I need to seal the gaps between my garage brick wall and the vinyl siding. Would product such as "Great Stuff Gaps & Cracks Insulating Foam Sealant" for example would do the work? or I need something else?

Gap between my brick wall garage and vinyl siding

  • 1
    Why isn't there a J-channel there?
    – isherwood
    Aug 10, 2023 at 12:51

2 Answers 2


As you've seen, caulking to vinyl is bad practice in general. Vinyl expands too much with temperature, and it's not really intended to be the drain mechanism anyway. That should be handled by house wrap behind the siding and appropriate flashing. Spray foam is never an exterior solution and wouldn't work well here with all that movement anyway.

  1. Remove the siding on that wall and scrape the bulk of the caulk off the brick.
  2. Install metal L-flashing to the brick. Caulk between the metal and the brick as you install. The caulk should be hidden for the most part. For best appearance the protruding flange should be hemmed.
  3. Install rubber flashing tape over the metal on the wall. This seals the metal to the house wrap I hope is present, and it also seals the nail penetrations from the next step.
  4. Install standard J-channel against the brick.
  5. Reinstall the siding.
                 ____________ <-- metal flashing
 |             ||  ~~~~~~~~~~~~~~~~ <-- rubber flashing tape
 |             |||‾‾‾‾‾‾‾ <-- J-channel
 |   brick     |||___
 |_____________|^-- caulk behind flashing

The product normally used in this instance is polyurethane caulk.

Use gloves, because this stuff is sticky and cannot be washed off with soap and water. Mineral spirits is needed to clean any mess, but it is paintable and flexible and stays that way in a wide range of temperatures.

Clean out any dirt and old caulking that is loose before applying and you will be good for years.

  • And, to reiterate, expanding foam is not the correct answer (unless there's a large gap and it's used to back fill - but in that case "backer rod" would be a better option behind the caulk).
    – FreeMan
    Aug 10, 2023 at 11:46
  • 1
    Caulking to vinyl is just a bad idea. That's not how either product should be used.
    – isherwood
    Aug 10, 2023 at 12:53

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