Onix Tubing Installation Manual

recommend a high-temperature poly-
isocyanurate board, such as Celotex
¤
Thermax
¤
. Even though there is no air
gap below the tubing, the foil will help
even out the heat transfer across the
sleeper spacing and the upper subfloor.
In the case of a Sandwich over Slab
application, especially a basement
remodel, a non foil-faced extruded
polystyrene insulation board, such as
Dow
¤
Blue Board
¤
, is recommended.
This is due to the tendency for mois-
ture to collect in basement areas, either
because of condensation or high sea-
recessed floor approach can be used.
This type of application mimics a sta-
ple up in every way except how the
tubing is secured. The following
examples require the original subfloor
to be removed, leaving exposed joists
in the area.
Insulate the joist cavity first, then
install the corresponding support sys-
tem. It is important to install the sup-
port system in such a way that when
the subfloor is replaced, contact with
the Onix is maintained, but not too
much to cause the tubing to flatten.
Likewise, renovation projects tend to
pose a problem in basements where a
concrete floor is already in place. In
this situation, a sandwich over slab
application is used. This application is
installed in the same manner as a
sandwich over a frame floor.
page 30 Watts Radiant: Onix Installation Manual
Insulation board is used to support the Onix tub-
ing and to provide a thermal break to the floor
below. Onix must be in direct contact with the
underside of the subfloor.
Poultry netting (chickenwire) is used to support
the Onix. A foil-faced batt insulation is used
below the Onix with a two inch air gap, foil facing
upwards.
Onix Tubing
Insulation Board
Nailer
Foil-Faced Batt Insulation
Onix Tubing
Poultry Netting (chickenwire)
sonal water table levels. An extruded
polystyrene board will withstand mois-
ture conditions better than a polyisco-
cyanurate.
Other Frame Floor
Techniques
Occasionally construction details pre-
vent tubing from being installed either
from underneath via a Staple-Up or
from on top with the use of a
Sandwich. In these conditions, a
Sandwich