Underground housing

Hey Paul, thanks for the video.  As you may know, Mike was at my place a couple weeks ago.

While he was there, his alter ego, Major Miracles dropped in and solved a problem at the Underground Complex.

He was going to send me a copy of the video but I found it on YouTube first.

Here is a link to his visit on my Underground Cabin topic.

http://countryplans.com/smf/index.php?topic=151.msg116608#msg116608

Here is a link to Mikes other Major Miracles stuff listed out with an explanation for those interested.  http://countryplans.com/smf/index.php?topic=151.msg115804#msg115804

For convenience here is a link to when Mike first arrived if you didn't already scroll back and find it on my cabin topic from the above link.

http://countryplans.com/smf/index.php?topic=151.msg115269#msg115269

I was exchanging emails with mike this morning and sent him a link to the video when it was up.  And then remembered that he said he would post some stuff in the MM stuff.  So I looked for "major miracles underground" and found the vid with you.  That one looked like it had a lot of editing!

I think Mike and crew really worked on that one, Paul. 

My son shot the video -Mike needed a cameraman and my kids used to do some of their own videos that were pretty good - most went well - some takes were first time - some were after many times.

My wife was a bit mortified that she didn't know how it would come out but she got quite a kick out of it when it was up.

Mike likes to get a good bit of humor in with his educational messages in his videos.

I am currently planning an underground cabin for a lady that will be built in an undisclosed location.... sounded a bit like Dick Cheney there didn't I? 

Paul, I have started an new underground cabin techniques thread about a cabin I am building, on our forum.

If anyone is interested, they are welcome to drop by.  Here is a link.

http://countryplans.com/smf/index.php?topic=9098.0

Glenn

Thanks Glenn.

It's really good to be able to keep up with the nuts-and-bolts progress of a real project in addition to the more theoretical ideas and plans in the books.

More power to ya.

Thanks for watching this project progress, Rob, and for commenting on it..  Just knowing that people are gaining knowledge and skills for their own benefit makes it worth documenting  to me.

If I don't know that anyone is gaining from my efforts to spread the knowledge, then I tend to slow down on posting it. 

I have read Mike Oehler's book on underground housing and have a question concerning the waterproofing.  I don't understand how the polyethylene (sp?) seals around the posts, especially those posts that hold the shoring for the outside walls.  Sealing the interior posts may be less of a concern, but those closest to the outside soil and moisture could be problematic.  Perhaps I am missing something but if these posts are not sealed at the juncture with the plastic waterproofing, water intrusion seems assured.  I know Mike has lived in his structure for nearly 40 years, but he always makes subtle disclaimers about the "waterproof" quality of this type of structure and I was just wondering if this concern of mine is one of the reasons he has made such disclaimers.  Anybody who has attempted this method and can confirm or refute my concern, especially as concerns the post/polyethylene juncture, please chime in and let me know what your experience has been.

Hi, John.  I think I can help with that.

If the posts are buried in the ground per Mike's original suggestion there is a chance of the posts rotting off.  I did three posts charred and wrapped in plastic as Mike suggested.  All three rotted off and had termites. 

Fortunately it took about 4 hours each to dig the holes with a jack hammer as my ground is hard,  so I decided that was too much work and went to an alternative method.  The alternative method requires temporary bracing of the posts before back-fill.

You can either pour a concrete pier  with a steel rebar - 5/8 minimum is what I went and drill a hole in the post or if your ground is extremely hard like mine (claystone and rock) you can drive the rebar into the ground using your jack hammer then put a plastic square vapor barrier out of 6 mil poly with a couple inches of rather dry concrete mix under the bottom of the post for solid contact to the ground.  You could also drill into the ground with a rotohammer for the pin.

I now recommend a French drain around the entire perimeter draining to daylight on the low side of the hill.

Mike mentioned similar problems with his ridge house but attributed it to the posts being exposed.  My posts were not exposed much but still had the rot problem --the water from the post will drain down into the plastic bags if the wood is wet then it becomes like a continuous recycled rainforest inside the plastic bags making a perfect growth area for mold and termites. If it could be kept dry with no holes in the plastic it might work with extremely dry posts, but in my opinion that will never happen - the plastic gets holes - the wood checks and cracks - no way to stop water entry.

I had a queen in one of the posts - maybe all of them.  I had to jack up the three posts and make steel foundations to bridge the holes, support the posts and bolt to the post braces about a foot above ground.

You can replace the posts with temporary jacks under the girders but I would rather just keep the post out of the soil and avoid the problem.

I thought the latest technique was to char the ends and skip the plastic.  ??

Could be Mike's and it could work in places.  I would say it is a step up from plastic.

