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General => General Forum => Topic started by: ShellyShelly on January 14, 2005, 06:01:33 PM

Title: Which foundation type?
Post by: ShellyShelly on January 14, 2005, 06:01:33 PM
I am considering building the Victoria's cottage in WA along the Columbia River gorge. How do I decide which type of foundation would be most suitable? The slab is appealing for stained concrete but it seems to be less practical as far as utilities? What is the least expensive?
THANKS!
Title: Re: Which foundation type?
Post by: John Raabe on January 15, 2005, 12:17:11 PM
If you have a stable flat site with well drained soil (low clay level) then the least expensive floor/foundation will usually be a slab on grade.

You are right about the utilities as they must be carefully placed by the plumber and perhaps the electrician prior to the floor pour. So this type of floor is not one for an inexperienced non-builder. You need to sub it out to experienced professionals.

The crawlspace option gets the wood floor up in the air and makes the utilities much less critical in their placement. If you plan to do your own framing then this may be the less money out of pocket solution.
Title: Re: Which foundation type?
Post by: jonsey/downunder on January 15, 2005, 08:39:35 PM
I would agree with John on the need for experienced professionals. Working with large areas of concrete requires experience and the plumbing and electrical penetrations do need to be placed with care. Having said this, not all of these need to be routed through the floor. With careful planning, you may be able to pop some of them directly through the timber framing to the outside.
If you are reasonably handy you my also be able to do your own formwork and steel placement, saving a bit on labor.
Here is a link to a slab system that is in common use here in Australia and NZ, I am sure there will be similar systems in the US.  
http://www.hunterpodsupplies.com.au/about.htm
I used a modified version of this under my laundry and carport. A great slab for highly reactive soils. (Link to my page is in the side bar) look under carport.
Jonesy
Title: Re: Which foundation type?
Post by: glenn kangiser on January 15, 2005, 10:01:50 PM
That waffle pod system is interesting.  I haven't seen it here but I work mostly with commercial stuff.  I did see them use solid foam in a few places and have worked on a couple ICF jobs..

Another way to give yourself some room to play with an on grade slab especially for tub or shower drains is to put a box full of sand about 1/2 inch below the top of the concrete with the pipe stubbed out below it. Pour your concrete.  Do your framing -break out the thin concrete over the sand filled box, get exact measurements then cut the pipe - put in your traps etc.  When done wrap the pipes and  grout the hole in as desired.  

Aquapex crosslinked polyethelene tubing can be brought up through the slab or pulled through the studs llike Romex so is another alternative.  It is not approved in all areas but is the best- it is good for hot and cold water and is guaranteed for 25 years in a certified installation.

Glenn
Title: Re: Which foundation type?
Post by: Lady_Novice on January 15, 2005, 10:55:07 PM
FWIW, John wrote an article about the "post" (wood) or "pier" (concrete) type of foundation (see the countryplans.com home page for the link) and he includes it as one of the foundation choices in the 20x30 plan (and most likely the other plans).

For my future small home, I'll most likely be doing the pier version of this foundation. It strikes me as being the most owner-builder-friendly type of foundation and most likely the least expensive, so I'm glad to find up-to-date information about it.

At first I was going to do the "post" (wood) version, as working with wood seemed easier than working with concrete. But a friend said that he thought the resale value of my home might be less with a post foundation (as wood is not commonly used as foundation material), so I'll likely go with the "pier" (concrete) version. (My friend also thought that even pressure-treated wood would be too affected by moisture and movement underground, but I think he just wasn't familiar with wood as a foundation material. I thought his concern about resale value could possibly be valid, though, just because potential buyers might not be familiar with it.)

You mention concrete flooring. For thermal mass, I want concrete or tile flooring. I'd prefer concrete (no grouting as with tile), which would go over a wood subfloor (which of course will sit atop the concrete pier foundation). So I'm searching for a simple owner-builder-friendly method of pouring a self-leveling colored concrete floor over a wood subfloor. Maybe I'm being optimistic that such a method could exist. I'll report back if I can figure this out.
Lady Novice




Title: Re: Which foundation type?
Post by: Amanda_931 on January 16, 2005, 07:08:28 AM
Concrete over wood?  Not for me.  

