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robmorin
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# Posted: 21 Jun 2016 09:29
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Hello all....
I started building 2 16' x 20' cabins, piers are done as well as subfloor, We want to change the height of the walls from regular 8 feet to 12 feet to get more clearance in the mezzanine.
Does anyone see any problems with this other than adding more horizontal stud supports?
As i was thinking the height will be the same as the length.
See attached photo of the 2 bases for the cabins.
Thanks..
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Nate R
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# Posted: 21 Jun 2016 14:40
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I don't have an answer on height, but am curious on your feedback on the foundation. Form the looks of it, you did helical piles? How did you end up deciding on that? Are you willing to share the foundation cost?
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bldginsp
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# Posted: 21 Jun 2016 14:45 - Edited by: bldginsp
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Your major issue will be your roof design, and where and how you do the connections of rafters, plates, ceiling/floor joists etc. Beware of locating the ceiling joists below the top plate on a ledger, unless your roof is a beam support design that requires no rafter ties.
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robmorin
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# Posted: 21 Jun 2016 14:56
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Hey Nate, In the northern Quebec area, helical piers are the norm now. We checked around with different people as to what they were using for their cabins, and called a few contractors to come do cement piers, they all said they do these helical piers now. They are easier and faster to install. They guarantee them for 30 years. You have to be careful when ordering them as some come galvanized and some not. We had 7 foot piers put in that are 2 3/4" wide.
We used 4 on the outer walls and 3 in the middle. This was suggested by a building engineer that owns the company that installs them based on cabin size and approximate load including snow. We paid $170 Cnd per pier installed. Each cabin has 11 piers. Corner brackets were $160 extra, for all 8 of them.
These piers are adjustable if the need arise with giant nuts, you can move up or down the pier height quite easily.
I hope I answered your question?
Thanks for your reply...
P.S. here is another pic before we did the framing for the floor...
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robmorin
Member
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# Posted: 21 Jun 2016 14:58
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Not sure why this pic upload sideways, sorry about that...
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robmorin
Member
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# Posted: 21 Jun 2016 15:04
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Hey bldginsp
We are gettign our trusses built by http://trussforce.ca/en/
We are getting "scissor" trusses as to have an open/cathedral ceiling to make the cabins look bigger inside. The sales rep at Trussforce said the trusses will sit on the top plates of the walls.
The sales rep's original suggestion was to build regular 8 foot walls then add a 3 foot knee wall, but i figure thats more complicated and might not be as secure as simply building higher walls.
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rockies
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# Posted: 21 Jun 2016 19:42
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Are you planning on putting a loft in part of the cabin? if so your loft floor would help tie the walls together in that part and then use a stem wall on top of the floor. The walls in the "full height" area could then be built using full height studs.
If you aren't planning on a loft I would be careful about adding too much extra height to the walls. With small buildings a too tall interior space can make you feel like you're standing in an elevator shaft.
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MtnDon
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# Posted: 21 Jun 2016 20:03
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Quoting: robmorin .....other than adding more horizontal stud supports?
Not sure what you mean by that statement?
Q? Is the upper floor full size over the entire footprint? Or just a partial length loft?
And curious... what does the spec sheet / engineering sheet on those trusses state the horizontal force at the wall contact points is? It should be fairly low.
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Don_P
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# Posted: 21 Jun 2016 23:39 - Edited by: Don_P
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I would check with the foundation engineer, you are changing the size of the "sail" that his work is anchoring.
I believe our codes are similar in this respect but am not sure. When I use an "engineered" product, unless it is something that there is clear manufacturers documentation for exactly my use, I'll ask the supplier for a stamped design. I'm asking for the engineer to acknowledge that he has checked and will accept liability for the design. That is also a code requirement here, aside from being just a good idea, it is part of the service of the sale.
The next engineered product you're using is the trusses. That is so mature that engineering is assumed, the supplier is clearly on the hook for design (but not bracing!) and the paperwork required is clearly spelled out. The printout is now so standardized I think I can tell you where to look for something. A scissor is not a rigid truss. They actually "spring" a bit under load which pushes outward on the walls. Nothing like an untied rafter but still something to check. Think about that if you build a short kneewall vs a taller wall. A 3/4" out of plumb on a 3' tall wall is different than 3/4" out in 12'.