Personally I will still keep them above the ground and use pins, vapor barrier and a bit of concrete or piers.  I can guarantee that.  I cannot guarantee a charred untreated post set in the earth.

I am working on one for a client and cannot have a future failure so will be using the French drains also.

For me I am willing to experiment.  For a client I have to do something I can count on.

A charred post can still split and defeat the charring exposing it to future moisture, rot and termite damage.

Moisture does not need much to contact the wood.  A bit of fungal growth gets started and the tendrils are sent out into the ground to bring moisture into the wood to feed decomposition.  That is why a log sitting on top of the ground but in contact with it will oftentimes be sopping wet and the bugs will be having their way with them. 

Granted that the plastic does magnify the problem, but drilled posts set on steel pins, piers or a bit of concrete if the ground is hard enough, a vapor barrier, French drains, and temporary bracing will eliminate the problem.

Note that this is not taking away from Mike's recommendations.  These were all alternative methods or modifications of alternative methods Mike recommended to me either through more of his publications such as his DVD's (I had his early tapes) of from a few phone conversations we had over the years.

My clay soil will hold moisture as well as a plastic bag here - I have seen water in the holes I dug on the hill for months.  That is more than enough time for decay and bugs to get a good start.

Note that other peoples conditions may vary and I am just relaying my observations from 8 years underground.

Hay Glen good to see you again

have you got any pics of the way you are doing your posts just for us visual learners 

Thanks, Cyric.

Best I can do is a sketch as I don't have anything exposed that would accurately illustrate this.

Hay the sketch is great, makes things easy to understand for me..

hopefully i'll have some pics to post one these days

LoonyK wrote:
actually being on a hilltop prevents more and earlier frosts because the cold settles in the valley.   

Actually a hilltop is a great place to make ice on a clear night with a temp as high as 10 above freezing.

I wonder if part of this debate over temperature vs. terrain has to do with local moisture levels.

Water vapor is a little more than half as dense as air, liquid water much more dense, so moist air accentuates convection quite a bit.

Dry conditions, on the other hand, offer a clear view of the sky, which is the coldest thing in nature. Fog or cloud cover would tend to scatter some IR radiation back to Earth, by contrast.

It sounds like we have a small consensus: for convection purposes, it's good to avoid any un-interrupted stream of cold air, and for radiation purposes, it's good to find a site that's under the stars as little as possible.

Maybe there's a mix of people from convection-dominated climates vs. radiation-dominated climates?

Joel Hollingsworth wrote:
I wonder if part of this debate over temperature vs. terrain has to do with local moisture levels.

Water vapor is a little more than half as dense as air, liquid water much more dense, so moist air accentuates convection quite a bit.

Dry conditions, on the other hand, offer a clear view of the sky, which is the coldest thing in nature. Fog or cloud cover would tend to scatter some IR radiation back to Earth, by contrast.

It sounds like we have a small consensus: for convection purposes, it's good to avoid any un-interrupted stream of cold air, and for radiation purposes, it's good to find a site that's under the stars as little as possible.

Maybe there's a mix of people from convection-dominated climates vs. radiation-dominated climates?

I guess I picked up on the word frost. I live on Vancouver Island, cool damp place. Snow does happen, but mostly rain. Frost... only happens on a clear night.... with temp. normally 2 to 5 above freezing at coldest. When the air is less than freezing, we get ice on the road. I would think that a valley would have cooler air than a hill top, but that a hilltop would be quicker to get frost... and have more sunshine. A hilltop with no trees will frost at even higher temp. because there is more more open sky to radiate to. Higher elevations have less atmosphere to interfere with the radiation too. This has been used to make ice in a cooler for the next day.

Of coarse to a plant, frost on a hilltop is as bad as frozen air in a valley. A gardener would see the same damage and call it frost. From that point of view a hilltop might have a longer grow season. A plant may even survive a frost on top, if the air is not frozen on the leaf bottom. I am not as much of a gardener as I would like to be

Joel Hollingsworth wrote:
I wonder if part of this debate over temperature vs. terrain has to do with local moisture levels.

What you're describing is called "radiant heat loss".  Heat always flows from warmer to cooler.  At night, when the air is cooler than the ground, the ground radiates its heat to the air.  If the air is humid or if there are clouds, a lot of that heat gets absorbed by the water vapor or reflected back towards the ground, heating up the air and minimizing the heat loss by the ground.

If, however, the sky is clear, the winds are calm (<5mph), and the humidity low, the radiant heat given up by the ground continues on up into space.  Since so little of the heat stays around or is absorbed by the water vapor in the air, the ground continues to radiate its heat into space to the point where the ground temperature (or the temperature of your car's metal, etc.) can fall below freezing and frost forms on the surface.

