Well the cabins done…..the studio’s done and I need something to build so I thought I’d build the grand kids a hobbit house in the hillside behind my place……..
These are just sketches but all I need cause there are no inspection down here in the boonies. Anyway I’m a bit unsure about the roof load with approx 2′ of soil, plants etc. So maybe someone can help me with the particulars.
The room will be 12×12 completely underground except for the front which will be weathered barn siding…..a small courtyard surrounded by retaining walls for the kiddies to have tea time, etc. The posts will be approx 5″ dia locust …the carrier beams will be 5×10 and the upper ones will be 5×5. the roof will have 3/4 beneath enough ice guard to keep the thing from leaking (2 layers?)
Think it will work?
Replies
I just heard a guy on the news yesterday, while discussing the rescue of a worker from a collapsed ditch, say that a cubic foot of dirt weighs 100 pounds.
I have no idea if this is true or helpful.
:)
Edit: sounds like a great project! Lucky kids!
Rich Beckman
Another day, another tool.
Edited 9/13/2006 3:01 pm by RichBeckman
"Think it will work?"
short answer . . . no
Loose dirt's about 75 pcf x (2) = 150lbs. Your spans are dividing the roof sections into (8) 3'-0" x 6'-0" sections, meaning each section is 150 lbs. x (18 sf) = 2700 lbs.. This isn't including snow loads (if applicable), live loads, water loads from saturation, etc.. It's a dead load equivalent of having (8) Honda Civics parked on the roof.
Even small retaining walls need a lot of reinforcing below grade to keep them from bowing over time. The force is roughly 30 lbs./sf lateral pressure for each foot of depth. Unless i'm missing something, the walls don't seem to be addressing this.
Cool idea, but it seems like a beefed up conventional frame with dirt on top and around three sides. i'd hate to see anyone hurt over it. Does there need to be 2'-0" of dirt on the roof? Can you 'mimic' a hobbit house built on grade and disguised with vegetation (i.e. ivy, roof thatch, etc.) rather than going all the way? Lack of inspections aside, a plans examiner will be the first to say the primary reason for codes is human safety.
Edited 9/13/2006 4:53 pm ET by draftguy
hort answer . . . no///Ok ..thanks. Now what if I added another main beam/center post ....that would mean 4 main beams instead of three.......added two cross beams.....that would mean seven instead of five and it would then be 2' o/c....(makes more sense to do that anyways considering layout and wasted plywood with five)I could also do the dirt on the roof at 1' or less instead of two cutting the load in half. The cut behind the structure would take into considration the hill pushing into it. (I have built lots of houses sunk into a hillside and can handle the regular stuff OK....)not trying to cut corners just never realized the dirt/roof load would be so heavy and definitely want the thing to be safe so do you think that by beefing it up.....it will work? Just so you know although I appreciate you're advice I wouldn't jump on your advice only......I will make sure I have a safe plan before I start....this is all in the planning stage.
Edited 9/14/2006 8:30 am ET by jjwalters
"Just so you know although I appreciate you're advice I wouldn't jump on your advice only...."i probably wouldn't listen to me either <g>If you're just planning on there being grass/small vegetation on the roof you could get by with just 3" - 4" of dirt. Earth sheltered homes tend to have some gravel beneath this and slope in one direction to keep any water from ponding beneath the soil. Beefing up the structure would definitely help. You might even drop by a small engineer's office just for a quick consultation to show them what you had in mind (no stamp, $100 fee). Just to be safe. hope it didn't sound like i was thumping on you . . . it's a neat idea :)
hope it didn't sound like i was thumping on you . . not at all...I appreciate the help.....I will have a bit of a slope back to front.....and can get by with 4-6 inches of soil.... foamboard above water guard- then gravel- then the sod roof oughta do it. I have ground pine (ivy like plant) and moss in the woods now so I'll continue it on the roof.......should work I suppose......realy no need for the deep dirt roof if I add the layer of foam.Since one of my sons moved in the art studio and don't seem to be planning on leaving any time soon maybe I'll take over the hobbit and if it don't cave in build another one for the kiddies :-)Got the time.... and am a bit nuts.....maybe I'll build a hobbit hill....or a nice tree house in that 12'circumference beech over the spring........ahhhhh life is good when you stay away from the news channels.Thanks for the advice.............
