I’m starting to built my house soon, and i’m planing to build my exterior walls 24” C/C, less wood, more insulation!!The walls will be 36’x 14′ tall (front and back walls) and 26’x14′ ( side walls), with the upstairs floor at 9′ high.
Anyone has ever done that?
Thanks
Fred
Replies
Wow, that'll be a tall house, 24' plus the roof, especially for only a 26x36 footprint.
you must be a retired NBA star, eh?
;)
yes, common to do. Lots of discussion here in the past on it. You might runa search on the topic here using the advanced search button
Are you thinking 2x6 or 2x4 studs?
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It's with 2x6.
The first floor is 9', then the joist (12'') plus 4' walls ( all one shot), then the ceiling starts at 45 deg., and the ceiling of the second floor is at 8' high. The second floor will be attached from the inside, fast and simple!!
So you are balloon framing this then.
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Fred,
I don't know where you are from. Some places that isn't allowed due to wind loads and other such considerations..
In the foot print you mentioned the few studs you save won't be a significant reduction in costs.. Also you failed to mention what sort of insulation your are going to use which is more important than the number of studs in use. Some locations it isn't critical others it can be a big deal.
It's in Québec, near Mt-Tremblant. Wind is not a consideration!!
Outside it's 2'' of rigid insulation and R-20 (batts) inside the walls.
I get the rigid insulation but I wish you could see the reports I have about the ineffectiveness of fiberglas.. Yes they get an R 20 rating in the lab. However lab results are perfect conditions..
Any moisture quickly drops the R value of insulation.. Very seldom do I see older homes pulled down that don't have signs of moisture getting into the walls..
House wrap can reduce air flow to manageable levels but the simple fact is that heat migrates to cold. The inner walls will be at 70 degrees while the outer walls will be whatever the outside temp is..
You learned in School that hot air rises and cold air settles.. You also know that fiberglas is what furnace filters are made of.. that's because they do a good job of flowing air..
So the outside air is dropping and the inside air is rising.. thus in a stud cavity there is a constant loop of hot air rising and cold air settling (that's inside the walls, in the stud cavities) effectively scrubbing off heat.
That doesn't happen significantly in the labratory because there is only A 10 DEGREE DIFFERANCE BETWEEN INSIDE AND OUTSIDE NOT 40- 50 OR EVEN 70 degrees differance.
So you need a better insulation.. Celluliose is about the same price and air doesn't move through it anywhere near as fast. True it can and does settle over time. So that in time the top of each stud bay will have an air gap. How much depends on many factors.
The best is sprayed foam or SIP's but there is a cost to those. True not enough that there isn't a pay back but like most people I assume you are concerned more about intial costs than long term costs..
You also need to consider your heating system.. Forced air tends to be the cheapest but least efficent while infloor radiant is more expensive but also more effective (and far more comfortable)
mostly true, but the 2" foam exterior will help buffer against thermal siphoning
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If you note I made mention of the superiority of celluliose over fiberglas.. however if we have say an R10 on the exterior while that will help it does not eliminate the problem..
Geez I said that poorly, Let me take a differant tack. An R value is only the rate at which heat (energy) is transfered not a way to block the transfer completely. It's sort of like a traffic jam. eventually the heat (energy) will get moving. The best systems are ones that put the biggest road blocks in the way.
I guess what I'm saying is that we're pretty much in agreement only a little differance in how we say it..
While I agree that cellulose is generally better that FG batts ( almost anything is) I was pointing out that the reason for that is because it eliminates convection loops in the stud spaces that transfer energy to the exterior.But the Foam exterior effectively reduces or eliminates the cause of convection loops.
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reduces yes!. eliminates? no.. celluliose slows air movement but doesn't prevent it. Vastly superior to Fiberglas. not as good as foam..
Foam on the outside also reduces heat loss through the studs.
The ideal insulation is like a thermos bottle.. seperated from the outside with no method of heat transferance.. Like either a SIP or ICF. On a purely therotetical basis the SIP is superior to the ICF but from a practical basis based on time to construct a ICF has it all over SIP's
Edited 10/24/2009 11:27 am ET by frenchy
Where are you in Mt-Tremblant? I'm in St-Jovite...or was, before the PQ 'merged' our parish with a couple of others to form the Big City.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Actually in Val-David,
Bonjour voisin..
