• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • r ranson
  • paul wheaton
  • Anne Miller
  • Mike Jay
  • Jocelyn Campbell
stewards:
  • Devaka Cooray
  • Burra Maluca
  • Joseph Lofthouse
garden masters:
  • Dave Burton
  • Greg Martin
gardeners:
  • Mike Barkley
  • Shawn Klassen-Koop
  • Pearl Sutton

Natural foundation for log cabin

 
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi all,

I'm in the process of building a log cabin tiny house in the woods adjacent to my home. I'm struggling quite a bit with the foundation at the moment. I began with the idea that I would build with urbanite (broken chunks of concrete), fastened with mortar (much like one would lay bricks with mortar). Someone said that was a bad idea (urbanite foundation at stackexchange) because water would penetrate the cracks between the urbanite, expand when frozen, and crack the concrete.

So I decided to put the urbanite chunks in the bottom of the hole (mixed with mortar), then make the top out of solid concrete. But now I have a new problem: The water table is quite high, higher than the frost line. I've been told by builders the issue itself is not a problem because concrete is routinely exposed to water. The greater issue is that if I do pour concrete, I need to extract the water to maintain proper mixing proportions. This is what I've been doing: extracting with a hand pump, pouring a load of concrete, waiting a few days, then repeating the process all over again. At this rate, I'll finish when I'm 192.

I'm trying my best to be environmentally conscious and cost-effective. To pour the foundation would cost about 1K. Not terrible, I supposed, but it's currently prohibitive. (The wife says I can't spend any of the family money on this cabin, so any money I do acquire would be bits at a time and in small amounts, until I land that movie star gig I've been auditioning for).

So, I have a couple of questions:

1. Is it really a bad idea to fasten urbanite with mortar? The logic makes sense (again, water penetrates, then expands when it freezes, thus cracking the foundation), but aren't homes routinely built from brick and/or stone and/or cinderblock foundations in exactly this way? What makes this situation any different?
2. Can I just backfill the holes I dug (9 in total) with urbanite, then set large stones on top of the urbanite? I'm thinking it would be way less money to buy 9 large stones than to pour concrete (and it's much more environmentally friendly!)
3. Any other cheap foundation ideas I'm missing? I'm in the northeast near Philly, so it gets pretty cold, but not massively so, if that makes a difference.
 
pioneer
Posts: 749
Location: 4b
110
bee building dog forest garden trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Depending on the size chunks you are talking about, could you just use the urbanite as a rubble trench foundation and then build up a foot or so above the ground level with concrete?  I think that is what I would try.
 
gardener
Posts: 1837
Location: West Tennessee
466
books building cat chicken food preservation homestead cooking purity trees
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hey Dustin I’ll offer my thoughts.

I’ve poured a lot of concrete in the last twelve months, and here’s what I’ve learned from concrete guys, my contractor, and my own obersvations.

Concrete is heavy, heavier than water. I was pouring concrete in three foot tall form tubes, with about two of those feet in the ground and a foot above ground. I accidentally mixed one batch with too much water. It was soupy, like really soupy. I poured it in, and in real time over the course of a few minutes, I watched the concrete ingredients (what they call “heavies” in the construction world) settle, leaving a puddle of water about an inch and a half deep at the top of my form tube. I dumped more wet concrete in, which displaced the water, resulting in a cylinder full of concrete. Having witnessed this, I like to think that if you were to pour a footing in a single pour, the heavies are going to occupy all the space in the hole and any ground water will be held back by the greater in mass & density concrete. If there is standing water in the hole, I suspect that as concrete is poured in, it will be displaced and come up and out of the hole in the ground.

You mentioned you’re up in Pennsylvania, and I imagine things are still cold. If I may offer a piece of advice, consider using the fast-setting type of concrete mix, and/or use hot water when mixing the concrete. I was chatting with my concrete guy and he said calcium carbonate is added to wet concrete at temperatures below 70 degrees to generate heat to help it set. The colder it is, the more is added, and on really hot days in the sun, retardants are added to slow the concrete setting so it can be worked. Concrete doesn't dry, it cures. The chemical reactions that make it harden vary in speed depending upon how cold or hot it is. Also, avoid letting fresh concrete that is 24-48 hours old freeze. The water molecules haven't had enough time to bond with the concrete mix, it can freeze and expand and structurally weak concrete or crumbling failed concrete can be the result.

