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cvinvt
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# Posted: 1 Jan 2022 11:31am - Edited by: cvinvt
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My wife and I are looking to build a 24x20 cabin. Thinking of framing it with 10' 2x6 studs for the outside walls to allow for a 2 foot knee wall upstairs. with the rafters coming from the 20 foot sides and a 12 pitch roof we'll have a nice sized room upstairs. The downstairs to be basically open as well with the exception of a bathroom in the left rear corner and we'll need some stairs of course going up and down as we'll planning on having a walk-out basement. The cabin is to be at the top of a nice incline with the 24' gable end facing down the hill facing directly south. Anyone have any thoughts/concerns regarding this plan? Anyone built a similar cabin with the gable end being the longer side? 10 foot wallls? Any input is appreciated.
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gcrank1
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# Posted: 1 Jan 2022 12:17pm
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That would be a nice size.
Be aware that building on a slope has some very important considerations especially for a sizable structure.
On grid, off grid, well, septic, permits/inspections, etc?
For a new build of that size Id be looking at plans, there are a lot online now.
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cvinvt
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# Posted: 1 Jan 2022 12:28pm
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It's not a steep slope...gentle slope really. The elevation from the back 20 feet to the front of the cabin drops about 4 feet. We're figuring to have the foundation step down 2 feet at the 10 foot mark so as to not have a lot of concrete showing. I haven't been able to find plans online for a 24x20 with the gable end being the 24' side. We've had a well drilled...500 darned feet and only 3/4gpm flow...grrr...We do have a septic design approved by the state for a presby system. Figuring to be on grid at this point as there is power right there on our little dead end dirt road. We're building up at the top of the pic to the right of the skeleton of the little shed.
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ICC
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# Posted: 1 Jan 2022 01:36pm - Edited by: ICC
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A 24 wide (gable) x 20 long (side) is just a short 24x30 built in the normal manner. That is how I would approach it. Floor joists run the same way as the rafters and then there is no adjusting needed to be made to the way all the parts are looked at.
I, personally, would have another look at whether or not to use those short kneewalls in the upper section. Structurally they are not good, and they get worse as the width gets wider and the snow loads become greater. No engineer I know would place their stamp on plans that include that detail. That sort of thing does not meet code, though that does not stop people who are not building where inspections are not part of the deal.
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cvinvt
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# Posted: 1 Jan 2022 03:47pm - Edited by: cvinvt
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I think I misspoke regarding the 'knee wall'. Bad choice of words on my part. I am not a builder but we do have someone that is, thank goodness.
We're hoping to use 10 foot 2x6 studs for the outside walls but put the floor at 8 feet so as to have a couple extra feet of height and width upstairs.
With the 12 pitch roof we hope to have about a 16 foot wide area by 20 feet where the ceiling is at least 5 feet high.
I'm told it's balloon framing?
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travellerw
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# Posted: 1 Jan 2022 04:46pm
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I would check with an inspector. What you are describing is a "Dropped Loft" and as I discovered won't pass in many places!
I would also start thinking about a layout and where the stairs will be. In a build like that, your stairs will need to run parallel with the rafters or you will need to do some engineering to keep the strength for wall push-out.
As to 10 ft walls.. Our cabin is 10 foot walls and I will warn you about how much more difficult it will be. It may seem like it won't be a big deal, but it makes EVERYTHING more difficult. A standard 6ft A-Frame ladder will not be tall enough to safely work at the top of the wall. Roofing will also be difficult as the roof will be like 25 ft at the peak (mine required equipment). Personally, I think it was worth it, but it added a TON of extra work!
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cvinvt
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# Posted: 1 Jan 2022 05:23pm
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I'll give consideration to your warning regarding the 10 foot walls. We do have some taller heavy duty step ladders. One being what ends up being an up to 12' Little Giant Heavy Duty Step Ladder.
What kind of special equipment did the couple extra feet of roof height end up requiring?
It never occurred to me that a Dropped Loft would not meet code.
The Town itself has no requirements or even Zoning...only what the State of NH goes by which I believe I was told was the 2015 International Residential Building Code. The Town does have a Building Inspector that must give an Occupancy Permit before moving in.
With the Rafters spanning the 24 feet we were figuring to have the stairs perhaps along the back running the same direction and the ones going down to the cellar going below them.
