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Roof Sheathing for timberframe

Started by jmaine, August 25, 2008, 08:29:18 AM

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jmaine

Hi guys, I finally got my timberframe up last Friday. It's a 28' x 36', story and a half barn with a 12' x 36' shed addition.  We got it up in one day, took about 10 hours.   I'll have to post some pictures (I saved them to a CD but now it won't open).  No major mistakes, I'm definitely happy with how it turned out.

I was going to use shiplap pine for roof sheathing, it's 55 cents/ lf for 10" wide boards (industrial grade). However, I found another place that has 12" wide square edge pine (surfaced three sides) for 40 cents a board foot.  So, it's 15 cents cheaper and it's a board foot cost versus a lf cost so I get a little more.  The 12" square edge is industrial grade as well; they actually look pretty clean for industrial grade. Both the shiplap boards and the square edge are kiln dried.

The square might not be as tight as shiplap, but with roofing felt and asphalt shingles over the boards, it doesn't have to be super tight.  I can use the more expensive shiplap for sheathing on the sides of the barn.

Should I have any concern with using these boards for roof sheathing?  The purlins are 3 feet on center (purlins are 6" x 7").  I'm afraid the wide boards might cup or expand and raise up the shingles a little bit.  Although, being that wide I think it's more likely that they'll shrink and not expand. 

Anyone here used wide pine boards for roof sheathing?  Any thoughts or tips that you might have would be greatly appreciated. 

thanks   

Joe

beenthere

Quote from: jmaine on August 25, 2008, 08:29:18 AM
.............Should I have any concern with using these boards for roof sheathing?  The purlins are 3 feet on center (purlins are 6" x 7").  I'm afraid the wide boards might cup or expand and raise up the shingles a little bit.  Although, being that wide I think it's more likely that they'll shrink and not expand. 
..................

Cupping will likely happen when your boards shrink as they dry. That is unless the boards are true quarter sawn, which likely isn't the case. Being wide, you might have success nailing them down tight enough that you won't see the cupping, however being such a wide span (3' on center for nailing) won't help holding them flat. So, I think you will experience what you are afraid of...seeing the raised shingles.

Look forward to the pictures... :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Radar67

Quote from: jmaine on August 25, 2008, 08:29:18 AM
Both the shiplap boards and the square edge are kiln dried.

If they are already kiln dried, I would think the chances of cupping are severly reduced.

For a 3 foot span, I would use no less than 8/4 material.
"A man's time is the most valuable gift he can give another." TOM

If he can cling to his Blackberry, I can cling to my guns... Me

This will kill you, that will kill you, heck...life will kill you, but you got to live it!

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krusty

It may seem like alot of work.....but rip them down the middle and you will minimize the cupping significantly to be of little notice.

Or you can stack them properly and let them air dry :)

Jim_Rogers

As mentioned, if they are kiln dried then they don't need to be stacked and allowed to "air dry", sorry krusty......

As far as the span going from purlin to purlin goes, it's hard to say, right now, you haven't told us the pitch of the roof or the snow load for your area.
Also are these boards truly 12" wide now? most likely not if they have been sized on three sides, and then with is their actual thickness 3/4" or 7/8" if they were standard ship lap and started out 12" wide they could be 10 3/4" wide now. Some processes remove as much as 5/8" off each side.

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

shinnlinger

Yep,

...cupping probably not much of an issue due to kiln, but 3 ft is probably too much for 1x span for a roof in Maine(is it in Maine?). 

Double it up?  OSB?  2x6 cardecking?

What is your pitch?  How much snow?  You said asphault so it will hold the snow.  Ribbed steel would be better in this category for snow shedding abilities.  If you have a full piitch or more and go w/steel, you might be able to pull the 1x off.  How big are your rafters and how far apart?

insulation?

PS congrats on the frame!
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

jmaine

Hi Jim, it's a 10/12 roof pitch. I'm up in Southern Maine so the snowload is fairly signficant, I think we average about 4 feet of snowfall a season.

No, the boards are not a true 12" wide, they are around 11".  The boards are surfaced three sides so the actual thickness is 7/8".

When I say three feet to center, keep in mind that the purlins are 6" wide.  So, there is an extra 6" of support under the boards (3" from center on each purlin). 


thanks

Joe

Jim_Rogers

Joe:
What town or county are you in?
If you don't know the snow load for your area, maybe I can look it up online, once I know the location.
From that we can figure the load on the boards and see if they'll hold up ok, or if you should be concerned....

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

jmaine

Hi Jim, I just looked up the snow load ratings on the town website, it's 40 lbs per square foot.

Joe

maineframer

Joe,

A 10/12 pitch in Southern Maine ---purlins 3' on center.
I would use 7/8" ship lap or v-match pine.
Check with your building inspector to be legit if you want.
Snow does not stay on a 10 pitch roof--especially in sorthern maine.
If you told me Fort Kent or Caribou ME (16 feet of snow in 2007-2008 )   ---- I would tell you the same---snow will not stay on a 10 pitch roof.
David

Don P

My gut reaction was that it was ok. Its very close to the span on my shop. I'm in 20 pound snow country though. I assumed you were talking about white pine?