I’m no concrete professional but it’s a few things I’ve learned along the way. I hope this helps you if you choose to mix more concrete for your footings. Best wishes!
 
pollinator
Posts: 114
Location: Western Idaho
27
earthworks greening the desert ungarbage
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
look into the frost depth for where you are building, it is usually listed somewhere on your county website in the building code section. You could also insulate the foundation which would help.
 
Posts: 731
Location: Bendigo , Australia
24
dog homestead
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Concrete can be poured into holes full of water.
Sometimes its done deliberately to prevent the form work collapsing.
BUT you need to pour the concrete mix down a chute to the bottom of the trench.
This causes the mix to stay as a mix and displace the water at the bottom.
By continuing to pour , lifting the chute until the concrete is at the level you want, the job will be perfect.
Its important to create a drain for the displaced fluid to run off to. Maybe a small dam to allow it to settle out the solids rather than have it go down a drain.
You can pour continuously
 
Dustin Fife
Posts: 10
forest garden rabbit woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks everyone for the thoughts. Let me clarify a bit. I am really trying to see if there's any problem with using urbanite and/or if there are other alternatives that are cost-effective and sustainable.

Some thoughts that I've considered (and sometimes dismissed):

1. Fill the holes with urbanite then stack boulders atop that. Alas, the boulders would be more expensive than the concrete, so no go (unless I find some boulders on craigslist or something).
2. Do a rubble trench foundation. Problem: the water table is too high to allow this to drain.
3. Use cedar logs on grade. I don't recall what the problem was with this one.
4. Similar to #3--stack urbanite inside the holes until they're just poking out (like a few inches), then stack the cedar logs on top of that.
5. Rather than bind the urbanite together with mortar, surround it with woven wire (or something similar) to prevent slipping. Then if water gets inside, it will freely drain out, rather than freezing and expanding.

Basically, I'm trying to avoid concrete because of the costs/effort/environmental impact. Any other out of the box ideas? Any comments on the ideas I just mentioned?
 
James Freyr
gardener
Posts: 1837
Location: West Tennessee
466
books building cat chicken food preservation homestead cooking purity trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hey Dustin!

I think I misunderstood your post earlier. Here's my thoughts on the urbanite. It's rubble, and rubble will shift and settle over time. I think it could be used, but I think having a plan to jack up and re-level the structure placed on top of it as it settles is something important to consider.
 
Aaron Tusmith
pollinator
Posts: 114
Location: Western Idaho
27
earthworks greening the desert ungarbage
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
you mentioned 9 holes, were these intended to be piers of some sort? I would imagine that since they have already been dug out I would fill them in with a stone/urbanite of some sort since the original ground has been disturbed. This may end up being a drainage problem as I imagine they would fill up with water since you mentioned the water table being so high. It seems that water infiltration is going to be an unavoidable condition with where you are building so perhaps it would be best to focus on letting the water out, with french drains, etc. I built a small 13'x15' cabin (in tiny house forum) and the foundation was basically a rubble trench but the entire thing was encased with hog wire -which we had tons of old rolls of lying around. So it ended up being a sort of gabion foundation which extended several feet above grade. I built on a slope so I dug 2 drainages at each corner of the downhill side. I used urbanite, angular rubble, bricks, river rock -I drove all around collecting this stuff. Once the gabion was finished I mixed portland cement 3:1 in a wheelbarrow and packed it into the voids of the foundation essentially capping it on the outside with concrete. You could go one better and "patch" the urbanite you have with blobs of concrete on the inside of the rubble assembly as well, that would help prevent any future slippage or shifting (which is what I should have done) because it seems like water is going to get in anyway. If this is the case I would invest in designing your drainage best as possible as well as extending your urbanite above grade as much as possible.

