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Thread: Cabin Roof Considerations, Rafter or Truss

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    Member ChugiakTinkerer's Avatar
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    Default Cabin Roof Considerations, Rafter or Truss

    Good day all. Am grinding through design considerations for a 16x28 cabin with half loft and had previously settled on a ridge beam design to support the rafters. Knee walls probably around 4 feet and 12/12 or 9/12 pitch roof. This is for a site that is 10 miles from end of the road, with everything hauled in by snowmachine.

    The ridge beam design will have support columns inside the cabin, but I'm toying with the idea of using trusses instead and doing away with the ridge beam altogether. The boss wants a cathedral ceiling, so I figure the two options are parallel chord or scissor trusses. If we were located next to a road I'd have already made up my mind, I'm sure. As it is I have no experience with hauling trusses on a sled and wonder what experiences folks have had in getting honking big trusses to their build site.

    Recommendations on hauling or alternative designs considerations would be much appreciated.

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    I built over 20 remote cabins in Gray Cliff and Moose Point. For most of them, I marked out a jig on the floor and built my own trusses. Outline the jig with blocks of wood screwed to the floor. Make pattern pieces. Mark all the other pieces and cut. Use construction adhesive and plywood gussets held down with screws. We usually made all the trusses for a cabin in one day.
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    Or, I got a glue lam from Spenard's, and 11-7/8" BCI's (light to haul), I put them 12" on center, ( you will want one space wider for the stovepipe to go thru),made a great open beam loft area. Get the hangers to attach the BCI's to the glue lam. makes quick easy assembly, the glue lam was a little heavy but the rest was a breeze to put up. There are also hangers for the bottom of the rafters to attach to the top sill plate.

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    You would have to haul trusses point down...you would be too wide flat unless the trail is really wide. And at 14 or 16 trusses...that would be a heck of a heavy load. There are some really good YouTube video of a Canadian cabin builder who builds a jig on the floor and makes them on site as previously mentioned. He also sets them by himself. He lifts them up on the sill upside down..then goes up and turns them over one at a time... Pretty slick. With just one helper it would be even easier.

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    Member ChugiakTinkerer's Avatar
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    Quote Originally Posted by joemama View Post
    You would have to haul trusses point down...you would be too wide flat unless the trail is really wide. And at 14 or 16 trusses...that would be a heck of a heavy load. There are some really good YouTube video of a Canadian cabin builder who builds a jig on the floor and makes them on site as previously mentioned. He also sets them by himself. He lifts them up on the sill upside down..then goes up and turns them over one at a time... Pretty slick. With just one helper it would be even easier.
    It's a narrow trail, at least as of now. I was thinking about hauling 8 or so trusses at a time just like you describe. Would have to build a rack to hold them upside down. They would still be pretty darn tall though, might be difficult to keep such a high center of gravity from falling over.

    Building trusses on site would be ideal. I would just need to ensure that I have a design that's adequate for the load and span.

    Or just order some scissor trusses from SBS and get them air-lifted. Actually probably worth at least seeing what that might cost.

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    I just got a quote last week for air lift . Northern Pioneer from Big Lake was the best deal..he charges $2400/ hour...but he will go in ten minute intervals and the competition would not. His price also includes fuel..others were rate plus fuel....and his reputation and reviews are all A+. Search those videos...I'm sure you could build them and save a pile of $$$. I'm thinking you will need some help though..yours will be high and awkward.

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    Default Cabin Roof Considerations, Rafter or Truss

    I hauled my last set of trusses in for my cabin, they are 20' Long and about 7' tall from tail to peak. If you are going scissor/vaulted 12/12 pitch they will be about 9 feet from tail to peak I'm assuming. You can probably snake them through a trail. My previous cabin I built on site trusses 8/12 pitch 24' long and they turned out well but they take time. If you go that route cut all of your plywood plates at home so they are ready when you get there, I stapled and glued mine. They are fairly easy to design, depending on your location and possible snow loads. Don't forget you have to roof the thing too, my 8/12 wasn't the easiest having to be tied off it just slows things down. Going the BCI route with the proper brackets is VERY expensive. More then buying a truss by the time you buy two brackets for each BCI. If you are only going ten miles I would find a way to haul them in.


