attaching the tube under concrete

spotts · March 2003

spotts · March 2003

I'm getting ready to start installing the tubing (½" Kitek) in the floor in my Dad's new shop/home. All one level in a steel building, 400 sq. ft. home with a 1200 sq. ft. attached shop. The last one we did for him we used that rolled mesh in the concrete to attach the tubing to. Hatefull to work with, not near flat, no way to know where the tubing really is in the concrete. I'm considering building a rebar grid system 16" on center then raise and shim it exactly in place before the concrete guy shows up. There must be an easier way. How do you guys install tubing in flat concrete? Last time we used a Burnham Revolution boiler. We were very happy with it. Are there any better choices today? If it matters..... I am a heating contractor, I just usually do repair, replace. This is only my 3rd infloor system and I'd like to smooth out some of the rough edges of the last couple. Who knows? This may become part of my livin' one day! Thanx, Jack Spotts- Spotts Bros. Furnace Co Inc Colorado

spotts · March 2003

I'm also considering my options

About the thickness and location of the insulation for this "slab on grade" pour. Is there any place to look for this info to save you guys having to re-hash something you've explained 100 times?

hot_rod · March 2003

bar stools.. I mean chairs

These are called bar chairs, around here. Intended to hold rebar in the slab at the correct location. The work well for remesh also. The continous rail, strip chairs work best over foam or tarp insulation.

You can buy these, and remesh in flat sheets (8X20') at concrete supply companies and some steel supply yards. The sheet mesh is much much easier to work on. Costs the same as roll mesh.

Unless you need the rebar for structural reasons the mesh works just fine for fastening the tube. I use the chairs every 4 feet to hold the mesh and tube into the pour. 1-1/2" tall chairs hold the tube about centered in a 3-1/2- 4" slab.

If you go with rebar it MUST be held in the slab to do any good. The concrete needs to surround it to "work"

Insulation, if you use EPS foamboard should be at least 1". 1-1/2- 2" is that much better and holds up to foot traffic much better than 1". I'd still use a 6 mil vapor barrier under the foamboards.

Remember slab edge insulation is also very important. I use 2" here.

The mesh in this pic is 6X6 #8 gauge for a commercial job. Quite a bit heavier to work with than typical 6X6 #10.

hot rod

spotts · March 2003

Thanx HotRod!

Im thinking 2" blueboard from the top of the concrete inside the wall straight down 24". Then (30x40 bldg) only 8' in from the sides under the concrete. Is it stupid not to insulate the center? I was thinking "thermal mass" but maybe I'm just being cheep. That sneaks up on me sometimes. Last one we insulated under the whole floor and it worked great. I never thought of the vapor barrior. Thanx! Do they make those barstools in 4'?

Rock Solid Restoration_3 · March 2003

When I did my basement slab I used foil faced polyisocyanurate insulation, then installed the 1/2" pex using plastic tracks that the tube snaps into(the plastic track is held in place with foam staples). Then I installed my wire mesh on top fo the tubing and the tubing held the mesh to the proper height.

I think it came out pretty slick. I can't imagine trying to do a decent job with rolled wire, what a nightmare.

Rock Solid Restoration_3 · March 2003

When I did my basement slab I used foil faced polyisocyanurate insulation. Then I installed my 1/2" pex with plastic tracks that are held down to the insulation with foam staples.

I then installed my wire on top of the tubing.

The wire was in sheet form, I can't imagine trying to use the roll type and have a good job.

Steve Bergerson · March 2003

Why not use foam staples

and save yourself some time and money.

Insulate the floor with a vapor barrier, and insulate the edges, then use a foam stapler, such as the one available from Wirsbo, and staple your tube directly to the foam. Pour the concrete... (we use fiber-mesh concrete. Concrete with fiberglass in the mix), and you're done in about 1/4 the time.

Unless there is a valid reason for all that steel, foam staples are the only way to go.

spotts · March 2003

floating tube

If I put 1" foam in the floor I'll have 5" concrete. From the classes I've taken, I thought I wanted that tube in the center of the pour, not dead bottom. Has the thinking changed on this? If it works I'll try it.

hot_rod · March 2003

It is always best

to have the tube up into the slab, as opposed to the very bottom. This link gives more specfic numbers on the output differences.

ttp://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,3185,00.html

I also have samples of tube that has been removed after years of service at the bottom of the pour. Wear marks from the tube abrading on the rusted wire mesh are somewhat concerning.

I spent some time on the phone with a Goodyear forensic guy recently, after sending a sample of damaged hose to him. Their concern is with the tube not being encased in the pour and the damage they have seen with the tube to mesh or bar connection. The tube will expand @ .030 as the water warms in the tube. At the bottom of the pour on mesh or bar this will cause a wear point.

Of course stapled to foam, the wear issue would go away, but the performance would still be best with the tube encased in the middle of the slab, in my experience. Just so you know the pros and cons

hot rod

Steve Bergerson · March 2003

Unless you are required to have 5\"

of concrete, lay down 2" of foam, staple your tube directly to the foam, and pour 4" of concrete on top. This will insulate better than 1" of foam, and save you money on the concrete.

This is one of the installation methods recommended by Wirsbo, and one that we use often. As for "floating the tube", I like to keep the tube at the bottom of the pour rather than in the middle for a couple of reasons...

1. When interior walls are nailed to the floor, the tube is 4" down, and out of the way of the nails. Also, any other penetrations such as bolts to hold a water pump, expansion tank, etc that might be drilled into the floor will also have less chance of hitting the tube.

2. The heat from the tube is going to heat the whole slab anyway... (above the tube, as well as below the tube) until it hits the insulation.

Granted, floating the tube in the middle of the pour might give you a slightly quicker response time, but in your application, how important is that to you?

attaching the tube under concrete

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