2nd layer – open cell insulation

The closed cell foam insulation is in place. We are ready to fill the remaining two inch gap to the wall framing with open cell foam. Another truck drives up and a new crew takes over the basement.

After having witnessed the closed cell installation, I was sure that the spraying of the open cell foam would be pretty straightforward. Not so! It actually is quite challenging.

If you look at the expansion rate of the liquid into foam, you may understand why I was so eager to get the three inch thermal break gap plugged. Same for the drywall we put around the window and door openings.

I knew that the listed expansion rate for the open cell foam is 1 in 100. But seeing it grow, expand and spread out into every little space is something else.

I have no idea how we could have installed the foam without plugging the thermal break gap and the drywall around the windows.

Because of the high expansion rate, it is rather difficult to consistently apply a two inch layer on the wall. Over spraying happened quite a bit, which resulted in a layer thicker than two inches; sometimes filling the entire wall framing.

The ceiling was easier. Here we specified a three inch application to air seal the space between the garden unit and first floor. In addition to the air seal, the open cell foam also reduces noise transfer between the two living spaces.

Tech time!

Here are some of the basic specifications for the open cell foam:


About Marcus de la fleur

Marcus and his wife Cathy purchased a 100+ year old masonry two-flat in the City of Chicago to start a new pilot project – a deep energy retrofit. He is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. Marcus developed his first landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has also worked on a number of LEED certified projects. In that process he expanded his expertise from landscape architecture to building science, which continues to grow and which he applies to his own home.

2 thoughts on “2nd layer – open cell insulation

  1. First, fantastic site. I’ve read it start to ‘finish’. We too took on a sustainable renovation of a historic building (workman’s cottage) here in Chicago though we contracted it out – lack of skills and time. Your detail and information has been inspirational and frustrating as we’ve learned of areas we should have addressed differently… to that end, my question, why open cell foam for the internal ceilings vs. dense back? Isn’t air leakage between floors OK as its sharing conditioned air?

    Thanks again. Brandon

  2. Brandon, each floor (including the basement) will be its own living space/apartment. Each apartment has its own heating and ventilation controls. With that in mind, I felt that we’ll be best of air sealing each living space, keeping the conditioned air in the space that it should serve, and not have it migrating into the unit above or below. In addition to that, the open cell foam helps with the sound attenuation between the units. Hope this answers your question.

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