Edited 9/14/2006 1:35 pm ET by jjwalters
I wouldn't put a dirt roof on anything kids (or adults) are going to be occupying. In addition to the weight of the dirt, you have a lot of potential weight in moisture. You are also going to have a leak sooner or later that will rot the wood.
If I had to have dirt on top, I would build a concrete structure properly sealed against moisture and with provisions for runoff.
Unless you expect your hobbits to spend time on the roof, it would be better to have a conventional roof, maybe with a small tower next to the house if you want them to be able to get up high. Some flower pots on a lightly sloped roof could make some safe plantings possible.
You need to get CloudHidden to do up the plans for you: his shapes would (probably) be far beeter to sustain those sorts of loads, for example. Plus, I think his techniques lend themselves more to round windows/doors.
Fighting Ignorance since 1967
It's taking way longer than we thought
My next door neighbor just finished his - I'll get over and take some pix - I was worried about the roof load, and he agreed to lighten it. Nice work.
Forrest
jj.. hobbit house my azz... that's a hooch with overhead cover
what are you ? some kinda survivalist ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Well...you know once you have a bunker mentality you always have one..........never know, you know....when the revenoors'll start shellin the valley. I'll send you a picture when it's done.
once you have a bunker mentality you always have one
Wow that struck a chord, I was trying to remember why that sketch (in 1st post) was nagging at me--you solved it, I was trying to remember a field fortifications manual.
For a field fortifcation, you set the sides with vertical logs/timbers, and then stack, lincoln-log-style, the sidewalls against that. You then span the roof at RoT (1" for foot of span) with corrogated steel sheeting over the "joists" . . .
Not very hobbit-like now that I think about it <g> . . . Occupational hazard of my occupation not being around (sorry Bubba)
Yeah..take some pictures and post them. That would be interesting as I've never seen one except in the movie.
My friend's is really nice - has a round concrete door frame and two round concrete window frames - that exposed wall (South) is rough parged over the stacked filled block (we decided that was the best construction technique).
He dug it back into an embankment just behind his house (I helped build the real house). Hobbit house is about 16' wide and 6' back into the bank, curved like a dam. Ceiling is about 5'
BUT - saw his mom on the road walking his dog tonight - Mr. Hobbit and his young wife are expected their first little one three days ago, and I was warned not to go over.
Pix as soon as the bambino (bambina?) is born and things settle down.
Forrest - awaiting baby news
Cool idea.
This type of construction is begging for concrete - where is VaTom - he's done this... I picture cmu walls, bar joists and vpan, covered with concrete, tar then a few layers of poly, then gravel, then dirt. Or just bury a large septic tank on its side. (don't tell the kids)
You could google "root cellar" and likely get some design tips.
I forget the name, but one of the alternative building guys from the 70's died when something like this collapsed on him in a rainstorm. PVC frame iirc - but wood in this application still makes me nervous.
<<<<
I forget the name, but one of the alternative building guys from the 70's died when something like this collapsed on him in a rainstorm. PVC frame iirc - but wood in this application still makes me nervous.
>>> bs... c'mon, you made that part up ...
Mike Smith Rhode Island : Design / Build / Repair / Restore
Thats pretty funny, but I'm not that witty...
I found some info online:
"Ken Kern wrote a series of popular books during the height of the back-to-the-land movement, circa 1975, starting with "The Owner-Built Home." In fact, he wrote so many books derived from that title that it began to seem like a joke to me.
"How he died: He was sleeping alone in an experimental structure he built, (I believe it invovled PVC pipe, plastic and soil) and during a rainstorm it collapsed on him. While I don't like to joke about tragedy too publicly, I file his death in my mind along with Adele Davis (promoted health food, died from cancer) and Jim Fixx (promoted jogging, had a fatal heart attack while running).