Extra work.  If your concrete floor is going to be thick--and HEAVY--enough to give you the benefits of thermal mass it will need a lot of reinforcing--Joists, beams, girders, and piers.  

A (ceramic) tile floor over subfloor sounds a lot more reasonable, give a bit of thermal storage.

A concrete (or earthen--more DIY but don't wear your outdoor shoes inside--I've heard of brick over sand as well) floor is great.   Thermal mass is good.   But maybe not a couple of feet up in the air.
Title: Re: Which foundation type?
Post by: JRR on January 16, 2005, 08:24:19 AM
OK, I'm going to let a small "cat out of the bag".

I have recently finished "pouring" a 2 1/4" thick slab atop wooden joists with no sub-flooring.  This slab is 8' above the basement floor below.  I developed a method of moveable forms and poured the floor in "strips"... after the concete cured for a week, the forms were moved and another strip poured.....this process is necessary to control the slab thickness and the precise placement of steel reinforcement webs.   In my case I chose to place two layers (webs) of reinforcing mats... spaced 1 1/4" apart. There is several inches of overlap of reinforcing web at the joints between strips.  PEXwOB tubing was included... but has not been put to use yet.

I have been, up to now, very pleased with the results.   The floor is approx 16' x 20' with a stairwell included.   It is very stiff (nat freq > 20 cps) and feels very secure.  

This was a first-time experiment and I had no other person's experience to build upon.   I know of no literature that treats this specific subject.  

Since there is yet no reference literature or data.... I can only advise the non-engineer to stay away!!   Keep in mind that concrete weighs 150 lbs per cu ft.  Amanda is correct in all of the concerns she posted... and there are many more.
Title: Re: Which foundation type?
Post by: Amanda_931 on January 16, 2005, 08:36:08 AM
 ;)

Why did I think somebody would say that, JRR?
Title: Re: Which foundation type?
Post by: Lady_Novice on January 16, 2005, 04:00:49 PM
Thanks to JRR for sharing the concrete flooring experience. I should have clarified that I was referring to a "thin" concrete floor that would be essentially similar to a tile floor (less than half-inch thick), but just without grouting. I would also want to end up with a polished (easily cleanable), colored surface like tile, not a rough (difficult to clean) surface like regular concrete. It may not have been a feasible or cost-effective idea (for example, if I would have to hire a concrete polisher/stainer or something).

I guess I had thought that I could get a worthwhile amount of thermal mass from a thin concrete (or tile) floor. But if the amount of thermal mass would be negligible, then I might as well just put down some pine wood planking (as planned for my loft floor above) and forget about concrete or tile.

Sorry, I hope this has not been a diversion from the original poster's question about concrete flooring/slabs. Hoping she was interested in thermal mass issues and whether you can still get a concrete floor even without a slab.
Lady Novice
Title: Re: Which foundation type?
Post by: shelly on January 16, 2005, 07:42:50 PM
Thanks to everyone for the insights, all were very helpful! I was wondering, as well, if a layer of cement could be a possibility. Not having any building experience, it appears a difficult undertaking.
Title: Re: Which foundation type?
Post by: glenn kangiser on January 16, 2005, 11:36:31 PM
Hi Shelly,

Sounds to me like you just want to try some concrete :)

Here is a link to the old forum light duty concrete floor discussion:
http://www.countryplans.com/bbs/messages/7258.html

This is a floor from Ken Kern's book that was developed in India.  It is 1" thick over 1/2 " of sand.  One top the sand is burlap or jute erosion control netting -they called for two 1/2 inch layers of concrete over the netting.  This was over about 8" of loose soil with a crowbar driven down to solid soil and the holes filled with cement before the top layers were put on. the holes made supports every 3' to solid ground.  I did it on 2' centers.  It made a great floor with no problems.  The edges will be a bit soft for the first couple weeks.

Conventional concrete slabs for houses are usually 3 1/2" to 4 " thick with at least perimeter footings.  You would need an experienced crew of probably 4 to 6 people, trowels, tamps, floats,edgers and a troweling machine to pour a house slab in one day.  I would think the best you could do is assist with the labor starting out.  Cement work has to be done fairly fast and right, because in a few hours you will have what you are going to have to live with for 40  years-- or as I had to do one time - call the demolition crew and remove it and start over - but that's no fun.

