One possible PSP plan

Hello Mike,

I guess I am blessed in some respects in that I live in an area that has no building codes, and only one local town even requires a building permit. It's not extensively wet here, average precipitation is between 30 and 40 inches a year. We have gently rolling hills comprised of a thin layer of topsoil and a heavy red clay. The problem that I see with this clay is that it tends to swell a lot with fluctuations in moisture. Many a basement around here has had to be reinforced because of buckling over time, and cinder block foundations are largely taboo due to its short life in this soil.

Around here we have a lot of oak, hickory, walnut, locust, red cedar, maple, elm, and poplar.

That said I have researched your methods extensively. My wife recently purchased the workshop DVD set for me and that has given me a great deal of insight into the method as well...

What I have come up with is sort of a mixture. I don't want to bury in a hillside as they tend to move a lot more than typical slopes and in the spring thaw, often there is no bottom to the mud...

My thoughts was more of what you describe in the $50 and up underground house construction book as a Ridge house. My thought is basically PSP construction back to back, north and south built on TOP of the existing ground (with allowances for water drainage in all directions) and berming up a mixture of sand and gravel around it (as this would not swell and cause the heaving issues that we here are familiar with in subsoil) and provide the necessary drainage. Cover that with a layer of poly, stretched out almost to the perimeter of the entire site (ensuring a large umbrella of relatively dry soil), and bury in a layer of topsoil as a growing medium.

I don't have access to cutoffs from a sawmill as these typically get sold for firewood (mostly hardwood) around here. My thought was mill two sides of the relatively small trees (8" average) that are on the lot that I'm looking to build on and build what basically would amount to log home construction. Is there a particular pitfall for that type of construction? Should I still look at setting posts in the perimeter as well as the center of spans? I would think that the weight distribution over the whole wall versus a few specific posts would be beneficial, but was concerned about needing traditional "footings" (or at least some rocks or something) The other issue that came to mind was the possibility of uneven settlement of the posts in the center of the spans. Possibly this would require a rather large pier, as in the case of the house that you mentioned in one of your videos that was built in sand.

By and large the structure that I have designed is very traditionally shaped with allowances for the appropriate runoff using your methods. Since I don't have an uphill and downhill I'm less tied to direction and I find it easier (at least from the design standpoint) to balance light and ventilation flow.

My wife and I have 6 children, so this allows us to use what is available to us and invest our time in a house, and not a lot of money. My family largely lives on a 4 generation farm, so I have access to a lot of equipment and tools that the normal owner-builder would not.

At any rate, if any of these ideas of mine throw up any flags, please let me know. I'm interested to read what you have to say.

Nicholas, Princeton MO

I would think appropriatly installed piers/footings under the posts should aleviate any uneven settling and would be a relatively cheap insurance on the overall integrity of the building. other than that is sounds great. some of the benefits of psp without some of the problems. this would be a hybrid i could live with.

Your concept sounds good to me. You are wise to be concerned about expansive clay. Don't build into it, or if you do use vertical crawl spaces. Yes, on an above ground structure, even one bermed, I think you will need footings that go below the frost level. As for the question of posts near the walls on the log structure you will have to ask a structural engineer which I am not.

Do you have any recommendations for figuring the span between posts?

the book "low cost pole building construction" has tables for how far apart to set posts.

if rafters as carried by a pair of girders (2)
posts set.....
8' apart use 2x6's
10' apart use2x8's
12' apart use 2x10's
14' apart use 2x14's or 3x 10's
16' apart use 3x12's

if using a single girder
post set.....
8' apart use 2x10's
10' apart use 2x12's
12' apart use 2x14's or 3x12's
14' apart use 3x14's
16' apart use 4x14's

hope this helps!

Would there be any drawbacks of putting the poles near the perimeter? 

Quittrack, what are you using for your walls?

Im planning on using stacked logs typical of log home construction.. I figure that holds back a lot more pressure and distributes the weight on the perimeter a little better... Plus I just like the look. I'm sure it has it's down sides but in this case I would be using what's available from the site itself. What grows there is primarily white and burr oak, and some shagbark hickory.

Wow!  I hadn't thought of that!  Pretty cool!  The inside would end up looking like a log cabin!

I read an article about the New Madrid Earthquakes of 1811 - 1812 which was estimated to have been an 8.0 quake. A large part of the population in that area lived in log homes hewn from the native trees. However, the town of New Madrid (for which the fault and earthquake are named) was a "modern" town at the time containing stick built and post and beam structures which collapsed. But by and large the log homes withstood the quakes very well, some shifting on their foundations, and a few near the epicenter actually shook apart. The quakes occurred in dec/jan and a large part of the population wasn't put out by collapsing homes as they likely would in such a scenario now days.

That bit of info really spoke to me as to the strength of log construction, plus the look and feel that it has are really appealing to me.

I see what you mean now.  That is pretty cool.  A lot more logs than Mike's PSP, but neat.  A lot of structural benefits too.  I saw this log cabin in Cle Elum a few weeks back.  They had carved grooves in the bottom of each horizontal log so it rested on the one beneath it.  It made for less, a lot less chinking.  Of course, it is more work at the time, but it would save you from re-chinking every year. 

That is similar to what I was planning... I was planning on milling the top and bottom sides of the log off so that they will sit relatively flush and chinking would be minimal anyway.

Logs are shoring as much as milled lumber, Steve. Posts would still be used in the interior of the house in the middle sections to support the weight of the roof. A log EI house would still be PSP.

I see.  So is shoring anything that would make the wall?  Would you use the posts on near the inner walls too?

I believe that I likely will, in order to keep the walls somewhat "true."

Im thinking at least toward the center of walls, where pressure from the earth is greatest, and the logs are most likely to distort and push in.