Is this foundation adequate for my cabin? - Photos

[Solar Burrito]

Hi I'm building a 200 sf cabin on a post and pier foundation but it doesn't come with plans for the foundation. Can I ask you experts out there if my joists and beams are sized correctly for my span???

It's going to be a 12' x 14' platform with a 4'x8' bump out. I thought I'd use 4x8" x 14' built-up beams with 2x8 joists. Will this work or is it undersized? Anything else I should plan to do? Also I'm not sure how to attach the deck to the beams??

[MountainDon]

To use 4x8 beams you should space the supporting posts no more than 4 feet apart in my estimation. I can't tell from your drawing what you might be thinking. You space them farther apart, say 6 feet, if you were to use 4x10 beams.

You can use the calculator at AWC to check on floor joists as well as size your ceiling joists and rafters. Species, grade and spacing all enter into the sizing. You may also want to oversize them to get more insulation in the floor.

You can toe nail the joists to the beams. Hurricane tie plates like the Simpson H-1 (usually used for rafter to wall connections)  can also be used; they make it easier to keep the joists positioned right where you want them when nailing.

There should also be lots of diagonal bracing between the posts and beams and joists.

What sort of footings are you thinking of? How deep is your frost?

A 4 foot deep bump out is quite a bump out. On what side? Something that size should likely have a beam and set of posts. That will complicate the structure.

[Solar Burrito]

Hi, thanks for replying. I'll give you some more info. I really want to get you guys to sign off on this before I start!

This is a better view showing the pier blocks 4' apart. Will the ones on the end of the beam be OK like they are positioned?



Here's the floor plan (above) i'm building you can see the bump out there, maybe bump out is the wrong phrase? It will have some kind of support under it with pier blocks but I haven't figured that out yet. I'll figure that out after it's done.

My frost depth near Hoodsport, Washington is 12" and it will be built on extremely rocky well drained soil. So I suppose I'll be digging down 12" then putting crushed rock under the blocks.

I looked at the Span calculator for Douglas Fir, I think that's what we have around here but I"m not sure. It said 2x8's are good for a 13 foot span. I'm not sure what is normal deflection so I didn't change it in the calculator.

Do you think I should use 4x10 main beams instead of 4x8s? Diagonal braces from the beams to the joists?

Since I love photos on this forum here are some more of what I want to build:


Photoshopped cabin on old yurt platform. it will be removed.


Here's a 3D model I made to figure out how to orient it on the property.

[MountainDon]

I'll figure that out after it's done.

No. An incomplete plan is a poor plan. A poor plan frequently leads to redoing things, extra expenses, or a structurally unsound building. Proper planning is one reason I like to draw paper plans. I go through the "building" process on paper, drawing in all the structural parts on multiple sheets. I find that helps me avoid some errors. Others prefer to build on the fly, so to speak. Until one has good experience I believe that has the potential for time and material waste.  

If you read enough of the projects topics here you will find several that had portions that had to be torn apart to some degree and then rebuilt. I believe those were projects that had incomplete or ill conceived plans. You are on the right trsack to be asking questions before so much as buying a stick of lumber.

As I stated above, you will likely need to place a third beam under the "bump out" exterior wall, with its own set of footings. At 8 foot length three posts on a 4x8 beam would be about right, MTL.

I'm not sure what is normal deflection so I didn't change it in the calculator.

Examples of code-prescribed deflection limits and live load values are:
   * Living room floors L/360 & 40 psf
   * Bedrooms and habitable attic floors L/360 & 30 psf
   * Attic floors with limited storage L/240 & 10 psf.
Rafters  L/240

Diagonal braces from the beams to the joists?

No. Diagonal bracing from the lower end of the posts to the beams and diagonal braces from posts to joists. That way the platform is braced in both the X and Y axis'.  Think triangles, not quadrilaterals. Triangle do not deform, all other geometric shapes can and do deform.

[Whitlock]

I love that cartoon picture of your soon to be cabin in the woods

[Solar Burrito]

Haha, thanks Whitlock, so far that's all I'm sure I can make. Cartoons and bad drawings!

[IronRanger]

I don't have any useful info to add, but I'd like to ask a question or 10,000.   

About a week ago, I found the same plan you're building.  Do you have a floorplan laid-out?  What's the head clearance upstairs?  Is there actually a staircase, if so, how wide are the stairs and how steep? 

I may have more.  You've been warned.   

I hope everything goes smoothly for you.  I got a good laugh out of the photoshopped house.  Very creative.

[MountainDon]

 What's the head clearance upstairs?  

Assuming that roof is a 12:12 pitch with 2x6 rafters and also assuming the loft floor joists are 2x8's the maximum headroom in the center of the loft would be less than 5 feet.That's assuming the ceiling joists are installed on top of the wall plates. That's with the gable roof across the 12 foot dimension; the ridge running parallel to the 14 foot dimension.

