Building on piers/pilings?

[MushCreek]

Hey- I just stumbled onto this site- it looks like exactly the group I need to talk to! First, a little backstory- We have 7 acres of sloping property in the upstate of SC, nearly at the NC border. We have a great (seasonal) view of the Blue Ridge, and plan to start building in less than a year. Partially due to economic conditions, and partially to fulfill a life-long dream, I will be doing much of the build myself, with some help on the heavy stuff. The original plan was a 1300+ sq ft home on a full basement. The slope is just about right for a walk-out basement. As the economy drags on, and the equity in our current house continues to drop , I keep trimming the size and complexity of my design. Although it's useful space for (relatively) cheap, one thing that could go is the basement, which leads to the point of my post (yes, there is a point!)

I'm thinking about building on piers. Obviously, the ones on the uphill side will be short, and the ones in the back (downhill) will be, well, long. Depending upon the size of the house, they could be 8', or even more. How tall can I go with concrete piers, and still have a safe, stable house? I've heard 10:1, which means I could go up 10' on 12" piers. I assume that would be from ground level, not to the footer under ground. The soil is sandy clay, so it's not a horrible soil, but not an ideal one, either. The frost doesn't go deep at all there; the ground never freezes, from what I hear. Still. I think I'd want to go with a pretty deep and wide footer, so my house doesn't wind up at the bottom of the hill! Any input/experience?

Right now, I'm torn between keeping everything on one floor, or having at least a partial 2nd floor. My original plan has an upstairs, and a deck above the back porch. This deck would face the view, and the floor would be nearly 20' off of the ground. I think that would be a neat place to star gaze and enjoy an adult beverage in the evening. But the missus and I are in our mid 50's, and will be close to 60 by the time this is all done. I'm not sure whether we want stairs to deal with or not.

[glenn kangiser]

to the forum. 

Blue Ridge Mountain Sky - MTB -- (After Euro tour intro) http://www.youtube.com/watch?v=BybCWNP-Bto

Must have been about your neck of the woods.

John has a plan that includes a PT Wood basement.  Would that be a consideration?

Stairs are good exercise if you can handle them and they may even make you healthier and more fit.

[Redoverfarm]

MushCreek I would think that 12" dia concrete piers should be ample providing that you give them approximately 24-30" footings.  They should be re-enforced piers with a re-bar cage 4" from the outside with an occassional horizontal tie.  The trick to that tall of a concrete pier would be 1. making them plumb and 2. filling them.  Have you considered using flue block and placing them on a decent footings.  The block can be filled (less concrete than poured) and verticle re-bar can be added for extra support.  They would not have to be filled at one time either.  Just leave a couple pieced of re-bar sticking out of the last pour to bond to the next pieces and lay two short pieces horizontal in the mortar joint and this should bond the first pour to the second.   The only down side that if you haven't laid block before is starting off the footer to graduate 8" (7-5/8 + 3/8" mortar joint) each time to reach your desired beam level(bottom) . That would mean that your footing top be of equal spacing of 8" graduated by the desirte heigth.  In your case of 10' would be 15 blocks on the high side.

I think IMO the key to high piers would be that they are built plumb, ample footing for weight distribution and proper structure placement for weight distribution.  I am not sure what the weight of your structure would be but with a little research I think you will find that a flue block(filled) would probably work and be a little more user friendly.   

[Don_P]

One thing to consider when using piers is that they fall under the "engineering required" section of the building code. This is for a reason.  Building plumb is one thing, keeping a structure built on tall piers from leaning or toppling through its life is quite another. Either the soil is bracing the piers, which requires sinking them quite deeply into stable soil of known strength or the piers must be braced adequately by some other means. There's a school putting out some fine engineers right down the road from you, I'd certainly get some advise from one of them. The walls of a typical foundation act as panels that resist the forces that frequently cause piers to lean. That is why conventional foundations are specified as standard by building codes but pier foundations require review. SC is one of the states that requires plans be drawn by a registered design professional. Although I've seen stuff in the upcountry that makes me believe enforcement of that is pretty spotty.
I've eaten at Pumpkintown in one of its incarnations, travel 11 down that way a few times a year.

