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grasshopper[_2_] September 5th 08 10:00 PM

radiant barrier in new construction
 
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?




ransley September 5th 08 11:22 PM

radiant barrier in new construction
 
On Sep 5, 4:00*pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


It should work, but what house wrap is a radiant barrier, unless its
foil.

grasshopper[_2_] September 6th 08 01:05 AM

radiant barrier in new construction
 
On Fri, 5 Sep 2008 15:22:47 -0700 (PDT), ransley
wrote:

On Sep 5, 4:00*pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


It should work, but what house wrap is a radiant barrier, unless its
foil.




The one I'm looking at is he http://www.radiantguard.com/ Looks
like there are several speciality providers.

My main concern was the possibility of trapping moisture between the
two barriers....


ransley September 6th 08 01:37 AM

radiant barrier in new construction
 
On Sep 5, 7:05*pm, grasshopper wrote:
On Fri, 5 Sep 2008 15:22:47 -0700 (PDT), ransley

wrote:
On Sep 5, 4:00*pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


It should work, but what house wrap is a radiant barrier, unless its
foil.


The one I'm looking at is hehttp://www.radiantguard.com/*Looks
like there are several speciality providers.

My main concern was the possibility of trapping moisture between the
two barriers....


Normal house wraps let moisture through but not rain so it likely will
trap moisture. Why not use it under drywall inside.

PerryOne September 6th 08 05:40 PM

radiant barrier in new construction
 
On Sep 5, 10:00 pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


Just what exactly is your target?
What are you trying to achieve?

grasshopper[_2_] September 6th 08 10:10 PM

radiant barrier in new construction
 
On Sat, 6 Sep 2008 09:40:52 -0700 (PDT), PerryOne
wrote:

On Sep 5, 10:00 pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


Just what exactly is your target?
What are you trying to achieve?




New construction. Goal is:

Repelling max amount of heat in summer before entry into the interior.
Repelling max amount of heat back into the interior in winter.

The wall studs are 2x6 with R19 fiberglass to impede movement of heat
in any direction. R19 is the greatest R value I've found so far for
5.5 inch wall cavities. Do you know of better insulation materials
that will fit into that cavity?

Ceiling will be ~R50 with perforated radiant barrier laid over top.
2x6 floor joists will be insulated but haven't addressed that yet.

Any info or critique would be greatly appreciated.



Wayne Whitney September 6th 08 11:46 PM

radiant barrier in new construction
 
On 2008-09-06, grasshopper wrote:

Ceiling will be ~R50 with perforated radiant barrier laid over top.


Radiant barriers can't be used facing up, as they will collect dust.
They must also face an air space, otherwise they are defeated by
conduction. For new roof construction, I think a radiant barrier on
the underside of the roof sheathing works best.

Cheers, Wayne

PerryOne September 7th 08 08:11 PM

radiant barrier in new construction
 
On Sep 6, 10:10 pm, grasshopper wrote:
On Sat, 6 Sep 2008 09:40:52 -0700 (PDT), PerryOne

wrote:
On Sep 5, 10:00 pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


Just what exactly is your target?
What are you trying to achieve?


New construction. Goal is:

Repelling max amount of heat in summer before entry into the interior.
Repelling max amount of heat back into the interior in winter.

The wall studs are 2x6 with R19 fiberglass to impede movement of heat
in any direction. R19 is the greatest R value I've found so far for
5.5 inch wall cavities. Do you know of better insulation materials
that will fit into that cavity?

Ceiling will be ~R50 with perforated radiant barrier laid over top.
2x6 floor joists will be insulated but haven't addressed that yet.

Any info or critique would be greatly appreciated.


Research has shown that a white or light colored roof works best as it
reflects heat.

The best form of roof is one covered with sprayed polyurethane foam
five inches thick, covered with two inches of reinforced concrete.
The downside is the weight.

As heat always moves to cold and you suffer from radiation, conduction
and convection.

You really must ensure that there are no gaps of any size through the
walls and ceilings gaps round all pipes and wires must be sealed.

Fibre glass is not a good insulator as it is impossible to fit without
leaving gaps for the heat to find its way through, also it sags over
time leaving space at the top for convection. Any gap over 16mm will
allow convection currents to start and transfer heat from outside to
inside and vice versa.

Sprayed poly foam between the studding will completely fill the spaces
for ever.

You need to ensure that all of the internal fabric of the building is
isolated from the main structure.
Placing two inch thick polystyrene over the main frame and walls on
the inside of the rooms will solve this.

Final point sprayed poly foam between the joists means that you can
use the loft for storage without the worry of compressing fibre glass
that loses if effectiveness (all be it small.) As mentioned elsewhere
a radiant barrier is a waste of money.
Perry

ransley September 7th 08 08:18 PM

radiant barrier in new construction
 
On Sep 6, 4:10*pm, grasshopper wrote:
On Sat, 6 Sep 2008 09:40:52 -0700 (PDT), PerryOne

wrote:
On Sep 5, 10:00 pm, grasshopper wrote:
Suppose a house has radiant barrier housewrap, then 1 x 2 furring
strips on the outside and topped with 4 x 8 hardie concrete siding.
Would there be any problem if I installed foil backed fiberglass in
the wall cavity with the foil facing the interior?


Just what exactly is your target?
What are you trying to achieve?


New construction. *Goal is:

Repelling max amount of heat in summer before entry into the interior.
Repelling max amount of heat back into the interior in winter.

The wall studs are 2x6 with R19 fiberglass to impede movement of heat
in any direction. *R19 is the greatest R value I've found so far for
5.5 inch wall cavities. *Do you know of better insulation materials
that will fit into that cavity?

Ceiling will be ~R50 with perforated radiant barrier laid over top.
2x6 floor joists will be insulated but haven't addressed that yet.

Any info or critique would be greatly appreciated.


Spray foam or foamboard at 5.5" can be R 40 with a radiant barrier on
the foamboard


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