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Looking for advice to properly roof my timber frame shed

Started by Brian_Weekley, January 25, 2012, 09:16:58 PM

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Brian_Weekley

I just started cutting my first timber frame structure after attending the Timber Frame Workshop at the Hancock Shaker Village in Sept (excellent course by the way!).  It's a variation of the "Sobon Shed" (14x20) with an enclosed lean-to on one side.  It will have 1x vertical barn siding.  I wasn't really planning to insulate it since it's intended primarily as a future shed/workshop, but I potentially may also use it as a cabin during the summer months until I build something larger.  I've really been struggling to decide on how to finish the roof (common rafters).  The roof will be metal--probably standing seam type, but I'm also intrigued with the option of metal shingles that have a pseudo slate look.  I'd really appreciate your experience, advice, or suggestions.  Here's my dilemma/questions:

Option 1. Originally, I was just going to nail 1x strips horizontally spaced across the rafters to attach metal roofing.  However, since this will be in a cold climate (Maine) do I need to be concerned about frost/moisture forming on the underside of the metal roofing and subsequently dripping inside the structure when the sun hits it?

Option 2.  The next option I was considering was to apply continuous 1x wood planks on top of the rafters, followed by a layer of tar paper, then the horizontal nailing strips, and finally the metal roof.  This would probably look nicer from the inside (instead of looking at the metal roof) and provide an air gap and some moisture protection under the metal roof?

Question:  Since the building will be in a cold climate (Maine), should I just go ahead, bite the bullet, and plan to insulate the roof from the start (especially if I find out later that I'm freezing my tuckus and decide to add foam panels to the outside of the barn siding too)?

Option 3.  1x wood planks, tar paper, metal shingles?  However, I don't want to see roofing nails coming through my nice wood roof/ceiling!  Would the metal shingles need nailing strips also?  Can't imagine metal shingles would be very strong to walk on.  I think they're intended to be attached directly to solid sheathing?

Option 4.  1x wood planks, 2" foam panels, sheathing, tar paper, then directly topped with either standing seam or metal shingles?  This seems like maybe the best option?  Are the components and order correct?

I've seen some things online about the foil/bubble wrap stuff, but certainly wouldn't want to look at that from the inside!  So you can see I'm making a lot out of this!  So how would you properly roof a "non-insulated, non-heated" structure (that who knows, might eventually have a small woodstove if I end up spending time in there during the winter)?
e aho laula

Jim_Rogers

Brian:
Welcome to the forestry forum.

On your idea about metal shingles and how to attach them. You should ask your supplier for their recommendations on how to do it. The should provide you with some installation instructions.

Having the nails show through is a common problem I hear about from many people.
One way is of course to get shorter nails. But that may not always be available.

Then you have to make sure you place the nails only where there is thick wood on the underside so that the nail tips don't show through. This can be a challenge if not impossible at some times. It is something that you'll have to figure out, which is best. Or what are all your options.

If you can afford to do it now, then insulate it now. Insulation is one of the easiest things to get a return on investment (ROI) right away. It starts paying you back as soon as you add heat to the building.

Good luck with your research.
Sorry I couldn't have been more help.

Jim Rogers

PS. I was the tool guy that came on Friday afternoon.....in case you didn't know....
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

piller

Welcome to the forum!  I attended the timber framing workshop at Hancock Shaker Village several years ago, it was an excellent experience, we built a 16x20 poultry house.  What was this year's class project?

Tell us a little more about your 14 x 20 Sobon style shed, how are you planning to frame the lean to where it attaches to the shed?  Just wondering. 

What's the pitch of your roof, 12/12?  Since you just did the workshop, and maybe some hewing and peg making, perhaps you want to go with 1x horizontal boards and then split some shakes.   That would be traditional, but might not work well with the lean to. 

Jim_Rogers

Quote from: piller on January 26, 2012, 09:51:19 AM
Welcome to the forum!  I attended the timber framing workshop at Hancock Shaker Village several years ago, it was an excellent experience, we built a 16x20 poultry house.  What was this year's class project?

He is doing a smaller shed then when I took his class.

He now does a 12' x14' shed instead of he 14' x 16' one he has been doing for some years now.

I was at the raising of that chicken coop......

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

Brian_Weekley

Thanks, Jim.  Yes, I recognized you at the workshop immediately—even though you weren't wearing your trademark Forum sunglasses!

Piller.  I don't think I would trust my shake making to provide a leak-free roof—especially on the shed portion.  Besides, I really prefer metal to help keep the snow off.  I've attached an image of what I'm working on.



 
I also found Rooster's nice photo essay showing his roof—that is very helpful.  I'm still debating on whether to insulate or not.  I was planning a double entry door on the gable end (W).  However, I was also planning a large sliding access door across one bay (S) which will make the shed far from air tight.  Then again any insulation with some felt to help prevent air infiltration would still make it more bearable if you're working in there.

Brian
e aho laula

Peter Drouin

Hi Brian.I see your going to strap on the rafters then put on some tin, If it was me I would board the roof then felt paper then tin, with hot and cold temp. the tin will swet and drip in side on you. you could make your trim boards 3" higher then the rafters 6 7 " wide or what works, then 1" boards 2" foam insulation then felt then tin. If you get the right length screws your good. maybe this will help :) :)
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

piller

Quote from: Jim_Rogers on January 26, 2012, 10:40:08 AM
He is doing a smaller shed then when I took his class.

He now does a 12' x14' shed instead of he 14' x 16' one he has been doing for some years now.

I was at the raising of that chicken coop......

Jim Rogers

I did not really care for the interrupted plate design on that poultry house we did, but it was a good learning experience.