To get your feet wet, find a place you would like a small slab or sidewalk. etc.  Even do something 2'x2' if  you like.  Nail some 2 x 4s together to make a form and make a Test slab. Get  a couple bags of concrete mix, a wheelbarrow hoe and shovel for mixing and have fun.  It should be fairly thick but workable.  Too much water makes weak concrete.  Get concrete mix- bag cement does not have rock.  If you like it you can get bulk later. A straight board longer than the width of the forms is used to rod it off - or knock the top down level with the forms.  An edger makes rounded corners on your slab.  A wood float smooths the cement and opens the pores so it will dry faster and helps to work out the bumps.  Try to do everything while it is wet and re-do it as it dries.  After it is set it is too late and gets real hard to do.  

If you get a chance try to watch a concrete crew pouring a slab.  Possibly a local contractor will let you watch.  You can learn a lot just by observing.

Quickcrete publishes a book about do it yourself concrete projects.  Here is a link to it.
http://www.quikrete.com/diy/howto.asp

Also check the links section of this board or go through their site for tons of free info.
Title: Re: Which foundation type?
Post by: jonsey/downunder on January 17, 2005, 01:01:37 AM
Here is another possible solution, still not cheap, but if time is not a problem you could do this as you can afford it.
You have probably done some research on staining concrete so you will no doubt be familiar with concrete counter tops. You Build a form from 3/4-in.-thick melamine-coated particleboard about 2' sq and make up your own pavers. I would suggest they be about 1" thick. If you vibrate the concrete well there should be no need to polish . Of course you will still have to beef up the supporting structure, but you will save on having specialists for the concrete work.  You could make a couple and see if it will work out for you. By taking this approach you get to perfect the art of working with concrete without it costing you a fortune. It will still be costly but it may be a way for you to have what you want. Get friendly with some of your local concrete workers they will often have small amounts of concrete left over on their jobs. If you have some moulds ready they may fill them for you.
You bed these slabs the same as you would tiles, I would suggest you use something like Hardibacker 500 instead of timber underneath.
jonesy
Title: Re: Which foundation type?
Post by: JRR on January 17, 2005, 05:19:52 AM
Lady_Novice
Now that I understand your idea, don't let me discourage you.  In fact, I've had the same thoughts....on top of standard subflooring, with all the usual preparation for installing a traditional wire reinforced mortar bed and tile....install the metal lath and mortar....just don't install the tile ....and add a bit more mortar thickness.   Don't know why that wouldn't work.   The challenge would seem to be controlling the surface to be flat and level.  But with today's laser level gadgets, it may be doable.

Understand, I've never laid a piece of tile in my life... but its in my plans.  
Title: Re: Which foundation type?
Post by: John Raabe on January 17, 2005, 04:48:43 PM
I don't know how common it is everywhere, but we often pour concrete on wood floors for radiant heating systems. For most houses the builder just adds an additional plate for the 1 1/2" thickness of the slab. The slab can be Gypcrete (lighter weight and self leveling) or standard concrete (adds thermal mass and can be stained, dyed, scored or whatever to be a finished floor).

This house http://www.countryplans.com/bjork/ has concrete floors on both the main and upper floors. This is a traditional house as you can see so the floors are wood, carpet and tile over the slabs.
Title: Re: Which foundation type?
Post by: J.C. on January 18, 2005, 09:04:26 AM
Quote
I don't know common it is everywhere, but we often pour concrete on wood floors for radiant heating systems. For most houses the builder just adds an additional plate for the 1 1/2" thickness of the slab. The slab can be Gypcrete (lighter weight and self leveling) or standard concrete (adds thermal mass and can be stained, dyed, scored or whatever to be a finished floor).

This house http://www.countryplans.com/bjork/ has concrete floors on both the main and upper floors. This is a traditional house as you can see so the floors are wood, carpet and tile over the slabs.


Is there a plan available for that garage?
Title: Re: Which foundation type?
Post by: John Raabe on January 18, 2005, 02:35:31 PM
No there isn't but it is not a bad idea!

Thanks, John
Title: Re: Which foundation type?
Post by: ShellyShelly on January 18, 2005, 08:06:38 PM
Thanks all! Great ideas!  ;D

The NZ pod method looks interesting and somehow "easier". I did not find an American company that deals with this in my search. Does anyone know if it has and can be used in the states? Jonesy did a creative substitution! Great to recycle those tires and use less concrete!!