Thanks for the explanation.  I have observed the frost on a warmer than freezing night but not understood the cause of it.

Muzhik wrote:At night, when the air is cooler than the ground, the ground radiates its heat to the air.

I was talking about radiating heat right through the air, and on into space.

If I recall correctly, the sky is about 7 Kelvin.

I guess I did not make my concern clear.  My concern is not with moisture gaining access to the posts (this is another subject) but with moisture getting inside the living space, through seams in the polyethylene and soaking the carpet.  Especially at the fenestration (sp?) through the floor's polyethylene where the posts enter the ground at the back wall.  Mike has made reference to this by stating that the polyethylene should be split and wrapped around the posts.  I don't recall any explanation of how this split in the polyethylene is then sealed so that the wet ground behind the shoring and polyethylene of the back wall does not seep up and around the post bags and into the carpet and living space .

As concerns the treatment of the posts, themselves, to keep them from rotting, I have recently come across some information about the use of Magnesium Chloride and Magnesium Phosphate for the preservation of posts set into the earth.  I have been told that the Finnish people have used a slurry of these minerals to coat that part of the posts of their traditional buildings that sit under ground, and that this treatment has lasted a verrrrrry long time, not only for protection from rot but also insects.  And above ground from fire.  The website www.geoswan.com has a link for information about the use of Magnesium cements, and also suppliers.

Also, Mike has addressed the possible use of pins set into concrete piers as a way of securing posts.  His caveat to this method has been that this type of arrangement is succeptible to "hinging".  The term "hinging" means that the pin gives way to lateral thrust and either bends or snaps at the juncture of the post and the pier.  What needs to be understood is that when posts are set ontop of piers and "secured" by pins that are cemented into the piers, these pins are now being asked to do the same work that posts set into earth are asked to do, as far as lateral thrust is concerned.  The posts set in earth can be from six to ten inches thick, and as long as they retain their integrity do very well at resisting lateral thrust.  When the post is set on a pin, that pin is only about 5/8" thick and is now being asked to perform the same function of a post that is at least six inches thick.  Don't want to step on any toes here, but think about it...does it seem likely that a 5/8" pin will resist lateral thrust as well as a six inch post? 

I have not yet verified for myself the use of Magnesium cements as treatment of subterranean posts, but this seems to hold the most potential as a solution to post rot while still retaining the strength of a post against lateral thrust.  Check out www.geoswan.com



[quote author=Glenn Kangiser link]
Hi, John.  I think I can help with that.

If the posts are buried in the ground per Mike's original suggestion there is a chance of the posts rotting off.  I did three posts charred and wrapped in plastic as Mike suggested.  All three rotted off and had termites. 
]

I would suggest the French drains to address any leakage that comes down the side wall and may drain into the floor.  Yes - it can happen.  Gophers rearrange drainage outside the walls etc.

The French drain will take care of the problem draining the water out before it reaches floor level if the drain is done properly.

Hinging on the posts- yes - it can be a problem but mainly for keeping the structure plumb during backfill.  The wood fiber stress pressure will likely be way over what an engineer would like to see in the case of massive over excavation.  I did not find it to be a problem doing it carefully and having temporary bracing as backfill was carefully installed.  I did not overexcavate and my ground is self supporting so the only loading against the pins was a small amount of loose backfill.

Remember that an engineer is going to have a cow if you don't have 8 or more square feet of concrete and rebar under each post to handle the 16000 or so lbs of weight on each one also.

I think what we are doing here is seeing what actually works - not what is common engineering practice.  Once the roof is loaded the post will also have weight holding it in place.  Done properly it could also be notched to lock onto a stepped pier if backfill pressure was a concern.

Glenn,  thanks for the info on these footings. While I did not have real concerns about posts rotting off, I do have a problem sinking my posts in the ground, because after excavation I am on solid rock. I'd already decided some keyed footing would be necessary, though now after reading your suggestions and having some concerns about hinging, I will likely key the footing into the stone, then also key the posts into the footing, or at least go with a stepped footing to prevent any inward pressure from causing hinging.

It seems to me that using that sort of method, I could forego the rebar into the post itself as the concrete would act as a superior retainer. I'd like to avoid that sort of pin if only because the posts I am working with are about two feet in diameter and so rather hefty and not easy to manipulate.. Thoughts?

My pleasure.

My posts were around a foot in diameter and rotted off in about 3 years.

The keying could work fine.  As an option with such large posts, you could drill about 6 inches up the side down at a 45  through the wood then with  a rotohammer into the rock and insert a steel pin. 

