# Pier foundation.



## TonyTheTiger (Jun 17, 2019)

I am planing an approximately 16x40something residential structure. Single story. I want to make three 2x2 foot piers along each side. Perimeter joists will be 2-treated 2x10s supported on the outer edge of these piers. The piers will have embedded anchor points at each pier. Block will be above the piers on top of a 4" concrete slab. Can I legally do this? And how deep will the piers have to be (just to the frost line or deeper?).


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## cda (Jun 17, 2019)

Welcome


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## cda (Jun 17, 2019)

So do you live in a city, county, state 

That requires plans and permit?


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## TonyTheTiger (Jun 17, 2019)

County. Ohio. Yes. I know. Just the code is hard to understand. I intend to well exceed code for weight, wind and snow loads, also insulation. Just 8 or 10 lor 12 larger than necessary piers (every 8 to 10 feet) would be easier for me to do than a perimeter foundation. Piers would be topped with a slab with just the anchor embedded into each pier sticking through. Anchors would be joined by steel to doubled rim joists at angles.


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## Mark K (Jun 18, 2019)

I  think you need to talk to a structural engineer.

If you find the code hard to understand then how can you have confidence that you will exceed code requirements?


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## TonyTheTiger (Jun 18, 2019)

Just trying to get opinions. Code says 4 inch wide concrete below frost line all the way around for a one story, but that doesn't seem like enough to me. Plus the piers would disturb less soil.

I also have a construction question. How do you get the forms off the footers once the concrete is set?


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## jar546 (Jun 18, 2019)

Lots of questions.  Let's start with the load bearing capacity of the soil you will be building on.  What is it?  Did you have soil testing done for load bearing capacity at the level of frost depth?  Are you near a body of water where you may need pilings?  How about the flood plain elevation?  What flood zone are you in?  What is the snow load of you area as you have to include that into the loads imposed on your piers?
There is a reason I am asking these questions.  The codes are not here to make things difficult for you, they are here to make sure your home does not sink into the ground or get blown over or have cracking on the walls every time the wind blows.  It is about safety for you or the next chump that buys your house in the future.
As stated by Mark K above, you need an engineer as what you are doing is outside the prescriptive codes.


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## tmurray (Jun 18, 2019)

Mark K said:


> If you find the code hard to understand then how can you have confidence that you will exceed code requirements?



Exactly my thoughts every time I hear this.


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## ICE (Jun 18, 2019)

jar546 said:


> Lots of questions.  Let's start with the load bearing capacity of the soil you will be building on.  What is it?  Did you have soil testing done for load bearing capacity at the level of frost depth?  Are you near a body of water where you may need pilings?  How about the flood plain elevation?  What flood zone are you in?  What is the snow load of you area as you have to include that into the loads imposed on your piers?
> There is a reason I am asking these questions.  The codes are not here to make things difficult for you, they are here to make sure your home does not sink into the ground or get blown over or have cracking on the walls every time the wind blows.  It is about safety for you or the next chump that buys your house in the future.
> As stated by Mark K above, you need an engineer as what you are doing is outside the prescriptive codes.



Golly Jeff, all he really wanted to know is how to remove the form boards.


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## cda (Jun 18, 2019)

TonyTheTiger said:


> Just trying to get opinions. Code says 4 inch wide concrete below frost line all the way around for a one story, but that doesn't seem like enough to me. Plus the piers would disturb less soil.
> 
> I also have a construction question. How do you get the forms off the footers once the concrete is set?




Not into concrete

Form release??


Or a big hammer?

https://www.homedepot.com/p/Kleen-K...orrosion-Coating-Spray-Bottle-30820/206965027


https://www.homedepot.com/p/11-1-2-lb-Compo-Cast-Soft-Face-Sledge-Hammer-57-554/203757918


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## steveray (Jun 18, 2019)

R602.10.9 Braced wall panel support. Braced wall panel
support shall be provided as follows:
1. Cantilevered floor joists complying with Section
R502.3.3 shall be permitted to support braced wall
panels.
2. Raised floor system post or pier foundations supporting
braced wall panels shall be designed in
accordance with accepted engineering practice.


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## tmurray (Jun 18, 2019)

ICE said:


> Golly Jeff, all he really wanted to know is how to remove the form boards.



I'm not sure what the question even is. I mean there is form board oil that helps, but other than that, jump in the trench with hammers and pry bars...


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## Rick18071 (Jun 18, 2019)




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## TonyTheTiger (Jun 18, 2019)

3000 lb per sq ft. Not in flood plain. Ground was dry at 3 ft. (Frost line is 30 inches). I don't know how to calculate weight of house, but it's small at 16x40. I would guess less than 50 tons. So in theory that would be 33.33 sq ft of pier so. 2x2 I would need 9 of them. Round it up to 10. 4 on each long side and 3 on each short side. Well within code span for doubled 2x10 too.

I guess it wasn't as hard as I thought...


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## TonyTheTiger (Jun 18, 2019)

tmurray said:


> I'm not sure what the question even is. I mean there is form board oil that helps, but other than that, jump in the trench with hammers and pry bars...



So that would mean a much wider trench than actually needed. I think I'd rather do the piers. I can auger the holes.


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## TonyTheTiger (Jun 18, 2019)

steveray said:


> R602.10.9 Braced wall panel support. Braced wall panel
> support shall be provided as follows:
> 1. Cantilevered floor joists complying with Section
> R502.3.3 shall be permitted to support braced wall
> ...