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    I thought very hard about the bci route until I walked into sbs and priced the adjustable brackets where they would sit on the wall. I think they were like $14 each. You may have like 4-600$ just in brackets.


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    Easiest and cheapest way....just stick frame it with #2 lumber....5' sidewalls and a 12/12 will put your rafter ties at a reasonable ceiling height, and in the lower third of the rafters per code....no ridge beam needed.
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    Member ChugiakTinkerer's Avatar
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    Thanks all for the input. Still planning on a vaulted ceiling, just need to decide on ridge beam vs. trusses. Trusses would be a lot easier to put up, that's for sure. Off to the property for the rest of the weekend, will check in later. Thanks again for the help!

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    I helped my buddy build his cabin- we built trusses on site and it went very smoothly and quickly. Hauled wood in by atv with trailers and then with 4wd truck when trail conditions allowed it. The first truss as a pattern for the rest. We set them up and over the walls resting nose down and then I pushed them upright with a board having a small y to lift the noses while he tacked them into place- then we nailed them. Just remember to get the last ones turned upright before closing the gap! LOL.

    Can't wait to build my cabin and after all the looking- think it will be stick frame as well...just easier and lighter with materials to my site. Good luck with your build.

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    On a 16' wide cabin there is no real reason not to use 2x12's on 16" centers for rafters. In a roof application, you don't gain any advantage using BCI's other than they are light. With a proper load bearing ridge, you do not have to use the fancy Simpson angled hangers either. I don't have the engineering to back it up, but my site built three layer 2x12 with 1/2 CDX layers ridge beam has been in place for 20 years with no sagging and a 20' span. If you put a center post on the ridge beam at 14' (carried all the way to the basement) you could easily use that system and have no hauling issues. For the ridge beam I built, I used construction adhesive between the layers and full 16d common nails holding it all together.
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    Get a plan from here. We did the 20x 30 1 1/2

    http://countryplans.com/plans.html

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    Quote Originally Posted by SmokeRoss View Post
    I built over 20 remote cabins in Gray Cliff and Moose Point. For most of them, I marked out a jig on the floor and built my own trusses. Outline the jig with blocks of wood screwed to the floor. Make pattern pieces. Mark all the other pieces and cut. Use construction adhesive and plywood gussets held down with screws. We usually made all the trusses for a cabin in one day.
    This is a good way to go, you will need a collar tie, at least every other one.
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    Quote Originally Posted by AKDoug View Post
    On a 16' wide cabin there is no real reason not to use 2x12's on 16" centers for rafters. In a roof application, you don't gain any advantage using BCI's other than they are light. With a proper load bearing ridge, you do not have to use the fancy Simpson angled hangers either. I don't have the engineering to back it up, but my site built three layer 2x12 with 1/2 CDX layers ridge beam has been in place for 20 years with no sagging and a 20' span. If you put a center post on the ridge beam at 14' (carried all the way to the basement) you could easily use that system and have no hauling issues. For the ridge beam I built, I used construction adhesive between the layers and full 16d common nails holding it all together.
    AKDoug, what you describe is my Plan A. I'm exploring whether scissor trusses have enough to offer to pre-empt ridge beam and rafters. I'm comfortable with the idea of designing and building my own trusses on site. I don't have a permitting authority so I don't need a PE stamp. I do need to be confident that whatever roof I put up will withstand the wind and snow loads around Lake Louise. Manufactured trusses offer certainty in that regard but I'm thinking they will be too cumbersome to bring in on a sled and too expensive to air lift.

    Rafters and rafter ties would be easy peasy. I like the pre-built ones akgramps posted. But a flat ceiling isn't on the table, even a raised one.

    By the way, I spent a little time this weekend playing with this plugin for Sketchup. Should anyone wish to install it, be warned. Much time will be consumed making all sorts of cool trusses.

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    Quote Originally Posted by ChugiakTinkerer View Post
    AKDoug, what you describe is my Plan A. I'm exploring whether scissor trusses have enough to offer to pre-empt ridge beam and rafters. I'm comfortable with the idea of designing and building my own trusses on site. I don't have a permitting authority so I don't need a PE stamp. I do need to be confident that whatever roof I put up will withstand the wind and snow loads around Lake Louise. Manufactured trusses offer certainty in that regard but I'm thinking they will be too cumbersome to bring in on a sled and too expensive to air lift.

