What choices are there for foundation types for houses built in the hill country of Texas?
I have heard about slabs and pier-and-post, but are there others?
What are the details of slabs? How about of pier and post?
How is termite control dealt with in the case of a wood frame floor system up on posts over piers?
Many of the hill country houses have a lot of stonework, inside and out. Does this stone cladding require footings beyond just thickened edges of the slabs?
How does one do the foundation when it is to be a raised platform pier and post, but a to-grade stone veneer is going to be wanted outside?
If you are familiar with all the stuff happening down between Austin, San Antonio, and Marble Falls, tell us about this.
Replies
what hill country???
define hill
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
Inthe Central Texas region, at the edge of the Balcones Escarpment, there is an area generally referred to as the "Hill Country". While this term may not mean much outside of TX, within the state, it is generally recognised as a beautiful semi-arid region (32" rainfall/yr) with gentle rolling hills yeilding to dramatic river and stream valleys. Elevation ranges from 550 to 2000 SL, typ 700-1200. Vegetation is a mix of (predominatly) Live Oaks and mixed hardwoods, with shrubby conifers called "Cedar" - which are actually Ashe Juniper. With regard to foundations, design and construction is a concern due to the unique geology of the area - mixed areas of high load-bearing limestone strata intermixed with clay pockets.Edward Sanborn
very informative.. thank you...
I had been to Texas and all seemed to me me as flat... very everywhere flat...
perhaps my question was because of my concept of "hills" as a result of where I live...
be and a little teasing...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
very informative.. thank you...
I had been to Texas and all seemed to me me as flat... very everywhere flat...
I think this illustrates that everything is relative. I've driven through the Texas hill country. It looked fundamentally flat to me. Yet other people there kept getting thrilled by the scenery.
still looks flat to me....
to each his own in likes and dislikes in the scenery dept...
some like the barren artic and others like downtown Burbank....
the folks in CT kept talkin' about their mountain... the peak was 75' above SL..Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I had been to Texas and all seemed to me me as flat... very everywhere flat...
In another post there was doubt about trees in TX.
I offer the following pics (no scrub brush state here):
very nice indeed...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I guess if I lived in <!----><!----><!---->Colorado<!----><!----> I would call <!----><!---->Texas<!----><!----> flat. I have been to <!----><!---->Alaska<!----><!----> and picturing <!----><!---->Texas<!----><!----> as flat with sage brush, cactus and no trees is as wrong as picturing <!----><!---->Alaska<!----><!----> as a frozen tundra. <!----><!----><!---->
Several years ago I built a hotel between <!----><!---->Antonito<!----><!----> and Platoro Colorado right on the <!----><!---->Canojes<!----> <!---->River<!----><!---->, southern border and mid state part of <!----><!---->Colorado<!----><!---->. We toured the southern portions of the state when not working. Took baths in the river. Beautiful, but the river was very cold even though it was summer.
We toured on some fire roads, no guard ralis and several thousand foot drops. It was July and passsed through some areas where the snow was as high as the 1 ton truck we were driving. We went to the state park that is a big pile of white sand....wierd in Colorado.
We went to Hooper Colorado where they had alligator tail on the menu at a small store / restaurant. I had to ask..... "Alligator?" Seems a fellow there was a fish farmer, raising and cleaning for restaurants. He had problems with disposal of fish guts. Got some alligators and the problem was solved. He now sells alligator meat. The alligators will sun themselves on the snow in winter. No kidding.
<!----><!---->
<!----> <!---->
Yeah, well, I should have given Marty directions back to Colorado through Davy Crocket Nat'l Forest, and through Ft Stockton--but that would have been a convoluted sort of trip . . .
Palo Duro is even prettier at sunup on a chill morning.
I've tried to "toob" the Guadalupe when it was running about as deep as in that photo, too <g> . . .
The "Texas Lake" picture sure looks like Possum Kingdom looking west from the escarphment on the east side of the lake. I may have to dig out some of the sunset pictures from the east side of Canyon Lake.Occupational hazard of my occupation not being around (sorry Bubba)
Yes, well my post was in interest of some misconceptions about Texas being full of scrub brush, having no trees and being flat. Seems folks get their ideas from cowboys western movies.
