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Are there concerns with having a fireplace in a home with spray foam insulation?

I'm building a home in southeast Alabama, and the general contractor mentioned that there are concerns about installing a fireplace in a home that is insulated with spray foam insulation. I haven't located any data on this topic; can anyone shed some light on this or point to a source for information?


Asked by George Tarbox
Posted May 7, 2012 4:34 PM ET


4 Answers

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Does he think the home will be too airtight and the fireplace won't have adequate combustion air? If so, there should be outside air inlets inside the firebox so that it's not an issue.

FWIW, I have not necessarily found that spray foam equals high levels of air-tightness. A lot of details go into getting tight.

Answered by David Meiland
Posted May 7, 2012 6:55 PM ET


Thanks for the reply. I'll seek clarification if the concern was about inadequate combustion air, but I believe the issue has more to do with concerns about inadequate ventilation of fumes.

According to our builder, the same vendor provides the fireplace and installs the foam insulation, and per this vendor, there was more concern about a wood burning fireplace, but also some concern about gas logs.

Our first preference is a wood burning fireplace, but if there are hazards related to the foam insulation, we'll go with another option for either the fireplace or the insulation.


Answered by George Tarbox
Posted May 7, 2012 11:19 PM ET


Many builders of energy-efficient new homes have concluded that traditional wood-burning fireplaces are incompatible with tight construction and low energy bills. That's because these old-fashioned fireplaces leak air up the chimney, and because it's tricky to provide ducted combustion air to a wood-burning fireplace.

A recent Q&A Spotlight here at GBA looked at a related issue (makeup air for wood stoves); you may be interested in reading the article: How to Provide Makeup Air for a Wood Stove.

If you have your heart set on an old-fashioned wood-burning fireplace, you'll have to accept the fact that the flue wastes energy every day of the year (because it is a thermal bridge, and because it will leak conditioned air continuously), and you'll have to be willing to open a window when you light a fire.

From an energy-efficiency perspective, a gas-burning fireplace with ducted outdoor combustion air makes more sense. (However, I hate fake fireplaces, so I wouldn't choose this option. If I were you, I would just skip the fireplace altogether.)

Answered by Martin Holladay
Posted May 8, 2012 5:55 AM ET


You can definitely have issues with proper draft of your fireplace in your sprayed foamed home. You need a fresh air ventilation system installed in your home as well as fresh air makeup air on your fireplace and kitchen exhausts. My company is located in Decatur, AL and we designed HVAC systems, install spray foam insulation, and offer building science consulting, We are Synergy Airflow and Ventilation LLC and our website is WeTestOthersGuess.com and I will be happy to discuss this isuse with you in person.

Answered by Todd Witt
Posted May 8, 2012 9:18 AM ET

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