Do the country house plans have details on radiant floor heating? Which is better for radiant floor heat, the slab or a concrete layer over the wood.....for cost and efficacy?

Well, I am off to play with some concrete! Shelly
Title: Re: Which foundation type?
Post by: Bart_Cubbins on January 18, 2005, 09:12:24 PM
Fine Homebuilding's More Small Houses has a couple of houses with concrete floors. With one floor, boards were used to divide the floor into squares of managable size. The boards, which were left in place, also served as leveling screeds and to control cracking. The result was a very attractive floor, though it might not meet the easily-cleanable criteria.

Bart

Title: Re: Which foundation type?
Post by: John Raabe on January 19, 2005, 07:07:05 AM
Shelly:

My plans do not spec out specific heating systems. However, any house plan can be set up for radiant floors by adding a plate to the walls and checking the joists for the type of concrete used.

The cost trade-off and other issues have to be addressed locally by finding a good installer with local experience. Your climate, fuel costs, etc. come into play here. In most cases, if you can build slab on grade and treat the slab for a finished floor, that will be the most cost effective.

Radiant floor heat is more expensive than most other options. I tell my custom home clients (who are not building their own houses, for the most part) that the entry fee is $5,000 to 10,000.

What you get for that money is spoiled! The warmth and comfort is very even, quiet and invisible. Nobody ever builds their next house with a furnace.
Title: Re: Which foundation type?
Post by: glenn kangiser on January 19, 2005, 10:46:36 PM
About the floor over wood- I did the floor in the underground bedroom over wood with soil cement 3 inches thick.  The mix was clay only as dug from the ground (my clay is hard with claystone and rocks- fairly non-expansive) -no added sand - 10 % cement -this also greatly decreases my shrinkage in the clay (from about 5% to about 2% and makes the clay water resistant).  It won't wash away and makes the clay set up in about 1 hour instead of 2 weeks to dry.  It is still a little soft without the added sand, but is easily repaired.  I added 5 handfuls of straw for reinforcement to each 10 shovels of clay.  Near the door I set local slate into the floor.  I have 3/4 inch sawn lumber over joists on 2' centers.  I find that the  soil cement floors have a nice warm ancient look even if they are fairly new.  We use concrete cure and seal to harden the surface and give it a shine.  Pledge polish will give it a quick new shine although there are better things to use I'm sure- it's what we had at the time.
Title: Re: Which foundation type?
Post by: Lady_Novice on January 19, 2005, 11:38:20 PM
Thanks to everyone for adding to my knowledge about concrete and concrete flooring possibilities.

Always looking for the "E-Z" solution, I was intrigued by John's mention of "gypcrete" due to the magic words "self-leveling." It sounds to me like some sort of underlayment product, but could I color it and use it as actual flooring (and then polish it to get a cleanable surface)? Or is it too soft to be flooring? Would it be just about as durable as tile? Would it provide less thermal mass than tile? Does it look decent?
Lady Novice
Title: Re: Which foundation type?
Post by: John Raabe on January 20, 2005, 11:31:01 AM
I am only familiar with the light duty Gypcrete that is used as an underlayment and needs to be covered. It adds a little thermal mass.

However, while searching for a link I found there are more options than I knew about.

http://www.durexcoverings.com/gypcrete.htm

Some of the higher density mixes could well be colored or stained and might do fine as a finish floor.

PS - About thermal mass. If you have sun to store or just want a thermal flywheel effect in the house, the best thermal mass is a thinner layer spread more evenly as opposed to a big pile sitting somewhere. Thus the first 2" of a concrete slab do much more work moderating the temperature than do the next 2" or the 2" below that.
Title: Re: Which foundation type?
Post by: Lady_Novice on January 30, 2005, 04:28:21 PM
Thanks to John for the durexcoverings.com link. It was interesting and it will give me another avenue for researching this. My eventual goal will be to find a self-leveling substance that could be a DIY finish (top) floor (plus easily colored and polished). Wishful thinking, perhaps.
Lady Novice
Title: Re: Which foundation type?
Post by: Don Fletcher on October 22, 2005, 01:27:21 PM
I would think that seismic considerations would be part of the decision process, as would any potential subsidance. (Might you have to re-level the structure for less than perfectly stable ground).

