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Insulating 1940s house with CMU walls

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Insulating 1940s house with CMU walls (post #207587)

user-2413098 on Tue, 03/12/2013 - 19:42
in

Planning a 2nd story addition to a 1940s house with CMU wall construction, plaster on the inside and stucco on the outside.  Thinking of some thickness of polyiso on the outside (2" min) and maybe something on the inside.  The wall, including stucco and plaster are in great shape, but must insulate. To insulate well, the walls will become quite thick.  The other extreme option is demo of the walls but that's a lot of extra scope.  Welcome to any thoughts.

-A +A

That's a tough one.  I don't (post #207587, reply #1 of 2)

by MarkH in reply to user-2413098 [original] on Wed, 03/13/2013 - 02:52

That's a tough one.  I don't know your location, but certain areas have environmental conditions that need consideration.  Earthquake, hurricane, tornado etc may make your existing walls unsuitable for more load.  Youcould use stud walls on the outside of the existing wall, but that will involve foundation work.

It may be possible to lift the existing roof with a crane and install new walls under it.  Then install foam inside the house on the lower level.  I think insulation on the outside would be better because you have thermal mass inside the house.

I would have an engineeer evaluate your possibilities.

Thanks.  It is in the Boston (post #207587, reply #2 of 2)

by user-2413098 in reply to MarkH [original] on Wed, 03/13/2013 - 04:15

Thanks.  It is in the Boston area, so no seismic requirements.