Craftsmanship in Wood

Building a couple of sheds this winter, by code in the here in the Columbia Gorge scenic area they must be under 60 sq ft, less then 10' tall, to go up without a permit. So, intent is to get the maximum possible livability out of 60 sq ft. The shed is intended to serve as shelter for camping out while building the main house storing a few tools, making coffee when it rains... plus, just an excuse to build a cool shed!

The thought on the roof is to use laminated 1/4" marine plywood, built up to around 3" deep ... just getting started on possible forms. Anyone ever laminated plywood before?

The model is 1/8 scale.

One question: why choose to build the 1/4" plywood up to a 3" thickness? That's 12 layers of plywood, which will be excessively strong -and excessively heavy- for the application. If water ever gets in there, and the bonding between plywood layers is imperfect, the interstitial spaces will wick moisture very effectively.

If a thick eave edge is what you want -and I agree that it is a pleasing look - wouldn't it be more efficient to frame in the eave perimeter strips and then build up the space in the roof membrane in a hollow-core fashion, topping off with plywood and then the roofing material?

What roofing material are you looking to employ?

I'm wondering if plywood is even necessary at all... Why not use narrow decking boards in the same way (it appears) you built the model? If the sharp corners of the boards would show through the roofing material it seems like little work to knock them down with a hand plane, power plane, or belt sander. If you don't want to see gaps on the underside it might take a some fiddly work to fit the boards together (beveled like staves in a barrel), but it would look sweet, and probably not be more work than 3" of plywood.

I too am wondering if you meant for the whole roof to be 3" thick, or just the perimeter.

Thanks Chris -

The span is just 7 feet, so maybe we reduce the lamination to just 2 in. thick? Would this be overbuilt do you think? The plan was 2.5 x 3 in. lamination. The wall framing is to be 3 x 4 and 3 x 3, so the thought was to keep the roof framing in scale with the rest of the structure.

I am not sure about a hollow core, do you mean a box beam type of framing? We are trying to keep as much clear space as possible to make room for a small sleeping loft.

As it is planned now, the decking is to be 1x4 bead board, followed by a membrane - Ice and water shield, and then asphalt shingle or roll roofing. The shed is not insulated.

Hopper,

The deck boards are to be 1 x 4 T&G, this size seems to form to the curve with very minor gaps... the thought was to use a set of 4 laminations, spaced 34 in. apart. Stretching the spacing a little for 1 x 4 T&G. The shed is just 7 ft x 8.5 ft.

Oh! You're talking about laminating the rafters, not the roof deck, right? I get it now.

Seems like laminating the curves in a form with horizontal plies (as I'm interpreting your intent) would be a more efficient use of material than cutting from solid or using vertical plies. But maybe vertical plies with staggered joints would be easier to construct? You could use cheaper, thicker plywood that way. I would just glue and screw the plies together. The screws could be removed after the glue dries if you want.

There would also be some springback to be accounted for with horizontal plies.

Aside from that I'm not sure I have any more useful advice... Anybody else?

Ah, so your intention was to laminate plywood to form rafters? I thought you were planning to construct the entire roof out of plywood sheets stacked up to 3" thickness.

If that was the route you were envisioning, then why not obtain some LVL and cut the rafters out of that?

Would prefer to use solid wood myself for something like that.

Yes, laminated plywood to form rafters. LVL lumber would work also, I hadn't thought of that. From what I remember the stuff smells bad and leaves nasty slivers though.

I would be interested in solid wood, and had thought about how to do this but abandoned the idea. All my thoughts involved cutting segments out of 2 x 12 and bolting them together. Seemed heavy and an invitation for warping and cracking.

The plywood laminated rafter idea was inspired by a camper I saw built last summer. Very light construction and lots of head room.

[img]C:\Users\User\Desktop\IMG_0324.JPG[/img]

The solid wood framing I have seen seems very heavy. Hard to get good headroom. Is there a lighter option?

[img]‪C:\Users\User\Desktop\IMG_0325.JPG[/img]

Here is a solid wood arch, I like the lines but very heavy and not much headroom...

Well, if the timber rafter sections impinge headroom more than you would like, then the options would seem to be:

-use a harder and stiffer wood for the rafters which can be employed in a smaller section size.
-use another material, like metal, which can be employed in a smaller section
-rise the wall plate so as to raise the roof

If the 'heaviness' of the rafters is objectionable on visual grounds, then one good solution to that is the Japanese double roof system. If the same sort of roof structure was done in Japan, say on an entry gate, the double roof system would be employed. Makes for a considerably more complex structure mind you.

Otherwise, the solution to this problem could be found in the realm of boat building. If you're happy using plywood, there are numerous possibilities i would think.