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about post and beams and stone foundations -preventing rot

beki gamble


Joined: Jul 31, 2012
Posts: 1
So the home we are building will have post and beams made from white pine that has been cured and had the bark and cambium removed. We are planning on submerging them in a stone foundation resting on a concrete footing with gravel back fill. the beams will go all the way to the footing. We were planning on using creosote where the beam will be touching stone or cement, because we will not be able to access it to re-treat it. We are hoping this will prevent rotting. the house is on top of a well drained hill and will have a very large overhanging roof. We are in NH, where it can get wet, cold, dry and hot depending on the month. I know creosote is gross, but I dont know what will work better. The plans have been approved by a building inspector.

My question is Will this be enough to prevent rot? Is there some fatal flaw I have overseen? Any suggestions?

thanks everybody.
Judith Browning
steward

Joined: Jun 21, 2012
Posts: 3436
Location: Arkansas Ozarks zone 7 stoney acidic sandy loam
    
111
Someone else will have a better answer for you but this will bump your question back up to the top. We did build something similar in the seventies but with no creasote that I remember and probably not enough overhang and a few years later (maybe five) my husband was replacing the posts that were set in cement because they rotted. I think they were white oak originally and the rest were peeled pine. Now we try to soak or paint on a borax solution on any bare wood that is not exposed to the weather. It won't work if the wood gets wet repeatedly and I don't know if it will help on a post set in cement.


EDIT...The posts were set into the ground in cement then rockwork built up between them, so not really similar to yours and my husband thinks they lasted ten years. (we were finishing someone elses design) .


"We're all just walking each other home."
Ram Dass

leila hamaya


Joined: Jun 30, 2012
Posts: 704
Location: northern northern california
    
  29
Is there some fatal flaw I have overseen?


everything is temporary, thats the basic "fatal flaw"
sorry- i am not meaning to be snarky!

no i wonder about this too....i have tried different things. and thought of a lot of things.
but it seems...if you put posts in the ground you are going to at some point be dealing with rot. its more of a matter can you get it to last 20-50 years temporary or just a five years temporary.

well i have just been researching this too, so just figuring it out.
- perhaps someone will be able to give a better answer.

with the posts i just set in the ground i used a soil cement/soil concrete kind of mix....and burned the post ends...but i am making a fence and so...accepting it will be temporary but hoping it will last a while.

i've been wondering about- ashes...and also roofing paper. we have all this roofing paper...that someone got for free...its just sitting around...so i started eyeing it to possibly wrap the post ends.....and then well just put the posts in without it. did use a lot of ash and burnt the post ends...to hopefully make it longer temporary rather than short term temporary. i think on the part i am about to do...i will staple the roofing paper to the bottom...or somehow make a roofing paper liner...in the hole...i cant say for sure this will be any good, just those are my thoughts. experimenting.
daniel mielke


Joined: Aug 13, 2012
Posts: 7
Location: South Central Minnesota, Finally Zone 4
I am in the long term planning stage for building with timbers and posts. Plan to in fill with straw bale. I've always been interested in creating a whole log home, framed with the logs vertically and beams through the horizontal with in-fill straw bales. When you say that the wood has a tendency to rot, wouldn't a pre-treat of some kind elevated this problem. Short of using creosote, would a borax, then linwood oil or some sort of organic pine tar to inhibit rot. If as I would like to do, using norway pine for strength, inclosing the entire log within a concrete foundation/basement wall, is there a treatment in the concrete that would encapsulate the timber to prohibit a rot situation? It seems to me when going through some cordwood classes (given by the Richard and Becky Flatau) that there are some kind of polymer additives to concrete that can seal/encapsulate or retard moisture. When looking at Cob structures in these forums, England is a wet North Atlantic country most of the time and they have structures with timber that are hundreds of years old and sturdy as heck. Hope someone with some experience can help us out here. Have been perusing this site for three years now without ever signing up. This is my first post. Thanks beki for forcing me out of obscurity and into this world of PERMIES!!!
Suki Leith


Joined: Jul 27, 2012
Posts: 99
Location: Oakland, CA
    
    6
First, thanks Beki for addressing this very real issue. It pains me to see people putting so much blood sweat and tears into their hand-made homes and yet letting the structural integrity be compromised. Water loves organic material...and will find a way...I understand wanting an all-natural house out of bio materials, but I don't want my all-natural house to bio-degrade! I'm always happy when I see a little common-sense compromise.

What you need/want is called a "stand-off." It physically separates the wood from the concrete so that water does not wick up the end of the post. There are all kinds of post connectors for dimensional lumber available. But for non-dimensional round timbers, there aren't many choices.

Traditionally (for non-temporary buildings) stone plinths rose above ground and a wooden post or column would sit on that, with the stone sloped to drain. Often (but not ideally) these were held in place by gravity and roof loads. Sometimes these were keyed in place. I don't know how or if they treated the ends.

Same idea applies today. A galvinized all-thread is set into at least 10" into the concrete. It has a washer/spacer on it midway. A water-proof barrier like EPDM or building felt can be added for extra protection. Then a hole is drilled in the center of the column and it is epoxied and set on the thread. This is the easiest method, but there's not much of a space.

Stand-offs can be purchased at great expense (but arguably worth it).

Here's one from Simpson, made of PVC

Also, a knife plate/stand-off combination is even better. It insures a strong hold-down connection to the foundation. It's basically, a tongue of metal perpendicular to a plate which is embedded into the concrete. The tongue has a hole(s) drilled in it. The column gets routed to accommodate the tongue, and - very tricky - a hole is drilled perpendicular to the slit and after assembly is through-bolted.

Here's one from Simpson



and here are some hand-fabricated ones. They should be galvanized. Not only are these strong, but hidden from view as well.

Hope this helps everyone have buildings that last for many generations!
leila hamaya


Joined: Jun 30, 2012
Posts: 704
Location: northern northern california
    
  29
daniel mielke wrote: When you say that the wood has a tendency to rot, wouldn't a pre-treat of some kind elevated this problem. Short of using creosote, would a borax, then linwood oil or some sort of organic pine tar to inhibit rot.

yeah i think those are all good ideas, linseed oil and borax, and then theres the cresote
and or some of the water proofing for wood products you can purchase- though somewhat expensive.
and not particularly environmentally friendly, but effective.

daniel mielke wrote:
If as I would like to do, using norway pine for strength, inclosing the entire log within a concrete foundation/basement wall, is there a treatment in the concrete that would encapsulate the timber to prohibit a rot situation? It seems to me when going through some cordwood classes (given by the Richard and Becky Flatau) that there are some kind of polymer additives to concrete that can seal/encapsulate or retard moisture.


yes i believe that is commonly available for purchase at ace or other hardware stores. like thin set stuff.... as an additive.

When looking at Cob structures in these forums, England is a wet North Atlantic country most of the time and they have structures with timber that are hundreds of years old and sturdy as heck. Hope someone with some experience can help us out here. Have been perusing this site for three years now without ever signing up. This is my first post. Thanks beki for forcing me out of obscurity and into this world of PERMIES!!!


i am guessing but i think that those older structures have some thing similar to the post above, or are basically with wood ABOVE the ground.
so no part of the wood actually comes in contact with the ground.
Morgan Morrigan


Joined: Oct 16, 2011
Posts: 1400
Location: Verde Valley, AZ.
or build it so the posts can be replaced easily. that means open frames above, with removable sections, so you can re-drop replacements.

look up covers over wells for ideas.

Best not to have moisture contact at all, and wood and dirt means compost....


Get involved -Take away the standing of corporations MovetoAmmend.org
Daniel Clarke


Joined: Sep 17, 2012
Posts: 67


i just layed my logs on rough poured concrete and have a very large overhang and eventually i will mortar in along the bottom when i figure out what exactly i need to bring in under the walls like electric or water etc



i also used white oak logs on the bottom verses the lighter popular or pine

i also have all the soil slopping away from the loghouse


http://directory.ic.org/22661/Central_Pa_Mountain_farm___for_Hip_open_minded_people
Aaron Esch


Joined: Sep 23, 2012
Posts: 26
Here is a bracket that you can have made by a local machine shop.

I can upload a sketchup model of these if you like.

Also you can purchase some really nice brackets from a company called perma column. They also have a precast fiber-concrete column that can bolt to the bottom of your post. You then install the conrete part of your post in the ground and keep all of your wood dry.


