Replies

1. 
   Guest_ | Oct 23, 1999 10:46pm | #1

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   Ken,

   Without knowing the pitch of the roof or the length of the outlook tails all I can give is a "guess". It's not so much the "bending" of the 1/2" plywood as to "what" will kept it in that shape. On top of the rafters there is probably a curved piece of solid blocking to produce the curve. It could also be 2 layer of 3/4" plywood. The 1/2" sheathing follows this to produce the curve. Probably something like the graphic below.

   

   Joseph Fusco

   View Image

   "The price of apathy towards public affairs is to be ruled by evil men." -- Plato

2. 
   Ken_Klingman | Oct 24, 1999 12:16am | #2

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   I wasn't sufficiently clear. Here's a line drawing of what I meant. Note that I need a concave bend to the plywood.

3. 
   Guest_ | Oct 24, 1999 01:42am | #3

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   Ken,

   That's a Unique detail, one I have not seen before. There is a produce that goes by several different names, "wiggle" board is one. Ed Williams referred to it as "bender" board also in a different thread. This produce come in 1/2" and would work well for your situation, you could a could also kerf the back of the plywood as you have mentioned. How well the joist tails are cut will play a large roll in how well the bend looks.

   P.S. It think the graphic I put up is "concave" and the one you put up is "convex" but, I have been wrong before, this wouldn't be the first time. ;-}

   Joseph Fusco

   View Image

   "The price of apathy towards public affairs is to be ruled by evil men." -- Plato

4. 
   Ken_Klingman | Oct 24, 1999 02:09am | #4

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   Whoops, you're right. I usually remember concave as in "caved-in", but must have slipped a gear there.

   My concern over the "benderboard" product would be the rigidity of the roof sheathing. I don't know how the benderboard product stacks up against plywood. Of course if I kerf the plywood it's probably no stronger than benderboard.

   Ken

1. 
   Ron_Budgell | Oct 24, 1999 05:06am | #5

   *The same detail appears on a house next door to where I'm working now. Their rolled edge is on the eaves and also all the way up the gables to the ridge. It took somde clever roofers (almost seems a contradiction in terms) to deal with the lower corners and the ridge, but they did, and very succesfully, too. That house was built in 1922. I dare say the builders used board sheathing and it would probably still work today. Something like a 1 x 3 laid across the rafter tails might not show any sign of ridging after the shingles were on. A couple of runs over the joints with a power plane would take care of it, anyway. If your rafters are too far apart for 1 x anything, then you could even use 2 x 2 and cut down the first piece or two to match the roof plane. Running up the gable is the same thing. The board sheathing would be fastened to tacked-on lookout stubs. Cutting a curled rafter stub for the corners is a hip rafter problem with a twist, so to speak.On the right house, it's a real eye catcher. The house next door to my jobsite is beautiful - pink with red roof shingles.

1. 
   Ryan_ | Oct 24, 1999 06:41am | #6

   *I think concavity is a matter of whether your above or below the roof.What exactly is "bender board"? I've never seen it before.

5. 
   Guest_ | Oct 24, 1999 08:30am | #7

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   Can you bend that radius with 1/4"? I havent tried it on anything that severe but I've used two layers of the stuff to match up with 1/2" on lesser bends, more like the one Joe showed.

   JonC

1. 
   Guest_ | Oct 24, 1999 08:32am | #8

   * Ryan,

   If you stood "below" the roof you might not see the curve at all. . . Since any curved area has both concave and convex surfaces, the "working" or "reflexive" side would take precedent. In a radar or satellite dish the structure is referred to as "concave", simply because of it's working end. Prospective/position or orientation as little to do with it.

   As far as "bender board" goes. . . You would need to ask Ed Williams.

   Joseph Fusco View Image

1. 
   Guest_ | Oct 24, 1999 09:07am | #9

   *To me, concave means you can make the bend by having a fat guy stand on it while you fasten it. For convex, you may need to attach the fat guy to the edge of the material to be bent with lines and push him over the edge. My lifelong exposure to gravity sometimes limits the way I percieve the universe to "up and down". This is especially true anytime my feet leave the ground.So can you bend 1/4" ply in an 8" radius or not? I'm sure someone on this board has at least tried it.JonC

6. 
   guido_sardonic | Oct 24, 1999 09:16am | #10

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   Jon

   Does the fat guys fat wife sing while you're pushing him over the edge. . .do fat guys bounce back up when they hit bottom necessitating faster fastening. . .is faster fastening more fascinating the faster you fasten. .. does the fat lady sing faster the faster you fasten???

   curiously

   Dr.G./Alice (no)Rbt

1. 
   Ryan_ | Oct 24, 1999 06:37pm | #11

   *I believe that concavity, like time is relative to the observer.-Ryan

1. 
   PRP | Oct 24, 1999 06:59pm | #12

   *Ryan: Ed. Williams described "benderboard" in my post on 'Who works w/ Plwd?,' - I think it is the same product that I described as 'flexible plywood.'Regarding the curved end rafters and sheathing it, I think that since plywood wasn't used on homes until more recent times that this would have been done, as Ron described, w/ a 1x material. I know you said this house has seen many remodels and that this detail is one of those, but I think you can do either detailing method described above. But if you have the thickness to do this, why not do both; a board sub-roofing topped w/ the plywood? This way, if the underside of the roof is exposed (no soffit) you can choose the board look, and the thinner thickness of plywood would be easier to bend. I've never done this before, but I think it is strong enough to work.Phil

7. 
   Guest_ | Oct 24, 1999 08:31pm | #13

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   Ryan,

   Time maybe relative but, relatively speaking, you'd be hard pressed to get a radar dish to work on it's "convex" side. . .

   Joseph Fusco

   View Image

8. 
   ron_bnudgell | Oct 25, 1999 12:11am | #14

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   On the house in Halifax I described, the roof shingle starts at the wall - installed overhead - wraps around the curve up to meet the roof plane. I thought about this a bit more and decided that if it was my job, I would cut off the roof rafters vertically above the wall and install false rafters both at the eave edges and up the gables. That way, they could be installed low enough that the sheathing (I would prefer 2 x 2) would meet the roof plane without further screwing around.

   The roofers added a nice finishing touch on that house by tapering the cap shingles down to about 3" as they rounded the curve to meet the wall.

   I'm nearly certain the 1/4" bending ply will wrap around a radius of 8", but I doubt it would add much here except cost.

9. 
   Ken_Klingman | Oct 25, 1999 12:11am | #15

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   I have a home that has been remodeled several times in the past, and which I'm about to remodel yet again. The last remodel left it with a very distinctive and very attractive rolled eave detail which I would like to duplicate in the planned addition.

   I can see pretty much how the previous builder cantilevered the joist ends another 16" out over the top plates. The ends of joists are rounded with an 8" radius. The parallel rafters are lined up with the joists and end such that the roof line slopes down to the rounded end of the joists. The composition shingles roll over this rounded end as well.

   Without dismantling the soffits or removing the existing roofing I can't quite tell how the builder rolled the first sheet of plywood roof sheathing over this rounded detail.

   I've considered sawing a bunch of parallel 1/4" deep kerfs in the back of the roof sheathing and bending it. I've also (briefly) considered steam bending it over a circular form.

   Anybody have any simpler ideas?