On the printout, under the drawing of the truss the first "paragraph" will be divided into columns, the first is loads, check your snow load. If it has a T&G ceiling you might want to bump the bc load to 15psf. Middle columns is where to look for horizontal deflection, this is the springing. If the walls are flexing more than a little bit have him up the size of the members and try again, watching the deflections. Normally first pass they will go for economy, this is a case where you might want to kick it up a notch, also check on an energy heel... anyway, rambled but trying to explain the design path with engineered products in there as well.
edit... uhh yeah what MtnDon said 
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robmorin
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# Posted: 22 Jun 2016 08:52 - Edited by: robmorin
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Thanks for all the replies so far guys!
It would seem the terminology we use here in Quebec and the
US is different.
When I say horizontal stud supports, I mean the 14 1/2" pieces of wood(braces) that are between the vertical studs.
@rockies & @MtnDon
Yes, there will be a loft, it will be half of the 16'x20' footprint so 16' wide x 10 length (deep)
I was thinking that loft would greatly help the structure of the walls by tieing them together so to speak.
If 12 feet is too much, i can do 10 feet, i guess it would be safer/easier?
Rockies, what do you mean by stem wall on the loft floor? I thought stem walls were part of the foundation?
I am awaiting the specs on the trusses, as soon as i get them i will post them here.
Thanks again guys!
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Jabberwocky
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# Posted: 22 Jun 2016 09:24 - Edited by: Jabberwocky
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I think Rockies meant a "knee wall" not a "stem wall."
I haven't done much framing in real life, but I have built a lot of stuff in my head  .
If I were building your cabin, the way I'm envisioning doing is to build the four sides (with top plates) using standard length studs (92 5/8"). Then install the loft floor joists and subfloor. Then build a knee wall for the remaining desired height. The studs for the knee wall would lengthen, of course, for the area not covered by the loft floor.
For those with more building experience than me, would that not be the way to do it?
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Nate R
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# Posted: 22 Jun 2016 10:20
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As Don somewhat mentioned: Would a raised heel truss be easier/cheaper? Build an 8 foot wall, put a raised heel truss on it. Not sure if a raised heel scissors truss is a doable thing, though?
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Nate R
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# Posted: 22 Jun 2016 10:22
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Quoting: robmorin Hey Nate, ......... ......I hope I answered your question?
Yes, thanks! That helps a lot! Helical piers are NOT the norm here in Wisconsin yet, so just trying to gather a bit more data on costs, etc.
I'm really attracted to the quick and easy aspect of the piers, and the lack of disturbance to the surroundings. (I envision my cabin being tucked IN the trees)
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robmorin
Member
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# Posted: 22 Jun 2016 11:25
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Hey Nate, the closest dealer to you would be here, but it's in Canada, but maybe he can help you out with any info you might need or if he knows any dealers in your area?
GUY DUFRESNE
Sales
1280 Rosslyn Road
Thunder Bay, ON, P7B 6V9
Cell: 807 633-0880
Tel.: 807 628-2542
Fax: 807 473-4418
thunderbay@postech-foundations.com
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robmorin
Member
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# Posted: 22 Jun 2016 11:28
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So i think i will go with 10 foot walls. I just feel safer and more confident to do it that way.
I will then "strap" 7 foot 2"x6" to the existing studs to support the mezzanine joists.
if you know what i mean?
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Jabberwocky
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# Posted: 22 Jun 2016 12:11
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robmorin
Would probably be less cutting than building a knee wall, but I have no idea if it's structurally sound or not. I don't personally see a problem with it.
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robmorin
Member
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# Posted: 22 Jun 2016 14:18
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I am going this weekend, I will take a pic or two, and post it here.
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rockies
Member
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# Posted: 22 Jun 2016 20:01
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Nate: There is another company called "Techno-Metal Posts" that has a dealer in Wisconsin.
http://www.technometalpost.com/en-CA/results-find-your-dealer/USA/WI/
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Don_P
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# Posted: 23 Jun 2016 00:17 - Edited by: Don_P
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This is the ESR for rockies posts.
http://www.icc-es.org/Reports/pdf_files/ESR-3418.pdf
check sections 3.2.4.1 and 5... although really the whole thing.
