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Building a new shop with attached house - Done.

Post Tensioned Concrete

Don Baer said:
on the signoff for the inspector, they have a place to be signed off about the slab being "'Post Tensioned", what in the Sam hill is that??:confused:
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Sorry I missed this earlier, Don. Frank's description of post tensioned (PT) concrete pretty much sums it up. In most PT slab on grade applications, there are cables running in a grid pattern throughout the slab and foundation. The grid is usually made up of squares about 3' or 4' in size. After the concrete cures a while and reaches a good percentage of its strength, the cables are tightened with a hydraulic jack, and locked into position under tension.

My dad was one of the first engineers in New Mexico to spec PT slabs for residential uses, and it's a great slab/foundation system in sandy soils that have settlement potential. I'd imagine there are a number of houses in the Phoenix area with PT slabs underneath them.

I've inspected PT slabs on commercial multi-story buildings, and installed a few miles of cable for residental slabs myself. It's been a lot of years since I did any, but as I recall, the cables are tightened to somewhere around 60,000 to 80,000 pounds of tension. They can be real exciting when one end happens to get loose. On one office building I was inspecting, a cable came loose on the fourth floor during the tensioning operation, and it shot 70' to 80' of 5/8" steel cable, with about 75 pounds of hydraulic jack and pump attached, across a busy 6-lane arterial street in Albuquerque. I'd imagine PT slabs will be a real adventure to remove 50 to 100 years from now.
 
Thanks Vaughn, for the explaination. I drove by today to see if they have started frameing. The roof trusses are on site but no sticks for the framing. I was hoping that they'd have the framing done by Turkey day but I don't think they'll make it. I guess they're letting the cement cure before starting the framing.
 
Don Baer said:
...I guess they're letting the cement cure before starting the framing.
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Don, Don, Don. :rolleyes: The framing goes on concrete. The cement is just the powder in the concrete. :D At least you didn't say "let the cement dry". That would have been several extra demerits. :laugh2:

Having a concrete (and cement) expert for a dad, I had the correct terminology beaten into me at a young age. I got in trouble in first grade for correcting the teacher when she started talking about "cement sidewalks". Dad just couldn't bring himself to discipline me for that one. (He had plenty of other opportunities to discipline me, though.) :eek:
 
Vaughn, I'm right with you on the concrete thing. I grew up in a redi-mix company. Family thing. Grandad owned it with 2 then 1 partner. Grandma was the head book keeper, Dad was the plant mangager, and Mom worked keeping books when my brother and I were at school. It still twists a little screw to hear it called cement, but I know people call it what they learned to call it growing up, so I try not to make a big deal out of it, any more. :D Jim.
 
cement/concrete all I know is I'vemixed my share. In my last neighborhood we, the neighbors went out and bought a cement/concrete mixer. I personally mixed several yards of that stuff. In one instance my son and I poured a sidewalk that was 4' wide and 70 ft long. I mixed and poured a lot of cement/concrete both at my house and helping my neighbors. I will not do it again. that is one task I will leave to others. What ever you call it, it's work.
 
Don Baer said:
...What ever you call it, it's work.
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Boy, that's the truth. I've poured and finished a bit myself, and know how hard it is. Having watched tens, if not hundreds of thousands of cubic yards get placed and finished as an inspector, I have lots of respect for the guys that do that stuff every day for a living. ;)

BTW, good to see the progress on your shop and house. :thumb: Keep them pics coming.
 
Don Baer said:
cement/concrete all I know is I'vemixed my share. In my last neighborhood we, the neighbors went out and bought a cement/concrete mixer. I personally mixed several yards of that stuff. In one instance my son and I poured a sidewalk that was 4' wide and 70 ft long. I mixed and poured a lot of cement/concrete both at my house and helping my neighbors. I will not do it again. that is one task I will leave to others. What ever you call it, it's work.
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Work. Boy you got that right.
Ever pour a 40x64 floor INSIDE a building? Now thats some real fun:(

I poured my shop floor in three sections.
I had every concrete friend I ever knew over here helping out.:D
I think about half of them abandoned me afterwards:eek: :huh: :eek:

Ever try to get a 12" tall concrete truck in a 10.5 tall door opening?
That was fun, and another story all by itself:huh:
 
No pictures this week. I drove by and the framers were there sorting though the lumber seperating the streight boards and going over the blue prints so it looks like they'll start framing on Monday. Boy thats a lot of lumber for a 700 sq.ft. shop/garage with attached 3000 sq.ft. attached house. I hope that when they get the framing done I can catch them putting up the trusses and get picture of that operation.
 
Don Baer said:
No pictures this week. I drove by and the framers were there sorting though the lumber seperating the streight boards and going over the blue prints so it looks like they'll start framing on Monday. Boy thats a lot of lumber for a 7000 sq.ft. shop/garage with attached 300 sq.ft. attached house. I hope that when they get the framing done I can catch them putting up the trusses and get picture of that operation.
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:eek: :huh: :huh: :thumb: :D
 
Don Baer said:
on the signoff for the inspector, they have a place to be signed off about the slab being "'Post Tensioned", what in the Sam hill is that??:confused:
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Hi Don just got a chance to check out your thread. Nice project you have going.

I am a place and finish contractor by trade. We do mostly industrial slabs(1,000 yd pours) and tilt-up panels, but have done my fair share of post tensions slabs.

After looking at your pictures it doesn't appear to me that you have a post tension slab. They poured your stem walls to FF(finished floor) If that's the case how did they tighten the cables after the pour? Normally the cables are tightened from the edge of the slab after the forms are removed.

Maybe I'm missing something in the pics? Did you notice any rebar in the slab before they poured? They usually don't mix rebar and pt together.

Doug
 
Don I don't know if you saw my post regarding your slab being post tension? If it was, it would also have a stamp in it somewhere saying not to penatrate or drill.

Doug
 
Doug Sinjem said:
Don I don't know if you saw my post regarding your slab being post tension? If it was, it would also have a stamp in it somewhere saying not to penatrate or drill.

Doug
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Doug, I think the PT slab question was just one of the checkboxes on the inspector's list...probably left blank or N/A on the checklist in the case of Don's house.

The "don't drill or penetrate" stamp is a good idea. I never saw it done when I was around a PT slabs, but that was 15+ years ago, so I'm sure some things like that have become common now. I always wondered about the crews that have to demo buildings with PT slabs 50 to 100 years from now. I sure wouldn't want to be running that jackhammer. :eek:

Progress is looking good, Don. It's looking more and more like a building, and I'll bet it's a kick watching it all come together.
 
Just a couple more pictures. They got most of the external walls framed just one small section left and are working on the internal walls.

Front of House framming.jpg


This is the front of the house framed in.


Patio header.jpg


This is the header for the patio. It is a solid piece of doug fir 4x12x 50 feet long, A single piece with no splices.
 
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