GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Wall Top Plate leakages – how big an issue?

tonymitch | Posted in Energy Efficiency and Durability on

A recent Energy Audit of a friends house demonstrated that their wall top plates may be leaking, by taking an IR image whilst performing the blower door test.   I understand the image showed larger cool spots at the wall/ceiling corners at ACH50.  However, the IR image under normal atmospheric pressure conditions show cool spots, but possibly no worse than that of thermal bridging.   the ACH50 for the house was 3.2.  An insulation company has quoted about $10,000 to 1. remove existing 12″ blown-in loose fill insulation, 2. spray-foam all internal and external top plates then 3. blow-in 20″ new insulation to R60.
I’m not convinced it’s worth it.  I modeled their house and come within 10% of their current annual energy usage. I estimate that getting the ACH50 down to 2.0 and adding 8″ of extra insulation will save them about $200 pa.   If all the gaps in can lights, electrical outlets and other wall/ceiling penetrations were sealed, surely there would be no source of air to form a flow into the attic space?  The cost to do that is just a few hundred dollars?   
Thoughts? Advice?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    DCcontrarian | | #1

    I think you know the answer. $10k doesn't justify $200/year in savings.

    1. Expert Member
      MALCOLM TAYLOR | | #4


      A $200 savings is really a $400 loss when GICs are yielding almost 6%.

  2. walta100 | | #2

    Simply because that is the location the thermal camera allows you to detect the air movement does not mean that is the only location you can stop the flow of air.

    The air moving thru gap at the top plate is flowing thru the walls and moving thru more accessible gaps to enter the walls. Where you stop the air flow is irrelevant so long as it is stopped.

    What you are looking for is someone to do blower door directed air sealing they will give you ACH50 numbers from before and after their work

    The way I see it air sealing is not complex work. Air sealing is a simple task that often requires you to work in difficult locations.

    If you don’t need ACH50 numbers tape a box fan into a window and use the smoke from incent sticks to find the leaks.


    1. tonymitch | | #3

      Walta, thank you for your words or reinforcement and encouragement! And what a great idea in terms of practically finding the sources of leaks. Im on it.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |