I have decided to make several "roundwood" post and beam structures, or at least using raw log posts as supports, but I can't figure out how to anchor them to the ground. I live in the mountains of TN and it is very moist here, so I am worried about moisture from concrete or stone seeping up into the logs via concrete piers and I plan on doing a few for porch posts outside. Any suggestions on anchoring?
My ideas were:
1. building a high concrete pier and running at least 3 piece of rebar up through the post a foot or so, but its still sitting on concrete. Maybe putting tar shingles between the concrete and wood? Steel plates between them?
2. Then I saw the 2nd and 3rd pictures below and thought about using knife plates or brackets. I want to do a couple supports that have angles like the 2nd picture, so a bracket of some sort seems necessary, but I know they are incredibly pricey and hard to find. Know where I can find them? And I don't feel like just rebar is strong enough to brace such large posts (12-20" in diameter)
3. My other concern is I have plenty of yellow pines on my property and was going to use those as the beams, but would they be too soft to use as posts, even if I coated them with boat varnish or (god forbid) treat them with nasty stuff? And I didn't know if mixing harder wood for posts and softer wood for beams would work. I might be able to find some black locusts, and I know that would solve my problems, but it would be easier to use other wood like Oak, and I would like to eventually be able to show others in my area that we can use local wood. Black locust is getting rather rare here.
Any ideas would be very helpful. I plan on getting Ben Law's book "Roundwood Timber Framing," but from what I have read he doesn't address anchoring in a vey detailed way or concerns of moisture seeping into the posts much.. and I didnt see any info on outside porch supports at all.
I would really like these structures to last a while so anyone with experience working with large wood who has any advice at all would be helpful.
Joined: Feb 02, 2011
Location: Cowichan Valley, Vancouver Island, Canada
I own the book "Building Green" by Clarke Snell and Tim Callahan. They go step by step through the construction of a guest cottage that incorporates four styles of building, one on each wall (cordwood, cob, straw bale, and conventional stick frame). Their cottage has round trees as supports for the roof in the four corners, and they go into great detail about how they put them in. They did use a piece of rebar, as you described, but lots of other stuff to keep out moisture, termites, etc. You might find it very helpful. Probably find it at your library (I did; liked it so much I bought the book).
Joined: Nov 05, 2012
Location: Northern California
I wholeheartedly endorse the "Building Green" book for answers to this question.
we built our timber frame structure out of round wood (peeled redwood) and have them sitting on concrete footings, bolted in with "L" brackets. I also put tar paper on the bottom, and we varnished them. of the 15, only 3 are inside the house. well, there's a 4th that hold up the loft, made from a Madrone tree. you can see the sort of work we did on our blog. Here's a relevant page: http://journeyinthewoods.blogspot.com/2008/10/still-pegging-brackets.html
Also loved Clark's books. I built a pole barn with a mix of woods and used binding wire to lash them together, all set on concrete piers. Large roof overhang keeps the posts quite dry. Boat builders use Pinetar for sealing seams. Also built a woodworking studio using Japanese joinery, also with 3' overhangs, post on rock or ledge. All in all, I've built 4 buildings with 3' roof overhangs, and more over entry doors. I make certain the roofs won't come off, and the feet are not in any water. Next building will also have a large roof. Also, see Christopher Alexander's books A Pattern Language, and The Timeless Way of Building. One thing I found out is how easy it is to get bark of a log when the sap is running in about June here in Vermont!
Joined: Nov 30, 2012
Location: Weston, Colorado
I'm building a post and beam with log infill from my land. I did, however, get the logs for the posts from Heartwood log homes when they closed their place out here in Colorado. These are Eastern white pine and about 12". The infill are my Ponderosa and Engleman Spruce and I have a few Douglas Fir for beams and interior supports. My guide is"The Craft of Modular Post & Beam" by James Mitchell - building log & timber homes affordably. Good Luck.
Home is where the hard work ends and the heart's work begins.
I've been building a roundwood henge framed home over the past couple summers. I did use a Behr's product for the stain and have not regretted it at all. All the wall caps are spiked into the uprights with massive nails then spiked to the following wall cap. The uprights are 'pegged' onto rebar set into the concrete footing below. The eves are 4' in hopes keeping moisture well away. I plan to bolster the joint with some kind of steel plate I fasteners. Here's some pix...
Using soft woods for post and beams has been used for centuries. Here in the northeast popular, bass, tulip, all soft wood were more used then pine(soft wood). I think any wood as ling as it's strong and sound can be used as long as y keep the weather and moister away
a couple of simple thoughts.. tar paper yes.. layered poly...consider this as the same material used foamed material for sill plates (why re invent the wheel) ... 2x treated wood sandwiched with tar paper between the concrete and the post. one really does not have to go up more than a foot into the base of the beam with your anchor rod.. it is there to keep the post from shifting.. and the thought of aurgoring three feet into the center of a post is daunting...
In some areas code will require that you also have a tie down strap.. so do keep that in mind if there is an aesthetics conflict
5/8 rebar is really all you need it is there to locate the bottom of the post .. remember you have a huge point load and with that much weight its not going to move unless you plan on running a bulldozer into the foundation
Joined: Nov 02, 2011
Location: Asheville NC
Posts need to be tied to the foundation to prevent uplift. Almost all buildings will experience high winds at some point and even heavy assemblies can experience damage from wind uplift. Its also very important in earthquake events.
Wood should never touch ground and best practice would not let untreated wood touch ANY masonry. Treated wood will last longer if it does not touch masonry and can dry out after getting wet.
Rebar or Threaded rod is fine if done right. Be sure to use some type of metal (1/4" thick at least) or plastic to get the bottom of the post off the masonry. Epoxy can be used for the wood connection to eliminate the holes you get with the strap style hold downs.
The bigger the overhangs the better.
"If you want to save the environment, build a city worth living in." - Wendell Berry
The Asians have been scribing wood to stone for thousands of years. The structures last hundreds of years and in some cases thousands. If done correctly wood can touch masonry.
Joined: Nov 02, 2011
Location: Asheville NC
Love those pics Jay. Do they have tricks for getting such a tight fit? I suppose the "if done correctly" would involve the proper management of moisture and water. Of course wood can touch masonry if the masonry if is not exposed to much water or moisture. I have to wonder about the longevity of some of those applications though..
Jay C. White Cloud
Joined: Nov 05, 2012
Do they have tricks for getting such a tight fit?
The timber framing of Asian is much more advanced, in many ways, than you find in the West. Center line layoff, templates and advanced scribing techniques have been practiced for thousands of years, well in advance of what was being done in Europe.
I suppose the "if done correctly" would involve the proper management of moisture and water.
You nailed it! It's all about the water. You can have it, but you have to deal with it in harmony with the material you build with. That is why so many of our historical structures have started to fail. We add things like concrete, foundations and "chinking," and the rot sets in. We have spent the last 70 years trying to reinvent the wheels of "good building practice," and have made more of a mess than a better wheel.
Of course wood can touch masonry if the masonry if is not exposed to much water or moisture. I have to wonder about the longevity of some of those applications though..
If done by a "Diaku" 大工 (master design/builder) or their equivalent, a naturally built structures on stone can have virtually endless life spans. If you just built one, using the old methods, and did nothing, (minus some major war, fire, seismic or climate event,) the structure would stand several centuries in livable condition, before becoming unsafe and melting back into the earth.
Joined: May 18, 2012
Location: Yalaguina, Nicaragua
I'm building in Nicaragua and plan on using round wood. I built a tenoner out of pipe and a 4" Harbor Freight grinder with a 4" wood blade. I can make round tenons from 3/4" to 6" with my $60.00 machine. I intend to bury my posts 2' in the ground and will wrap the bottom three feet in two layers of fiberglass and resin. Has anybody done this? Any comments?
Joined: Dec 16, 2012
I have built chikee(tiki) huts for around 10 yr in southern Florida. All with the poles into the ground. My experience with this is that eventually they all rot. We wrapped in roofing material, soaked in preserving materials, even concrete. The one that have lasted the longest(7-10yrs) were the treated telephone poles with concrete around them. Hope that helps in any way.
Jay C. White Cloud
Joined: Nov 05, 2012
I have built both traditional Chickee and Palapa, and if done properly, (ie. correct "posting", wood selection and treatment, and proper backfill methods with proper "drip line" design) they should not rot for a minimum of 20 years, and can go over one hundred if the structure is traditionally built and maintained.
Joined: Dec 08, 2014
Location: Acworth, New Hampshire
Gary Crays wrote:I have decided to make several "roundwood" post and beam structures, or at least using raw log posts as supports, but I can't figure out how to anchor them to the ground. I live in the mountains of TN and it is very moist here, so I am worried about moisture from concrete or stone seeping up into the logs via concrete piers and I plan on doing a few for porch posts outside. Any suggestions on anchoring?
I think that any anchor you decide on will work for you. Just keep the wood off the dirt and don't allow water to get to it and the wood should last more than a lifetime. If it makes you feel better, use some boiled linseed oil on it. Be careful to read the MSDS on BLO....some of it is not truly BLO and contains icky chemical dryers.
2 cents from a permies forum newbie.
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subject: Anyone have experience with Roundwood or "whole tree" timber framing?