House foundation question-Updated

[Kenneth Brown]

Hope to be starting the house real soon but still in the question stages. First off its gonna be built on piers. I have one company that wants to do 15" diameter, 15 FEET deep, with a 30" bell at the bottom. I have another that wants to do 9" or 12" diameter, 4 feet deep, with probably a 20-24" bell. The first company wants about $14,000. The second company is only about $1,000. While I don't want a cheap house I do want an INEXPENSIVE one. Thats a lot of difference. Second company says there is no need to do the deep drill. He's a home builder that is local to the area and has been building homes here for at least 20 years. What do ya think?

 

[SS MAYFLOAT]

Re: House foundation question

Re: House foundation question

KB do you have a codes/permits? They are the ones that I go by around here. If you don't do as they say, they can make you take everything down. I know some places don't require it and this maybe your case.

I would ask the second contractor for some references on jobs that he has done. Then go check out his work and ask the occupants if they are satisfied.

I have to say the the first contractor seems to be a bit overboard on depth as well. Could depend a lot on your subsurface. Is it single story and how far up is it going to sit off the ground. If your in a hurricane zone, maybe the first contractor does have the right plan. Lots of ifs involved as you know. Keep asking them questions,,,,,,,Good Luck............SS

 

[Kenneth Brown]

Re: House foundation question

Re: House foundation question

Two story house, 1800 sqft of living area, total of 3000 sqft when you include the porch. No chance of hurricanes here. County doesn't car what you build or who does it, no permits at all. Initial plans are for it to be about 2 1/2'-3' of pier and then the first floor starting. It'll be up in the air a little.

 

[KRS]

Re: House foundation question

Re: House foundation question

gotta be well below the frost line... or your piers will be moving.

 

[Kenneth Brown]

Re: House foundation question

Re: House foundation question

Thats only about 3" or so.

 

[Bob_VT]

Re: House foundation question

Re: House foundation question

I would judge the depth on the soil conditions. Do things settle and move? Is it flat? Sand? Drainage? Groundwater? All those are factors and if it shifts your walls could crack and doors stick. Keep checking around and see how deep other builders are going.

 

[SS MAYFLOAT]

Re: House foundation question

Re: House foundation question

KB, with that said, check those reference and /houses of the lowest bidder. I would opt for the 12" vs the 9" since you will be having 2 floors. Then there can be the question of how many and where the placement is. With them being smaller, more maybe needed than the 1st contractors. The bigger/deeper piers could mean less of number of piers.

Not much is built on piers around here. I think it is one of those code/permit things. Your lucky that you don't have to worry about them. Still you should stay within normal building practices to make your house strong and secure.

Edit: forgot to mention, make sure there is rebar in those piers plus the fiberglass fibers in the mix adds strength as well.

Best of Luck to ya Ken, you gotta a long way ahead of you yet!

 

[beezee28]

Re: House foundation question

Re: House foundation question

When I relevel my pier house about 2 years ago, the company did a 8' deep 12" dia with a 24" bell at the end of the hole (column). Then he used engineering block to go on top of this foundation post and jack up the beam and shim it to level. I presume that all the concrete post is going to load bearing and my opinion is that you go with the bigger column.

 

[jtexas]

Re: House foundation question

Re: House foundation question

as the owner of my very own shifting foundation, all I can say is...GO DEEP, KENNETH

or at least get an independant engineering assessment (should be around $300)

 

[tommays]

Re: House foundation question

Re: House foundation question

im moveing i gotta get a permit for a darn yard shed


Tommays

 

[aspeck]

Re: House foundation question

Re: House foundation question

I agree tommays! If ya want to inflate one of those inflatable pools, you need a permit! Build a playhouse for your daughter - get a permit! Build a porch - get a permit!

That said, deeper and bigger will always be safer and more stable. It would be interesting to hear the rational that each individual contractor had for their recommendation. Are they basing it on sound engineering, or "that is the way we do it around here and it seems to work."? Pay the extra for the engineering and get it done right the first time, so you don't have to go back and straighten everything out in a few years.

 

[Kenneth Brown]

Re: House foundation question

Re: House foundation question

The deep one is engineered, maybe thats why it costs so damn much. The other contractor is true to the statement of thats the way we have always done it. My current house, circa 1957, sits on blocks. It moves with every rain. I leveled it 4 times the first year. After that I learned to deal with it. Most of my doors are trapizodial (sp?) cuz we trimmed the edges so they would open and close all year. Yep, it hoovers. I'm looking to see what other builders think is necc. Thanks for this installment of "This old house"

 

[ED21]

Re: House foundation question

Re: House foundation question

The way to do it is to calculate the loads on the piers & then determine the bearing capacity of the soil. Then you should know if the piers can support the house. Adjust depth & size as required.
How far out of the ground makes a difference too.
An engineer can easily calclaute.
Be sure to leave room under the house for a proper crawl space. Without looking up the code, 3' is about right.

 

[rottenray6402]

Re: House foundation question

Re: House foundation question

I used to build a bunch of decks to put sunrooms on and the rule is to always go below frost line. Most movement of piers comes from water being under the pier and freezing. Once in awhile if we were in a soggy area we would have a danger of them sinking. The variables involved have been brought up already in your thread. Type of soil, drainage, how far they extend out of the ground, temperatures you expect, all things that may make it worth while to hire an engineer in your area. Good luck! These will be the best of times and the worst of times!

 

[JRJ]

Re: House foundation question

Re: House foundation question

Do the raised foundations typically have a concrete or block perimeter in your area? Grade the dirt for drainage and make a drain under the perimeter if needed. I like lots of "headroom" under the house and lights are a simple and easy option when you're building. What are you planning for stringers and subfloor? Enjoy the project.

 

[Kenneth Brown]

Re: House foundation question

Re: House foundation question

Very few new houses in the area have raised foundations, most are slab. The ones that I have seen raised are generally on a poured footing with blocks. I'm not real comfortable with that right now. Subfloor will be 3/4 t&g plywood. The stringers/joist are still undecided. I would prefer to use 2X10 or 12 for the first floor. I also have the engineered beam specs and the corresponding product numbers from Boise. They say they are just as strong or stronger than solid wood but I'm still stuck in the old days, I just really like a solid piece versus a 1X2 with 1/2" OSB inside it.

 

[KRS]

Re: House foundation question

Re: House foundation question

If frost isn't an issue, then I'd do a floating solid concrete pad, with a little downturn at the edge.

 

[PAMedley]

Re: House foundation question

Re: House foundation question

If I were you, I would have a Registered Professional Structural Engineer obtain a soil evaluation of you building site and determine whether you need to have piers. You may not even need them. If you do, the PE will design and specify your piers. As a retired general contractor with 40+ years of experience, I assure the PE's fee will be "money well spent". Soil condition determines whether piers are needed or not. Your house is only as good as the foundation under it is!