Dugout Plans

This summer I hope to start work on my underground shelter but as I'm reviewing material about design and construction approaches, I'm not certain what would be the best options to include and best design.

This would be a very small dugout cabin basically. I tested a few years ago with a smaller version 4x6. It was wrapped in plastic sheeting and then I used conventional lumber for the walls and roof. After 2 years I went back in and dismantled this shelter. There was no leaks, no mold, no wet wood at all so I think the basic material and rough designs will work okay.

The permanent shelter I want to try this year is a 10x7 one room. It will have a single pitched roof that is covered with about six inches of dirt. The soil I'm working in is rich soil, no clay to speak of. It drains very well (no puddles ever). It will be approximately 7 ft into the ground at the back wall and 4-5ft at the front wall. The roof will be about ground level.

If looking from the back wall forward, I would like to put a door on the right wall, a window on the left wall and and narrow windows along the front wall (on top of the 4ft wall). But, from some of the reading I've gone through, it appears this is not suggested, that I should have the windows on the back wall, facing uphill? I'm not really excited about this idea. One, it would require much more digging. Second, I don't like the idea of a hole in the back side, terrace or not.  

When I pulled the old dugout out the back wall showed no signs of leaking or mold and all the wood used on the back wall was completely dry. It rains a lot here but the soil drains incredibly fast.

The sketch below is the basic idea of what I would like to build.

1. The window on the left wall faces a small terraced area.
2. There would be a small vent or window in the back wall at the roof that can open and close for circulation and to help get rid of moisture.
3. The windows in the front wall would theoretically open, but will most likely be screen on the inside and plastic on the outside (so they most likely would not open in the winter and would just been screen in the summer).
4. The highest point in the structure would be at the back wall with the overall structure facing north.  

Does anyone see any red flags here before I start building this summer?  

My previous dugout worked great in many respects but it was too small for my hammock (which I was not using at the time I built the dugout). I also did not have the vent in the back wall at the ceiling.  This new version will accommodate the hammock plus should have better ventilation and will have an improved wood stove.  

Any tips appreciated....

I would put less glass and more mass by the wood stove.

Ok, so what steps are you taking to resist the earth pressure to ensure collapse does not occur.

If you haven't read it, I would highly recommend Mike Oehler's "The $50 and Up Underground House Book".  It will answer all your questions as well as explaining how important those windows on the back wall are.  Personally, I wouldn't even considering building underground without thoroughly digesting everything in that book.

The main reason to have the uphill side of the house open is for drainage. Underground houses have lots of drainage problems. Mike Oehler's book has scads of information in it, but he adheres to the open on the uphill side way of thinking.

If it's not the end of the world if it doesn't work out, go ahead with your design, though. Maybe it'll work out exactly the way you want.

Are you using standard dimensional lumber? If so, might be easier to work in lengths divisible by 4 to minimize the amount of cutting and waste. So instead of 10x7, do 12x8.

I think  the 10 x 7 is the room size, not timber size.
From your words its hard to work out the front, the back and where is the 4 ft wall?
An advantage of clay on the roof is that it seals against watewr.

Jan White wrote:The main reason to have the uphill side of the house open is for drainage. Underground houses have lots of drainage problems.

Yeah, this is what I've gathered. I read about an underground house that had an uphill opening and in a downpour the rain funneled right into the house, flooding it from back to front.  

Based on my experiments with the previous (smaller) dugout and from other digging projects on the property, I don't think drainage would be/is a problem at all. There is very little in the way of topsoil to begin with in most places on the hillside, lots of vegetation, and the rain does not linger in the soil hardly at all. It runs out quickly and into the lake. The first year after buying the property I dug a few test holes and never once had water puddled up and a few of those went all the way to the shale rock underneath.

Jan White wrote:If it's not the end of the world if it doesn't work out, go ahead with your design, though. Maybe it'll work out exactly the way you want.

It would not be the end of the world. It also won't be a whole lot of work going forward as I'm using the existing hole that had the previous dugout in and it's already been widened and lengthened. It just needs to go down a few more feet and then I need to dig out the entrance.  

I'm certain there will be complications as I progress. But I'm not expecting a great deal.

