Top plates are very leaky.
Top plates are where a variety of building materials come together.
Top plates are a focal point in almost every energy audit and air sealing job we perform. Imagine your home. Think about the rooms right below the attic. The room most likely has drywall walls and ceiling that meet flush together. Everything looks completely sealed off and connected.
Now think about the walls of the home. There is wood framing behind the drywall. The drywall is attached to the framing of the walls and the joists of the attic for the ceiling. Take a look at this connection from above when looking down at it from the attic space. Clearly there is a gap between the wood and the drywall!!
Now for a look at what the gap does for air leakage. Tremendous amounts of cold air pouring through them!
Now, as you can see, top plates are very leaky and run throughout your attic space. To solve the problem, we make sure to determine your home's Building Airflow Standard and run a blower door test to make sure your home maintains adequate levels of air changes. Then we air seal the top plates and perform a blower door test afterwards to confirm we have left the home with adequate air changes.