You seem to have a worse water situation that I had so it will be a lot of work, I spent far more time completing my foundation that it took to build my entire cabin. "Big shoes, big hat" is the best advice I heard when researching natural buildings. If you are willing to spend a little money then if it were me I would have truckloads of rocks delivered to save money rather than pouring of concrete, but thats just my opinion. Sorry for the long post but your situation seems similar to mine. My foundation has had one soggy winter so far and hasn't moved, so far so good. Best of luck.
DSCN0716.JPG
[Thumbnail for DSCN0716.JPG]
 
Posts: 34
Location: Cincinnati, Ohio
6
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Dustin, everyone.
Please let me know what you think about this post, but there is nothing wrong with mortaring Urbanite. It's basic rubble masonry. Urbanite is artificial stone, broken up in rubble. Specifically artificial conglomerate stone. Read about rubble masonry, for thousands of years almost ALL domestic architecture stone masonry was done in rubble work, using roughly dressed stones for corner quoins and window/door surrounds at best, in far weaker mortar than our cement mortars today.

This is a picture of an old Punic/Phoneician town in modern Tunisia, notice the rubble masonry walls, it's older than the Roman Republic.

This stone is probably limestone. Chunks of modern concrete, Urbanite, when mortared are going to be as strong if not stronger IF you use proper wall building techniques.
IF you build a mortared Rubble wall using drystone wall principles you could get something very strong indeed. If you do it well, using hearting, and through stones, a rubble foundation pier with urbanite and modern type S mortar or stronger could actually exhibit better compressive strengths than some of the thousand year old rubble work walls still standing.

If you want to avoid portland cement use a Pozzolan + Lime mortar mix. I asked some questions about lime, mortar, and concrete here 2 or 3 years ago here, and some folks gave great detailed answers. They are floating around in the forum archives. There are a couple of companies - one is HEss Pumice and their "limestrong" product - making "Roman" pozzolan + Lime mortar and plaster formulations. You can also use brick dust, which makes what's called in the Middle East "Horasan Mortar" or Khorasan Mortar

The traditional way of building foundations wasn't using piers or posts, it was digging a trench and building a masonry wall. Here is a method used by some rural Berbers in Morocco to this day.  It's the same method that used to be used in Italy, Spain, and elsewhere in the old world going to pre-Roman times. Heck they even did this in Canada, and called them grouted rubble foundation walls.

Simply dig a 3 ft deep by 3 ft wide ditch around the perimeter of the house. Line the bottom with some gravel and ram it solidly.

Then pour a mortar bed, Start laying two walls, to "wythes" (or "leafs" the terminology varies).

You basically build two 1 ft thick walls against the sides of your trench, leave the center empty. Build your first course then second with urbanite as if you were building a stone wall. Pack the nooks and crannies with mortar then squeeze in small stones, serving as "heartning". If in doubt look at photos of REAL old Rubble walls, anything built 150 years ago or older.

You build up the two walls against the side of the ditch, then in the middle pack with a lose slurry of lots of small chunks of rubble and mortar grout. An easy way, lay down a 2-4" thick bed of soupy or peanut butter consistency mortar, shove a layer of small chunks of broken rocks, slap down another soupy layer of mortar, then shove lots of small broken chunks of urbanite and rocks.

hen ram it or tamp it lightly with the tamper. Come back the Next day, build another 2 feet above it in the same way, but this time build the two ft thick walls first, leave the center empty, let the mortar set since the ditch isn't serving as a form constraining it. Then fill in the middle of the two ft tall walls with successive layers of mortar then loose fill, tamp it at the top, congratulation - you have something stronger than a gravel trench and something that would pass most building codes (lots still have a provision for rubble foundation footers without rebar, around 3 feet wide.

Or simply dig a 3 ft by 3 ft trench, fill it all with gravel in layers, tamp each layer down, then about 9" below the ground line start building your rubble wall. Same way as describe above.

If you do it right it will last a thousand years beyond your log cabin, which will probably rot in 100 - 150 years. Future Permie types a thousand years from now will be able to reuse your foundations and build a future cabin. Hip Hip hooray.