[MushCreek]

Glenn- Yeah, I've looked into wooden foundations. I found enough negative stuff to scare me away, though. SC is termite central, and the soil has just enough clay to make me wonder, especially in an unbalanced backfill situation. My original thought was to go Superior Wall, and there's a rep literally right in my neighborhood. I've read some bad press on them, too, however. Plan B was to do ICF, and I've even considered doing the whole build in ICF, but it's pretty expensive compared to stick framing. I have a friend who did a DIY ICF in TN, and it went very well for him. I'm worried about finding the right guy to pour the concrete.

Don- By 'down the road', I assume you mean Clemson? My son is graduating this year with a degree in Mechanical Engineering- close, but no cigar. I'm afraid that paying for engineering may run the cost back up. As long as I build to normal standards, Greenville County is pretty easy going. They have no plans review- all they want to know is square footage and number of bedrooms (to calculate septic load). But it does have to meet IBC 2006. Way back, when we first bought the land, I had the romantic notion of using my own trees to do a timber frame, at least for a great room. I was told that the timber had to be professionally graded- not a cheap proposition, either. My only reason for looking at pier construction is to keep costs down. I've estimated that I can DIY ICF for about the same cost as having someone do a poured foundation. That decision is a no-brainer, IF I have enough $$$ to do a foundation at all.

We own the property outright, and have maybe 50% of what we need to build right now. We're depending on the sale of our FL house to cover the rest. A couple years ago, we had enough equity to pay someone to build our new house, and have money left over! Now the whole project is in jeopardy- that's how much our house has devalued. A mortgage is out of the question- too hard to get on a DIY build, and we're too old for a mortgage anyhow- it's time to live 'rent free'.

[Don_P]

Yup I was thinking of Clemson  .
Kinda makes me wonder if their forestry and engineering dept's would gang up to design, grade and oversee an affordable project utilizing real "green" techniques  

All of the foundations you have rejected as having problems have a better track record than piers and do not need engineering to do safely.

There may be a mill nearby with a grader you can get to inspect and write a note if the inspector is agreeable. Some of ours will also accept an engineer's blessing. Short of that Timber Products and SPIB have check graders travelling through the area. It shouldn't cost more than about $500 to get a houseworth of material graded. I've had a small stack done by a mill grader for a small fraction of that before.

They tipped over and burned a ton of trees on the last road work through there, if it wasn't so far I was tempted to load my truck every time. You can of course use timber off the property for non structural uses, cabinets, panelling and trim. That's what I've mostly done since the hammer dropped here.

There is a kinda pricey antique shop up on the border, I'd have to dig for the address if you don't know what I'm talking about. We picked up some nice arts and crafts stained glass windows there, they had some nice solid oak doors and other architectural details there.

[JRR]

I think open reinforced concrete piers is a good choice for the site and building you describe.  I know about those Carolina termites.  But keep in mind that the weight of the building still has to be supported by the bearing of the foundation ... and that brings us back to soil conditions.  You need to find out what the total bearing area, in square feet, your building requires.  The total cross sections of the piers may not add up to be enough ... you may require additional footing area.  One solution could be a perimeter footing with piers growing out of it ... another solution might just be to add big "feet" to each pier.  This is where an engineer, with local knowledge, might save you some bucks and grief.  I am lucky to know a guy whose gets most of his income from large subdivision projects and charges me, a DIY'r, almost nothing to look over sketches ... over coffee at a local eatery.

You might consider slip-forming the piers ... makes it easier for the DIY'r.

[John Raabe]

Have you seen the article I did on Post and Beam foundations? http://countryplans.com/foundation/index.html

That has some general guidelines as to height. The taller you go the more cross bracing you need to include.

[MushCreek]

I'll have to do some more checking on having lumber graded. I was told it could cost $5000- but not by someone who necessarily knew what they were talking about. I have access (for free) to a bandmill, and I already have a planer and jointer, so using my own timber is not out of the question. I was already planning to mill my own flooring and maybe trim. I'm not sure I want to try stick framing with oak though. It gets pretty hard once it's dry! Any pointers on how to find someone to grade my lumber?

We went to an antique shop in Landrum that had lots of architectural stuff. Nice stuff- way out of our league, money-wise, though. Since we are on a (very) tight budget, I plan to make a lot of my own detail items. All of the internal doors will be plank construction, with wrought iron thumb latches. I'll probably start making and finishing doors here in FL long before I break ground on the new house. All of my internal doors will be 36" anyway, so all I have to do is the final fitting.

