Insulating with Subfloor Radiant tubing

Unknown

it's personal preference in the regard that it doesn't matter much. it's not needed though.

RLYable Handyguy

Difference of Opinions

when it comes to Installing Fiberglass insulation between floorjoists... after tubing, WITH heat transfer plates, and possibly radiant barrier/foil. SOME people insist that there should be a 1 1/2inch to 2 inch airspace between the insulation and tubing/plates... where others .. including the Wirsbo Instal Handbook... shows NO airspace with this instal method.. unless youre doing a suspended tubing instalation method... then yeah.. you're heating the AIRSPACE which heats the floor... needs the gap between the batting and flooring... thats a given... BUT... is this another personal preference? or equally effective methods varying from one Radiant manufacturer to another?

Thanks again
Russ

Alan(CaliforniaRadiant)Forbes

With floor plates,

you're heating by conduction and an air space is not necessary. So, to answer your question it's not a personal preference; it's physics.

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jerry scharf_3

bad news, good news

Russ,

The bad news is that you are talking about pink stuff. It's my least favorite insulation material. The good news is that insulating the joist bays on a subfloor transfer plate install is the best possible case for pink.

The problem with pink is that it does not resist air motion very well, so convective currents can set up greatly reduce the insulation value. The good news is that a subfloor joist space with top surface heat is the most stable air pattern to be found in a house, so the pink penalty will be less. I would use a better insualtion than pink near the rim joists, as that is the greatest loss area and the air is less stable there.

There is no purpose for the space in a transfer plate installation. Leaving the space makes it harder to get the tightest possible fit for the insulation, which is always the goal. So I would fill it up and make sure it is installed with as close to zero voids (small uninsulated sections) as possible.

hope that helped

jerry

Ron Schroeder_3

I second the reservation about fiberglas

whether it is pink or yello. A far better product in every case is called Roxul which you can get at HD. This stuff is a byproduct of some kind of mineral smelting. It is green in color and in its environmental impact. It is also much more benign to work with.

Keep the air spaces to a minimum, as already stated by those with practical experience. Don't lose sleep over the inevitable small voids where plumbing and electrical services interfere with a perfect insulation installation.