Again you don't need to use Portland cement mortar, many people will object to it for reasons of embodied energy. That said without steel rebar to rust and cause spalls a portland cement mortared wall, with portland concrete based urbanite as the masonry, will last a very, very, long time.

Why do this instead of piers? It's more labor but it's stronger. As intermediate floor beam supports you can simply do piers on the same principles, mortared 3ft x 3 ft urbanite posts going down 3 ft on a packed gravel bed. THEN you have space under your floor boards you can build a winter root cellar. Also since there is a three foot thick mortared rubble perimeter wall that goes up two feet from the ground or so as a stem wall. The chances of Rodents getting in are considerably less. If you aim to build a log cabin then rodents, as cute as they are, will not be your friends. Mice are about the cutest vermin there are, but they remain vermin.
 
Simon Malik
Posts: 34
Location: Cincinnati, Ohio
6
  • Likes 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Dustin, James Freyr, Aaron:
Rubble work if on a well drained gravel lined bed, that has been well rammed, dug sufficiently deeply, shouldn't shift much.

Aaron, that's a great picture. And inspiring !

All of these ideas are compatible in a way, Your rocks and boulders, well Urbanite is basically rock chunks, chunks of broken up concrete are artificial rocks. The problem with round rocks even if in a gabeon is stability. Urbanite chunks would stack very nicely and their geometry would enable a more stable stricture when stacked.

Mortar it well and pack the nooks and crannies with hearting, smaller chunks, and if you have a gravel lined trench with a porous drainage pipe underneath, leading away from your foundation to drain elsewhere, you would remove a lot of the risk of hydrostatic pressure shifting things and there would be less water to freeze in the winter underneath causing heaves.

Look at the rubble foundations of homes in the city of Motya, it is also a Phoenician / Punic city, but in Europe, in modern Sicily


Well over 2000 years old

Here are rubble foundations in the town of Sa Caleta, another Phoenician city in modern Ibiza from 654 BC


Mortared - OR dry - Rubble masonry foundations and footings can last a very, very, long time. Certainly several lifetimes beyond the builder and most of the building itself.

 
Posts: 60
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Just as an aside ,  how many cement structures with steel re-bar today are crumbling just 60 or so years after their making. Cement has its place but not anywhere near a genuine stone and mud mortar house, ive seen the result of cowboy builder jobs on stone houses and its ugly. For stone its got to be a natural material such as lime or mud .
 
Malcolm Thomas
Posts: 60
2
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Another quickie , You wanna get your hands on the Foxfire book , my copy AO-36, deals with all matters of log cabin construction and its very detailed , first printed in 1968 !!!. Ive had this book for 40 years. Its all about natural living and all things . A bunch of students in the 60s had the great foresight and  went out and interviewed the elderly people who were around during the 1800s and had knowledge passed down to them from their elders who originated from Scotland Ireland  and England who brought their hand skills with them including making shine. You wont find any cement construction in this book !. A book about life in the hills on the east coast of america , a simple but hard life. Sadly the romans never documented their building exploits it was all passed down to a select few i suppose.
 
Dustin Fife
Posts: 10
forest garden rabbit woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thank you all for the excellent advice. It sounds like urbanite will work, if I do it right (namely, draining the foundation).

But now we have a new problem: The cabin location is probably only about 2-4 feet higher than the lowest point. It runs right next to a creek that drains into swampland only about 20 yards from the cabin site. Poor planning on my part. Needless to say, I don't think there's enough elevation to keep the foundation well-drained. What do ya'll think?

As an aside, a few days ago I decided against a log cabin and instead am doing a timber frame hay bail structure, so there's much less weight to support now.

Thoughts?
 
Simon Malik
Posts: 34
Location: Cincinnati, Ohio
6
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Malcolm Thomas wrote:Just as an aside ,  how many cement structures with steel re-bar today are crumbling just 60 or so years after their making. Cement has its place but not anywhere near a genuine stone and mud mortar house, ive seen the result of cowboy builder jobs on stone houses and its ugly. For stone its got to be a natural material such as lime or mud .



