Insulation under staple up

Jim_142

I will be installing my first radiant 'staple up' job in the next few weeks. I cannot seem to find foil faced insulation in my area to insulate the joist space under the tubing. Is the foil faced that critical or can a paper faced be substituted? Any suggestions on an alternative?

Thanks, Jim

ALH_4

Foil

The foil is unimportant. What is much more important is that the tube is in contact with the subfloor. "Staple-up" is used to describe many different installation methods. In warmer climates, sheet metal "plates" will probably suffice. In my opinion, their primary purpose is to hold the tube in contact with the subfloor. In colder climates, extruded aluminum plates may be necessary. They conduct the heat from the tube into the subfloor. Check the manufacturer's published output numbers against your heat load in each room to be sure you won't have unhappy customers in Jaunary.

1974bobcat

The foil reflects the radiant rays back towards the space you are trying to heat. If you can't find it use the bubble wrap insulation the duct guys use and put insulation beneath that. Remember to leave a 1-2" air gap between the buble wrap and the tubing. I've found the bubble wrap at home depot.

BOBCAT

hot_rod

If it is a direct

tube to floor staple up, without any transfer plates, then the reflective layer does add some value. But it is no substitute for the conductive transfer that the transfer plates offer.

Keep in mind those reflective layers do have a tendency to dust over and performance will drop.

Look at yourself in a clean mirror... now sprinkle a layer of sheetrock dust and floor sweeping dust over the mirror... like what you see??

Ideally the reflective material should be smooth not rippled and without any printing, like foil backed insulation has.

I suspect "dusting" is why it is common for installers to return to those type of staple up jobs to "crank 'er up"

hot rod

Rich L.

> tube to floor staple up, without any transfer

> plates, then the reflective layer does add some

> value. But it is no substitute for the

> conductive transfer that the transfer plates

> offer.

>

> Keep in mind those reflective layers do

> have a tendency to dust over and performance

> will drop.

>

> Look at yourself in a clean

> mirror... now sprinkle a layer of sheetrock dust

> and floor sweeping dust over the mirror... like

> what you see??

>

> Ideally the reflective material

> should be smooth not rippled and without any

> printing, like foil backed insulation has.

>

> I

> suspect "dusting" is why it is common for

> installers to return to those type of staple up

> jobs to "crank 'er up"

>

> hot rod

Rich L.

Foil Insulation

"If it is a direct tube to floor staple up, without any transfer plates, then the reflective layer does add some value."

Is this the only application you feel the foil faced is justified? If so why? Just curious. I quit using foil bubble completely about 5 years ago when I first heard about the dust layer issues, made good sense to me! All I use now is fiberglass batts. I haven't done an underfloor job without plates at a bare minimum in over 8 years. I'd much rather use a mod-con or heat pump at lower temps. Efficiency and happy customers are a good thing!

Thanks, Rich L

hot_rod

The lack of conduction transfer

is my biggest issue with direct tube staple up. In theory a reflector would add some value to the radiation transfer. Again, only if the reflector can reflect.

I know radiant barriers work and work well in attics where they can have the air space to reflect. that's not the case with foil products under a concrete slab, for instance.

I'm with you on plain batts or spray foam under transfer plates is fine. Really no need for an air space if all the transfer is conduction. Which is by far the most powerful in low temperature radiant applications.

My test also show only a small portion of staple up tube actually touches the subflor. Unless you plan on stapling every 2 inches

Hense the amazing output of the Warmboard product. all wall to wall conductive surfaces...

Personally I would rather do an Ultra Fin installation, as a bare tube to floor, it at least has a means to leverage some transfer from the tube to the space, and it doesn't stripe like direct tube staple does. At least from my testing and infared themography.

hot rod