Fred
Hi Fred,
You might want to fill in your profile so that people know you live in Canada and don't give you advice based on US codes. I'm an ex-Quebecer too.
Done
Thanks
Bon, salut mon gars....
I can't recommend you balloon framing your place for a few reasons.
First, it's much more complicated and difficult to hang a floor partway up a bunch of studs than it is to simply build one on top of the plates. I know you're thinking it'll be nicer to frame that floor under cover, but it ain't that cold yet. You've got another month or so until it'll be below minus ten on a regular basis, and you oughta be able to frame that floor in a day. Plonk your ply on that the next day, then start on the roof. You'll be under cover in a week.
Second, you'd have to special-order the 18- through 24-footers you'll need for the gable-wall studs...and I'll betcha dollars to doughnuts unless you order 'em green, they're gonna look like hockey sticks. And do you have any idea what a green 24-foot 2x6 weighs?? Yowie.
For that matter, if you want 'em KD, you're gonna have to wait. Claude Forget might be able to turn them out for you in a month; I dunno. You'll have to call them and ask. Timberjack might do it--they're closer to you--but I think he's all BC fir and that will cost you.
Third, you might have to bring in an engineer to convince the local BI a balloon frame is structurally sound; nobody I know of frames like that up here, and some of these local BIs are real creatures of habit.
Also, a balloon is not as inherently strong as a stacked frame because the floor system depends on fasteners piercing the studs to hold it up, instead of the joists bearing on solid wood plates.
That said, there are some positive structural aspects to balloon frames in this kind of design. One of which is that your upper storey walls would have more wind resistance...but you don't get the kind of winds that tear off roofs, so I don't see what real advantage that would give you.
Now, as to framing on 24" centers, yeah, that you can do. But your roof, even at 12:12, needs to be sheathed in 5/8 ply, not half-inch Beaver Barf. Yeah, I know the code permits ½" OSB, but it ain't enough to stay flat on 24" centers with our kind of snow load. Val David isn't listed in the tables, but Ste-Agathe is and their snow load is even higher than ours.
Finally, I'm not sure about your idea of using XPS on the outside of the wall sheathing; that will tend to act like another vapour barrier, and it'll be on the wrong side of the wall. Not a good idea, IMO.
If you want to boost your R-value a bit, I'd let 1x3 cross-bracing into the studs, use Black Joe on the outside as sheathing, lay 5½" FG in the stud bays, then use Reflectix 'bubble-wrap' mylar on the inside as an insulated VB, and strap that with 1x3 before hanging your gyprock. The Black Joe will give you maybe R-1 or 2, and the Reflectix will get you at least an additional R-5; R-10 if you believe the manufacturer's blurbs. I've used it in gambrels to help compensate for the two-inch loss in rafter-bay depth given over to vent bays in the lower roof.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
The 24" oc isn't a problem, but if I read you correctly you are using continuous studs from foundation to roof with the second floor attached to the side. It is called Balloon Framing, and you may want to re-think building that way. Most people have abandoned it as a framing method because the increase in insulating value is offset by the added complication of firestopping and supporting the intermediate floor structurally.
Balloon frame has a lot of advantages for the kneewall upper floor and roof
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This is a neighbor of yours
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So, you are building a balloon frame house?
Are you building a rocket ship or a house?
I've never seen a 36' tall wall in a house. What are you using? 2x4's? That will be very, very flimsy.
Please set up a 24 hour live cam feed at justin.tv. I want to watch you frame it.
If your primary reason for 24" OC framing is insulation, perhaps you might consider 2x6 sill and top plates with 2x4 studs instead of 2x6 and alternate them so that the outside and inside walls would have no direct path for heat or sound conduction from the inside to the outside.
If you use batts, alternating stud walls are almost impossible to insulate properly unlss they are on completely separate plates.
I am half way through framing my own house with 2x6s at 24 oc.(8.5' walls) With help from my engineer I also have abandon most cripples and trim studs. I also used ladder blocking at all the interior wall tie-ins (which incidentally are working great as actual ladders.) It being my 1st time attempting this I am both excited and nervous to see how well it all works. Saving money and trees while increasing the insulation dramatically is great. Just hope it doesnt end up with any excessively wavy walls! It sure is wild to step back and look at the lack of lumber in the first floor that I finished this weekend!Good Luck!
I framed lots of houses with the ladder blocking and fewer cripples. All those cripples on the ends are a significant waste of good lumber.