If keyed properly the concrete should hold it if it is deep enough and the soil firm enough IMO.  Lots of variables so what works in one case may not work in another. 

Temporary props from post base to post base could help too.  Backfill would still have to be kept even as the top could still push over.

Just use temporary bracing and careful backfill equally on both sides - then the hinging should not be a problem.  Once the backfilling is done the bracing can be removed.  Don't get crazy compacting the fill - do as Mike mentioned and hand backfill with only light tamping - shovel handle etc. just to get it in - Refill later after mother nature compacts it if necessary.  The main thing is not to compact enough to push the structure sideways.  Alternately fill each side a foot or so, plus or minus to keep pressure even on both sides.

The ground is certainly firm enough, it is simply ledge beyond which we could not excavate. I can break some bits off for a key-way, which is my plan currently, and then forming up a step from is no trouble.

The posts themselves are cedar, and have long since dried as much as they could (this build was supposed to happen two years ago!) so I expect to have good rot resistance, though I like your solutions with regard to a moisture barrier as that part of Mike's method did not sit well with me, for some of the reasons you cited yourself. I will likely char them though, for whatever benefit that can provide but then use a couple of vapor barriers to help ensure that moisture is not a problem. Add to that a french drain and soil which I have seen after nearly two weeks of constant rain that was soaked for the first 18 inches, then dry as dust lower down. The hill is also quite steep, which of course will help with drainage. I am not too concerned, but I am certainly willing to take some extra precautions since I only want to do this one time..

I am considering running concrete sleepers from uphill to down hill posts, then just temporary log sleepers for the side to side direction. I'd love to do an earthen floor of some kind, but the soil here just does not lend itself to that possibility, so I can consider adding in the concrete sleepers without changing how I will finish the floor.

But I ramble.. I've been in the planning stage for so long it is hard to avoid doing ever more planning...

Here is a link to an alternative concrete floor I have done at my place and decided it is about the best for durability but not wasting resources.  Designed in India - it is the CBRI light duty concrete floor - like jute reinforced stucco about 1/2 inch thick - with some of my variations on the idea.


http://countryplans.com/smf/index.php?topic=151.msg100949#msg100949

Thanks for the link.. I am likely to do something very similar now. I'd already considered concrete in part because of the ease of levelling the floor, but did not want to take the hit on my budget. However it looks like I can devise something like what you are doing, or do exactly that, and I should be able to keep the costs within budget.

Sounds good.  A bag or two of cement will go a long way with the CBRI floor.

That has always been a pet peeve of mine-- why do people need  the same thickness floor that a tractor can safely park on.  When I get away from accepted traditional methods here and look at what they are doing in other places, I find out that, as I suspected, people do not need a 4 inch floor of concrete.  A 1/2" floor with jute reinforcement will work fine or maybe even better than the 4" floor.

We were looking at mine today - no cracks even where the appx. 300 lb Franklin stove is.

So what does Mike Oehler think of Glenn's post rot problems? I'd *love* to know a way of doing this with as many locally-available materials, and charring post ends seemed like a winner.

Maybe find large rocks to support the poles. Would need to be a solid variety, and you may need to shape the ends of the posts.

Thoughts?

Could tire walls or earth bags be substituted for poles?

cdevidal wrote:
So what does Mike Oehler think of Glenn's post rot problems? I'd *love* to know a way of doing this with as many locally-available materials, and charring post ends seemed like a winner.

Mike has had similar problems in his ridge house although he attributed it to weather exposure - open to the elements for a long time. 

Mine were under cover but still got rot and termites.  I cut about 5 plastic bags off of mine when replacing the post bottoms with a steel base.

Mike has found that studies show preservatives end up in the blood stream - possible carcinogens - if they are used to treat the poles in the living space.  He is looking for the best alternative to make the poles safe to live around but not deteriorate.  Under the right conditions - dry poles - dry covered area, etc. the charring could work.  Wet logs drain water down into the bags even if charred.  Cracks - checks in the logs could allow water entry- exposed bag tops allow water entry.  Hard for me to trust that method and in fact I do not trust the 4x4 wood post sleeves for other uses  now either.

cdevidal wrote:
Maybe find large rocks to support the poles. Would need to be a solid variety, and you may need to shape the ends of the posts.

Thoughts?

I used some flat rocks and most places I used a couple inches of concrete mix (damp but rather dry) under the post to conform to the ground and post.  I drove a 3/4" or so diameter rebar into the ground about 2 feet with a jack hammer leaving around 8" or so sticking above ground. I drilled 1" holes in the base of the posts and set them on the rebar stake.  Holes could be drilled in the ground if hard, with a rotohammer or a concrete pier poured in a hole with a pin also.