Hi Malcolm, and everyone. I agree to a large extent. Concrete has its problems. What you say is especially  true certainly in the case with reinforced concrete. But here are some thoughts. Not to challenge you and everyone, but just some ideas in my head. And I welcome critique, criticism, and advice from everyone. I could be seeing things wrong, and everyone here has more building experience than I do.

I feel as if cement and modern concrete themselves often gets a bad rap. In some cases it's deserved, but in other cases it is an undeserved bad rap.

There are problems with concrete, but these are problems in certain applications that are advantages in others. Lack of breathe-ability and vapor permeability is a problem. but it can be an advantage in some cases.

Re-bar is the problem often enough, not cement per se. IF we encapsulate unprotected steel rebar in a concrete made of lime mortar (e.g. a 'gravel wall' or Roman style concrete) or a random rubble wall bedded in mud mortar then the same thing would happen. The rebar would rust, and eventually make the wall crumble. It's reusing rebar that's the main problem when it comes to the crumbling. Steel rusts, it expands, this produces spalling, this lets more water in, and with freeze/thaw cycles the wall crumbles.

But there's an alternative. If someone's using steel re-bar coating it would prevent this. There's also newer fibreglass or basalt rebar, which also has embodied energy.. and is more expensive(though the price is coming down), and involves artificial resins.... which is a problem for sure. It certainly isn't natural. But if you are doing a small, tiny house, then the expense wouldn't be that much more...

I really don't think there is anything magically less reliable about modern concrete per se, rather I think it's all a mater of how it's done. There's an immense amount of modern knowledge about how to make modern concrete more durable. A durable structure can be re-used over and over. Which means the structure has less ecological impact. If someone is doing a log cabin, additionally, on a very firm foundation cement and stone that resists settling then this aids in the long term durability of the log structure, its resistance to settling, and gives a base that can be rebuilt upon when the log structure finally rots away.

Mud mortar or lime mortar are alternatives to cement mortar, but of course there's the matter of building code. Some places require cement based mortar in rubble stone walls. Now that still lets one use rubble stone instead of concrete for foundations. Old fashioned mortared rubble foundations are allowed in some locations, but the foundation has to be such and such thicker than wall on top. Where I live if I recall inspectors are willing to consider a 36" thick rubble foundation. That's a yard thick. So you get away with a mortared 3' thick and 3' deep rubble wall foundation. Which interestingly enough is about the thickness of historic stone foundations in Morocco and many other parts of the Mediterranean.. anyway, I doubt any inspectors in the USA would let anyone use mud mortar though.

We could construct a foundation wall on dry stone walling principles, with lots of through stones for bonding and chinking and hearting stones, making sure all voids are structurally filled with small sharp edged stones, and the mortar is mainly just filling very small gaps. But in that case instead of mud why not use a lime mortar with pozzolans? Since foundation walls are underground, and exposed to water, and mud mortar will disolve, let incests and rodents in, and allow displacement of wall stones and increase settling? And in that case if we are using lime mortar then why not just add cement to the mortar to make it more durable and harder anyway?

A random mortared rubble foundation is basically concrete anyway. That's all Roman "Opus Caementum" was. It wasn't concrete in our sense, it was layers of pozzolanic mortar, rubble tamped or rammed in, then topped with more layers of mortar, and so on.

Ecologically, if you have a foundation that can just be reused for generations and rebuilt upon, wouldn't that offset the ecological issues of producing cement? I mean, if someone's in an area where they can get away with a lime based mortar, it will have better performance for underground applications than mud. But why not sparingly use cement? If we are using a harder stone? And that's a serious issue.

From my understanding, some of the problems with stone and cement based mortar are mainly when you're re-pointing old stone walls, made with lime bedded mortar, and whose whose joints were originally lime mortar. Especially stone walls with softer stone. Mortar joints those kinds of wall are sacrificial,  designed to be less durable than the stone, and to be re-pointed using the same kind of (or similar) mortar material as the bedding mortar. If we use cement based mortar on older stone walls then we will ruin the walls, for sure. Water gets into the joints, it freezes during the winter, it causes the stone to breakdown and crumble.

