot to mention in my first post that a crane/boom truck isn't an option(at least for the far end of the house). That's how i've done them in the past but there is no way to get the rigging in there.
David,To clarify, did you cut through asphalt shingles along with the sheathing?
Jon Blakemore RappahannockINC.com Fredericksburg, VA
No, it was a corrugated steel roof and we stripped the metal off first.
If I had to cut shingles I would look into a carbide tipped chain. We have those at the fire house for roof ventilation, and they cut right thru everything. It helps that the saw has what seems like a 260-HP motor on it.
Now *there's* the best solution: Let your fire department practice roof ventilation on it. ;-)
-- J.S.
For better or worse the houses that we can use as practice burns are few and far between. First of all the EPA has to allow it. It has to be a sound structure in the first place, and there have to be minimal exposures (other buildings, large trees, etc.). There has to be enough room for a lot of apparatus at the site. We've had a few to burn, and a few others to cut holes in. The Stihl chainsaw on steroids with the carbide teeth is truly a vicious instrument--you can plunge it thru a roof covered with layers of shingles, and not even notice when you (accidentally) cut the rafters.
So it sounds like the OP might actually be able to work a kind of "Tom Sawyer" deal with his FD to do some roof-cutting-only practice. At least worth asking about.
-- J.S.
I suppose it's possible. Their goal might only be to cut the recommended vent openings without cutting any framing. If it were our department we would be cutting out ~ 4' x 4' chunks of ply and dropping them into the building. We would destroy the gutters, but that probably doesn't matter. It definitely wouldn't be a substitute for well-planned demo.
Did a similar roof, but was plwood sheathing instead of plank. Used an old circular saw and a sawzall. Cut the ply in half (4'x4') and tossed them into a dumpster, dropped close to the roof. Took me and a laborer about a day for a 40' x 24' 6:12 roof.
Jim,
I like the approach you suggest. The cost of blades might grow but time is typically of the essence when taking off the lid. Go for it.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Don't bother stripping the shingles.
You can saw through the shingles and sheathing with a circular saw with inexpensive carbide blades. You can get the nail cutting blades, but they are thicker and are harder on the saw. Just stay away from the obvious path of the hidden shingle nails. We use Skil Mag Worm Drives for this.
Remove the shingles and sheathing about 24" down from both sides of the ridge to give you access to the ridge.
Remove the gutter and faceboards.
Saw vertically halfway between each rafter through the ply and shingles from top to bottom of roof.
Cut through the rafter near ridge.
Lift rafter off with sheathing and shingles attached. If you keep your dumpster close, you can toss the whole thing in at once.
When you are making your cuts, you immediately remove each rafter and work your way from one end to the other.
It's best to stick to using the circular saw for as much of the cutting as possible. Sawzalls will slow you down. If you need to cut the rafters in half because of the weight, then remove the sheathing at the cut point from one end of the roof to the other to give you access to cut the rafter with the circ saw.
It's nice to have the full rafter length for leverage to lift and pull the rafter nails out of the plate
We usually can have 60 lineal feet of gable roof stripped to the plates in about 2-3 hours using this method.
carpenter in transition
Tim,Exactly the advice I was looking for. This will work perfect...except for the dumpster location. I'm gonna have to hump the debris about 75 yards down range.Thanks.
Jim
Edited 2/15/2006 2:32 pm ET by Jimcope
Is any of the lumber worth saving? Maybe pick up a day laborer to strip it?
-- J.S.