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Community and Q&A

Converted Attic and Soffits

VinceB | Posted in General Questions on

I recently had my attic converted from cellulose to spray foam.  

This was done to facilitate moving my Air Handler into the attic at the recommendation of my HVAC technician.  When planning the work he indicated that it would be very important to close and seal my attic Soffits while the Foam installer indicated it wasn’t really necessary.  

I had 6 inches of open cell spray foam installed and went on with my life.  

Now that some time has passed and being in south Florida in the back of my mind I am wondering if I should actually seal up my attic soffits better and if so what method would be easiest.

I have searched the web and found many explanations on how this should be done in new construction but nothing on upgrading an existing home.

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  1. Expert Member


    I assume the foam installer said the because he used a continuous layer of foam over the top plates so while the soffit vents still allow air to circulate in the overhangs, it can't get into the attic. If that's so, there is no real benefit to closing off the soffits.

    More important with open cell foam is that you condition the attic to keep humidity levels low. Otherwise moist air can move up through the foam and accumulate in the roof sheathing.

    1. VinceB | | #2

      Thank you for sharing your expertise!

      My attic is cool, however there is not dedicated return up there. The HVAC Tech indicated the "Squish foam" ducts that were installed with my home are leaky enough that a dedicated return was not necessary, was that incorrect?

      what humidity level would I want to ensure I was staying under?

      If I installed a vent up in the attic, wouldn't the can lights and humid areas become a source of condensation? as essentially my attic would become pressurized and cold air would be coming through the light fixtures and what not.

      Sorry if these are dumb questions.

      1. Expert Member
        MALCOLM TAYLOR | | #3


        Not dumb questions at all.

        Probably the simplest way to moderate humidity would be a dedicated dehumidifier. I'm not sure what the appropriate humidity level for an attic in Florida should be. Hopefully other posters will chime in with the information.

        You may find this article useful:

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