Soft stone has serious issues with cement mortar. There's also how porous the stone is. Porous stones are destroyed by cement mortar joints. Sandstone and many limestones are porous. Some limestones are less, however, and granite is far less porous than cement. Portland cement would ruin sandstone walls longterm. But if youa re building a new wall out of hard limestone rubble, or granite rubble, what would be the harm in using portland cement mortars or concrete? Other than the large amount of embodied energy.

But if we build a stone wall using entirely cement based mortar and stones that are stronger than the cement based mortar from the beginning this shouldn't happen, again provided the stone is harder than the mortar itself. Sandstone masonry is very weak, much weaker than most cement mortars. But some limestones are stronger than some cement mortars, and all granite is far stronger than cement mortars. I just don't see why not do the same thing. If your building code lets you do a thick stone rubble foundation without re-bar reinforcement then if you build it with cement mortar you basically have, once cured, a large monolithic artificial conglomerate stone mass. Concrete in other words.

There are things other than rebar, of course, that take away concrete's long term durability, but a lot of them could be addressed with less water in the mix, and using pozzolans, and other additives. Some of which have natural alternatives (for example, using brown sugar in a concrete mix to retard the set. Or certain kinds of soaps for air entrainment.

There are Flagg stone and Slipform stone cement based stone houses that are over 100 years old and performing well, today. Old cement mortar stone walls and structures all over the country. If they were built well with good craft then many of them still last.

Why should we see Portland cement, other than its the massive embodied energy from the manufacturing process, as some evil thing?

The base of the Statue of Liberty and the foundation of the Washington Monument are well over 100 years old, constructed of modern concrete (though in the Statue of Liberty's case I think Rosendale Cement, not Portland Cement, was mostly used. I could be wrong). Neither are crumbling at all.

The Hoover Dam isn't crumbling and is going nowhere any time soon.

Roman concrete has lasted thousands of years. True. But It's not magically different than modern concrete, other than it doesn't have Rebar. Modern concrete without steel rebar should have superior performance if it's a good blend. It's essentially Mass Concrete. There are mass concrete based foundations well over 100 years old all over the place, not displaying any issues.

Chemically both old Roman Concrete, which was perfectly fine for stones, and modern concrete are very similar. Both are largely lime: Calcium oxide, Ca0; silica, Silicon dioxide, SiO2; Aluminum oxide, Al2O3;  And traces of other minerals.

Much of what made Roman Concrete so reliable was less the ingredients, though the pozzolan helped, but the process of working it. The mortar was dry, almost zero slump, and the aggregate stones were rammed in it. It was a  rammed earth like process. Everything was well consolidate, and the porosity of the mass lessened by repeated mechanical compaction. Guys ramming it over and over. It was a hydraulic set mortar, the lime and pozzolan and other impurities created a sort of natural version of hydraulic portland cement. Especially if they used brick dust and potshards (what was called Horasan mortar in the middle east). If you use a stiff dryish low slump and less fluid cement mortar or concrete - with just enough water for a hydraulic set and cure, and ram the rubble into place, which is how they did concrete even in the late 19th and early 20th century, then you would get a good dense well set wall. The problem is it's a lot of labor to repeatedly tamp. But since this is going to be a small or tiny house the labor shouldn't be too exhausting.

Wouldn't modern concrete or a cement based mortar using a pozzolan, like actual Pozzolana, or volcanic dust, or brick dust, or metakaloin or a clay based pozzolan, or finely ground glass dust, have superior performance than most historical badly done 20th century concrete?

Using lime in the mortar mix will give free lime to carbonate and increase the mortar's workability. If the mortar does crack the free lime would leach out and self heal. Using pozzolans also will greatly strength and increase the durability of it. Mixing small amounts of natural cement in Portland cement mortar also helps durability (But it's hard to get natural cement. They started making Rosendale cement in New York but it's expensive and shipping it increases the amount of energy in the process of using it, which makes it less ecologically friendly).

I welcome your thoughts !
 
Simon Malik
Posts: 34
Location: Cincinnati, Ohio
6
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Dustin !