Seems folks get their ideas from cowboys western movies.
LoL!
There's some VN movie that opens with a scene of the CA Santa Monica mountains, but has a caption of "West of Galveston" . . .
There's a world of difference in visiting the Liberty, TX in Liberty Co., versus the one in The Train Robbers, too. (Though, the Liberty's in Coleman, or Lubbock, Cos., might . . . <G>)Occupational hazard of my occupation not being around (sorry Bubba)
and some prettyful bluebell field flowers
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
what hill country???
define hill
Google Big Bend National Park Texas
Edited 5/3/2006 7:47 pm ET by txlandlord
Edited 5/3/2006 7:50 pm ET by txlandlord
it's still flat...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Dang you ask a lot of questions.
Here in SA the ground is mostly limestone, so minimal digging is the key. Concrete slab on grade, thickened edge, probably post-tensioned cables. The stone veneer is done just like brick veneer, with a brick ledge cast into the slab.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I'll be interested to see if any custom builders in the area post or contribute, but my $0.50, based on two foundations I built in the Hill Country (San Marcos /Wimberly area) are that a variation of Pier& Beam called a "Perimeter Beam". This has worked well for me. I used footings of 24"w. x 12" high (w/ #5 rebar) perimeter beam was 12" w. x 4' high 2' below grade for first on, and 6" w. x 3' high for second. 3500 PSI concrete, centered on footing, leaving a generous shelf for future rock work if desired. Kept grade min of 10" from top of foundation on exterior to minimixe insect issues (not just termites, but scorpions) Both scenarios used minimal piers (2/3 internal piers supporting a site built girder 3 x 2x12 to handle floor joist span. (miidpoint) Use a lot of rebar in the beam, esp. when crossing clay pockets or boulders.
Historically, "traditional" foundations in the area are pier and beam, and these seem to age well, but do not mix well with masonary veneer. They also experience a lot of settling. Most common current practice I see are slabs, but these seem to leave a lot to be desired in terms of stability, with cracking due to high clay content and wild swings in soil moisture.
There are so many soil types in the "hill country" that I'd suggest that you do a soil analsys before construction. Lots of good info there that will be much cheaper than a foundation repair later. Upscale subdivisions do this as SOP.
Gene,
Most new construction in and around Austin is monolithic slab-usually a single level regardless of site topography. On the monolithic slabs, many are post tensioned and some are traditional rebar. We use rebar.
Grade beams on slabs are a function of soil. Real bad clays may have three to four foot thick grade beams. Good soil usually has a minimum of two foot thick grade beam. In both cases grade beams are one foot wide. Grade beams are generally laid out in a grid pattern based on point loads or bearing wall locations with maximum spacing of 10 to 12 feet.
To support brick and stone facades, the slab is usually extended to whatever the support needs to be-usually a 2x4 laid flat creating a 3 1/2" ledge at 1 1/2" below slab level.
We just finished a 1700 sf slab in central Austin in terrible soil with over 400 linear feet of grade beams at 3' 6" thick . My client is creating a photo documentary with his interesting dialogue of the process.
http://www.mine-control.com/zack/house
Pier and beam is common on older homes. Usually an 18" or 24" square footing at appropriate depth (12 to 16" thick) and 12" diameter pier around 3' above grade. Some folks run a perimeter beam to support brick and stone facades.
Termite control consists of metal flashing over the top of the pier.
In really bad soils and higher end homes, drilled piers to bedrock are not uncommon with a monolithic slab then supported by those piers.
I'll see if I can figure how to get some of my eningeers details posted.
Bruce
drilled piers to bedrock are not uncommon
Interesting to hear you guys mention pier & beam foundations . Down here, it's all monolithic slab, from the el-cheapo KB starter homes to million dollar places in the Dominion.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Eddie,
Some of the most expensive neighborhoods in Austin are built on really expansive clays on hillsides. My engineer designed one house where the piers were surrounded by several feet of vermiculite to allow the clays to expand without moving the piers.
The rise in drilled piers here is because most engineers do not want to risk a slighty moving slab and the third party warranty programs that cover the TRCC 10 year requirement usually want a geotechnical report and structural report. For the geotechnical engineer, if there is any question, the best way to CYA is to require drilled piers in even slightly challenging soil.