Wood allows for re-leveling, and will tolerate more seismic activity.  If it is covered with stucco inside and out, wood can remain draft free and at the same time have a bit of thermal mass.

However, in our region we can not put wood structures within one foot of the ground because of carpenter ants.  

As a consequence we have a slab on grade, but with a tamped gravel base, and concrete walls insulated on the outside with SM blue insulation, backfilled to one foot below the floor with granular fill.

We solved the problem of putting the pipes under the slab on grade by not doing it for anything but the main DWV to the toilets.  We put a single greywater entrance into the main (10 cm).

We ran cold water pipes along the floor to the sinks, shower, washing machine, and a 2 gallon electric heater at each of those destination points.

As our house is passive solar, and earth embanked, pipes on the surface have no freezing problem even with no auxiliary heating.  We have recorded our temperature for 26 years, amd with wind and outside temps of -25C our inside temp has never dropped below +9C.

We have no seismic activity greater than Richter 3.6.

Ours was an experiment in poverty driven design. We maxed out our debt at $15,000, but that did not include our farm land.      
Title: Re: Which foundation type?
Post by: glenn kangiser on October 22, 2005, 06:28:48 PM
Sounds like it was an interesting project, Don.  Now we have Aquapex so through the wall plumbing or under the slab is easier.

What area are you in, Don?

Much of the construction around central California is on grade slabs with all house plumbing under the slab.  Waste lines going through the slab have to be wrapped with insulation or cardboard  etc. to keep the concrete from grabbing the pipes and stressing or breaking them.
Title: Re: Which foundation type?
Post by: Amanda_931 on October 22, 2005, 06:31:02 PM
Some of the thermal mass people would disagree about the thickness of the mass.  I think you're right for fairly conventional construction.  

But I know a house built with no insulation and slipformed concrete, sunk into a hill, from most perspectives way too much south facing glass, etc.

You really can't cool that place down to 48 degrees F--somewhere in the 9 degrees C range) and pop it back to reasonable without a sweater temperature in an hour and a half if you have feet of thermal mass all cooled down.  On the other hand it would take a good while to get that far down if you had, for instance, a green house with a blower that puts anything over 80 degrees F--a bit over 25 degrees C--into the house, nearly solid window walls on the south side (except for that greenhouse.  

The people with that house believe that extensive thermal mass is the only only only way to go, and their house is quite comfortable in the winter, not bad in the summer with minimal air conditioning, and the pergola in front of all those windows covered with vines and awnings.   (People who've had retinal tears in their eyes--or oncoming cataracts--are not going to be terribly happy there, but not for reasons of temperature.)

Ianto Evans says that cob would be terrible house to have if you're wanting to come in once a month for a ski weekend and the only possible windows are on the North side in the Northern Hemisphere, and you were expecting the house to be comfortable without outside heat.  Or if the only windows were on the  South side in Tierra del Fuego--but he doesn't say that.
Title: Re: Which foundation type?
Post by: Lady_Novice on October 22, 2005, 07:49:49 PM
Seeing that this thread was active again, I had to report on my experience with my foundation since I last posted.

I'm in cold country with a south-facing lot, so I decided to get thermal mass with a slab foundation.

John and others are right that a slab foundation is best handled by professionals. Besides the extra expense this entails, if you're in a booming building area like mine, good professionals are difficult to find. With a slab foundation this problem is compounded because the work of each professional (in my case, the foundation contractor, the in-ground plumber, and the excavator) has to be coordinated with the others, and each may have to come out two, three, or more times to complete various steps in the process. Because they're so dang busy, with each separate step in the process, you are on the phone begging each professional to now please come and perform this or that step in the process and you may wait a long time for the completion of each step.

So, believe it or not, it has taken three months just to get a slab and utilities in. The snow is about to start falling here, but I can't start framing until just one more thing, the final slab pour, is done. But my highly recommended foundation contractor is dragging his heels again, probably busy with more important clients. I've been leaving him messages for two weeks, and he's been completely ignoring my calls. He did this with the other steps, too, so I think he plans to follow through and complete the final pour, but he can't be bothered to let me know if or when he might do it. I wasn't planning to frame in the snow, but that's now a given.

