Spraying modular home construction with top 3 inside boards on walls left off | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

Q&A Forums

Spraying modular home construction with top 3 inside boards on walls left off Post New Topic | Post Reply

Author	Comments
Jim Hollander Posted: Jul 25, 2008 05:38 AM	Spraying modular home construction with top 3 inside boards on walls left off On a new modular log cabin, normally fiberglas insulation in installed at the factory, with the sides of the building laid flat. Then the inner sheetrock or 8" boards are put on. The building has not been ordered yet. If it were ordered with NO insulation except under each window, could it be sprayed with .5 lb. SPF from the top of each 8' high wall inside if the top 3 boards were left off? Maybe a special small pattern nozzle to have a smaller pattern at 6' distance. Or will the expanding pressure from .5 SPF blow out the boards? I assume that 2 lb. SPF would blow out the weakest of the inner or outer walls? Can you make any suggestions? If the inner walls are not installed, then added later, the cost rises by $6000. Is it a mistake to have the factory install their fiberglas under the windows due to the compromises in permeance and changes of air per hour? (ACH) Is it practical to simply cut open the wood board areas under each window and spray under them individually. Again a concern about access and appearance. Thank you in advance.
mason Posted: Jul 25, 2008 03:07 PM	The expanding foam would cause a lot of heat and pressure and yes cause structural problems and possible a fire. There are formulas specific for cavity fill. Most are low density foam but there are some closed cell products that may work. Contact a full service foam supplier that supplies material for OEM manufacturing. (doors, insulated panels, spas, boat flotation foam, etc.) They are more likely to have a system that will work.
philip mullins Posted: Jul 25, 2008 11:12 PM	i have done some research into this application and always ran into the same problem. inspections. none of the factories i spoke with could pass code inspections without insulation in the walls.

Author

Comments

Jim Hollander

Posted: Jul 25, 2008 05:38 AM

Spraying modular home construction with top 3 inside boards on walls left off

On a new modular log cabin, normally fiberglas insulation in installed at the factory, with the sides of the building laid flat. Then the inner sheetrock or 8" boards are put on.

The building has not been ordered yet. If it were ordered with NO insulation except under each window, could it be sprayed with .5 lb. SPF from the top of each 8' high wall inside if the top 3 boards were left off? Maybe a special small pattern nozzle to have a smaller pattern at 6' distance. Or will the expanding pressure from .5 SPF blow out the boards?

I assume that 2 lb. SPF would blow out the weakest of the inner or outer walls? Can you make any suggestions? If the inner walls are not installed, then added later, the cost rises by $6000.

Is it a mistake to have the factory install their fiberglas under the windows due to the compromises in permeance and changes of air per hour? (ACH) Is it practical to simply cut open the wood board areas under each window and spray under them individually. Again a concern about access and appearance.

Thank you in advance.

mason

Posted: Jul 25, 2008 03:07 PM

The expanding foam would cause a lot of heat and pressure and yes cause structural problems and possible a fire. There are formulas specific for cavity fill. Most are low density foam but there are some closed cell products that may work. Contact a full service foam supplier that supplies material for OEM manufacturing. (doors, insulated panels, spas, boat flotation foam, etc.) They are more likely to have a system that will work.

philip mullins

Posted: Jul 25, 2008 11:12 PM

i have done some research into this application and always ran into the same problem. inspections. none of the factories i spoke with could pass code inspections without insulation in the walls.

You need to login to reply to this topic. Please click here to login.