The piers won't be the ONLY thing supporting the walls, they'll just be the only part that extends to below the frost line.

I was planning on pouring the piers to 4" above ground level, then preparing the center part (compacted gravel with vapor barrier on top) and pouring a 4" slab (leaving openings for utilities). From there it will be enough block to make an adequate sized crawl space all the way around, and he house on top. Each pier will have a steel anchor embedded in it.


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## TonyTheTiger (Jun 18, 2019)

Nothing will be cantilevered.


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## TonyTheTiger (Jun 18, 2019)

Just asking opinions before paying an engineer. If I can get close, I'll only have to pay him once


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## cda (Jun 18, 2019)

I saw this on a build off the grid Alaska show


https://www.technometalpost.com/en-US/advantages/helical-piers/


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## Mark K (Jun 18, 2019)

A recipe for disaster.  A 4" slab on grade resting on piers??   No building official should issue a permit for this idea.

Don't believe that you can protect him from what he "knows" will work.


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## jar546 (Jun 18, 2019)

Mark K said:


> A recipe for disaster.  A 4" slab on grade resting on piers??   No building official should issue a permit for this idea.
> 
> Don't believe that you can protect him from what he "knows" will work.



Part of me believes we are just getting trolled because this design is so bad.  You know what.  Let him build it without engineering if there is no code enforcement and see what happens.


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## ICE (Jun 19, 2019)

jar546 said:


> Part of me believes we are just getting trolled because this design is so bad.  You know what.  Let him build it without engineering if there is no code enforcement and see what happens.


I got the same feeling when he asked how to remove form boards.  In another thread he's shooting for R-70 attic insulation.


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## tmurray (Jun 19, 2019)

TonyTheTiger said:


> So that would mean a much wider trench than actually needed. I think I'd rather do the piers. I can auger the holes.


It's probably cheaper to build on a code prescriptive frost wall than to build a engineered slab on engineered piers. 

The reason that the code has prescriptive ways to do things is that is the typical construction technique in the field. It is the typical construction technique in the field because it is the cheapest.


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## rktect 1 (Jun 19, 2019)

Seriously?  A 16'x40' residential structure with a total of six piers and the beams are double 2x10's?

Stop designing and hire a professional before someone gets hurt.


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## ADAguy (Jun 20, 2019)

He is only proposing to address the perimeter, what of the interior supports? No interior walls? Under slab membrane? 
Watching too much DIY.


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## TonyTheTiger (Jun 20, 2019)

Mark K said:


> A recipe for disaster.  A 4" slab on grade resting on piers??   No building official should issue a permit for this idea.
> 
> Don't believe that you can protect him from what he "knows" will work.


I don't "know". That's why I ask.

The slab is not going to be bearing any weight of the house, nor will it be supported by the piers. It's to fill in the area under the house to create a clean crawlspace. That's all. It will be properly vented for radon abatement (a big deal in this area).

One of my goals is ease of access for maintenance. I even designed the closet placement and wall panel removability for access to the shower plumbing without having to tear out a wall, as well as convenient plumbing and wiring runs. 

I believe I have a good idea for a small home for a single person, a retired couple, or a "mother-in-law" suite etc. It will be efficiently insulated, nicely, comfortably, and conveniently accessorized, and legally movable if necessary, but not a "mobile home" or "tiny house". I will be combining new technology with old. A semi-open floor plan using old ways of engineering for airflow purposes. No back door, but an egress window in the sleeping area. Storage areas fit in between traditional appliances and bathroom fixtures. Large bathroom with laundry. 

Meeting every applicable code and exceeding most for sturdiness and longevity is my intent.


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## TonyTheTiger (Jun 20, 2019)

2x8 will span 15' on 16 inch centers. My Max joist span will be 14'6". Plus in heavy areas I plan on 12" centers. Ten piers, not 6. Max span on perimeter will be 7'6" on the ends and 8' on the sides. Well within code for a single 2x10, let alone doubled..


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## TonyTheTiger (Jun 20, 2019)

The only interior wall will be to the bathroom in back. 7' deep. That area will have 12" on center joists.

The sleeping area will be a partial wall.


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## TonyTheTiger (Jun 20, 2019)

I was guessing 24" of cellulose. Don't think that's quite R70


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## TonyTheTiger (Jun 20, 2019)

cda said:


> I saw this on a build off the grid Alaska show
> 
> 
> https://www.technometalpost.com/en-US/advantages/helical-piers/



Interesting, but without digging a hole, how do you know the load bearing capacity of the soil?


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## TonyTheTiger (Jun 20, 2019)

TonyTheTiger said:


> I was guessing 24" of cellulose. Don't think that's quite R70


Oh, I guess it is. I read something wrong.


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## TonyTheTiger (Jun 20, 2019)

cda said:


> I saw this on a build off the grid Alaska show
> 
> 
> https://www.technometalpost.com/en-US/advantages/helical-piers/


And I found this for exterior walls.

Structural Insulated Panels | SIP Panels | Insulation Panels | EZ SIPS https://structuralinsulatedpanels.com/


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## TonyTheTiger (Jun 20, 2019)

ADAguy said:


> He is only proposing to address the perimeter, what of the interior supports? No interior walls? Under slab membrane?
> Watching too much DIY.


Inside length of joists will be 14'6". No need for interior bracing.

And 16' is the maximum withh. Insulation, siding and all, to meet transport requirements. 40 is the length including front deck. Living area will be 34 or so, whatever the stud spacing works out to.


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