(Actually, my experience with him has been much better than my experience with the plumber, so I'll give him some credit.) :-)

So if I were to ever build another home, I wouldn't do a slab, or I would hire a general contractor to handle it (in which case, the additional expense of using a G/C could in itself make it a lot more costly than other foundation types?).

In short, I can see the value of do-it-yourself building techniques (such as the concrete or wood post foundation that John has detailed). I have really disliked being dependent on these professionals as I'm under the impression that owner-builders (i.e., people who can't offer them repeat business like a general contractor) are their lower-priority clients?? But I'm guessing here.

But that's another thread, one that I thought about starting, called "Experiences with Subcontractors."
Thanks for listening,
Lady Novice
P.S. If you're a subcontractor, I hope I didn't sound as if I'm generalizing about professionals. I believe my experiences have been unique? I'm easy to work with and very understanding if a subcontractor is under time pressure, but I just wanted them to return my calls, which usually didn't happen without incredible persistence.
Title: Re: Which foundation type?
Post by: Amanda_931 on October 23, 2005, 04:54:33 PM
People around here are notorious for not showing up.

Maybe the worst of them was a guy who underbid the job so much that he really couldn't afford to bring his equipment in unless he had a job across the street.

Nice guy, probably trying to save me money, but....  Three years later that project, which should have been a half hour job, still hasn't been done.

and I admit to doing a bit of badmouthing.  Especially trying to suggest that if the subcontractor underbids by too much, it will never get done.
Title: Re: Which foundation type?
Post by: Billy Bob on October 23, 2005, 05:59:56 PM

Then there's the middle of the road, where you get someone who knows concrete work, and you provide the bullwork.
Last slab foundation I worked on (about fifteen years ago) was for a thiry foot square shop.  Three of us took about five hours to pour, screed, and float the thing.  The guy who ran the power trowel spent another couple of hours, and a couple of hours getting a nice edge and setting anchor bolts after pulling the forms.
For the bathroom, we used a variation on glenn's technique by stubbing the drain for the john into a piece of sonotube.  I guess we could have poured concrete in the hole after getting the final placement of the drain, but we just stuffed some scrap insulation in the hole and nailed a half sheet of PT plywood over it for a floor.

It's nice to have a friend/neighbor who knows how to do this stuff (AND owns a power trowel ;))
The other two of us had some experience, and with a pro to direct, it went well.  In addition to the concrete and reinforcement, it cost $100 and a case of Heineken for the professional help.
(The previous job I was one of the guys got the c note and Heineken; is that the going rate or something? ;D)
Title: Re: Which foundation type?
Post by: pforden on November 05, 2005, 02:01:04 PM
Hello, All,
We've just joined because we love the Grandfather's house -- my son is a wheelchair user and this plan is so disability friendly.
We are building in central Texas. We have a couple of soil types, both sandy loam and deep sand. We understand there is some clay under each, maybe as deep as 48 " or more under the deep sand. The soil survey site says that both of these soil types in this area are fine for building houses without basements.

Any ideas of which would be preferable for building upon? and which foundation we should use?

Thanks.

Penny and Allen
Title: Re: Which foundation type?
Post by: glenn kangiser on November 05, 2005, 03:06:33 PM
Hi Penny and Alan.

I am going to copy this to the plans support section since it looks like you are planning on using Johns plans.  You can get there by clicking on Design Build Forum above the choosing plans support.

I will put it under Grandfather's House question.  John checks there regularly for his plan purchaser support.
Title: Re: Which foundation type?
Post by: Okie_Bob on November 08, 2005, 01:52:49 AM
Welcome Penny and Allen! Hope you enjoy this forum, there are so many helpful, friendly people on this site. Glen and Jonsey too!