"Kern printed one quote that serves me daily, which he attributed to the Chinese, "The man who finishes his house, dies."
Treat every person you meet like you will know them the rest of your life - you just might!
Here is a "hobbit house" shed a developer created for a community in Bend Oregon called the Shire.
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I see ICFs (Reward Systems) in the back of the photo - what materials were used in building the hobbit house?
Treat every person you meet like you will know them the rest of your life - you just might!
I am not sure how they built it, here is a link to the site, perhaps you could contact the builder. http://www.bendshire.com/View Image
That's kinda what I had in mind except the behind would go up into a hilly woods.....What is it made of? I can see the wood, but what about the sides in the dirt?
Smell them little flowers...play marbles with the kiddies...listen to them birdies....and don't forget to laugh at the pomposity of yourself.
There's an underground house a few miles from me on Bramans Lane in Portsmouth, RI. I've never seen the front fully, the back end of it (looks like a hill!) faces the road. I built a dommer on a friends house on the opposite side of the street, Very intriguing. I'll investigate more the next time i drive by.
nope....don't like cement.....it's so cold and has no class....a hobbit can only be made of warm good smellin wood just like Bilbo Bagins's.:)alternative building guys from the 70's died when something like this collapsed on him in a rainstorm.//////////I can see that happening that's why I'm asking before I leap.....plus I have two escape windows out the back hillside...and this will be built in pretty deep woods with a good root system so rain stays pretty much where it lands.
nope....don't like cement.....it's so cold and has no class....a hobbit can only be made of warm good smellin wood just like Bilbo Bagins's.:)
You could still put wood everywhere but the structure...(inside and wherever else there isn't dirt.) There are a few guys on the FHB site that do PAHS & underground buildings - maybe one will offer some advice on structure, weight of soil waterproofing and the like. I'd think keeping mold & mildew down would be a challenge - how do you plan to vent.
Our property has old raised railroad beds surrounding it -perfect for this- now I want a hobbit house too...
Treat every person you meet like you will know them the rest of your life - you just might!
I know with your experience you would have an informed opinion on this idea.....
Yeah, but I'm in a hurry this morning. Our houses are designed for at least 300psf total load, including 75psf live load (snow or occupants). Wood I don't know a lot about structurally, wouldn't use it myself. Why have any posts?
Our steel bar joists lend themselves to a wood ceiling or anything else for that matter. We use multiple 6 mil poly for water-shedding, I hesitate to say waterproofing because there's none. Not necessary, but we're very careful about the poly.
Underground houses, concrete or not, aren't any worse for humidity than any other. Gotta have air changes and control the humidity. I've got lots of engineering for concrete walls with dirt on one side if anybody needs. Again, wood I wouldn't use. Rots, burns, and bugs like to eat it.
PAHS Designer/Builder- Bury it!
Why have any posts? //////The thing about a post is it must fit into some kind of design pattern and not just be a 'post'....... my Hobbit posts will look like they are there for some other reason then holding up the roof beam.Even then exposed post/beam are themselves a design factor in some instances.....(timber frame, etc.)
Even then exposed post/beam are themselves a design factor in some instances.....(timber frame, etc.)
I understand. Even built a dovetailed post&beam outbuilding here (for my lumber) which sits on a 2 story concrete foundation. Very enjoyable thing to do. Were hobbit houses post&beam? I was thinking much more curvilinear, which is difficult with wood but very simple with concrete.
There's an underground house (box) near here, about 20 yrs old that's post&beam with drystack block infill. IIRC, they spanned maybe 10' between the posts. 2x decking over the beams. Earth cover was just enough to grow grass. Don't remember what they used for water-proofing, but it didn't work very well. Probably just damp-proofing. Owner/builders who were thrilled with the result. By my standards they required an objectionable amount of heat to stay comfy, but it didn't bother them. They'd never heard of annual heat storage.
You have a lot of company, folks who dislike concrete for one reason or another. That particular guy, middle school science teacher, simply built what he could figure out. Which is pretty much what I did, just different materials.
Have fun.PAHS Designer/Builder- Bury it!