I wish I knew someone that was adept with something like SketchUp to draw some simple framing plans up. I've tried learning it a bit but well...it's slow going.
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ICC
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# Posted: 1 Jan 2022 06:29pm - Edited by: ICC
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Balloon framing is fine, but what you describe does not fit the IRC framing requirements. Proper balloon wall framing has joists or rafter ties connecting the top plates of the walls, at the top plate or to meet the requirements of using a raised tie. (see code)
The problem comes from the roof requirements. A gable/rafter roof assembly must have a rafter tie that connects the rafter tails which must be sitting on the wall top plates.
Here is a link to a page in the 2018 IRC that may help explain. Scroll down to figure 802.4.5 (disregard the purlin braces in the illustration).
Short stubs of wall that have rafters tails fastened to them as proposed, MAY not be strong enough to resist the outward forces on the stubs by the rafters. Doing so is not good engineering. It has been done many times and mostly without any problems. However the wider the span and the higher the snow loads, the more the potential for problems. Just pointing out the potential problem and the fact that building like that is not going to meet IRC. Some inspectors may give a pass on that sort of thing, but IMO, that still does not make it good practice.
You may also want to keep in mind that the IRC gives minimum requirements. Better is always, well, better.
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travellerw
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# Posted: 1 Jan 2022 06:48pm
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Our cabin has a Gambrel roof, so the one pitch was too steep to safely roof off ladders or even supports. We had to rent a towable man lift. We have a height at the peak of about 25ft, so nothing to sneeze at. We talked with a couple of roofers that said they would pass on the job based on the height and pitch!
In your design, the second floor joists become the rafters and ties. Many engineers don't want to sign off on the concept of a dropped second floor. I'm not sure why as its basically a cantilever, just on a different plane!
However, I'm not sure you will be able to span 24ft unsupported without engineered wood. If I remember right the span tables are only about 20ft for a 2X12 (maybe even less). Even a 2X14 might not be able to do that. With standard wood, I think you will require a support in the middle down the length of the cabin. I would start studying span tables.
Another thing to consider, is many locations now have a minimum amount of insulation in the ceiling. Even with 2x8 rafters you can't get enough insulation in there to meet the code. You have to build the rafters out to get enough room for insulation and venting.
Of course, this is if you are getting it inspected.
Have you looked at SweetHome 3D? Its free and has a very simple learning curve. There are a bunch of videos on Youtube that can teach quickly!
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cvinvt
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# Posted: 1 Jan 2022 06:50pm
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So the top plate, rafters and joists all should come together at the top plate?
That being said, how does one get the added couple feet upstairs? It was previously stated that a 2 foot knee wall would also be unacceptable.
Presumably, there is a way to frame in the loft at 8 feet but have the walls 10 feet tall to get the 2 extra feet upstairs?
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travellerw
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# Posted: 1 Jan 2022 08:30pm
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Quoting: cvinvt Presumably, there is a way to frame in the loft at 8 feet but have the walls 10 feet tall to get the 2 extra feet upstairs?
Like I said, I think there is no problem with that design (its how mine is built). However, my research says they usually don't pass unless and engineer signs off on it (and many won't). I'm pretty sure if you found an engineer that does more than just rubber stamp old designs you could get it approved.
On my build, I used 2X6X10 studs, then sistered 2x4x8 studs that the joists/rafters rest on. Each connection has 5 nails and 2 screws. I also upped the top plate to 3 laminated 2X6s (screwed and glued) to counteract the push-out. We did a %60 loft and the open area will use stainless cable in place of the rafter ties (just 3 as the cable has way higher strength and combined with the triple top plate should have no problems). Of course ours is not inspected as its really in an area where inspections aren't a thing!
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Brettny
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# Posted: 1 Jan 2022 08:36pm
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Quoting: cvinvt Presumably, there is a way to frame in the loft at 8 feet but have the walls 10 feet tall to get the 2 extra feet upstairs?
Are you really just wanting head room in a loft by doing this?b there are other ways and far less complex. A gambrel roof is a good choice. If you run the rafters the 24ft direction you will have 10ft at the peak under 2x12 rafters and above 2x12 floor joists.
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ICC
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# Posted: 1 Jan 2022 09:18pm
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Quoting: cvinvt Presumably, there is a way to frame in the loft at 8 feet but have the walls 10 feet tall to get the 2 extra feet upstairs?