Jan White wrote:Are you using standard dimensional lumber? If so, might be easier to work in lengths divisible by 4 to minimize the amount of cutting and waste. So instead of 10x7, do 12x8.

I'm using the lumber that is available on the property from old docks with the purchase of some cedar fencing stock for the walls that are 6ft. I've thought about going larger, but really have settled on the 10x7. It's just big enough to house my hammock stand and give me still enough room for the wood stove and possibly a small table and supplies/storage as needed.  There's never waste on lumber on site. Anything that's cut always finds a use somewhere else, even stubs end up in the stove (but I can usually find use for them elsewhere before then too).

The soil stands up on its own, even at 6ft and higher, so the weight or pressure is light against the walls.

John C Daley wrote:I think  the 10 x 7 is the room size, not timber size.

Correct. Room size not lumber size. The lumber I'm using is mostly used from old dock sections that came with the property. They are all shapes and sizes. Framing lumber is also used from previous structure and is also different lengths.

John C Daley wrote:From your words its hard to work out the front, the back and where is the 4 ft wall?

Back wall on picture states "back wall."  
The wall with the wood stove and "window" is the left wall.
The wall with the "door" is the right wall.
The wall with the "narrow windows" is the front wall.
The pitch of the roof runs from the back wall at its highest point to the front wall at its lowest point.

John C Daley wrote:An advantage of clay on the roof is that it seals against watewr.

I have no clay on the property and it would be prohibitive to bring it to the site (boat access only - no serviceable or public accessible roads within 2 miles of site). I would leave the roof just a tarp but after debating it for a year or two now, I've decided I don't want the added concern of "things" falling through, either tree branches (or whole trees) or four legged things. I often get deer and bear that come down off the mountain and also the occasional elk.

John F Dean wrote:I would put less glass and more mass by the wood stove.

I would agree in theory but I want to get as much light as possible and also use the window I have on site. It is a vinyl double pane window that was extra from when I replaced the windows on my house in town. One thing I did not like about the first dugout was it only had the front window opening which was only about 2ft in height and though it ran the length of the shelter it still was darker than I would have liked inside.

I have a skylight window on site that I could add but from the reading I've done this is discouraged. I do have lots of trees and falling branches all the time. I also think it would leak over time since I'm doing the work myself. It may be one of the few items that I don't use.  

I'm hoping the extra mass by the stove will not be needed. With the typical temp range here in winter (30-50 degree f) coupled with the small footprint and the larger stove I'm hoping the stove will overpower the space used (finger's crossed). I really don't need the stove at night since the hammock is a complete system that would keep me warm and dry when out in the elements without a shelter. The wood stove is really for cooking and for keeping the temp comfortable when I'm lounging in the shelter during the day while reading, writing, etc. I'm not certain how long the future stove will run but the current one will run for about 2-3 hours before it needs wood added.

Cool project. Sounds like a cozy place to dwell.

I think the idea of the stove being closer to mass isn't only for heating but also for helping manage the ambient temperature (maybe?). What do you think about moving the stove to the back wall?

Do you have any photos of your test structure or the hill? It might help in identifying problems before they arise.

The issue with any wood stove in a small well-insulated space is that it is going to be hard to run it slow enough to not overpower the room with heat, without being a dirty inefficient fire. I think a small rocket mass heater would give you warmth throughout the night without having to tend a fire, and not get the room too hot while the fire is burning.

A 4" batch box with the top of the firebox turned into a hot plate for cooking would probably give enough heat from a compact package. Running a bench bell along the side wall under the window to the back under the hammock would give well-distributed heat.

As you say there is no clay on site or nearby, I would make the whole thing from brick (or stone if you have any for the outer shell) with possibly a small barrel for part of the enclosure.

Our wood stove is 20x15" in a 12x16' house with as much leaky glass as wall. When coming home to a cold (only a few degrees above freezing) house after being away all day, it only takes about 20 minutes after lighting a fire before we're stripping down to underwear. There's wood we burn only during a cold snap (-15C or lower), like Doug fir, black locust, mature birch, etc. The perfect wood for us to burn is actually cedar. We can burn it hot and clean and don't have to keep windows open.

If you can swing it, I think you'd be happier with an rmh, too.