Well it seems I'm voted out when it comes to wood, (Don't know why you guys are so afraid of wood).....but you gotta go with what you know and I've been building stuff out of wood for over thirty years (and have been running from cement work for just as long):) This is a one man operation and I still remember the time I poured a garage floor by myself...in the sun.....oyvey! Other than that I've gotten some pretty good advice from you guys so...thanks.You gotta remember though this just one square room 12x12 so it's gonna be easy (in relation to a whole underground house with rooms, plumbing, etc.) one electric line from the studio and a small wood burner will be it. cross ventilation.......tatami floor mats and wood sided walls. Diggings free, beams and posts laying all over the place so Im thinking less than a thousand for the whole thing.....I had to bribe my wife with a potting shed before she'd sign off so that's gotta be first I guess.......
So you wanna bury a wooden box? Pretty much what you said in the beginning.
What's hobbit about that?
Be defensive all you like about wood, but it rots and bugs eat it. And putting it underground doesn't help, unless disposable is part of your plan. Alternatively, building a post&beam with a living roof makes a lot of sense.
(Don't know why you guys are so afraid of wood).....
Nobody I noticed is afraid of wood. Was that supposed to be a joke? Or just annoying? Picking the most appropriate material for a project is not exactly bad planning. Last I looked, this was Fine Homebuilding. You sound like the kinda guy who'd want papercrete for a roof in Seattle.PAHS Designer/Builder- Bury it!
so is this where it gets nasty? I got some good advice concerning my project and I'll take it....not being defensive about anything just aknowledging my preference for wood over concrete......as to fine homes I've made a pretty good living designing and building one of a kind structures that my clients considered fine.....even in Seattle......what the hells wrong with papercrete on a roof anyways?.......(just kidding of course in case you gotta ask)I see no problem using wood as long as I keep it segregated from the earth, but I can acknowledge the fact that Cloud makes real nice houses out of concrete that will last far longer than my little box in the hillside will........and Clouds a gentleman to boot.
The problem is that you are going to have 2 feet of turf on top of it.Nothing wrong with building a shack that won't last forever, but if/when it fails, you don't really want it dropping a few thousand pounds on top of whoever is under it.
no two feet......draft guy squared me away on that one......6 inches with an extra beam will work.......and it ain't goin to be a shack. The front (that will be exposed) will be worked up to look like a hobbit.When I was building in Alaska (80's)everybody used treated lumber for basement/crawl spaces...... This little hobbit will be as safe as they are.
There's no way I could get a cement truck back there or any other kind of vehicles cept a backhoe or bobcat so wood it is. I understand all the downsides but....I just gotta do maintenance every year like on the cabin. A gallon of bora-care will kill everything including mold and rot (so they say) As to ventilation.......the back side of the hobbit will have two windows. The hill will be dug away in that area to form a window well like a basement well only larger. If it gets damp an exit fan in the window will clear it up in a jiffy.Drainage is a no-brainer cause it's on a hillside.....just have to deal with ground pressure and "WALLA" a hobbit the kiddies will be proud to put their hairy little feet in. (hobbits have hairy feet, you know)I am building it myself of course, and I don't do concrete so a guy should stick with what he knows IMO.
Go for it...
We want to see pictures!
But if I ever build my hobbit house, it will be ICFs, vpan, rebar and 4K PSI mix.
Treat every person you meet like you will know them the rest of your life - you just might!
But if I ever build my hobbit house, it will be ICFs, vpan, rebar and 4K PSI mix.
I agree. Wouldn't use anything weaker than reinforced concrete.
jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
>don't like cement.....it's so cold and has no classI beg your pardon!?fwiw, I'd also avoid the wood frame. Either Tom's approach with concrete walls and bar joists, or a ferrocement approach with a frame of rebar and mesh, and concrete added as convenient, mixed on site. You'd get the safety that the purpose warrants, and the aesthetics are just a matter of appropriate design.
I'm surprised none of your clients have asked for a Hobbit house. Those concrete dome shapes would be perfect. With proper finishing, it would be as cozy as ...well, as a Hobbit hole is supposed to be.
