Question

How can I add insulation without major renovations?

Asked by Theresa
Basking Ridge, NJ

I recently purchased a condo, but it is exposed on 3 sides and the walls always seem to be cold. It was build in 1994, so I'm not sure how well insulated it is. It was suggested to just add 2 x 4s on the outer walls and insert insulation between them, and cover with a second layer of drywall though this would make the rooms smaller and would require redoing the heating ducts Of course I could tear out the drywall and re-insulate, but that's a lot of work (and messy). Would it just be better to line the outer walls with floor to ceiling bookcases? Is there a third option?

Answer

Michael Holcomb

Answered by Michael Holcomb

Byron Center, MI

Alliance for Environmental Sustainability (Headquarters)

November 20, 2012

Theresa,

Condominiums tragically often use low cost materials and low bidder when it comes to insulation. There are always exceptions of course but your walls being cold suggests this might be your problem.

Convective loops

I suspect that your walls are insulated with fibrous (fiberglass blanket) insulation. This material is ineffective in cold weather states at preventing heat transfer through convection.

Convective loops may also downgrade insulation performance.

  • Air trapped within the wall cavity is warmed (and rises) along the interior wall of the cavity and is cooled (and drops) along the exterior wall of the cavity.
  • This looping action draws cold air through the insulation resulting in reduced performance.

Fiberglass blanket is oftentimes installed poorly, with gaps, compressions and shortages which further reduce its ability to reduce heat loss.

Use an infrared camera

Poorly installed insulation can be verified by hiring a qualified contractor to complete an Infrared analysis of the walls in question. 

Thermal images con provide you with valuable information concerning the condition of the thermal envelope.

  • In this image every stud is clearly visible. Insulation density is uneven in the darker blue wall cavities in the left quadrant of the image. 
  • Defects in the thermal envelope can then be addressed by a remediation contractor.

Remediation

You could take some strips of siding off the exterior and cut the sheathing to expose the insulation. An insulation contractor could remove the old fiberglass and replace with dense-packed cellulose to fill the cavities fully.

  • Once the cavities are full you would repair the sheathing and siding.
  • If possible caulk the window and door openings with low expansion foam/sealant to reduce air intrusion into the cavity.
  • This could also be done from the interior side by removing strips of drywall but it is more disruptive.

Many condominiums also have a significant amount of convective communication with the attic. So you should address air sealing the attic at the same time.

  • Cover all can lights with suitable sealed covers.
  • And spray a thin layer of closed cell foam to the attic floor at pipe and wire penetrations as well as top plates to significantly reduce heat loss through the ceiling which would also reduce air intrusion through the side walls (air in equals air out).
 


Start with an energy audit that includes Infrared analysis and follow the detailed recommendations of the energy professional.

It is my recommendation that the person that analyzes the home is not connected to the company that makes repairs. You’ll pay more for the audit but you’ll have more confidence that the information is not biased by other services the company may have available for hire.

 

For more information:

Read "I want to add wall insulation to my 1920 home. I have two locally available options -- Icynene and Tri-polymer foam. Can you advise me?" a Q&A answered by Alex Georgiou.

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