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Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Hello Beki,

I live not far from you, over in Vermont. There aren't a lot of folks out there that try to build as natural as they can but there are a few of us. It is a lost life skill to build naturally, and many are forced to rely on more modern, and often misleading modalities of building. I stay as far away from concrete as I possible can. I don't care for the environmental foot print, and as a seasoned timber wright, I have seen more problems than good in 37 years of doing this kind of work. Don't miss understand me, I still use it in certain circumstances, but I do it with a keen eye to the applicable reason, and understand all it's short comings. I would have to see a visual description to give you my two cents worth on what you are planning, but there are a number of natural solution to preserving wood, even below grade, where you could expect to achieve 100 plus year lift span. Still not as good as above grade application with good drainage and architectural overhangs.



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http://about.me/tosatomo

"To posses an open mind, is to hold a key to many doors, and the ability to create doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader."
Daniel Clarke


Joined: Sep 17, 2012
Posts: 67
well you all up there in granite country are lucky in a way LOL.. i like my softer stones down here in Pa where we can use some mortar and a hammer to build





Aaron Esch


Joined: Sep 23, 2012
Posts: 26
Those are some nicely fitted and beautiful stone foundations! Awesome work! You guys are truly masters at your craft.

Concrete is for the rest of us who aren't wizards with stone. For all of it's shortcomings it serves the purpose. How I wish there where many more craftsman like you throughout the country, but alas those days have passed us by.

We have to live in this modern world of slap it together conventional construction methods. Every time I see a pole barn or stick built building go up it saddens me. Not only because its low quality, but because most of that wood has been shipped hundreds if not thousands of miles.

That's why I have been designing buildings and steel brackets that allow people to build a more traditional post and beam style building from locally harvested timbers without having to become a master craftsman. My hope is that people will be able to use my designs and build their buildings with local materials and leave the conventional stuff at the lumberyard.
Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Aaron,

Don’t sell yourself short, if you have the skill to design and fabricate metal bracketing that can withstand the riggers of post and beam architecture, I, (as a teacher of timber wrighting,) can guarantee you have more than enough innate talent to cut even a complex timber frame. You may need a little guidance but I have seen novices, (with good mentoring,) cut marvelous frames.

Your metal brackets are an art form in themselves. When a client wants something a little more modern, or they want a post and beam structure instead of a timber frame, I turn to a metal smith like you. Some of “Green and Green,” architecture from the turn of the century had some of the most beautiful metal wedge keyed strapping you could ever find.

As for concrete, that is something Americans have just become addicted to. Now everyone thinks it is the only choice they have, and most contractors won’t talk them out of it, because it is easier for them to facilitate from a business perspective. Nine out of ten times when I am call to consult on a project, not only can I avoid the use of concrete, I can do the work less expensively for the client, and if they do use concrete, it is in a very limited, and conscious of method.
Aaron Esch


Joined: Sep 23, 2012
Posts: 26
I had a thought. I see you have used stone for a natural foundation. Would it be possible to use a rammed earth process to make a foundation? I'm thinking dig a post hole and fill it layer by layer with a clay/sand mix or another type of cob mix. Then use a 4x4 to compact the mix as you fill it bit by bit, giving you a solidly compacted footing without concrete.

I have experienced clay like that around my home. I have such hard compacted clay here that I have to dig with a pick, Tposts bend when I try to drive them through if they drive at all, whenever I dig post holes I have to dig a foot at a time filling them with water overnight before I can go another foot. I cant imagine that kind of a footing not being solid enough to hold almost any timberframe structure.

What do you think? Have you done foundations like that?
Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Even’n Arron,

“Your standing on the right path, but looking in the wrong direction” as my grandmother would say. Dig that foundation hole, (or trench) and pack it tight, but never with clay!!! Your idea about rammed earth is spot on, it’s just your deployment of the methodology that needs to be adjusted. Lets take one of the oldest architectural examples of rammed earth there is, the Great Wall of China; you can see that thing from space. A lot of it is made with rammed earth, but only above grade. It sits on a compacted gravel and stone trench, not laid flat mind you, but with the ends pointing skyward. It is done this way because: one, it drains much better than ashlar laid rock, and two, during seismic events it packs even tighter.