According to code and best engineering practice? Not without an engineer's study and stamp. There are many structures built with 2 foot or so stub walls (knee walls).... Many survive for years with no problems for a long time. Maybe because they are narrow; 12, 14 feet wide means there are lower rafter loads. Maybe because the snow load is low to non-egsistent.
I have worked with, had many conversations with engineers during the course of my construction experience. This question of "kneewalls", or "dropped loft floors" comes up all the time. The answer is always the same. No.
There is an old section in the nearby town where I live. The homes are 100+ years old unless they have been recently demolished to build a new one. The old homes are mainly 20 feet wide with a gable roof cross the 20 ft width. Not quite half of them are single sory with a simple attic, no habitable space above the main floor. A few 2 or 2-1/2 story homes are scattered here and there with the rest being 1-1/2 story homes. The upper floor in every one of them is centered across the width. Usually two rooms one to the front end, one to the back and the one bathroom in the center with the staircase. Most often a shed roof dormer for the bathroom. There is a "wasted" 4 foot strip upstairs along each long sidewall; a triangle of space that extends out to where the rafter tail meets the wall top plate. Each upstairs room has a short wall, about 4 foot tall or so, then sloped ceiling/roof, then a center horizontal section of ceiling about 4 feet wide; above which are loated the rafter collar ties. Some of those upstairs rooms were built with a dormer or sometimes two, which greatly increases usable space.
As I said those are 100+ years old. No sagging roof ridges, no wall tops being pushed outwards. That triangle formed by the rafters and the rafter ties that are also ceiling/floor joists make a rigid triangle. Change that by dropping the upper floor joist down the wall studs and you no longer have a rigid structural triangle.
I am not going to argue this point any further unless specific questions are asked.
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Aklogcabin
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# Posted: 2 Jan 2022 11:11am
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I think you're plan is fine. Not an engineer but have built plenty.
Our cabin is 16x24 with 10' tall walls. 12/12 pitch. With a full upstairs. And we really like the room.
Your roof. Actually becomes easier for putting the roof joists on. You can stand on the upper floor. We're in AK n get lots of snow. And big earthquakes. Our cabin has done great.
You are not making a hinge with your walls, the studs are 1 piece. You can build the support in your walls to support the 2nd floor. Sunken living rooms used to be popular one time.
Putting your ideas n wants down on paper, all of them. Talk to an engineer if the plan needs to have an approval from an engineer. There are plenty of more technical builds than yours around. And lots of ways to skin the proverbial cat.
Have you considered using manufactured joists ? Get them as long as you need. 12" tall joists can span 24' with one joint but will need a support wall in the middle. I used 6"x12" glue lams to bridge the 16' wide that sat in pockets with 6"x6" beams bisecting them into smaller sections. Then 2x6 tongue n groove for the floor. Very solid. And ties the walls together solidly.
We enjoy having our bedrooms upstairs. I built a little deck off the main bedroom and an opening window on the other end for a cross breeze. But would like to add another deck some day. And an planning out a chair lift for getting up n down from upstairs using a 12v winch. My beautiful wife has foot problems. Will keep the stairs also.
I also have a longer tail on my roof joists of 3'. This keeps the drip line further from the foundation. And having the dry usable area next to the cabin is nice.
Just my advice. Design what you want. Then go from there. Lots of ideas here no doubt. So if you need engineered plans talk to an engineer. Don't disallow doing something because someone on the net wrote something.
I also believe that building is expensive. And there is a break point where you can overbuild. It all costs more time n materials. You could put r 80 in your roof for insulation but you would not amoratize your cost for a long time with little gain.
Built what you need to. Unless you have unlimited funds.
Your only in the planning stage now and will get plenty of advice. But the buck stops with you.
I know this. I've learned to build the way I want, and glad I don't have to think back about how I really wanted to have a feature but didn't because someone said or wrote something regarding a question asked on the net. Your doing your homework n asking questions. I'll add a couple pictures of mine .
Good luck on your build ! Try to enjoy the process and try to stay a couple steps ahead concerning planning.
And staying positive really helps
Upstairs
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Lower level, kitchen, bathroom in left rear
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Side view
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Our little slice of great
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cvinvt
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# Posted: 2 Jan 2022 11:34am
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I do believe we will decide on 8' walls and sacrifice a bit of loft/bedroom space.
