Floor coming soon

[MongoTom]

I've been lurking here for a while now, picking up many great ideas. We're rebuilding our garage from 20X20 to 26X26 with 12' ceilings for a lift. We're going to put PEX in the floor for radiant heat. The building is now framed and roofed and the floor is getting close. This is the scary part.
The soil in our area is clay and nasty. This will have a 6" base and the contractor is using pea stone. Not my choice, but he uses it all the time and likes the result and the fact that it self-compacts. In any case, that's in already. He was going to use 6 mil poly for vapor, but I stopped him and ordered 15 mil Perminator to use instead. Over that will go 2" rigid foam (polystyrene, I presume). Then 6X6 wire mesh with PEX attached. The plan is to pour the 3500 psi concrete to 8" to accommodate whatever lifts I plan to install.
Here's the really scary part.
Due to the location of the garage and surrounding trees and houses, we can't pump the concrete. The concrete guy is planning to run his power buckets across the floor (covering the route with plywood, I hope), dumping the concrete and then pulling up the mesh to the proper level. He says there's no other way to get it into the garage.
When I heard this I nearly crapped. Is it possible to do this without destroying the PEX, the insulation and the vapor barrier? What happens to the pea stone under that load? Will it shift and leave air gaps?
I'll have lots of the vapor barrier and I could easily put a second layer over the insulation to help protect and distribute the load.
Is this as bad as I think or am I panicking unnecessisarily? Thanks for the help.

 

[anthony666]

the plywood will spread the load sir, don't worry

 

[brewchief]

8" of concrete is a lot, how big of lift are you thinking of?

Without chairs under the mesh they will never get it pulled up consistently.

Are you leaving areas with no tube for the lift or going to just hope you miss the tube?

I've never seen anyone run a power buggy over an infloor job with or without plywood but I would make very sure the tube was under a pressure test the whole time.

The peastone should be fine, all the slabs I've seen poured over peastone cracked far less then those over sand.

 

[Fastback]

Elevate the steel with chairs, the PEX works more efficiently when it is closer to the center mass of the slab.

Also be sure to use expansion/thermal break between the slab and anything it would touch, you dont want heat climbing the walls.

If your garage door is high enough get an extended chute for the truck, around here all of the trucks empty from the front and the extension helps. My concrete guy owns his own extension chute that he sets on horses to keep the muck buggy from rolling as far or at all in some instances. Ask your guy if he owns one, if not maybe you should ask around to borrow one or consider a specialist that already has one?

 

[MongoTom]

I asked about chairs for the PEX and they would be crushed by the buggy.
Yes, the PEX pattern will be designed so there is none under the lift attachment points. Don't want to puncture that.
Yes, the plan is to pressure test and leave the PEX under pressure during the pour. That should help protect it.
The garage is 75' from the road and the drive is too narrow for the truck, so it would take a 90' chute or better to get it into the garage. Not likely.
Yes, the thermal break will also be on the sides.

Okay, I'll take this day off and be there the entire time. I'll have to trust that the plywood will distribute the load and keep an eye on the pressure. I also want to make sure that they don't water the mix. I understand it should be a thick mix to avoid problems.

Any harm in the second layer of vapor barrier to help stabilize the insulation, etc.?

Thank you all very much for the responses!! I'm new to this and need all the help I can get.

 

[Fastback]

Serious question, but if you can't get a mixer truck to yor garage, how would you get a f-350 or ups truck back there? It would give me pause enough to consider making something wider? Mixer trucks around here can get into tight spaces, it boggles my mind how a future driveway can't be wide enough for a truck?

 

[MongoTom]

Good question. Let's just say the space between houses is very limited and the odds of me ever owning an F-350 are zero. My interest is sports cars. That said, concrete is cheap and I didn't want to limit the floor capacity in any way.
Also, I'm overly sensitive about the driveway. It's 20 years old, hasn't heaved and has no cracks, probably because I don't allow loaded cement trucks to drive on it (if they could, which I doubt).

 

[Jackfre]

I used to take a few drops of oil of wintergreen or peppermint and put it into the tubing. Pump the pressure up on the tubing and stay close during the pour. If you smell the additive, you have a leak. With the pressure you can find and repair. This worked for me years ago when I had a bunch of meatheads with shovels doing a large pour.

 

[MongoTom]

Great idea! I'll try that.

 

[MongoTom]

A change of plans. We're going to pull down a retaining wall and level a hill on the neighbor's lawn so we can make room to drive the concrete truck on the driveway. The driveway butts right up against the house, so one danger is breaking that wall. They're going to split the load into multiple trucks to lighten the load. Nothing is ever easy.

Now to find a heavy mesh and appropriate chairs to elevate it.

 

[Fastback]

Menards has plastic puck like chairs...

 

[Highbeam]

I guess this must be a regional thing but I have done several pours at my house in the last few years and they have all used something called a line pump. It is either a trailer or a truck mounted pump that sends the concrete down 10-25 long sections of 3-4" hose to the pour site. The pump truck can be 100 feet away from the pad. The concrete trucks dump their loads directly into the hopper on the pump. We poured my 30x60 this last Saturday, 33 yards of mud, and pumped every bit of it this way. Bill was 400$ for the pump. Beats the heck out of risking your driveway or destroying retaining walls.

 

[MongoTom]

That sounds great. I was told $1200 for a pump truck. I'll look into this. Thanks.

 

[Will67]

I would suggest a pump truck, there has to be someone in your area just waiting to work!

And add dobbies or plastic chairs under rebar and/or remesh...I say BULL **** to any concrete guy who say they will pull up remesh as they pour. Yeah then someone steps on it or gravity does what it does and remesh winds up in the bottom. With chairs/dobbies it stays where set!

 

[MongoTom]

We're using chairs. They come in 5' strips. We're running them 1' apart. The mesh is 0.3 inch wire in a 6"X6" grid. With that many chairs and wire that heavy, we should be able to walk on it without problems.

 

[MongoTom]

I guess this must be a regional thing but I have done several pours at my house in the last few years and they have all used something called a line pump. It is either a trailer or a truck mounted pump that sends the concrete down 10-25 long sections of 3-4" hose to the pour site. The pump truck can be 100 feet away from the pad. The concrete trucks dump their loads directly into the hopper on the pump. We poured my 30x60 this last Saturday, 33 yards of mud, and pumped every bit of it this way. Bill was 400$ for the pump. Beats the heck out of risking your driveway or destroying retaining walls.

We found a company that will do this, so we'll avoid potential damage. Should be pouring it next week.