Checking it in the codebook they have a 24" span for which they want at least 5/8" thick and then it hops to 48" for which they want 1-1/2" thick. So they are of no real help, it defaults to the NDS,

Running the numbers I'm happy if you use some common sense about rejecting pure trash. If you're in inspection country it needs his blessing, (industrial grade is not a stress grade so your judgement is part of the equation here). It should deflect about 1/16" under full snow load (I called the load 103 lbs/board in the free span). The Fb needs to be 280 psi or greater, a #3 stress grade (adjusted for snow and repetitive members) is around 455 psi, so it isn't requiring much of a board. . I'm about 180 lbs and was comfortable walking anywhere on my roof, that'll give you a little under 1/8" deflection under foot.

shinnlinger

If your gunna build it...OVERBUILD it.

When in doubt build it STOUT

still I guess the numbers say you are alright and throwing money away on a barn isn't smart either...I have seen a lot of very scary frames that have been together 200+ years, but I have also seen wet heavy snow stick to asphault shingles on a 10/12 pitch.
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

jmaine

Thanks for all the input guys, it's greatly appreciated. It turns out that the place where I was going to buy the 12" boards is all out. They think it will be a few weeks until they get more.

So, I'll probably be going with 10" shiplap, 7/8" thick.  It will cost a few hundred more to sheath the roof, but I'll feel a little better having the shiplap versus the square edge.

I'll try to figure out how to post pictures this afternoon,  I tried earlier this morning but couldn't get it to work (it said my files were too large).

Thanks again.

Joe

Jim_Rogers

If you do a search here there is a thread that tells you how to reduce your photos to fit into your gallery, once you create one....

Jim


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

beenthere

jmaine
Go to the "help" button up top of the screen (then down to "how to post photos", and remember, once you crop the photo to the area you want to feature, then size it (reduce the longest side to 450 pixels) before changing the file size.  Changing file size first will just give a small photo. Several examples of small photo's shown on the FF that are not much more than postage stamps and very hard to see any details. Doesn't have to be that way.  :)

We like good pics...and look forward to yours. I think you will like the T&G better too.   :) :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

jmaine

Here is the completed frame. This is a test for me, let me know if the upload didn't work. I'll post more photos once I get the first one figured out.   Joe

Joe 


Jim_Rogers

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

beenthere

Good Jmaine. And you can preview your own posts, to tell how your post will look before sending it to the forum. It will save you from wondering.... :)

The Preview button is right beside the Post button.

What will go in the barn?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Brad_bb

Nice looking frame.  It is somewhat similar to Tyson's in Alaska, except he clear spanned the middle two bents and added a extra room up top.  Any connection there?
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!

jmaine

Here are a few more photos, I think I've got the hang of it now.

No connection to Tyson's frame.  Although, I did look at his blog and saw that the guy that designed it lives here in Maine.  I didn't hire someone to design the frame, but it is similar to other frames I've seen built in the area (and similar to one they build at Fox Maple school).  I took a class at the Shelter Institute in Woolwich here in Maine.  I can honestly say that I cut every joint myself, the only help I had was at raising day.  There are things I would do differently if I cut another frame. I would get a tractor or some type of heavy equipment to move timbers around. I had a timber cart and I built a tripod to lift the some of the heavier stuff, but I don't think I'd go that route again.  It's exhausting work and can be dangerous.

It looks as though Tyson's frame is considerably larger than mine. The clear span would have been nice, but I was limited by height restrictions on the finished building (30 feet at max).  The "clear span" requires a long brace, maybe a 6' run.  I couldn't make my posts long enough to have the brace out of the way.  I don't know that I'd call it a clear span if you bumped your head on the brace every time you walked by. 


Joe









Brad_bb

Is that guy in green standing right under the bent being lifted?  Not sure I'd do that.
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!

moonhill

jmaine, what part of Maine do you live in?    Tim
This is a test, please stand by...

jmaine

Hi Tim, I'm in Buxton, about 15 miles directly west of Portland.

Joe

Jim_Rogers

Joe:
Are you the Joe who was my classmate at Fox Maple?

Jim

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

jmaine

No, I took the class at Shelter Institute.  I enjoyed the class, but after I did some actual timberframing, I realized that there was a lot they didn't teach us in class (and there was a lot of wasted time).  They didn't teach us anything about pegging, the use of power tools, or square rule layout.  They also seem to take some shortcuts that I wouldn't do; halp lap on the rafters versus tongue in fork and they use lag bolts in a lot of connections.    I probably would have gotten more from the Fox Maple class.   I was thinking about taking the advanced timber framing at Fox Maple but money is a little tight.

On a side note, I noticed that your from Georgetown Mass. I've been there many times, my aunt and uncle and two cousins lived there. I used to spend a fair amount of time down there in the summer visiting them, it's a nice area. 

Joe

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