Whenever you build you want to get your foundation, (what ever type it is,) down to a mineral soil. The concept of, “below frost line,” is rather a misnomer. Frost isn't really the issue; it is soil type that holds moisture so you can get a heaving frost, and you already know what that soil type is, CLAY. Clay, (particularly expansive clay smectite,) are the worst thing to have under your structure. Many of these clays, even without the effect of freezing, can expand enough to rip a foundation apart just by adding a little water. So don’t ever put clay under a foundation. Clay as a building material should always be kept above grade and as dry as possible, some minor wetting is fine, but do not allow it to get saturated.
steve pailet


Joined: Dec 01, 2012
Posts: 35
concrete by its nature wicks water. as does wood ... best not to let either come into direct contact so standoffs and rot resistant pads of some nature should be used.. If you have to pour concrete around a post.. do wrap the post so that again the concrete will not be in direct contact with the wood.

Something I was looking for in the comments but did not see is about grading and layering materials in a similar way to passive annually heated homes Move as much water away from the wood and concrete foundations as you can. this includes putting foam below the concrete and perming the land away from the posts so that they stay dry even when there is snow or high water table

water and wood = rot... one can never make it water proof but do your best to make it water resistant
Paddy Murphy


Joined: Feb 13, 2010
Posts: 6
Location: Carmel, ME 04419
beki gamble wrote:So the home we are building will have post and beams made from white pine that has been cured and had the bark and cambium removed. We are planning on submerging them in a stone foundation resting on a concrete footing with gravel back fill. the beams will go all the way to the footing. We were planning on using creosote where the beam will be touching stone or cement, because we will not be able to access it to re-treat it. We are hoping this will prevent rotting. the house is on top of a well drained hill and will have a very large overhanging roof. We are in NH, where it can get wet, cold, dry and hot depending on the month. I know creosote is gross, but I dont know what will work better. The plans have been approved by a building inspector.

My question is Will this be enough to prevent rot? Is there some fatal flaw I have overseen? Any suggestions?

thanks everybody.
I would be cautious of using white pine, it is a pretty soft wood that can go punky quite easily, just take a walk through a white pine forest. I would suggest investing in white cedar, which is available locally, much stronger and is more decay resistant. White Pine is not use for structural support. Your building inspector is not doing you any favors, it is not the right material for the use you are planning, use White Cedar instead and consult with the university extension service for selecting the proper materials.
Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Hello N. McCoy,

I have some reservation about Beki Gamble's general plan, but with some "tweaking" it could work fine. I must point out some misinformation in your post.

White Pine is not use for structural support...
This is plainly not a true statement and must be corrected for the betterment of this forum's general information. I am a traditional timber wright, and can assure you that White Pine is not only a structural timber, it is one of the leading timber species used in vintage traditional timber frames, as well as, contemporary timber frames and log cabin architecture. That includes the posts, beams, and all structural timber elements, when done correctly.

white cedar, which is available locally, much stronger and is more decay resistant...
Again, other than decay resistance, this comment is not accurate in any way. I will just list a Compression Parallel to the Grain Maximum Crushing Strength in psi, then provide a link for the others structural numbers. As you can see, White Pine is 840 psi stronger than White Cedar. Cedar in generally a very weak wood.

Cedar, Northern White: 3,960

Pine, Eastern white: 4,800

http://www.woodworkweb.com/woodwork-topics/wood/146-wood-strengths.html




Paddy Murphy


Joined: Feb 13, 2010
Posts: 6
Location: Carmel, ME 04419
Jay C. White Cloud wrote:Hello N. McCoy,

I have some reservation about Beki Gamble's general plan, but with some "tweaking" it could work fine. I must point out some misinformation in your post.

White Pine is not use for structural support...
This is plainly not a true statement and must be corrected for the betterment of this forum's general information. I am a traditional timber wright, and can assure you that White Pine is not only a structural timber, it is one of the leading timber species used in vintage traditional timber frames, as well as, contemporary timber frames and log cabin architecture. That includes the posts, beams, and all structural timber elements, when done correctly.

white cedar, which is available locally, much stronger and is more decay resistant...
Again, other than decay resistance, this comment is not accurate in any way. I will just list a Compression Parallel to the Grain Maximum Crushing Strength in psi, then provide a link for the others structural numbers. As you can see, White Pine is 840 psi stronger than White Cedar. Cedar in generally a very weak wood.