I built a small dugout as the first building on my property. I didn't want an uphill patio, which would have been on the north side. So, I did something I had never seen done. I turned the building having a corner post uphill instead of a flat wall. 10 by 10 structure for 100 square feet of space. Instead of a 10-foot walls running west to east and north to south, the walls run north to west and north to east. Roof slopes to the west and east. I did use a white oak post in the north corner that is buried 4 feet that is 22 inches across. Everything drains around the west and east side and after a year seems to be working great.

Cletus Albrite wrote:I built a small dugout as the first building on my property. I didn't want an uphill patio, which would have been on the north side. So, I did something I had never seen done. I turned the building having a corner post uphill instead of a flat wall. 10 by 10 structure for 100 square feet of space. Instead of a 10-foot walls running west to east and north to south, the walls run north to west and north to east. Roof slopes to the west and east. I did use a white oak post in the north corner that is buried 4 feet that is 22 inches across. Everything drains around the west and east side and after a year seems to be working great.

Hey Cletus,

This is a very interesting idea to turn the shelter so the corner goes into the back wall instead of a flat wall. I'll definitely have to think about this. It would give the structure a very different look, too. Thanks for the tip.

IH

Glenn Herbert wrote:The issue with any wood stove in a small well-insulated space is that it is going to be hard to run it slow enough to not overpower the room with heat, without being a dirty inefficient fire. I think a small rocket mass heater would give you warmth throughout the night without having to tend a fire, and not get the room too hot while the fire is burning.

I've definitely thought about a rmh but along the lines that the wood stove would not be enough. I never thought about needing it to slow down the burn. I'm not all that concerned with the heat overpowering the room. I'm all for it if it does. I call that a rich man's problem. It is quite possible that my current stove will be sufficient. We will see once the structure is built and I install the current stove and do some testing on it. There is another size up that I can go to that will fit the space if it's needed.

I'm not fighting a huge temperature difference that I have to maintain. In the worst parts of winter, the property (on site) hasn't been below 25 degrees F. It's a coastal climate which means lots of rain, wind, and fog. It can rain off and on for a week, but every time the rain stops even for a few hours everything seems to quickly dry out (including the ground since it drains so quickly), I'm assuming because of the breeze. It's a bizarre kind of environment. Doesn't get too hot in summer, not too cold in winter. My last garden patch never required a single watering all summer long. I don't think it was the water retention in the ground (since there isn't any), but the dew in the mornings and frequent brief rains even in summer seems to keep thirst away.

So the temperature I need to make up in the shelter will be from 25 to 70. If the wood stove overpowers the room, I'll just strip down and bask in the warmth. I can get used to 80 degrees in the winter if I need to.

IH

Jan White wrote:Our wood stove is 20x15" in a 12x16' house with as much leaky glass as wall. When coming home to a cold (only a few degrees above freezing) house after being away all day, it only takes about 20 minutes after lighting a fire before we're stripping down to underwear. There's wood we burn only during a cold snap (-15C or lower), like Doug fir, black locust, mature birch, etc. The perfect wood for us to burn is actually cedar. We can burn it hot and clean and don't have to keep windows open.

If you can swing it, I think you'd be happier with an rmh, too.

This is my hope that I'm overshooting and the small stove I have will be more than adequate. This is actually how I grew up in my parents house. They had a typically large wood stove in the living room and my mother and sister loved living in 90 degree weather, so all winter long I would hunker down in my bedroom with the door shut an often with my windows wide open and still be in shorts and a t-shirt. I typically now hang out during the day in a t-shirt and boxers so this would not be a big change. Plus, as I said in a previous replay, the temps are quite mild here in the winter, right now they're averaging 59 in the day and 45 at night. We have not yet had a freeze this year and may not.

As for the rmh, I think those are great. I don't know if I would need it in this project. I've considered it though. Given the fact that I don't have clay on site and the only way to the property is by boat, I'm not certain its a great option. My hope is my current stove will do the job and then an upgrade to one size bigger will allow for longer burns. I don't really need heat at night since my hammock has a pod sleeping bag with blankets inside, with the option to add an additional under quilt + a ridgeline that I can throw a blanket over with a camping tarp over that which makes a ridiculously warm enclosure that's tested well. The heat is really only needed during the day when lounging around reading, writing, watching tv.  

IH