Dustin Fife wrote:Thank you all for the excellent advice. It sounds like urbanite will work, if I do it right (namely, draining the foundation).
But now we have a new problem: The cabin location is probably only about 2-4 feet higher than the lowest point. It runs right next to a creek that drains into swampland only about 20 yards from the cabin site. Poor planning on my part. Needless to say, I don't think there's enough elevation to keep the foundation well-drained. What do ya'll think?



A couple of ideas:
1. You could raise your foundation/stem wall even higher? For example:


Many buildings historically had their first floors considerably elevated. If you're near a flood plain, why not build the mortared urbanite foundation up a good 3 or 4 feet high. Build stairs. The interior space you can, again, use as a cellar.
Ventilate it though, notice on older buildings with elevated first floors over a high crawl space/ foundations they had grates to vent the space underneath.

Or just fill in the entire space with rubble. They used to make artificial building platforms in some parts of Asia and the middle east, essentially stone walls filled with rubble. Or

As an illustration, the people at the This Cob House blog are doing something similar:




2. If you have gravel bed drainage under the urbanite foundation wall, with a perforated drain tile (like a rigid PVC pipe or something) in the middle of that tamped/rammed gravel bed, in the bottom of your foundation trench, with an outlet to another drain pipe leading well away from your house (like toward the creekbed..) then why not also surround the perimeter of your house, a couple of feet away from your foundation, with a second small gravel filled ditch, and direct it away as well. Either with a drainage pipe in it or not..

Imagine this a few feet around you:

And:


Basically you have the foundation trench, at the bottom of which is backed gravel and your drainage pipe, right? Then you build up your foundation walls with urbanite - thick, and solid. Then around the perimeter or your house you have another drainage ditch/trench, filled to the brim with gravel and small rubble, and with another trench leading away from your property, wherever you want the water to drain into. With or without a perforated pipe inside.


- Now you want another trench that this all connects to, leading away from your property toward where you want your water to drain.

3. If you can afford it and it's not too much labor, perhaps you could grade the land your house will be on, making in effect a small artificial hill. Dig and compact the dug out area, put your drainage ditches and pipes in, build up a mound that's several feet wider than the perimeter of your house, hard core rubble - like chunks of urbanite and gravel - a couple of feet up . An artificial hill or mound, put some clay and top soil over the artifical hill around your house. Build on top. To prevent settling build your foundation from the ground level as you build your mound around it.

Kind of like.. this, Imagine your house in the middle:


Basically making a tumulus or barrow, with a hard core interior (stone, urbanite, rubble and large gravel) will packed, pounded, consolidated, and laid. On a firmly compacted ground. So when you dig out the perimeter area beyond the immediate space of your house, maybe a foot or two deep. further inside this dug out area further dig another 2 or 3 deep the wide foundation trench for the perimeter of your house itself. Rent one of those jumping jack pneumatic compactors and seriously compact the dug out area in and manually compact the inside of your trench and the area near your trench, so that you don't collapse it with the pneumatic compactor. Lay down your gravel, drainage tile, etc. in the foundation trench, build up your foundation wall and build it up 2 - 3' high beyond the trench, now start filling the area around it, in the dug out impression that will soon be a mound, with rocks/ urbanite chunks, fill in spaces with gravel. Tamp, repeat with layer two, and so on, until you have reached the height of the mound that you want. cover it with clay and topsoil, presto artificial hill. Put sod on it, etc. Now continue building the rubble foundation and stem wall a couple of feet, then build your house.

This could be done in a way that it's a large water swale, you can redirect the water flow strategically. So now you have drainage under the foundation, a mound around it, and the first floor considerably higher than the ground level and water level, and a drainage trench around the larger perimeter, further collecting and redirecting water.

To prevent turning places even swampier strategically put swales, berms, gravel drainage ditches, etc.

I welcome criticism, critiques etc ! If any of these are really dumb ideas feel free to shoot holes in them.

Cheers all !

