Insulation – how it started

Our two key goals are super-insulation (high R-value) and air-tightness (elimination of leaks and drafts). Simple enough, isn’t it? To my surprise, this issue got me deep into rocket science. There was a very steep learning curve and my ideas and aspirations on insulation options had changed several times over the past year based on emerging facts and realities.

While we were house hunting, we were only considering buildings with a masonry shell for the structural and longevity aspects (see also “Dream home wish list” post). Another idea of mine was to use the masonry building shell as thermal mass by leaving it exposed to the interior and applying the insulation on the outside.


Fast forward. We now own our house with typical Chicago common-brick side elevations and an ornate front elevation. Our dream of exposed interior brick walls radiating warmth appears to materialize. To get there, we will need to super-insulate the building from the outside. I began to research our options, and ran into a brick wall (pun intended).


Do we really want to hide our ornate front elevation behind insulation? Of course not! We would insulate the front from the inside – and would be left with big thermal bridges to the left and right. Not good.

Then there is the dimensional issue. Portions of the west side of our building are almost on the property line. We would encroach into our neighbor’s property if we began to insulate on the outside of these wall sections.

How about insulating portions on the outside and others on the inside? Not only is this getting really complicated, but I end up with a whole bunch of thermal bridges that would defeat our insulation goal.

And, of course, there are code issues to contend with. Chicago common brick has an excellent fire rating. Whatever I would use to cover the outside insulation will have to meet the one-hour fire rating requirement.

Most innovative ideas start with an uphill struggle. If we really pushed it and worked long and hard, we possibly would find a way to make it work. The question is: Is it worth it?

I talked with a lot of friends, contractors and green building professionals and did not receive any encouragement for my idea – absolutely none. Nor did I find any supporting clues in my research. The consensus was that insulating our building from the outside was too resource intensive and expensive to justify any thermal mass benefit in the interior – thermal mass we may not even need with a super-insulated and airtight envelope.

Time to hit the reset button! How about insulating the shell from the interior? But what would be the best material choice? And how can we do this without compromising the integrity of the 100+ year old Chicago common-brick walls?

About Marcus de la fleur

Marcus 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. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

2 thoughts on “Insulation – how it started

  1. Hi Marcus,
    Did any of the people you consulted mention a possible downside of super-insulating old masonry building on the inside? When you insulation the masonry from the inside of the house – by using a high R value – you move the freeze point of the masonry inward. The end result is that the masonry experiences much more extreme freeze/thaw cycle – which could – in the presence of moisture -lower its structural integrity. So far from what I have researched, this is avoidable if employ other means to make sure that the masonry is not absorbing more moisture than it is able to expel via evaporation. ItHave you looked into this? And have you come to any conclusions?

  2. Daniel – you make a very good and very important point!

    The insulation questions must be answered on a project by project basis after careful analysis of the existing conditions and potential risks that could come along with SPF on the interior walls. Here is a quick link that cuts to the point:

    But you may also want to read through the insulation series:

    Insulation – how it started
    Insulation – lots of conflicts
    Insulation – starts with moisture management
    Insulation – which material cuts it
    Insulation – how much is needed
    Insulation riddle resolved
    Following the control layers
    The insulation riddle is back
    Insulation update

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.