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Roof sheathing boards

Started by TimFromNB, July 01, 2016, 05:46:00 PM

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TimFromNB

Hello there,

Long paragraph for a quick question. I apologize in advance.

I will be building a 14'x20' camp next summer and have the possibility to mill some free spruce and maple. To keep the initial costs down, I plan to build it in steps. The first year, my plan is to build the timber frame and sheathe, insulate and shingle the roof. The sheathing boards will be visible inside as the insulation will be rigid foam over the top (with some form of weather paper in between). I will temporarily enclose the walls to keep out the elements until the next summer, when I will hopefully have some more boards to enclose and insulate the exterior walls. My original thought was to use the spruce for 1"x5" and wider for the roof boards, however they will not be tongue and groove. I will be air drying them for 1 year. Should the sheathing boards be T&G or can I get away with tightly butting them together? If I can get enough maple, I will mill them to 1" and plane to 3/4" after air drying for flooring.

The other option was to purchase T&G for the roof and use the spruce boards for exterior wall enclosure in similar style as the roof.

Any advice is appreciated.

Thanks,
Tim




Jim_Rogers

Using boards instead of planks depends on what the rafter spacing will be. Some boards may need tongue and groove to help support the load. While with narrower spacing of the rafters you may be ok.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

TimFromNB

Thanks Jim. What is the difference between board and plank? I've checked online but can't really find the answer.

Thanks,
Tim

Jim_Rogers

Quote from: TimFromNB on July 04, 2016, 07:46:04 AM
Thanks Jim. What is the difference between board and plank? I've checked online but can't really find the answer.

Thickness. Boards are usually 1" thick, planks are thicker like 2" and up to 4" thick.

http://youtu.be/KoBwMYXMIm0

There are other videos about definitions of lumber after this first one, as others advised me that some of mine needed clarification.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

TimFromNB

Great. Thank you so much.

Tim

ppine

Traditionally, the old shake and shingle roofs had no sheathing, but simple 1x2s across the rafters. This allowed a lot of air circulation, and many of those old roofs lasted 100 years or more.  For a rustic cabin in the bush, it would save a lot of work and material to do it that way.
Forester

TimFromNB


bluthum

Square edge decking under shingles does have some issues. Assuming it is strong enough [unmatched] for the span between rafters the next problem usually happens when roofing nails land in the joint between the boards.  This can happen in a line and the nails may actually work back out through the roof.  Getting the board side joints tight is almost impossible unless the boards are resawn after drying. Also no shingle manufacturer is likely to honor any warranty claims [so what though].

Having said all these downsides I wouldn't be afraid to use unmatched boards in some situations. Up to you to decide [unless there are codes to deal with] your situation but long story short matched boards decks are best.

sbishop

Tim, which part of NB you from?

If you can get T&G that would be better, especially if you are looking at it from the inside.

Sbishop

TimFromNB

Quote from: sbishop on July 09, 2016, 06:18:10 PM
Tim, which part of NB you from?

If you can get T&G that would be better, especially if you are looking at it from the inside.

Sbishop

Hi Bishop, had not seen your post and came across this while reviewing some answers. I am in the Moncton area. Yourself?

Brad_bb

Tongue and groove increases the load capacity of the roof because when boards are locked together with T&G, multiple boards share the load.  With no T&G, you are depending on the bending of a single board.

If  you go T&G, I recommend UDL 50 Titanium roofing synthetic paper(more plastic like than paper).  I use SIPS over this but I put a firring grid of 2X spaced 2'x2' over the paper to create an air space between the paper and the sips.  I use this space to run conduit for electrical for lighting etc. After installing the sips, I also then put a similar grid on top of the sips and then the metal roof is screwed to that.  The gap/air space acts as a cold roof and allows any moisture to run down/evaporate/breathe.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Don P

I know a lot of people like to create that breathing space under a metal roof, I've done it both ways. Another way to think about it and the way I've moved to is to seal the metal roof down to the deck using the foam closure strips bottom and top and not allowing it to breath there. The metal is often below dew point in the mornings, think about how often you see dew on the top surface in the morning. By venting under the metal that moisture is also condensing under the metal. If it is sealed to the deck that isn't happening.

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