The 12' x 14' shed that he is doing now, is it two bents or three bents?  Any pictures?  Thanks.

piller


Rooster

Brian,

Here are some random thoughts for you to ponder,

Roof/ Insulation:

I think that it is a good idea to at least insulate the roof...you can always go back and insulate the walls and even the floor, but once you put the roofing material down, you probably will not want to pull it back up later on.

Decking the rafters with 1x is a good idea.  You could save on material if you spaced them 8" apart, and then put a layer of felt paper over the top and used it like a "curtain", so that you wouldn't see the underside of the insulation or the white primed surface of the roof steel.  I have used this technique when I re-roof old barns, which often times have roof boards that are spaced between 1"-3 ".  (I don't like looking up at the "White Wood" of OSB or Plywood peaking through the gaps in a barn roof that is 125 years old.  It looks out of place...IMO.)

After you put down the tar paper, then lay down your insulation.  Securing the steel through the insulation to the decking will work structurally, but the heat generated from the sun on the steel (when the steel is in direct contact with the foam) can cause the foam to break down. Adding straps (2x4s on flat) to the topside of the foam, screwed through the foam, through the decking, and to the rafters, (spaced according to the steel specs) not only gives you an air space, but then you have a "ladder" type roof surface to work on while installing the "slippery" roof steel.

Doors/ Insulation:

I like your double walk doors...and just like the roof, if you insulate them as you build them, then you don't have to go back later and re-do them.  A full 2" frame covered inside and out with foam sandwiched between the outer and inner sheathing will give you a very solid door.  I like jander3's hinge set up with the large strap hinges. Here is a photo from his gallery.  Thanks Jon!

Making one door "fixed" with barrel bolt latches, and the other lockable and used for everyday access will help with heat loss and security. 
(Tip: I usually build both doors as one large door, hang it as one door, and then separate them by cutting/ ripping them down the center...perfectly matched and at the same elevation.)

Your larger sliding door will be more of a challenge.  Again, building it insulated as one door but this time, separating before you hang them from the track...One door is heavy, two doors are half as heavy...that's if my math is correct...DanG calculator!!

I have come up with a simple closer system that will help reduce the air infiltration, but I don't have any drawings or photos yet...but it is basically an adjustable interior jam/stop, with an insulated weather stripping, that has slots cut for threaded bolts and large wing-nuts.

Hope it helps.

Rooster
"We talk about creating millions of "shovel ready" jobs, for a society that doesn't really encourage anybody to pick up a shovel." 
Mike Rowe

"Old barns are a reminder of when I was young,
       and new barns are a reminder that I am not so young."
                          Rooster

Brian_Weekley

Thanks to everyone for your advice!  Makes a lot of sense to deck and insulate the roof.  Very good information that I will certainly incorporate in my building.  --Brian
e aho laula

Dave Shepard

Brian, welcome to the Forum! I helped out on your workshop frame this year, I don't know if you remember me.

The 12'x14' frame is still Dutch, so it's got five bents, just like the 14'x16' frame, which is the one we did when I took the course in '06.

I just finished raising the '09 Hancock frame this month. We sheathed the entire building with pine boards. 1" on the sides, and 5/4 on the roof. It will get asphalt shingles in the spring. Metal roofing is loud inside during a rain. Trying to get pics off the phone, but no luck. I'll try later.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Piston

Brian,
Welcome to the forum.  That frame you posted looks incredibly similar to the one I'm working on.  Mine will be a 16x24 but same idea, with half dovetail joints as the tying joint in the 3 main tie beams.  I will also have a common rafter roof.  My idea for the insulation in the roof is as follows:

2x roof decking, tongue and grooved. 
Vapor barrier
2" or 3" foam insulation (whatever I find on craigslist for a good deal)
I will lay the foam between 2x6 on edge, going up to the roof peak.
then lay more decking over the foam (secured to the 2x6's), leaving an air gap between foam and outside roof decking
Then lay strapping down over the roof decking to put the metal roofing on, which will create another small air gap. 
Then install the metal roofing.

That is my plan. 

-Although, your way ahead of me, I haven't even milled my timbers yet  :D :D :D 
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

Brian_Weekley

Hi Dave,
I didn't remember your last name, but thought that might be you based on your location and picture of the Dutch frame.  I remember your cool TF Guild toolbox!  I'd love to see some pics of the sided frame. 

Piston,
Can you share what you're building?  I'd be interested to see your design.  I don't know what the intended use of your structure is, but I was thinking that 2x6's on end against the decking (with the insulation in between the 2x6's) might not provide a thermal break to the inside?

Thanks, Brian
e aho laula

Piston

Brian,
I'll post some pictures of my frame design and I'll post my sketchup file in the timber framing directory. 

I will be building a similar frame to yours.  16'X24' with 3' overhangs on the gable ends.  It will be 3 bents with continuous top plates (that's gonna be fun to mill!  :D)
My intention is to use it as a combination tractorshed/workshop.  I'd be happy to answer anymore questions you have about my design. 

-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

Piston

 

  



  

 



This is a variation of a frame I've been thinking about doing for a while now.  There is a lot of information in this thread as well:
https://forestryforum.com/board/index.php?topic=44472.0
There is a copy of my original plan here: https://forestryforum.com/board/index.php/topic,50083.0.html

I am taking a timber framing course this June at Heartwood School and hope to start shortly after that.  I was trying to get this to be the course frame at the class but it isn't going to work out. 

I've uploaded my .skp file of this final plan here:
https://forestryforum.com/board/index.php/topic,55956.new.html#new
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

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