This method requires temporary cross bracing until backfilling is done evenly to keep the structure plumb - or plumb as desired - most logs are tapered allowing only one side of them to be plumb.

I have no problems with the posts that are not buried in holes in the ground - using the rebar pins and concrete under them at the base.

cdevidal wrote:
Could tire walls or earth bags be substituted for poles?

As long as something solid prevented them from caving in toward the center from side wall caving pressure.  Mikes engineering on the posts would not then apply so you would be experimenting on your own.

Rock walls - steel pipes - other things could work also but you would need to assure your own safety and adequate design.

Quick and solid answers, Glenn. Thanks.

Glenn Kangiser wrote:Under the right conditions - dry poles - dry covered area, etc. the charring could work.

I'm thinking somewhat in terms of dollar down, SHTF scenario, as well as the benefits of locally-obtained materials.

With this in mind, charring poles may be worth the risk. After I asked my questions, I saw in Mike's $50 house book that replacing the posts does look easier than I thought. Jack up the roof in that spot, dig in front of and underneath the pole, pull out. Replace with a pole of similar height. Not bad. Could probably do in a few hours, and if poles last five years, a couple week's worth of maintenance and you're good to go. Compared to the ongoing maintenance on a regular house, that's not bad, and would probably be the worst work you'd do.

Just be sure your design allows for freedom of removal; Mike said don't nail the crossbeams to the posts for this reason. As long as nothing significant is built in front of the posts (like a bath and porcelain toilet) it ought to be doable. Better than nothing in a grid-down scenario.

Can termites really dig that far down? Post bottoms would be at least 10 feet under the surface. Maybe they came from above?

Glenn Kangiser wrote:
I used some flat rocks and most places I used a couple inches of concrete mix (damp but rather dry) under the post to conform to the ground and post.  I drove a 3/4" or so diameter rebar into the ground about 2 feet with a jack hammer leaving around 8" or so sticking above ground. I drilled 1" holes in the base of the posts and set them on the rebar stake.  Holes could be drilled in the ground if hard, with a rotohammer or a concrete pier poured in a hole with a pin also.

This method requires temporary cross bracing until backfilling is done evenly to keep the structure plumb - or plumb as desired - most logs are tapered allowing only one side of them to be plumb.

I have no problems with the posts that are not buried in holes in the ground - using the rebar pins and concrete under them at the base.

Do you think multiple rebar pins would cut down on hinging? Probably would be a real pain to line up right.

Glenn Kangiser wrote:
As long as something solid prevented them from caving in toward the center from side wall caving pressure.  Mikes engineering on the posts would not then apply so you would be experimenting on your own.

Rock walls - steel pipes - other things could work also but you would need to assure your own safety and adequate design.

I believe someone in this thread mentioned earth bags. Perhaps in a dome shape?

Warnings about experimentation understood. Plus you'd lose that cool log cabin look.

Nonetheless, Mike also was an experimenter, and because of that you now have a great cabin 

cdevidal wrote:
Quick and solid answers, Glenn. Thanks.

I'm thinking somewhat in terms of dollar down, SHTF scenario, as well as the benefits of locally-obtained materials.

With this in mind, charring poles may be worth the risk. After I asked my questions, I saw in Mike's $50 house book that replacing the posts does look easier than I thought. Jack up the roof in that spot, dig in front of and underneath the pole, pull out. Replace with a pole of similar height. Not bad. Could probably do in a few hours, and if poles last five years, a couple week's worth of maintenance and you're good to go. Compared to the ongoing maintenance on a regular house, that's not bad, and would probably be the worst work you'd do.

Just be sure your design allows for freedom of removal; Mike said don't nail the crossbeams to the posts for this reason. As long as nothing significant is built in front of the posts (like a bath and porcelain toilet) it ought to be doable. Better than nothing in a grid-down scenario.

Can termites really dig that far down? Post bottoms would be at least 10 feet under the surface. Maybe they came from above?

The new active area with oxygen etc is at the floor surface then down 6 inches to a foot - so the termites and fungus get there - had a big queen - nice.

Even if spiked with rebar, a sawzall will make removing the post easy enough.  I just put a steel foundation under the first 18" of my damaged ones but it is easy enough to change the post with temporary shoring and jacks - I could do it in less than a day.

cdevidal wrote:
Do you think multiple rebar pins would cut down on hinging? Probably would be a real pain to line up right.

You would still get the hinging at the floor surface, but temp bracing takes care of that just fine until back fill then there is no more problem - the earth takes care of all earthquake bracing.