Board sheathing a roof with green pine

[eastbayamateur]

Hello all,

I'm in the planning stage of building a 28x30 garage on my property in Rhode Island. My plan is to build out of locally milled Eastern White Pine, probably green. (There is a wonderful place "over the border" in Massachusetts.) 

My plan right now for the assembly:
- 1.5 story main building, 16x30
- 1 story "shed" workshop on the side, 12x30
- stick built, 2x6 24 inches o.c.
- the main structure will be balloon framed to prevent roof spreading
- sheathing will be diagonal 1x pine, covered with tarpaper
- siding will be 1x board-on-board or board-and-batten pine

I am not a builder, but have done a fair bit of renovation and repair (bordering on rebuilding) my 18th century house. I like the solidity and drying capacity of solid pine, it brings back childhood memories, yada yada. I especially like (1) the price and (2) the fact that I can wrangle pine boards up and down ladders without too much trouble, unlike say plywood.

General question: Am I way overbuilding this thing?? I would like it to be a solid barn/workshop for many years, and maybe something that can be converted into a house by a future generation. More immediately, I plan to use the upstairs as a part-time office, so having that weathertight and insulate-able is a must. But my plan right now means 2-3 inches of solid wood outboard of the studs.

Specific question: How do I handle the roof? My plan right now is to use asphalt shingles, though I'm not stuck on that. I am planning to use common rafters, 24 o.c. and stacked on top of the studs. I will run either steel strap bracing or let-in 1x4s as diagonal bracing. Then horizontal pine boards (rough, not t&g). Again, I'm not a fan of wrestling with plywood, and I like the ability of the pine to dry out (from internal condensation or, God forbid, leaks).

Questions and input very welcome. You can also send me elsewhere. 

[Nebraska]

So no top plate for the rafters to sit on? 

[GAB]

eastbatamateur:
Wet wood will shrink.  If you properly stack it for a few months and allow the wood to lose a good portion of its moisture the shrinkage will be less and therefor the openings between the boards after it totally dries over time will be less.
Just a suggestion.
GAB

[Jeff]

This is whitepine, nailed up as it was sawn.

[eastbayamateur]

@Nebraska Yes, it will have a top plate ... but the rafters will be placed directly above the studs, not offset. 

@Jeff and @GAB I know that the green wood will shrink. Just not sure if that makes a significant difference for the performance or longevity of the roofing material. In other forums folks recommend board sheathing only for metal roofs. Wanted to know if anyone had input on that.

For more background, my current garage is an 18XXs stable. It was moved about 60 years ago and placed on "temporary" half-blocks that became its permanent foundation. Today it is worm-eaten and racking, and the roof on it is at least 30 years old. But the board sheathing is still mostly working well and you can't see any daylight. 

@Jeff that looks great! 1x or 2x ?

[Jeff]

6/4. Or 1.5" I used cedar shakes for roofing

[Wlmedley]

I can't speak for pine but I've used green poplar for roof sheathing on a couple buildings. One I used metal roofing on and even though there was quite a bit of shrinkage it didn't effect the roofing any. The other one I used shingles on and the only problem I had is my drip edge which I ran across the bottom and up the sides buckled where I ran it up the sides causing my shingles to pucker a little. If I did it again I wouldn't put drip edge up the sides.

[Rhodemont]

I am not sure by your post if you plan to use local green pine for the framing.  If you are, check that you can get a building permit (if you plan to) for framing with local lumber.  Coventry requires graded lumber for stick build of permanent building.

If you have any thoughts of insulating and heating use Typar wrap rather than tar paper.

Jeff points out having used 6/4 for roof sheathing.  Two good things about that, stronger/stiffer than 4/4, and roofing nails will not poke through (if you care about the look).  Side note: my roofer friend will not put asphalt shingles on green as sawn roof sheathing.   Nails hitting in board gaps and then subsequent shrink loosening nails.   I used ash boards on the build I am doing and he put down plywood first.

[firefighter ontheside]

I would say 2 things about using green boards for the roof.  The wider your boards are the more likely they will split in the middle as they dry.  As a rule I would say pine is going to shrink at least a half inch per foot.  If a 12" board is nailed at its edges,it will either split in the middle or at the nails.  Also, the narrower your boards are, the smaller the gap will be between boards.  

As someone else said, if you can let the boards dry for even a month, they will lose a lot of moisture and make a difference in gaps.

[barbender]

There's no reason you can't use tarpaper on a conditioned building. Some builders still prefer it. 

[Jeff]

I used rupper ice guard over my entire roof area versus felt. The pic I provided shows the shrinking, but the iceguard didnt care.

[eastbayamateur]

I am not sure by your post if you plan to use local green pine for the framing.  If you are, check that you can get a building permit (if you plan to) for framing with local lumber.  Coventry requires graded lumber for stick build of permanent building.

If you have any thoughts of insulating and heating use Typar wrap rather than tar paper.

Jeff points out having used 6/4 for roof sheathing.  Two good things about that, stronger/stiffer than 4/4, and roofing nails will not poke through (if you care about the look).  Side note: my roofer friend will not put asphalt shingles on green as sawn roof sheathing.  Nails hitting in board gaps and then subsequent shrink loosening nails.  I used ash boards on the build I am doing and he put down plywood first.

Very helpful notes -- thank you. I'm in Warren; I think I will be okay on the lumber as the mill I'm dealing with can provide a stamp. The note on 6/4 vs 4/4 is also of interest. I'll have to figure out whether it's worth special ordering 6/4 to not see those nails. I'll consider drying the roofing boards (at least) before nailing them up. 

[eastbayamateur]

There's no reason you can't use tarpaper on a conditioned building. Some builders still prefer it.

One thing I DON'T hear from anyone is that my wall assembly is too much! But I guess this is a forum where everyone likes several inches of solid wood ...

[thecfarm]

I use EWP on The Women Cave. Cut the tree down, saw the lumber and it went on the roof.
But I did not put the steel on for a couple weeks.
Knowing me it might of been a month. 
No problems at all.