Cedar, Northern White: 3,960

Pine, Eastern white: 4,800

http://www.woodworkweb.com/woodwork-topics/wood/146-wood-strengths.html



I have to concede, I am not an expert in these matters, but I had looked at a USDA Plant Guide site and it had said that cedar is used for log cabins and poles, I am assuming telephone poles. Felt that cedar would be a good alternative to pine. Maybe modern day timber framing uses pine, but in the old days, chestnut is used. I know it is no longer available, there are a couple chestnut trees that are maturing to their former heights, so maybe a resistant strain is evolving and we can get our chestnut trees back.

Revisiting the pine issue, pine does poorly in wet conditions, so I still have reservations on that one. I also thought creosote was an endangered species and could not be gotten, except maybe by special permit or maybe smuggled in across the border.

Thanks for correcting my errors.

Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Hello Nitepagan,

Cedar (actually Arborvitae sometimes (called a Cypress) as we have no native Cedars in the either South or North America,) is a good choice, don't get me wrong, my house sits on many White Arborvitae posts. So it wouldn't be incorrect to use them in that way, they just aren't as strong, so should be increased in size according to structural parameters.

As for the White Pine in vintage frames, you may wish to check my links. I am a Historical Timber Wright, and make a fare share of my income working on vintage frames, (circa 1650 to 1850, and older in Asia-Europe,) Many are all White Pine. I have even found White Pine sill plates. It's much more rot resistant than folks gives it credit for, it just needs to be able to dry out, and not stay damp.

Regards,

jay
Richard Cobbs


Joined: May 18, 2012
Posts: 11
Location: Yalaguina, Nicaragua
Hi,
I'm looking for comments on wrapping posts in fiberglass and resin to prevent rot. I intend to wrap the bottom three feet and bury the post two feet deep. My thinking is that swimming pools, bathtubs, etc. are made out of fiberglass so it should work. All comments are welcomed.
Thanks,
RWC
Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Hi Richard C.,

Great concept but it does not work in real life. I have seen this concept applied at the Brookfield Zoo and one other. One use fiber glass and the other epoxy. They both became unserviceable in an accelerated time frame as the "polymers only trapped moisture in the wood and promoted fungal grow. There still has not been an improvement on traditional methods for wood below grade "Posting."

Regards,

jay
Richard Cobbs


Joined: May 18, 2012
Posts: 11
Location: Yalaguina, Nicaragua
Thanks Jay,
That explains why I never heard of it being done; nobody likes to broadcast their failures. Now to plan B. I like the stability of embedded posts and I recently made a machine that allows me to turn any size round tenon up to about 6". What I have in mind is 4" metal pipe piers set on a concrete footing and partially filled with concrete. The pipe would extend 12" minimum above ground and my post bottoms would be turned (rounded) to fit inside of the pipes. Probably keep the concrete 8" down inside the pipes and make the round tenon 6" long to separate the wood from the concrete. Also, probably a "washer" (metal plate with a four " diameter hole) so the wood has more to bear on than just the pipe. Any opinions, suggestions?.
Thanks,
RWC
Jay C. White Cloud
volunteer

Joined: Nov 05, 2012
Posts: 1400
Location: Thetford, Vermont
    
  80
Hi Richard,

Sorry to keep poking holes in your ideas, I like your inventiveness, but I guess that's why I'm here for folks, so they don't have to muddle through things. What you are describing is called (in PE language) your "moment connection." Now I am about 98% sure I have a good mental picture of your plan, and can tell you that it would probably "meet muster" but is way more convoluted than it needs to be. There are at least a 1/2 dozen other solutions that are simpler. It would really help if you could do a hand drawing or a CAD with Sketchup, but in general if you want speed and a more natural treatment just bury them with the methods I described above in this thread, (I think it was this thread?.) If burying does not appeal to you, (I try to avoid it to in most cases-not all) I would scribe to a plinth of stone, or, if you must, concrete. I have done several big job with post that over 300mm to 400mm in diameter (~12" to 18") and your steel pipe goes into them about 200mm to 300mm, and are either pinned to the pipe or glued with structural adhesive. This is just one of several methods. Hope that helps. Keep trying and asking, I'll do my best to respond.

Regards,

jay
 
I agree. Here's the link: http://permies.com/battery
 
subject: about post and beams and stone foundations -preventing rot
 
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