 
Simon Malik
Posts: 34
Location: Cincinnati, Ohio
6
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Malcolm Thomas wrote:Another quickie , You wanna get your hands on the Foxfire book ,



Hi Malcolm !The Foxfire books are amazing ! I stumbled on a near complete set at Half Price books last year. Imagine how much vernacular wisdom and know-how that just goes extinct over the years ! It's heartbreaking, but so amazing this stuff could be preserved.

If only someone could do something similar worldwide. Go to Rural Asia, Rural Europe, Rural Africa, record what the people are doing, how they naturally solved problems in the old days. The old timers worldwide have treasures of wisdom that can illuminate our situations all over the world.
 
Malcolm Thomas
Posts: 60
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I do take your points about cement , it does have its place , building tall with stone would impossible .
The Foxfire book is a look into the past and those building skills and knowledge came from europe. From what i have read and seen here  the stone house rubble infill design housed animals underneath the occupants for shelter and added heat for the floor above. On the floor is placed dried  gorse and scrub for the animals.
The floor bearers are chestnut logs and on them sit 30mm chestnut planks of various shapes nailed to the log bearers. For the roof its the same wood , heavy duty log as the main structure with smaller ones supporting the chestnut planks on top these are the barrel tiles and either side of the ridges and along the roof edges there are placed heavy rocks. How would anyone get that past modern building codes , answer they woul,dnt . Its possible to restore or repair stone houses or a ruin as long as its in keeping with the architecture.
The other thing is the availability of oak and chestnut trees , their planks etc come at top notch prices . 200 years ago you could just fell a few trees of enormous proportions and they were abundant but the chestnut blight put pay to that species especially in the USA.

Yes the old timers are the ones who have a lot of knowledge and are very often overlooked

And building a log cabin i think should be done by setting the logs on a stone wall 18" or 2 foot above ground level or the like or on pillars as in the Foxfire book . And infill the floor with say limecrete .



 
 
Dustin Fife
Posts: 10
forest garden rabbit woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks again for the comments. I don't mind raising the foundation higher, but how does that fix the high water table problem? Also, it seems that a higher foundation would require rebar?
 
gardener
Posts: 2917
Location: Upstate NY, zone 5
124
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I think the idea is not to have a taller foundation out of the ground, but to raise the foundation and ground surface above the existing water table. As long as you use solid porous fill at the bottom levels so water is not seriously wicked up, you will have drier ground to build on. This would not require rebar any more than the original elevation would, as long as the base is well compacted. (Ground which can be waterlogged in freezing climates will be loosened by frost heave every year, so needs to be compacted and/or dug out before building on top of it.)
 
pollinator
Posts: 149
Location: SW Ohio
22
chicken duck fish forest garden fungi cooking tiny house trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Dustin Fife wrote:Thanks again for the comments. I don't mind raising the foundation higher, but how does that fix the high water table problem? Also, it seems that a higher foundation would require rebar?



To my (limited and fallible) understanding it's normal for foundations to be in contact with water. What's important is that the foundation be able to bear the load without danger of failure. As long as the wood and living space are kept dry, if you build the foundation properly and with proper drainage so the water isn't stagnating in the crawlspace, it should be okay? Our house has a sump pump to keep it dry, which is definitely not ideal as it regularly requires electricity. I would consider building the cabin on piers because of the grade and water... but I've never built anything so I'm way ignorant. Unfortunately I don't think there's a way to keep your foundation from coming in contact with water? It's just a matter of building it to tolerate those conditions and keep your living space dry. I think you can probably build higher foundations without rebar by making them wider at the base, after reading all that about rebar rusting and destroying the concrete it's embedded in... I would be reluctant to use it.
Anyway if you're still trying to sort out the foundation, do you need to insist on that location? It sounds like a bad spot for a building, if you haven't invested more than time into that spot I'd try to find a better one. A graded hill near a creek is probably going to erode quickly, especially if the soil is disturbed and tree roots are cut and such. I'm afraid your cabin may have the soil crumble out from under the foundation and go plop down the hill.
I had fun reading all the info about building stone and mortar foundations
 
moose poop looks like football shaped elk poop. About the size of this tiny ad:
It's like binging on 7 seasons of your favorite netflix permaculture show
http://permaculture-design-course.com/
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!