Radiant pipe heating in structural slab on metal deck

[DST148]

thread507-315447
We have 3 1/2" LWC on 3" composite metal deck (total 6 1/2" thick), spans 11'-0" , total load 110 psf. The owner wants to install 1/2" plastic pipes at 9" o.c. in the structural slab. The pipes run parallel and perp. to deck in a serpentine fashion.

ACI 302 - Guide for concrete floor slab construction requires 2" concrete cover under the pipe and 2" to 3" cover over the pipe.
I have never done in-floor radiant heating.
Any help would be appreciated.

 

[structSU10]

ACI 302 is really for slab-on-grade. In these situations I have looked at the slab as a fixed-fixed beam spanning over the pipe as a plain concrete member. For such a small diameter, the slab itself is likely not an issue. The only thing I get concerned about is if there are shear studs near the piping - if a pipe is located right at a shear stud it may not be effective at transfering the load. I would also reduce the composite action of a beam in your situation by removing the area of concrete removed by the pipes running parallel with a beam.

 

[DST148]

Thanks structSU10.
Detail on Uponor website shows 3/4" thick concrete over tubes.
The detail from Watts Radiant cautions about maintaining minimum 2" concrete
thickness above tubing.
We have suggested detail per attached sketch: the WWM supported on
deck and tubing secured to WWM. We have also added 4 feet wide strip of WWM
over all beams and girders to mitigate cracking.
Does embedding radiant tubes affect fire rating performance of the floor assembly?
I would appreciate your thoughts on the suggested detail.