Efficient Tiny house ideas?

[shinnlinger]

Looking for opinions on what you think is the most efficient way to build a sub 500 sqft house if you had virtually unlimited access to decent white pine and a sawmill?  Small capes?  Geodesic domes?  Gothic arch trusses?  A frames?  Keep in mind these need insulation as well, so funky garden sheds that are tough to seal up aren't ideal.  Looking for a structure that is somewhat inspiring.  

Thanks.

Dave

[EOTE]

Since you've already got experience with post and beam construction, consider that as a possibility.  The neighbor is building one that is about 800 sq. ft. on two floors.



 

[shinnlinger]

I certainly have considered that but realistically, TF are not efficient because you basically have to build an envelope around it to insulate it.  On a small structure, that outside insulated envelope could likely support the entire structure, making the timber frame itself irrelevant structurally.  They look great, but wasteful in a tiny house IMO.  Open to contrary views to mine though.

Dave

[D L Bahler]

If you have unlimited access to white pine as you say...
Why not a timber frame with solid timber infill? If I were to build myself a tiny house, it's what I would choose. If you have the wood and can work it up yourself, you can't beat the price with a stick. Also with an interior envelope, you really can't beat the performance with a stick either. 

My baseline is something like this stylistically:


 
But I'm biased, since it's built by my great great (and so on) granddad some 332 years ago 

[shinnlinger]

I am a fan of those overhangs!  So you are suggesting a log cabin or stacked up 8x8's or something?  I can't believe that that would have fantastic R-value, but of course it not a lot of space to heat either.  I am weighing how much do I need to insulate/make a tight structure vs how much do I really need to get after it because the space is so small.

Dave

[D L Bahler]

Big overhangs for the win... (how else you think this house looks so good after 332 years?)

stopping air movement is far more important than r-value, especially on something small, and control of dew points is also a big deal. Massive wood construction is good on both of these accounts. What I personally would do is some sort of massive timber wall system with an interior insulating envelope. So a moisture permeable barrier on the inside face of the structural wall, or maybe even simply a good quality building tape to seal all connections, and then some sort of insulating envelope inside of that. 

The construction method of these buildings is upright posts with a squared timber infill of the same thickness. Upright posts have structural and stability advantages over horizontal log building. A common approach is to use a lower story framed in this way with a true log second level (because log building is easier, and they weren't as concerned with having a nice finish in the upper level so moving up and down wasn't a super big deal. But with modern tools, the ease of log building over framing is largely negated)

So basically, you have upright posts that have a vertical tongue, and horizontal stacked timbers that have grooved ends. You could also groove the posts and have tenons on the ends of the timbers, but this is an inferior practice. Introduces a line of stress in the post, and also it's easier to cut grooves in the ends of the horizontal timbers than to cut a log groove in the posts, at least when using hand tools.
If you fit everything up properly, bracing is unnecessary. 

white pine is something like r-1.3 to 1.5 per inch, but of course the U-value of the system is what really matters, and stopping air movement is where you should focus your efforts the most. I would go with a 5" thick solid wood wall with a 4 to 6" interior envelope. I like thick walls. That would get you something like r-28. But in a tiny house, not sure how much that matters. Put one window and door in the wall, your u-value for the system drops dramatically. So the average r-value of your walls is realistically going to be low no matter what you do. I'd focus my efforts on making the walls as air tight as possible, and then thoroughly insulating the roof deck (since you lose many times more energy through the roof than you do through the walls). With a tiny house, you're not really going to have a hard time at all keeping it at a nice temp, and you're probably going to lose more money due to economy of scale (smaller air units are relatively less efficient than bigger ones) than anything else.

It might be obvious by now I've spent some time thinking of building tiny homes...

[shinnlinger]

I really appreciate your thoughts and am going to mull on this some.  Thank you.

Dave

[D L Bahler]

No problem. I'm under quarantine and am exceedingly bored! Just grateful for any sort of distraction at the moment 

[dgdrls]

Octogon shape, 10' walls
keeps you under 500 @ 483 Ft Sq

Tilt the walls outward to allow more shoulder room inside.
Walls as D L Bahler suggested.

I like the extended overhangs 

D

[doc henderson]

who is this for, and what are the goals/uses of this building/home?  I always like the idea of a multi-level for small houses to add visual interest to the outside, and separate living, sleeping areas by story, not walls.  how old are the occupants.  that might change to single level if older.  many older folks are looking to downsize.

[doc henderson]

rustic, mobile/moveable, ADA compliant?.  too tight and humidity from cooking and bathing might be and issue.  I would pick a side to make it air tight.  i.e. tight inside or out.  spray closed cell foam?  interesting.  is this going to be a school project?

[Don P]

2 stories in small homes have 2 major disadvantages. The stairs eat up a large proportion of the space, and the upstairs tends to cook.

I'm loosely working with a group that is working on the same idea using CLT's, cross laminated timber, basically 3 ply plywood made out of 2x6's glued together. They will be insulated outside of that to keep the thermal mass inside the envelope.

This is a project I'm almost wrapped up with, just stick framed 16x28. We did buy osb for wall sheathing, all the other wood was homebrew.




I do like DL's idea though

[shinnlinger]

I am considering an intentional community of tiny houses on my property, so different types of structures are worth entertaining.  I am teaching woodshop online right now so maybe I would start on one and show the kids.  Open to  Foundation ideas as well.  

[Dave Shepard]

Yes, the skin could support ther entire structure, but what can you eliminate? Six or eight posts? You still have to have the interior structure, and you loose the bracing if you take out the posts. I think people make too much fuss over the redundancy of a tf. 

