We recently bought a 16 year old house that has aluminum capping over the trim around the garage doors. The gap between the aluminum and the brickwork (and the wood behind the aluminum) is large enough that you can see light leaking through and feel the cold air blowing through. I would like to caulk this to keep out the cold/heat, moisture, and pests (of which we get a lot) but I'm questioning why it was never done in the first place. So, a few questions:

  • Is there any reason you wouldn't want to caulk these joints?
  • If caulking is acceptable/recommended:
    • What type of caulk would be most appropriate? I'm guessing silicon?
    • Should the caulk be placed between (sandwiched) between the aluminium and brick, or just around the perimeter (meaning, should it have been placed during installation, or can I apply from the outside as usual)?
    • Is there anything else I should know before undertaking this task?

For reference, here's what it looks like: enter image description here

1 Answer 1


Backer rod and sealant is appropriate for joints between dissimilar materials such as that pictured in the question. Preparing the brick surface, correctly sizing the backer rod, and properly installing the sealant may all play a role in long term performance of the system.

Select the sealant for your application based on manufacturer's literature. The label on the tube often contains clear guidance.

Filling voids behind the joint with fiberglass insulation or with spray foam insulation prior to sealing may also improve thermal performance and reduce air infiltration.

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