Punching Through A Radiant Slab

[bigmig]

Just wanted to bounce a common question around to see what kind of methods are used.....I'm trying to get a square concrete pad footing below an existing 4" slab on grade with radiant. My past experience with cutting through radiant slabs is that things don't fare too well for the radiant (impossible to splice and avoid leaks).

I'm looking at micropiles as an alternative. Has anyone else used any other techniques to avoid disturbance to the slab but still get good bearing? Compaction Grouting?

The slab can not support the column load by itself, so that is out of the question.

Being as how this is in the inside of an existing house, it would be great if the solution didn't involve a drill rig the size of a truck.

 

[msquared48]

How big does the footing have to be?

Ridiculous as it may seem, depending where it is, is there any way the footing could be poured above the slab?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[SLTA]

Mike, that's a good idea, if it can be verified that the slab is still really well supported by the ground underneath. It may have settled.

Bigmig, our radiant floor heat was about 6" apart, max. Can you span across the slab to the outside and avoid an interior column?

 

[ACtrafficengr]

Could a GPR locate the radiant tubes so you could avoid them? Or would you have to give the heating system a barium enema first?

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

 

[bigmig]

The footing is going under living space, so unless the owner wants a permanent coffee table in the shape of a big square concrete block we will have to pass on that idea of going above slab.

We have investigated the clear span idea, which is an option, but we want to compare that option to this one as far as price goes.

I have worked on jobs where we located the radiant in the past and finding it is not the hard part. The hard part is getting the concrete out while leaving the radiant. The hardness of the concrete takes a jack hammer and the softness of the radiant hose does not do well when jack hammered.

Thanks.

 

[SWComposites]

could you use a core saw to cut a series of hole between the radiant tubes?

 

[azcats]

How about driving small diameter piles through the holes cored out that SWC suggested above?

My wife's uncle had a settling basement that was reinforced like this with a bunch of driven piles around the perimeter that were bracketed to support the foundation. There was no radiant to consider, but all the installation was done inside the basement.