Icynene

[depeche2u]

My wife and I are building a home in Houston, and we are exploring our energy efficiency options. We are interested in icynene, but our builder has not used foam insulation, and has expressed some reservations about moisture buildup behing the icynene. Is this a valid concern in a humid climate such as houston. With foam insulation, what things should we insure to prevent moisture/mold problems. Additionally, what other thing are needed to ensure a fresh air environment for the home since it's now a sealed home?

[ga-hvac-tech]

Properly installed, there should be no moisture build-up behind foam... PROPERLY INSTALLED.

Foam houses are structurally stronger than conventional, a good thing in hurricane proned Houston (grew up there).

You will need an ERV (energy recovery ventilator) installed with each system. Ask your HVAC contractor to include this.

Also, be SURE the load calc is done to reflect a foam house. It will be different (lower capacity equipment).

I would look for a builder that has experience with foam, and an HVAC guy that has experience with foam also.

[jimj]

Properly installed, there should be no moisture build-up behind foam... PROPERLY INSTALLED.

Foam houses are structurally stronger than conventional, a good thing in hurricane proned Houston (grew up there).

You will need an ERV (energy recovery ventilator) installed with each system. Ask your HVAC contractor to include this.

Also, be SURE the load calc is done to reflect a foam house. It will be different (lower capacity equipment).

I would look for a builder that has experience with foam, and an HVAC guy that has experience with foam also.

Very important, that this is done.

[energy_rater_La]

most foam companies have hvac companies that they work with
that understand the cause and effect of foam insulation and how
it will reduce tonnage of hvac.
load calc will relfect these inputs

you are doing open cell??
closed cell will cause moisture to be trapped and open cell will
let it dry

your best option is to foam the roofline and use conventional insulation
in the walls. the walls should be sealed using the air tight drywall approach
and 1" foam sheating (with seams taped)to exterior of walls.
sole plates should be sealed to slab and attention to air sealing details

southface inst has great air sealing factsheets.
this is by far the most affordable and efficient way to stick build.
more info at buildingscience.com under hot humid climates.

best of luck.