And it would be able to hold the weight of the dirt.jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
I do have buried and bermed projects. Not every project gets pix or publicity. Some clients choose privacy.
I do have buried and bermed projects. Not every project gets pix or publicity. Some clients choose privacy.
IMO, either a through a hill application, or one where you could poke a window out a second side would be the best Hobbit house.
I've been through earth sheltered houses where they only had one side getting natural light. I wasn't real excited by that application. Somewhat better if they included some SunTunnels and really improved it if they had a window on a different side.
jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
Yeah, I know what you mean. That said, you gotta work with the site you got......or spend the $$$ to contour it otherwise. Got one now that's backed into a hill. The hill backs into the road, so there'll be no going out the other side. And they want privacy, so we won't be projecting out or up. But with the exposure and design, they won't be hurting a bit for natural light. Work with what you got.
Nothing like well designed concrete structure and good windows to filter out a lot of noise. Is that one you're working on gonna have dirt on top or just earth berming at the back?
If they're within driving distance and don't mind, some pics would be nice.jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
I doubt there'll be pix, as they specifically want things positioned so they cannot be seen from road. No one should know the hill was disturbed once all is done. Lots of dirt on top, but no problem with 2500+ psf load capacity.
Sounds pretty neat. Lets see, how could I improve on that:
1. stick it in the middle of 100 acres (privacy is easier when you own your surroundings)
2. wells and cisterns (less dependant on the city water)
3. super insulated and high efficiency appliances
4. some passive solar in the mix
5. Maybe some active alternative energy? PV's or turbine..
6. solar water heater.
Add environmentally responsible building materials and a large garden into the mix and that just might make Mother Earth News house of the year ;)
jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
Why 2' of dirt? As others have said, that's a HUGE amount of weight.
Green roofs typicaly only have a few inches of soil on top. But even that can get heavy and needs proper engineering, though.
I've heard of people using potting soil and peat moss and so on to grow plants on roofs--weighs alot less than normal soil.
That's a good idea.........think I'll do it.
This does sound cool, my kids would love it too.
There are some green/vegitative roofs on a campus where I work. The typical detail is a thick layer of perlite (light, porous, volcanic stone), with some soil on that.
The perlite is for drainage, insulation, and a friction reducer to extend the life of your waterproofing membrane from freeze thaw movement of the soil above. Perlite is pricey though.
You'll have to strike a balance between good drainage for the structure, and having enough water retention to grow plants. There is a nitch horticultural market that's growing these days to supply drought-resistant plants (native grasses etc...) specifically to plant on green roofs!
Don't assume that the native stuff growing next to your hobbit house will grow on the roof. The roof will be too dry much of the year to support it. Look at what grows in the cracks of your driveway, and plant that!
Best of luck. I'd like to see a pic when your done too. Cheers.
Ithaca, NY "10 square miles, surrounded by reality"
I guess I have to join the group that is skeptical of using wood, but I'd still love to see pics of the finished product. Sounds like a fun project.
Here's a guy who believes in wooden structures with dirt on the roof (usually just a couple inches):
jt8
"Success is not the key to happiness. Happiness is the key to success." --Albert Schweitzer
I been following and you seem to have you mind made up. but here reality if you use wood, you going to die.
Okay - finally got with my friend - they had a little boy Sunday - their first. I think he'll enjoy what his dad built!
This was all hand dug, hand mixed, and hand laid - by a first-timer. Stacked CMU block; filled solid and parged. Back wall curved like a dam to resist soil pressure. I think the HO workmanship is just super. Wood framed roof; some metal and poly on that, and then a little earth and a lot of transplanted ferns. Wood doors and windows to go this winter.
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Forrest - surrounded by talent
That's cool!
Thought you'd like the curves!
Forrest
I like do something like that for a hurricane shelter
Give your neighbor my congradulations....that is really niceI'm still thinking whether to go his route or use wood......I could stone the front and of course do what I want with the interior if I do cement.....
Smell them little flowers...play marbles with the kiddies...listen to them birdies....and don't forget to laugh at the pomposity of yourself.