I grew up in a 200+ y/o cape in CT. In addition to the old plank doors, it had hand hewn flooring up to 14" wide. The floor was face nailed with hand forged nails, and the gaps that developed between the planks were sealed up with manila rope pounded into them. The builder and owner was a whaling captain, so that makes sense. My floor won't be quite that rustic, since I'll be KD'ing my flooring, but I am going to face nail it with forged nails from Tremont. I like the idea of an interior that you don't have to worry about every scratch and bump that comes along.

I guess I'll do some asking around about using piers, including the Building Dept. We've met twice with the head of the department, and he was very helpful and encouraging. Some parts of the country really seem to frown on DIY builders, but Greenville County was nice about it. They didn't even have a problem with DIY electric and plumbing, and the guy implied that the inspectors would be willing to offer some guidance if I ask nice.

[Don_P]

That's the shop I was thinking about, yeah I drooled and bought for my client who actually comes from down there, but I couldn't swing anything in there for myself either. Those are good idea places too though.

One thing to remember when asking an inspectors advice is he is also between a rock and a hard place. He is not allowed to design or he may be putting the county in liability danger. The same holds true for allowing ungraded lumber to slide. If he gives you bum advice and you sue, your neighbors have to pay for his mistake. The county attorney coaches these guys, especially after such a failure. Bear that in mind as you phrase inquiries, as always its a human interaction. I've found if you act like a human its appreciated and reciprocated, get into a contest and his is always yellower. I've started on a few framing jobs for owner builders where the inspector showed looking like an old bear... only to find out the culprit was a homeowner who couldn't see the inspector was just another neighbor. I can hate the system without acting hateful to a man just doing his job. I'm not lecturing you its just one of those broad sweeping generalized rants that came to mind   .

If you have a nearby mill that produces graded framing lumber and if the inspector will allow one of the mill's graders to check your lumber this may be more economical. That grader can mark the pieces and write a note, again if the inspector is agreeable. This adresses the spirit but not exactly the letter of the law, a disinterested and qualified eye has looked at your timber. He is not allowed to use in any way the mill's "stamp" off the mill premesis, but he can grade, that's the intent the code wanted.

The "correct" way is to contact one of the grading agencies and ask for them to arrange for one of the agency graders to come out and look at your timber. Last time I checked this was $60/hr including windshield time. The closest guy to me is about 1-1/2 hours away but if I'm not in a hurry he can drop by on his pop inspection rounds of the local mills, reducing the windshield time, but not convenient if you're not around. You are bound to be closer to one as you are in the yellow pine belt. I'm in the furniture hardwood belt, he comes up here to check a few log home companies but we don't have softwood framing mills.

Have a saw at the ready, he may point out a defect that drops the grade that you may be able to cut off and bump the grade... ok for 2x's maybe not as doable with timbers. Also have plenty of room, the timbers spread out, and hands to flip it, he has to see all 4 faces and you don't want to slow him down or wear him out at those wages.

This link will take you to Timber Products Inspection's contact page;
http://www.tpinspection.com/contactus.html

This link will take you to SPIB's contact page;
http://www.spib.org/contact.shtml

I'd contact both and inquire about getting a grader closeby and current costs.

The Northeast Lumber Manufacturers Association, another grading agency, has their grading rulebook online here;
http://www.nelma.org/Page-10.html
NeLma actually wrote the rules those other agencies will be using to grade your hardwoods so that book is good for your stuff.

If you decide to go this route I'd be glad to offer what help I can. I did train at Timber Products and can translate some of the obfuscation in the rulebooks.

Red Oak isn't too awful bad. There was a hickory on my barn site that I figured I might as well make studs out of. That was fun 

[MushCreek]

Thanks for the links, and the advice, Don! I've worked with inspectors before, on everything from minor projects to large additions. I always treat them with utmost respect, and never imply that I know more than they do. Being a tool maker by trade, all of my work is overbuilt, precise, and very neat. I've even gotten complements from inspectors! As annoying as it can be to deal with codes and inspectors (especially when you know what you're doing) I understand the need for them, and accept it as part of the process.