As you mentioned, pretty much everyone goes with slabs except in the more difficult soil.
Bruce
When I lived in Dallas, slabs were still the most common. And Dallas has some really nasty expansive soil. Foundation repair is a big business. If you drive in the Las Colinas area, even the roads are bad. They look like a mass of frost heaves ... but it doesn't get cold enough.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
>They look like a mass of frost heaves ... but it doesn't get cold enough.<
The only way to stop that is 24" of lime stabilization with black base on top, then RC roadway.
Wonder why nobody does LS for slabs? Maybe yer engineer would know.
Wonder why nobody does LS for slabs?
Reason one is "nobody does that 'roun' here."
Reason two is that LS is finicky work, and fussy what with a truckload of lime not being fun to get stuck in traffic in a rain shower.
Mostly reason one.
Some of those roadbeds are victims of drainage, though, not a lack of sub-grade stabilization--water will undo lots of good prepwork.Occupational hazard of my occupation not being around (sorry Bubba)
It is amazing the movement that can occur in really expansive soils. I saw a 20 year old house on a hillside. Over that period, the house moved horizontally over a foot and a half. The reference point was the broken PVC sewer line in the ground was a foot and half away from the the part in the concrete. Where was that smell coming from?? Owner didn't care-it's a rental
Bruce
in Dallas, slabs were still the most common. And Dallas has some really nasty expansive soil.
Still is--both things. The "Blackland Prarie" is named from the montmorillite clay that is the topsoil. It's fun stuff. Rock hard when dry, sticky when wet; the most "heave" by volume of any of the expanding clays.
Here's the gotcha that always confused me--there's bearing ston not that far down in a big portion of Dallas County. The Austin Chalk layer is nothing an engineer would let you anchor a commercial building to, but is more stable than the black "gumbo" sitting atop it. There's blue shale under the chalk (which is a strong, bust-the-teeth off your bucket, bearing material). So, you could drill relatively shallow (and nice, compact, non-belled) holes using a lot les concrete than a reinforced slab (especially pre or post tensioned) has to have.
My 'fave' slab fix is nothing more than a fancy T-post that is set using a gizmo like an upside-down bumper jack to drive the t-post until it hits chalk. That then "anchors" the slab (after they set a dozen or so). Or, at least anchors the edge.Occupational hazard of my occupation not being around (sorry Bubba)
Some of the most expensive neighborhoods in Austin
I copied that from your post as a starting point, but I am redirecting the topic from what you were talking about there.
I was in Austin around January 1 and looked at a few houses close to the center of town. Everything close in looked expensive, at least compared to what I am used to. 1,050 square foot houses for $300-$400,000. These were houses that appeared to have been very inexpensive places when constructed in the 1920's and 30's.
My question - is there a housing boom going on down there? The rest of the country is slowing.
Ed,
Austin has been in a housing boom for a long time now and it does not seem to be slowing down. Central Austin prices have rising rapidly. When we moved to Austin in 1991, a 1000 sf bungalow near town was $40/sf. Today that same house in need of a great deal of work is going for $200/sf and with some remodeling done, you can ask for $300/sf.
This is due to that fact that Austin's population has doubled or more in that time frame, but the city has not developed any additional transportation infrastructure to deal with the growth. For example, we lived 12 miles from downtown in 1991. My morning commute to the University took 15 minutes. In 1998, just before we moved, that same commute took a minimum of 45 minutes. I cannot imagine what it is today as I live in central austin 5 minutes to anywhere.
Bruce
Edited 5/3/2006 9:08 pm ET by Hiker
but the city has not developed any additional transportation infrastructure to deal with the growth.
That just about covers it!
Read an article about a well known Austinite that made that same comment. Said that it was Austins way to stay small, didnt work all that well for them though.
Doug
Hi,
I returned to look at your web site, but the link is now gone.
My quick looking there in January was near South Congress bit far south of the river and Travis Hts. Any pricing boom will put what was at the upper end of my range out of my range.
I thought that that city exuded such a healthy and optimistic attitude.