We're not keen a gambrel style roof.
We'll still have a decent sized room upstairs with the 12 pitch and overall it sounds like it will keep things simpler.
The discussion, has been appreciated. -Chris and Vicky
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Grizzlyman
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# Posted: 2 Jan 2022 05:01pm - Edited by: Grizzlyman
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I built your cabin this summer!!! 22x20 with the 22 being the gable side. 10’ walls. Same thing- ballon framed with loft at 8ft. I used a center wall to support the loft and make a bedroom. Everything else is open. I used a shallower 6/12 pitch for the roof.
You can check it out in the member projects section. If you want to see what it looks like in real life- here’s a YouTube playlist of the structure- from beginning to end.
https://youtube.com/playlist?list=PLymhUcxN9AzNYfNXWCTn-xbvGjrfELk3K
I’ve said before that if I had to redo…the one thing I’d change is the 10’ walls. I’d do 8’ walls if I did it again. As stated above the extra 2’ of walls adds another 50% or more difficulty and work to it. In addition the 10’ is kind of wasted space since I have a cathedral ceiling anyways.
Hope this helps.
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travellerw
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# Posted: 2 Jan 2022 05:26pm
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Quoting: Grizzlyman As stated above the extra 2’ of walls adds another 50% or more difficulty and work to it.
I remember you giving me this advice.. However, I'm actually glad I didn't listen to it (no offence). My wife and I both agree the extra work was worth it for the effect.
But that is how life is.. People see things differently. For you, it wasn't worth it, for me, it was! We just look at things differently. It sure would have been nice if you and I had 2 examples to look at before we began though!
Unfortunately, that doesn't help the OP though! Either way, I think he will be happy no matter which way he goes!
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cvinvt
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# Posted: 2 Jan 2022 07:14pm
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Well, we're in the planning stage as was stated.
I have not looked into SweetHome but, will. Thanks.
Why 22? Why not 24 for the gable end? I'll check out your videos. Thanks.
Sounds like all are in agreement that the extra 2 feet does add significant difficulty to the job. For some, worth it...others not so much. Strong enough...sounds like yes...meets code...No
My concern bigger than job difficulty now leans more towards the Inspector saying...no...you shouldn't have built it like that.
The Town does not require any stamped, engineered drawings to get a building permit but depending on the Inspector I fear he could call us out on it after its built. That would be a crushing blow.
We are wanting to keep things simple.
We're figuring with the 12 pitch roof if we do go with 8 foot walls and the loft at 8 foot we'll still have a nice large room upstairs. Essentiallly 12x20 with 6 foot ceiling height and the remaining space as it tapers down to the triangle still usable.
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gcrank1
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# Posted: 2 Jan 2022 07:37pm - Edited by: gcrank1
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Im afraid the 6' height is not going to be enough unless you are pretty short.
Our 1st build 12x24 with loft had an 8' to the bottom of the ridge board (no knee-walls) and we were always ducking or banging into the rafters (I was 6'1" and trim then, wife 5'8"). It gets narrow very quickly!
And it means your ladder/stairs has to land right at the center.
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Grizzlyman
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# Posted: 2 Jan 2022 08:01pm
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Quoting: cvinvt Why 22? Why not 24 for the gable end?
No real reason other than that’s what we decided on. Keep in mind too that if balloon framing a rake wall that is 24’ wide and 18-20ft tall it’s gonna be a heavy beast!!
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cvinvt
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# Posted: 2 Jan 2022 08:10pm - Edited by: cvinvt
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Well, my wife is 4'10"...me, 5'9"
She'll be more at home and less likely to bump her head than me no doubt but, I did once upon a time live in a cabin that had a loft where the peak was about 4 feet...basically a sleeping loft. Hopefully, I can draw upon those old days to dodge the ceiling.
Keep in mind our ceiling will be 12 feet wider than yours if yours was only 12 feet. Ours is 24 feet. That should make quite a bit of difference. 12 feet wide where it's 6 feet or higher ceiling height.
I hear you though...more height would be nicer but, we don't want a gambrel roof and it's seeming the two extra feet from 10' walls are problematic even to the point of not satisfying Code.