Their size selection guide... which is less conservative than the ESR. Notice cottages start at 3.5" posts and work up in size from there, assuming you are picking up lateral resistance somewhere. Again get a sealed design, that is the guarantee.
http://www.technometalpost.com/en-CA/professionals/selection-table/
A cantilevered attic truss might also be worth looking into.
A ledger would be notched into the studs rather than simply attached to the faces of them.
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robmorin
Member
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# Posted: 23 Jun 2016 09:14
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So here is a draft of the truss that Trussforce sent me this morning.
Comments?
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davexc
Member
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# Posted: 23 Jun 2016 14:54
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I am about to start building a 20x16 off-grid cabin myself in Quebec (near Megantic) and will be following your progress with interest!
What company did you chose for your piles? I have been calling a couple of contractors but none of them had prices as low as the one you got.
Merci
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Don_P
Member
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# Posted: 23 Jun 2016 22:55
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cantilevered overhang, plenty of insulation room, looks fine if the dimensions work, need the next page for loads and reactions it looks like.
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Diver
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# Posted: 24 Jun 2016 18:50 - Edited by: Diver
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Robmorin, it looks like you are well underway. I also used Techno metal posts for my cabin and I am extremely happy thus far.
If you haven't ordered your trusses yet, you could ask your truss designer to quote attic trusses for your loft. You could build the walls supporting the scissor trusses 10'-0" height and the walls supporting the attic trusses 8' height or even 7'-6". The truss manufacturer would just need to adjust the heel height of the trusses accordingly. This way you gain more height in the loft. I put together a few truss designs to show what I am trying to explain.
The doubled top chord of the attic truss is only required if you intend to add significant insulation. If not it could be removed to increase headroom and lower costs.
I would not recommend building a 3'kneewall over an 8'wall without adequate bracing (Floor joists, tie beams...) as this will create a hinge point which could lead to problems down the road.
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rockies
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# Posted: 24 Jun 2016 19:47 - Edited by: rockies
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One thing not discussed so far is what type of roof you're going to be putting on top of your scissor trusses. I know you said that you wanted a more open "cathedral" style of interior so you'll be building your entire roof structure on top of the trusses (rather than creating any kind of "attic" space).
I plan on using 12 1/4 inch thick SIPs (structural insulated panels) for the roof that will rest on top of the exterior walls and interior ceiling beams. The panels are structure, insulation and vapor barrier in one and you just seal the edges between panels and then screw them down. The reason for using them is that it is really hard to get an adequate level of insulation into a maximum 11 1/2 inch deep rafter cavity and still provide space for venting. A 4 x 8 foot panel costs about $400 but they go up really fast and once the exterior roofing is on you're done.
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Don_P
Member
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# Posted: 24 Jun 2016 23:21
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Diver, that looks nice.
What are you generating the truss drawings with?
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Diver
Member
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# Posted: 25 Jun 2016 04:45
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Quoting: Don_P What are you generating the truss drawings with?
Truss drawings were created with Mitek Sapphire which is a truss/whole house design suite. I took PDF screenshots instead of showing truss design outputs to keep my post as generic as possible. Truss designs vary from region to region and must be adjusted to meet local codes, snow loads... which will affect lumber and gusset plate sizes.
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Don_P
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# Posted: 25 Jun 2016 07:39
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way cool, stick around
Is the interior ceiling in plane or is there a jog at the intersection of trusses? another thought... if that is the case, can the attic trusses be packed at the cathedral edge and support a structural ridge and stick frame or mono slope trusses instead of the scissors to keep that interior slope smooth?
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Diver
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# Posted: 25 Jun 2016 11:54
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Yes there is a jog at the intersection. This was do to maximize the headroom in the loft and minimize truss costs.
If the attic truss is built down to match the scissor truss the headroom in the loft would be less. If the parallel chord scissor truss is made thinner to match the attic truss it may not meet the horizontal deflection design requirements. One could do a bit of both, do a slightly thinner scissor truss and slightly deeper chord build-out on the attic truss. it would however increase the overall cost of the truss system.
Every building design is unique as truss span has a huge effect on the parallel chord trusses. They usually work best for spans 20' or less after that their depth can get really unpractical where other design alternatives may be better.
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