Ed
Sorry for the confusion. I had not been to the site in about a week. Gene Davis was hit by a trojan when he went there- so I removed the link. My apologies to Gene and anyone else who went there. I left a message for my web designer but have not heard back and we have not had power for a day and a half.
You can reach me at [email protected]
bruce
Edited 5/6/2006 10:43 am ET by Hiker
Travis Heights is one of those nearby neighborhoods that can command very high sale prices. The east side if I-35 is where some affordable housing projects are being developed, but those projects are competing with house flippers and people who want to live downtown and can afford upto $150 to $200 thousand for a home.
Bruce
is there a housing boom going on down there?
Has been for about two decades now. It's not at the "1000 per month" level the Austin/Travis Co types were quoting upto about 5 years ago. (It's possibly slowed to near "sustainable" levels, but too much of the building is by tract builders, IMO.)
The rest of the country is slowing
Depends on how you define growth, too. And location, and all sorts of things. Houston, SA, Colin County, the "mid cities" area between Dallas & Ft Worth are still chuggling along.Occupational hazard of my occupation not being around (sorry Bubba)
Down here, it's all monolithic slab, from the el-cheapo KB starter homes to million dollar places in the Dominion.
Which is dumb for a number of reasons. The tract builders won't buy anything but a stock plan, so the houses look a little silly when the lot slopes 60" in any of the dlab dimensions.
It's just got to be from a lack of local experience. We could probably find any number of folk with experience casting to ledge, so Hill Country limestone would not be so very different. (Well, after we acclimatized them to 80-90s in April-May, that is . . . <G>)Occupational hazard of my occupation not being around (sorry Bubba)
Well, after we acclimatized them to 80-90s in April-May, that is
For the concrete workers around here, 80-90 in April is cool compared to where they come from.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Over on JLC in the BS forum Alan Edwards showed the details of a building pier and beam foundation. Sometime within the last 3-6 months.
But I don't remember what part of TX he is in.
Slab foundations start at about $5 a square foot.
Pier and beam starts at about $12 a square foot.
This drives all but the high end homes to some type of slab foundation.
>Slab foundations start at about $5 a square foot.
>Pier and beam starts at about $12 a square foot.Square foot or lineal foot? Are foundations measured by sf? A 20x50 has the same sf as a 31.6x31.6. But one is 126.5 perimeter and the other is 140 and would require a different amt of material.Just curious how they're measured be/c I have a design project that's gonna be on piers.
Cloud,
Piers around here cost between $300 and $400 per pier with an allowance for 4 foot tall 12 inch diameter pier and 2'x2'x1' footing with limited excavation. Pier layout is generally on a grid of 8'x8' or 10'x10' with point load managed with addition piers.
Bruce
Gotcha...I was thinking perimeter and not whole field. Brain cramp.
Piers around here cost between $300 and $400 per pier with an allowance for 4 foot tall 12 inch diameter pier and 2'x2'x1' footing with limited excavation.
Hmm. The cost of steel will fuss with those numbers, so maybe that's what has my mental "estimates" awhirl.
Up one of the arroyos off the Colorado, we were able to just use drilled piers, no separate footing or bells, as we had a good stable limestone strata only about 3' down. Cost more to run the piers "up" to the sill elevation, really. Only one day with the drill truck, which was only $500 (but that was a decade ago, too).
I'd hate (in many Travis or Williamson County locations) to have to but square footings in first. But that may be because I've used too many engineers who preferred a cast-in-place monolithic foundation "beam" for the perimeter foundation.Occupational hazard of my occupation not being around (sorry Bubba)
I think alot of the foundation designs have been set forth by the warranty insurance companies. "Central Texas" is the only region with extensive detail as to what types of foundation are mandated, almost down to the street. Finding limestone makes better foundation opportunities, unfortunately where I do most of my work it 20 or 30 feet down.
On our current project, every house surrounding the jobsite is pier and beam, some with original cedar posts from 80 years ago. Our house has 4 tons of steel and 110 cy of concrete-go figure.
There are three I have seen in that part of the country: 1. Foundation wall with pier and beam 2. Poured cast in place piles with beams on top 3. A slab that looks like an inverted U with sand bags in the middle and concrete poured over the top to form about a 30" high wall and slab on top.
Edited 5/5/2006 12:14 pm by gb93433