[Bobmarlon]

I am not an engineer so I can not sign off on this although based on other peoples cabins on this website that are still standing it looks like it would be fine.  I would like to say though that this is the worst time to cheap out do what you think will be the best because after you finish this stage of your cabin you will get very used to spending money.   

[Solar Burrito]

 What's the head clearance upstairs?  

Assuming that roof is a 12:12 pitch with 2x6 rafters and also assuming the loft floor joists are 2x8's the maximum headroom in the center of the loft would be less than 5 feet.That's assuming the ceiling joists are installed on top of the wall plates. That's with the gable roof across the 12 foot dimension; the ridge running parallel to the 14 foot dimension.

Don is right on, and all from looking at it! Also thanks for the comments about not cheaping out on the foundation. It's a good point I think I'll get full length 2x10 x 14' to make beams instead of piecing them together from shorter sections. I'm wasn't sure how to do that properly anyway.

How far off the ground should non-pressure treated beams be??

I want to use pressure treated posts but not beams and joists? Is that ok?

I don't know the roof pitch as I don't have the plans yet but I do know there is 5' of headroom max in the loft. It's meant to be not considered living space apparently. The stairs shown in the floor plan are optional the "kit" (not pre-cut) comes with a pull-down attic type stair. Which works better for us anyway since it won't take up any floor space. I was told there is 8 foot of headroom on the main floor. The loft is 12x14' as mentioned above. The covered porches and deck are my additions.

I don't have a floor plan yet but I do think the 4x8 bump out would make a great dinette, perhaps convertible to  bed like an RV?

I made these models of a dinnete last night. The guy in the pics come with Sketchup and he's 5' 10" tall. So it looks pretty spacious for 1 person.

[MountainDon]

How far off the ground should non-pressure treated beams be??

Non pressure treated wood should be kept a minimum of 6 inches above the ground level.

Also note that most codes want 12 inches ground to the bottom of the beam and 18 inches to the bottom of the joists. This is for ease of access. Even if there are no codes to be bothered with that is a good minimum suggestion.

[MountainDon]

I want to use pressure treated posts but not beams and joists? Is that ok?

Yes.   Be certain to use the correct type of metal brackets and fasteners with any PT wood.

[John Raabe]

A couple of comments on the "plan".



And thoughts on the section:



I think this is planned as a kids playhouse as the scale works for that. However, if you are over 5' tall there are issues.

[RainDog]

 I've run across the site selling these a few times. It's one of those "tiny houses".

http://www.pennypincherbarns.com/CabinKits/MiniCabinsTinyHouses.aspx

I imagine the OP knows what he's getting into, at least in theory.

Good questions for him to ask the dealer, though. Be a shock to find the wall to be flat 2x4s upon taking delivery.

[Solar Burrito]

A couple of comments on the "plan".

And thoughts on the section:

I think this is planned as a kids playhouse as the scale works for that. However, if you are over 5' tall there are issues.

Thanks for all your help everyone, I've been lurking on this site for years. It's great to almost have project moving...

I didn't draw that drawing showing a green cabin and floor plan, Penny Pincher Barns did and since they design dozens of different type of buildings I hope they knows people don't want a cabin that's 6' tall. As you point out it's not to scale. Just to clarify I'm not building a doll house, it's a small cabin with loft. As said above I'm told the walls use full 8' 2x4 studs and the loft joists sit on top of that so it will be plenty of headroom for me. Sleeping loft is 5' tall.

The drawing may show their post and beam option for this plan?? The stairs are also just an idea of what could go there. It comes with a pull down attic type stair.

Should this thread be moved to Owner-Built Projects?

[John Raabe]

Ok, that sounds better. Those drawings are not to scale and the building is taller than drawn. 8' frame (and insulated) walls with the loft rafters on top will work fine. You can go as low as 7'-6" for a ceiling in a small space but not as low as shown in the elevations. A pull down ladder or a Jefferson stair would work fine for the little attic.

[IronRanger]

 What's the head clearance upstairs?  

Assuming that roof is a 12:12 pitch with 2x6 rafters and also assuming the loft floor joists are 2x8's the maximum headroom in the center of the loft would be less than 5 feet.That's assuming the ceiling joists are installed on top of the wall plates. That's with the gable roof across the 12 foot dimension; the ridge running parallel to the 14 foot dimension.

Thanks, MtnDon.

To the OP:

Where you located the bed, I was thinking kitchen.  Bath would go directly above, on the 2nd floor, of course.   

I really like the design of this.  It's simple, yet has character.  If one changed the framing to allow for 6-foot (or greater) head clearance upstairs, I'd think it'd be a very usable little home.

