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scott moss Posted: Aug 02, 2009 07:16 PM	ventilation when spraying a residential home do you have ventilation for the home or do you completely seal the house up while spraying.
mason Posted: Aug 02, 2009 08:21 PM	Ventilation is part of providing good indoor air quality. The insulaton, air barrier, vapor retarder and HVAC equipment is to be designed to control the strong interactions of heat air and moisture transport within buildings. Sprayfoam insulates and provides an air barrier. Once that is accomplished, the HVAC equipment can function more efficiently and reliably. I suspect you are talking about vented or unvented attics. You can install sprayfoam in either concept. If you have duct work or HVAC equipment in the attic, you can spray foam to the underside of the roof deck and seal the attic. This makes an unvented attic and would be more energy efficient. If you do not have duct work or HVAC equipment in the attic, you can install the foam to the floor of the attic. Then you would vent the attic as usual. It is important to remember that when you install sprayfoam to a building that it makes the building more air tight. In some cases depending on the degree of air sealing, additional air may be required in order to provide the appropriate air exchange. So, the HVAC contractor in new construction should consider this fact and size the HVAC units and provide make up air. In remodeling projects, make up air may or may not be required, depending on how leaky the building is and how tight the foam makes the building. For example in my townhome I sprayed foam in the basement, sill plate and floor of the atttic, I did not require additional make up air. But if I would have replaced my windows and sprayed foam in the walls, I would have required it.

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Comments

scott moss

Posted: Aug 02, 2009 07:16 PM

ventilation

when spraying a residential home do you have ventilation for the home or do you completely seal the house up while spraying.

mason

Posted: Aug 02, 2009 08:21 PM

Ventilation is part of providing good indoor air quality. The insulaton, air barrier, vapor retarder and HVAC equipment is to be designed to control the strong interactions of heat air and moisture transport within buildings.

Sprayfoam insulates and provides an air barrier. Once that is accomplished, the HVAC equipment can function more efficiently and reliably.

I suspect you are talking about vented or unvented attics. You can install sprayfoam in either concept. If you have duct work or HVAC equipment in the attic, you can spray foam to the underside of the roof deck and seal the attic. This makes an unvented attic and would be more energy efficient. If you do not have duct work or HVAC equipment in the attic, you can install the foam to the floor of the attic. Then you would vent the attic as usual.

It is important to remember that when you install sprayfoam to a building that it makes the building more air tight. In some cases depending on the degree of air sealing, additional air may be required in order to provide the appropriate air exchange. So, the HVAC contractor in new construction should consider this fact and size the HVAC units and provide make up air.

In remodeling projects, make up air may or may not be required, depending on how leaky the building is and how tight the foam makes the building.

For example in my townhome I sprayed foam in the basement, sill plate and floor of the atttic, I did not require additional make up air. But if I would have replaced my windows and sprayed foam in the walls, I would have required it.

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