foam insulations

molly

All radiant slab installations we've done have been over the blue styrofoam. Recently, the G.C. on a residential new house made the decision to use the pink stuff. The tubing is 1/2" staple down with a 4" pour over it. The job is done but I'm still wondering if there are any known problems associated with using pink foam instead of blue, as the pink didn't seem to be as rugged as the blue.

hr

It's not the color

that matters, really. The important thing is the load ratings on the board. Some of the less expensive stuff has a much lower PSI rating, which may be an issue depending on the application.

I haven't found any foamboards that are termite proof, that may be a bigger concern depending on your location

hot rod

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[Deleted User]

Load ratings...

Interestingly enough, I called in the structural engineer on the current prject I'm working for snowmelt with the potential of large heavily weighted 18 wheeled trucks driving over the slabs which I'm insulating AND snowmelting. He said that 25 PSI crush resistant insulation equates to a crush factor 3,600 lbs per square foot. This far exceeds most soil crush resistant capabilites of 3500 Lbs/PSF.

When asked about the compounded crush forces of a fully loaded 18 wheeler, he said that that was the LEAST of his concerns. Something about load spread potential and so on.

I am NOT a structural enginner, but it would appear that based on this conversation, we as contractors are OVER concerned. Best to run it by YOUR structural engineer to be sure.

ME

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hr

Hmmmm

The fellow from Dow Styrofoam Division that spoke at the RPA several years ago had a different perspective. He suggested High Load 40, 60 or 100 (psi) for slabs with heavy, or extended truck traffic.

I have a Dow application book and they list High Load be used for "highways, airport runways, taxiways and aprons, culvert retaining walls, transmission tower footings, septic tanks, swimming pools, and a list of others.

In addition to the added weight bearing it also has a very low water absorption rating, and is virtually unaffected by freeze thaw cycles, they state.

It sure is expensive and only comes in 2" or thicker and 2'X 8' sheets. It's much heavier and almost feels like wood. I asked my rep how it can still be so good of an insulator when made so dense, He told me the air bubbles are much smaller. Oh, okay, I guess They also offer a 60 psi "Plazamate" for pedestrian traffic and light vechicle areas.

You might want to get a letter from that structural guy to cover your butt. The blame for cracked and moving slabs often comes down on the radiant installer

hot rod

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