I've just built in East Central Tx, actually about 30 miles east of Corsicana on Cedar Creek Lake. I built a 24 X 50 garage on a slab floor. I too have the sand/clay problem we all have in Tx. As I've heard said, there are only two types of slabs in TX, those that are cracked and those that are going to crack! I figured I'd be smart and start with a 24" deep X 24" wide footing with enough steel in it  that it would never crack, the poured a 6" slab again with way more steel than recommended.  And YEP, within 3 months I had a crack!
I just don't believe there is anything you can do to guarantee a slab around here won't crack at some point. Drout or deludge, clay is going to contract and expand and concrete just won't hold up forever. But, you can usually live with it, if you want a slab foundation.
PS: I'll bet there are more foundation repair companies in TX than the rest of the world combined!
Okie Bob
Title: Re: Which foundation type?
Post by: keyholefarmhouse on November 08, 2005, 03:59:47 AM
Can't you first put down crushed gravel, or get it below frost line.  I live up in the cold north country and have decided to use a full basement, with the floor below the frostline (four feet) for this very reason.  We also have big clay issues.  A lot of people use floating slabs.  But then our problem might be much worse than in TX.
Title: Re: Which foundation type?
Post by: glenn kangiser on November 08, 2005, 06:51:22 AM
Me and Jonesy too----humpf---- :-/  Then there's the normal ones.   I get it, Bob.   ----------Thanks for the compliment. ;D

If you guys weren't getting so rich down there in Texas pumping all that oil out from under your ground, you wouldn't have the subsidence and your slabs would stay together. ;D

Actually you can do anything you want and it doesn't do much but minimize chances of cracking.  If it wants to crack it will.  You won't find one contractor who will guarantee no cracks.  As you say - with proper reinforcing they don't go anywhere or bother anything.
Title: Re: Which foundation type?
Post by: pforden on November 08, 2005, 07:10:44 AM
Hey, Bob,
Thanks for letting us know how you dealt with this. I am sure a lot of steel goes a long way! I note that virtually every construction in the area is pier and beam, but we have not talked to people who've built recently in the area. There are a lot of engineered foundations, some miles to the southeast, but we are not going to get into that!

We spent a long time finding sandy soil that should be okay for a building without a basement. Where we are has buildable sand down at least 48 inches on parts of the property. But we are going to dig down to the clay if we can to see what we are really dealing with.

We'll keep you all updated. Thanks again.
Penny


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Welcome Penny and Allen! Hope you enjoy this forum, there are so many helpful, friendly people on this site. Glen and Jonsey too!

I've just built in East Central Tx, actually about 30 miles east of Corsicana on Cedar Creek Lake. I built a 24 X 50 garage on a slab floor. I too have the sand/clay problem we all have in Tx. As I've heard said, there are only two types of slabs in TX, those that are cracked and those that are going to crack! I figured I'd be smart and start with a 24" deep X 24" wide footing with enough steel in it  that it would never crack, the poured a 6" slab again with way more steel than recommended.  And YEP, within 3 months I had a crack!
I just don't believe there is anything you can do to guarantee a slab around here won't crack at some point. Drout or deludge, clay is going to contract and expand and concrete just won't hold up forever. But, you can usually live with it, if you want a slab foundation.
PS: I'll bet there are more foundation repair companies in TX than the rest of the world combined!
Okie Bob

Title: Re: Which foundation type?
Post by: glenn kangiser on November 08, 2005, 07:20:50 AM
I built on bad clay once - the engineer had me put a deep footing around it like Bob's and raise it above the surrounding area --about 2' of compacted fill. 12" wide by about 30" deep footing to seal surface runoff from getting under the slab clay and expanding it.

That building was about 60' x 120' if I remember right.  No major problems over the last 25 years or so.

You can also add fibermesh to the concrete now as additional reinforcement or even in place of some of the steel in many cases.
Title: Re: Which foundation type?
Post by: tjm73 on November 08, 2005, 10:36:35 AM
Many years ago now my parents had a small incredibly old bathroom removed from their house to redesign it along with a kitchen remodel.  It was always cold in this bathroom.  ALWAYS.  Liek 15-20 degrees colder.

Their was a concrete shower.  Yes it was concrete.  The contractor brought in his young helper who tried to take it out with sledge hammer.  HA!!  It laughed at them.  In the end they had a jack hammer in the bathroom as the entire room (about 5.5'x6') was setup on top of about a 4" thick concrete slab over wood.  The house is built on 10" diameter trees (it's like 200 years old and the trees still have some bark on them) so weight wasn't the issue.  Kinda funny looking back.  Took them a full day to get that concrete out.  Then they had to build a proper floor and go up from their.  that was unexpected.