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cvinvt
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# Posted: 2 Jan 2022 08:15pm
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We'll recruit whatever muscle is needed to put up the walls.
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travellerw
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# Posted: 2 Jan 2022 10:35pm
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Quoting: cvinvt The Town does not require any stamped, engineered drawings to get a building permit but depending on the Inspector I fear he could call us out on it after its built. That would be a crushing blow.
If an engineer signs off on the design, then I think you are %100 safe. I have never seen/heard of an inspector not passing an engineered design. I have seen them ask for an e-mail confirming the design, but never failed. At least in the oilfield, maybe its different in residential, but I don't think so.
Another thing to think about is your stairs. There is a bunch of code around not only the stairs, but headroom at the top and bottom. Just make sure you know the code as it really dictates where your stairs can go! However, you should be in better shape with a 20X24 building.
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Brettny
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# Posted: 3 Jan 2022 04:43am
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Quoting: Grizzlyman I built your cabin this summer!!! 22x20 with the 22 being the gable side. 10’ walls. Same thing- ballon framed with loft at 8ft. I used a center wall to support the loft and make a bedroom. Everything else is open. I used a shallower 6/12 pitch for the roof
I dont think the issue is how the loft floor joist is suspended. The issue is you dont have anything tieing the two walls together becids the loft floor joists that are 2ft below the top plates.
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ICC
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# Posted: 3 Jan 2022 08:41am
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Quoting: Brettny I dont think the issue is how the loft floor joist is suspended. The issue is you dont have anything tieing the two walls together becids the loft floor joists that are 2ft below the top plates.
Correct
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Aklogcabin
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# Posted: 3 Jan 2022 10:55am
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Good luck on your build. Lots of ideas n concepts when you ask about ideas on the internet. And generally several ways to get any job done.
If I may suggest one more thing. Build what you originally would like the most. Ask a qualified engineer if its feasible. Since you have to have an approval plan by an engineer anyhow. And maybe that also will give you some comfort knowing your cabin will be safe.
I can say this, after build a few homes. You are going to get one chance at doing what you want. And the more you things you change, that you originally wanted start to build up themselves. And you don't have the dream home ,cabin you always wanted.
And not let internet chatter change your mind. Take comments for what they are are. I wouldn't write this but you seem to change your wants because of internet comments based on very limited information.
Again good luck, have fun
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travellerw
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# Posted: 3 Jan 2022 11:16am
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Maybe this isn't the right place, but the logic doesn't seem to agree here. Its still a triangle, except the bottom 2 foot is cantilever. Its still relying on the connection between the top plate and rafter to resist push-out. I have to think toe nailing or hurricane ties are going to be weaker then a 1.5 foot section of 2x6 under cantilever stress!
Anyway.. I would love to see an actual engineer do the calculations (or use software) to show the data. I would love to see what the actual push-out forces are under maximum snow load.. and how moving the tie in lower affects that stress on the building...
Now back to the OP... I %100 agree with Aklogcabin! I don't think anyone here is an engineer or inspector (even if they are, different parts of the county have different rules). Use this information to help you know where you might need to do more research or enlist a professional. Don't rely on it for decision making.
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ICC
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# Posted: 3 Jan 2022 11:45am
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Give me a snow load for the area where this cabin is to be built, please.
Rafter spacing = ??
Building width = 24 feet and 12/12 pitch roof?
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travellerw
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# Posted: 3 Jan 2022 12:11pm
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Quoting: ICC Give me a snow load for the area where this cabin is to be built, please. Rafter spacing = ?? Building width = 24 feet and 12/12 pitch roof?
Lets do it in my area for fun.
Snow load: Ss = 1.5 kPa / Sr = 0.1 kPa. Run through a calculator that is about 18psf and I believe code says we design for 30psf
Rafter spacing 16"
Building width: 24' 12/12 pitch
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Brettny
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# Posted: 3 Jan 2022 12:12pm
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Quoting: travellerw Its still relying on the connection between the top plate and rafter to resist push-out. I have to think toe nailing or hurricane ties are going to be weaker then a 1.5 foot section of 2x6 under cantilever stress
Hurricane ties and toe nailing dont keep the walls together. Typicaly you would nail all three together, the rafter to the ceiling joist and both to the top plate. Making for a very strong triangle and the ceiling joist acting as the wall tie.
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