[Solar Burrito]

Ya more headroom would be nice but it would break the 200 square foot "shed" rule in my area and I want to get it up and "legal" for a few years at least before I make it bigger. If I ever do. I really don't want to get the county involved! The road is private and steep up to the property... too steep for firetrucks so the county wanted me to put in a dedicated fire suppression system.... blah blah.. I'm totally off grid with no water or power available. It would involve tanks, pumps pipes, union pipe fitters etc etc. So we thought about what we need and how we would use the cabin and this plan suited us and didn't look too "shed like". This is just a small camping cabin for us and it will actually be bigger than what we are used to. We used to have a 16' diameter yurt on the spot and that didn't have a loft at all.

Interesting idea to have a kitchen in the bump out, that could be cool. It could look very built in. We arent going to have a dedicated kitchen though. I don't know if the table will ever be converted to a bed since I'd need to have cushions fit properly like an rv to make the table and the bed and that sounds hard. But I thought it would nice to have a dedicated table inside to play cards on or something.


Ya bathroom upstairs... I wish! We have composting toilet now in an outhouse... The ladies tolerate it but its definitely camping.

In the past we have cooked outside 95% of the time. Only on cold raining mornings have we cooked some coffee and eggs inside the old yurt on the wood stove. So with this cabin we'll probably have a 6' counter top with cabinets under it that would allow us to have a Coleman portable stove on if we want. Also I'm thinking a small sink that would just drain into the ground I suppose. We had one in our yurt and it was nice once in a while. Our soil drains and drains so even though we are near the Olympic National Rain Forrest and get lots of rain it really doesn't puddle. That must be how the old sink worked... However I don't know since I didn't install it.

[MountainDon]

I was thinking kitchen space in the alcove, too. 

No need to move this topic. You could start a new one in the Owner-Build board whenever you would want to.


When you finalize the foundation or have any new questions on that might be an opportune time.

[Solar Burrito]

This is the best floor plan I could come up with:

[MountainDon]

I am wondering about the wood stove. A 200 sq foot cabin does require many BTU's to keep warm if the cabin is insulated well. Do you already have a wood stove from the yurt? You may want to consider a small direct vent propane wall heater. Just a thought. I do like our wood burner; somehow it doesn't seem right to not have a wood stove especially if you have your own available firewood.


It would also appear that the illustrated position of that wood stove would have chimney interference problems with the roof ridge.

[JRR]

You are obviously well adjusted to "living small", ... and that's commendable ... we all need that quality.  But that is a very small building plan .... it may not suit you in years to come. 

Another approach might be to build a very large sturdy barn ... earth floor ... large glazed windows, etc.  And inside ... park a camping trailer, a trailer with all the modern amenities.  Used trailers can be bought fairly reasonably.  Would be well protected inside the barn ... and you would have additional protected storage for tools, vehicles, etc.

Just a thought ....

[Solar Burrito]

Jrr - I guess you didn't read the rest of the post?

[JRR]

Not well enough, I suppose ...

[Beavers]

Solar Burrito,

Just a couple of thoughts/suggestions.  I'm building a 12x16 house (full time living, not a cabin).


If you are trying to stay under the 200 sqft. footprint a 12x16 would get you the most space possible.  That extra 2' of width is a lot a space in a small house!  With a 12x16 you can actually fit a kitchen, living area, and a bathroom into the space.   If you stay with the outhouse, it would downright spacious inside. 

You might consider a set of plans from John.  They are pretty detailed, and spell out all the stuff like pier spacing, and beam sizing so you don't have to guess, they also include a ton of other useful info.  The plans are also VERY cheap!  I didn't look at the cost of the plans you are looking at, but I doubt that they are any cheaper.    These plans are proven with many houses built from them.  Not trying to sound like an advertisement, but as far as small house plans go, the CountryPlans ones are about the best you can get.  How many other websites can show you dozens of houses built from their plans? 

I went with 10' sidewalls, and a dormer on each side.  This really turns the loft from a small cramped space into an actual usable space.  With 8' walls and only 14' wide that loft is going to be very tiny, even by small house standards.  The extra wall height is just really cheap usable square footage IMO.  You would have to double check to make sure if it would work in your area, but if building again, I might even think of going with 12' tall sidewalls.

I also really wanted a wood stove.  Even with the high dollar Jotul, and Vermont Castings small wood stoves, the clearances would eat a huge chunk of the floor space.  I've settled on a direct vent propane heater. 

This is just my 2 cents, I know that it can be kind of hard to info from people who are actually building tiny houses to live in, so hopefully some of this is helpful.  I'm still figuring this out as I go, but I think we will be able to make a go of this tiny house living thing!