- My Forums
- Tiger Rant
- LSU Recruiting
- SEC Rant
- Saints Talk
- Pelicans Talk
- More Sports Board
- Fantasy Sports
- Golf Board
- Soccer Board
- O-T Lounge
- Tech Board
- Home/Garden Board
- Outdoor Board
- Health/Fitness Board
- Movie/TV Board
- Book Board
- Music Board
- Political Talk
- Money Talk
- Fark Board
- Gaming Board
- Travel Board
- Food/Drink Board
- Ticket Exchange
- TD Help Board
Customize My Forums- View All Forums
- Show Left Links
- Topic Sort Options
- Trending Topics
- Recent Topics
- Active Topics
Started By
Message
re: conventional vs post tension slabs?
Posted on 3/14/14 at 10:33 pm to soccerfüt
Posted on 3/14/14 at 10:33 pm to soccerfüt
Conventional steel is reinforcing from Day One, a PT slab has no active reinforcement until the stressing is done, normally after a week or so.
Comparing a PT and conventional slab both done half-assed, the conventional wins every time. If there is any problem with any part of the PT slab, the entire slab is compromised and no engineer would stand behind it or authorize a repair. This is not necessarily true with conventional reinforced slabs. They can be patched or cut and repaired. This is very difficult to do on a PT. house slab.
Risk:Reward? Conventional is easily worth a premium of 5-10%.
Comparing a PT and conventional slab both done half-assed, the conventional wins every time. If there is any problem with any part of the PT slab, the entire slab is compromised and no engineer would stand behind it or authorize a repair. This is not necessarily true with conventional reinforced slabs. They can be patched or cut and repaired. This is very difficult to do on a PT. house slab.
Risk:Reward? Conventional is easily worth a premium of 5-10%.
This post was edited on 3/14/14 at 10:36 pm
0
Posted on 3/15/14 at 7:42 am to vettegc
quote:
re: conventional vs post tension slabs? (Posted on 3/14/14 at 10:10 pm to urinetrouble) quote: Post-tensioned done properly should not be cheaper than conventional. Why? Here are my numbers from the quotes Conventional material quote(wire,rebar)-$4000 Concrete 160 yds * $92/yd = $14,720 Total = $18,720 Post tention material+eng(cables)-$4,800 Concrete 140 yds * $92/yd = $12,880 Total = $17,680
You do not have sales tax figured on your concrete pricing nor do you have labor for concrete placement in your analysis, fwiw.
Posted on 3/15/14 at 11:23 am to 4LSU2
quote:
You do not have sales tax figured on your concrete pricing nor do you have labor for concrete placement in your analysis, fwiw.
You are right about the sales tax on the concrete. So The labor price on the form and finish will be the same. PT will end up being about $2000 cheaper overall.
I want to know who has seen foundation issues with PT. Dont just say its overkill or you dont trust it.
Posted on 3/15/14 at 3:58 pm to vettegc
(Puts hand up in air)
One bad concrete load ruins entire slab.
You can't cheaply effect a fix, it's a system which has to have no defects.
Poorly consolidated concrete around PT anchors.
PT cables missing, misplaced, misrouted, cut or otherwise compromised.
Huge full-depth cracks in slab occurring before stressing. Does stressing "heal" them? I wouldn't want a slab like that.
It isn't enough difference between them to risk the lesser quality option. We have 150 years+ of conventional slab history to look back on; how does PT age? Not well if chlorides are present in the concrete.
Ask WalMart's Construction division what they think of PT.
One bad concrete load ruins entire slab.
You can't cheaply effect a fix, it's a system which has to have no defects.
Poorly consolidated concrete around PT anchors.
PT cables missing, misplaced, misrouted, cut or otherwise compromised.
Huge full-depth cracks in slab occurring before stressing. Does stressing "heal" them? I wouldn't want a slab like that.
It isn't enough difference between them to risk the lesser quality option. We have 150 years+ of conventional slab history to look back on; how does PT age? Not well if chlorides are present in the concrete.
Ask WalMart's Construction division what they think of PT.
Posted on 3/16/14 at 9:39 am to soccerfüt
quote:
PT cables missing, misplaced, misrouted, cut or otherwise compromised.
Isn't this one of the reasons why there pre-pour inspections are done?
Posted on 3/16/14 at 9:45 am to urinetrouble
quote:
However, that being said, ensuring a properly compacted subgrade and avoiding expansive soils are more critical in most cases.
Avoiding expansive soils is a pretty difficult task to do here in Louisiana, but residential PT slabs are still very common regardless. I would think the most critical thing to do is for the owner to spend the money to have a soils test done to confirm the sub-surface conditions and provide the results to the engineer so he can design a site-specific foundation system accordingly. Having this information will decrease the chances of having foundation issues down the road.
Posted on 3/16/14 at 8:56 pm to TigerDeBaiter
You can work the estimates, but every PT slab I have done has been over dug. Another poster hit it on the head, but reading further it needs to be said again. What works on paper, generally 12" wide footings for PT, rarely happens in real life. The footing will be 14"-16". Surface cracking in res. construction is part of life. The cost of keeping cracks to a minimum is too high. That said I would still do PT if the clay was very fat and expansive.
Posted on 3/16/14 at 9:15 pm to Libertariantiger
If you want the slab dug to the proper size then you have to be there bitching and measuring.
Also, good luck getting the concrete to achieve the correct slump. Most residential crews will not work with a low slump mix.
Also, good luck getting the concrete to achieve the correct slump. Most residential crews will not work with a low slump mix.
Posted on 3/16/14 at 10:15 pm to eng08
Upgrading the concrete mix to a mix design which is designed for a higher slump is better than bitching at one's finishers for placing too high slump concrete.
The cost of an upgrade to add a high-range water reducing chemical to the concrete mix is usually only around $4-$5 per cubic yard. This will allow your foundation crew to be as stupid as is the usual norm on pour day and not compromise the concrete strength or workability.
The cost of an upgrade to add a high-range water reducing chemical to the concrete mix is usually only around $4-$5 per cubic yard. This will allow your foundation crew to be as stupid as is the usual norm on pour day and not compromise the concrete strength or workability.
Posted on 3/16/14 at 10:17 pm to vettegc
I built a home in 03 and asked the PT company a lot of questions. One was about commercial slabs that they had done in the past. They had done none and conventional has a great track record. just my two cents.
Posted on 3/17/14 at 12:36 pm to Roscoe
quote:
Avoiding expansive soils is a pretty difficult task to do here in Louisiana, but residential PT slabs are still very common regardless.
Not really, considering the vast majority of houses don't have problems with expansive soil.
There are known places where it has been a problem, like along Highland Road in Baton Rouge (especially near CCLA), lots of places on the Northshore, and the Jennings/Crowley area, for example.
Page 2 of 2
Popular
Back to top
Follow TigerDroppings for LSU Football News