Building a Roadhouse 8'x12' cabin with a sod shed roof.

[Buddamonk]

I have recently accuired a small parsell of land on fellow Country Plans forum member Bobmarlons deep woods West Coast property. I plan build 8'x12' cabin with a shed roof. I want to have a sod roof so that my cabin is not an eye soar from Bobmarlons roadhouse cabin. I have been working construction on the west coast for the last 7 years. I have a really good idea of how I'm gonna frame this thing up, I'm just not sure how I'm gonna build and waterproof the shed roof so that I can put 4" of dirt on top of it and plant grass on the roof. Possibly have the tee box for a pitch and putt hole on the top of it. I would really appreciate any ideas on how to make this happen. I look forward to keeping you guys posted on the progress, it's gonna be a slow process since I'm gonna be a weekend warrior.   

[Bobmarlon]

Welcome to the neighbor hood

[Redoverfarm]

 

I know nothing of this type of construction but I do know that you should install a weatherproof membrane such as they use in pool material or flat roofs.  Keep us posted and make sure you include pictures.  Interesting build.  I am sure someone out there has "been there and done that" as they say and you might have to search a little for the right application.

[Squirl]

My understanding is that normally the shed roof doesn't have a great slope.  Then a EPDM layer is put down with great care not to put holes in it.  Then boxes are built over top and it is filled with a thin layer of gravel with drain holes in the box.  Then a loose soil with perlite is put in the boxes and planted with grass.  Just my basic understanding.

[dug]

Here's one that is next door to me-



It looks like the roof is started with closely spaced timbers, followed by perpendicular saplings, then heavy plastic and finally about a foot of dirt.
I'm not saying I would do it that way, but I waited out a heavy storm in it once and it was very dry.

I do love the way it blends into the hills.

[Freeholdfarm]

You might want to take a look at Mike Oehler's book, The $50 and Up Underground House Book.  He talks about the best way to build a sod roof.

Kathleen

[glenn kangiser]

Mike also recommends the EPDM liner material for roof verbally over the phone - I don't know if he has updated the book info or not.  It can be obtained at Home Depot as pond liner but it is about half price out of Oregon over the internet last time I checked.

[MushCreek]

I'd build up a strong, waterproof roof, and THEN put EPDM over it. It would be nice to know that I had secondary waterproofing if the EPDM ever failed. I don't think 4" of dirt would be enough- here in FL, it would dry up by noon, although your climate is much different.

[glenn kangiser]

I think maybe the 4" of dirt for fire protection, then humus on top of that for moisture retention may help.  I need to do more of that.

[Buddamonk]

Thanks for all the tips guys, that's great!! I have used EPDM before on some coustom gutters we built for a house. It seems to work great, that's probably the best way to go I think. It's gotta be better than ice and water for this type of application. I waa also hoping that the sod would add some pretty good R value to the roof itself any one have any idea how much 4 or 5 inches of soil and grass would give me? First things first tho, I need to work from the ground up. The water table in the area is pretty high and Im almost positive I won't be getting down to hard pan or bedrock. I was thinking some 3'x3'x1' concrete pads sitting on compacted crush rock would be enough if I had 6 of them. Do you guys think that's over kill, just right or not enough?

[glenn kangiser]

Sounds about right to me.

Sod - not a lot of R value - maybe a bit of a solar flywheel effect though, storing heat in the day and giving it back off at night.  A good layer of grass on the sod would help a bit more.  Bruce in Minnesota plants squash on top his for shade.  It is also easy to heat at night as the earth temp in the winter is pretty warm compared to outside so we only have to raise the temp around 20 degrees or so.

We find that extended hot times in the summer heat the sod on the roof pretty good keeping the inside temperature in the 80s.  That is when it is over 100 out days and never cools below 80 at night here though.

[Buddamonk]

Thanks Glenn, that is awesome stuff. I didn't think of that at all. Solar flywheel effect, good to know. It may be a little while before I get power out there so any help I can get cooling/heating the place is gonna be great. I guess it will have the same effect as a large concrete wall with a good sunny exposure inside your house. I hear that it heats up during the day and radiates the heat over the night. Looks like the roof is gonna be more than just easy on the eyes... Was that sounds about right for the footing sizes I mentioned???

[glenn kangiser]

Yes - I think they sound good for that size building.  What portion of the west are you in - general area? PNW?  Looks a bit like California.

An 1866 building I had to supervise the demolition of, had red bricks under the roof tin for just that purpose - to act as a heat buffer.

[Buddamonk]

It's in BC, the winters are long and cold and the the summers are awesome and hot! i feel like the sod roof is really gonna work to my advantage in all aspects. Thanks for the tips, keep em coming!

[glenn kangiser]

OK, after the sod for roof protection in case of fire, a layer of straw- thickness from a flake to a full bale if you like, will make better insulation on top in the summer and a base for growing stuff if covered with manure and a bit of soil.  As it decomposes you can add more,  It holds moisture well and if all purpose fertilizer is used about anything will grow in it.

It gets you a thicker covering without as much weight as soil.  If you want it to decompose faster to make soil it will need extra nitrogen.

[Jens]

I think maybe the 4" of dirt for fire protection, then humus on top of that for moisture retention may help.  I need to do more of that.

I love humus with pita and veggies.

[glenn kangiser]

I see you could spell it that way but,

Humus
From Wikipedia, the free encyclopedia

This article is about the organic matter in soil. For the band, see Humus (band). For the food, see Hummus.
Humus has a characteristic black or dark brown color, due to an accumulation of organic carbon

Humus (origin: 1790–1800; < Latin: earth, ground)[1] is degraded organic material in soil, which causes some soil layers to be dark brown or black.

[Buddamonk]

Here is a quick sketch I did of what I want the place to look like. The amount and sizes of windows and doors are gonna depend on what I can salvage from other jobs I'm working on.

[Buddamonk]

Checked some prices today, changed my mind about the 3'x3' footings. Gonna cost way to much for my liking. I am trying to do this as cheaply as possible. I'm hoping to be able to use a lot of reclaimed stuff for it. We just demolished an 1 story house last month and i have my eyes on plenty of stuff. Just gotta clear it with boss before i haul it all away, HAHA! I think I'm just gonna dig down deep and use a lot of crushed rock, tamp it well and put pier blocks with treated 6"x6" posts. Its gonna be way cheaper that way and also its gonna be just fine for a 8'x12' cabin.

[psammy]

3'x3'=9 sf  x  8 footings = 72sf.  72 sf x 1500 psf = 108,000#.  Using a low assumed bearing pressure for the soil and not fussing with a safety factor, might be a little bit of overkill for an 8'x12' cabin.....

Work from the top down from the live load on the roof to the dead load of the (soaking wet) sod roof, to the floor load, then figure what you need for the footings.  6 - 2'x2' footings w/ piers should be very conservative still.

psammy

[Buddamonk]

A few shots of the location of the cabin.




Bobmarlons cabin is real close buy.


Scored some free windows and a sliding glass door.