[doc henderson]

ok, so do they need to me able to be moved.  i.e. built near a shop and then moved 1 block or 1 mile.  or built on the foundation?

[Don P]

Basically if you are teaching, do the foundation correctly, braced walls go over a bracing foundation wall, it is ignorant as all get out, and non code, to put a braced structure on an unbraced set of piers, not that I'm opinionated. I've picked up too many ignorant houses :D

[shinnlinger]

I don't have a preconceived notion of what I want.  I don't mind building on site, down at the barn and drag into place or a trailer model the students make.  I have been looking at octagon houses and am intrigued.  I've seen houses on stilts and full basements.  Floating slabs, whatever.  

[doc henderson]

a basement would be neat for utilities, tornadoes ect.  I assume if you are building numbers, you also want to keep it less expensive.  If building several, it may be nice to be near a shop for air and electricity.  I see in a prev. thread you were rejuvenating a generator.  If to be moved, part of the design could incorporate a floor frame that can be easily lifted and set on a concrete footing or basement wall.  neat ideas.  most of us do not have time money or space for this.  

[Don P]

It sounds like start by studying the foundation chapter of the building code. Frost protected shallow foundation would be your floating slab. Rubblestone or slipform is pretty easy and fun if rock is available. "Stilts" are an engineer's playground, as are piers or post frame. All worthwhile if taught correctly. I'd have the engineer come to the class before that to explain.  Pier and curtain wall is the minimum braced wall but takes good brick laying skills, I've found block is easier and much faster. We did the basement under the little house above, Reinforced footings with frost wall at walkout, poured cores per unbalanced fill and soil pressure, then parged and dampproofed, perf drain, gravel in geotextile, fill, subsurface independent gutter drain, finish fill.

[shinnlinger]

floating/alaskan/monoslab are probably the most cost effective for a dwelling in a cold climate, but what do I know?  In my neck of the woods, the frost line is down 5 ft so by the time you dig that far, you might as well go full basement, and that of course is a fair bit more money than a slab, especially when you hit ledge as you have to blast/betonomite or form around the rock.  Rocks are absolutely no problem for me to come by.  I have miles of stone wall but literally piles of them as my property was a farmed for 200 years.  Stone foundations certainly are worth exploring as I would like to get away from concrete even if I don't have to use that much as they will be smaller structures. I have a love/hate affair with concrete.  It is something I have to buy and the raw materials come from far way, but once done, it is cost effective as it won't be something I will have to deal with again.  Short answer, I don't mind using concrete and doing it right, but I also don't mind exploring rational alternatives.

[Hilltop366]

I have no experience or opinion on it but was watching a few youtube videos on aircrete the other day, quite interesting but I have no idea how practical.

As far as I can tell it is cement and a foaming agent to make light weight concrete also makes a bag of cement go much farther, suppose to offer good insulation value and be insect and rot proof.

[doc henderson]

Is there a way to provide a thermal break for the mono slab.  now you can design from there up.  I had thought of a cabin style home with loft area at each end.  one extending say 6 feet over a front porch, and at the back over a bathroom kitchen area.  maybe ladder steps, no traditional steps.  woodstove maybe in an alcove somewhere in the middle.  part stick build walls with rough live edge siding, and exposed wood ceiling with beams, topped with foam and plywood and then metal roofing.  I wanted mine to go on a trailer so more narrow, but on skids to drop off and reload as needed, maybe 8 by 18 total.  maybe a gambrel roof with dormer style windows  for character.

[Don P]

Our code is here, pretty much stock;
https://codes.iccsafe.org/content/VRC2015P2
Chapter 4 is foundations, chapter 3 is basic design requirements.

Our building official, and most of them would be the same, is happy to help teachers. He worked pretty closely with the building trades program and mentored several students.

Especially with smaller houses, but really any time, do a scale drawing. The attic of that 16' wide has headroom only under a narrow strip under the ridge at 12/12 pitch. Remember if a space is habitable, area and access has to comply (chapter 3).

[Hilltop366]

I have several apartments that I rent in the 500 sqft range, some of the apartments are 16'x30' others are 20'x24',  they are the same size but the 20'x24' ones feels roomier, it is split into two 12'x20' rooms. One room is open and has the kitchen/dining/living area and the other is a bedroom with a closet and the bathroom and laundry area, it works well for single occupant and still doable with two people.

One thing we learned when building a 6 one bedroom units apartment building is not to put small kitchens in the corner, we ordered and installed the corner kitchens as per the stock plans we bought but after installing the kitchens it became clear that it was a bad idea, even though the kitchens take up 13' of wall space and 8' of counter there really is only about 2 feet of counter top left once you put the sink in.  

 

  

You can easily see the difference in the two kitchens and the amount of counter top, they both take up about the same amount of wall space. (the straight one is actually 1' shorter)

[shinnlinger]

 

 
  AN inspiration for me is the cottages of Bayside Maine.  They are roughly 12x18 or 16x24.  They can be added on to easily off the back or side, to be expanded and customized.  With DLs suggestion, I am thinking a Board and batten but the boards are 2x10s and I would essentially make a plank house.  If I kept it square, I could put 4x8 sheets of polyiso in for insulation and then put a 2x4 on the flat against the poly 2ft apart on the inside and attach it to the outside 2x10s with panel screws.  This would prevent a thermal  bridge unlike a conventional stud wall.  The polyi iso seams would be fairy easy to seal with sprayfoam or tape.  interior wall of choice could be attached to the 2x4's and poly iso strips could be laid between the studs for additional insulation/firebreak.  The same construction could be applied to the octagon as well.