    Rafters and rafter ties would be easy peasy. I like the pre-built ones akgramps posted. But a flat ceiling isn't on the table, even a raised one.

    By the way, I spent a little time this weekend playing with this plugin for Sketchup. Should anyone wish to install it, be warned. Much time will be consumed making all sorts of cool trusses.
    This is the finished look, we originally planned on a loft, sometimes at remote sites with limited equipment it can be easier to build a bigger footprint rather than go up. Especially for old guys.....

    We didnt want a flat ceiling inside either but we kept the pitch relatively low, we used a double collar tie on every other one with a single king post. The rafters are on 2' centers. Walls are 8' tall & Pitch is 5/12. Still open but not really usable for anything. All done with rough cut lumber.

    A 4' knee wall will give you some room in the middle if you go 12/12, w/o a dormer it will be a tunnel.

    Instead of a knee wall, balloon frame it and put your floor joists where you want them, or use some larger beams on 4' or 6' centers to act as collar ties, then deck the loft portion with 2 X T&G. I built one years ago with 10' walls and we gained a full loft, add a dormer and it added a lot of room.

    16' is on the narrow side and even with a steep roof there is not a lot to be gained for space in a loft, even with 12/12 you may want a dormer. 20 X 24 will give you more sq feet with same amount of walls.

    Having a post in the center to hold up a ridge beam in the middle of a 16' wide cabin will be annoying... IMO. If its 6" walls then you have a 15' wide room with a post in the middle it will not be a lot of room and depending on your foundation... (Assuming remote and some type of pier block).. will require a support under it, point load, may settle at a different rate than the walls and.... oh well you get the picture...
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    Quote Originally Posted by Akgramps View Post
    This is the finished look, we didnt want a flat ceiling inside either but we kept the pitch relatively low, we used a double collar tie on every other one with a single king post. The rafters are on 2' centers. Walls are 8' tall & Pitch is 5/12. Still open but not really usable for anything. All done with rough cut lumber. If you want more space you can build a steeper roof and use some larger beams or 4' or 6' centers to act as collar ties, I built one years ago with 10' walls and we gained a full loft, add a dormer and it added a lot of room.

    16' is on the narrow side and even with a steep roof there is not a lot to be gained for space in a loft, even with 12/12 you may want a dormer. 20 X 24 will give you more sq feet with same amount of walls. Sometimes at remote sites with limited equipment it can be easier to build a bigger footprint rather than go up.
    That's a mighty fine interior there, akgramps. I'll run that past the client and see what she thinks.

    As far as footprint, I'll bump up the knee wall first if I need to increase the usable head room. A dormer might be worth considering, particularly since the orientation we are considering doesn't take advantage of the southern exposure. A south-facing dormer will let the winter sun in nicely.

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    So here's where my brain is at tonight. I messed around with the Sketchup plugin I linked above and generated a 12:12 scissor truss. It's shown here on the left, with my hatchet job on the right of turning it into the truss I want. The plugin doesn't do raised heel scissor trusses yet, so I'm making do. Using 2x4 for the truss construction, I estimated what it would cost for each truss. I think I erred on the side of caution, allowing a whole sheet of plywood for gussets, a whole tube of Liquid Nails, and 300 8d nails. Total cost for 13 trusses (gable ends will be framed) comes to $832. If I instead build with a ridge beam constructed of 3 2x12 and use 2x12 rafters and 6x6 posts, the cost for the lumber alone is $975. Just using 2x12 rafters and 2x6 rafter ties, the cost is $803. I'm intrigued enough with the raised heel scissor truss that I'm going to get an estimate from SBS or whomever. The time I spend hauling in cumbersome trusses will probably be equally consumed building trusses on site. Of course all of my scheming and calculations will be trumped by whatever my lovely bride wants. Rule #1 on this project is Keepin Mama Happy.


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    Before picking a truss design I would think you would need to know how much snow load the cabin needs to carry. You may already know the answer, if so forget I asked.

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    One thing to consider is that you could lay out the truss plans at home in a garage and pre-cut all the pieces and haul them in to be assembled on site. Generator and air tools make the job pretty quick. That is what I am planning to do for my place anyway. Thanks for mentioning Sketchup BTW.

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