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Should I Use Foam or Silicone?

Mariane Garcia
  • Updated

Perimeter sealing best practices — and mistakes to avoid

A properly sealed door system protects against air infiltration, moisture intrusion, and long-term movement. The question isn’t foam or silicone — it’s knowing where and how to use each one effectively.

 

The Quick Answer:

Use low-expansion foam for insulation and high-quality silicone sealant for water and air sealing. Each serves a different purpose and should be applied in specific areas.

 

Where to Use Each Material

Low-Expansion Foam

Where to apply: Inside the wall cavity between the rough opening and the door frame.

  • Provides thermal insulation

  • Minimizes sound transmission

  • Helps reduce drafts

  • Must be low-expansion to avoid distorting the frame

Note: High-expansion foam can bow or warp the frame and should never be used.

 

Silicone Sealant (Exterior Grade)

Where to apply: Around the exterior perimeter of the frame where it meets stucco, siding, masonry, or trim.

  • Prevents water intrusion

  • Creates a flexible seal that accommodates structural movement

  • Critical for long-term weather resistance

Product guidance: Use a UV-stable, paintable silicone or hybrid sealant. Avoid acrylic caulks, which dry out and crack over time.

 

Common Mistakes to Avoid

  • Using high-expansion foam, which can distort or push the frame out of alignment

  • Sealing only one side of the opening (either inside or outside)

  • Applying sealant without a backer rod where joint width exceeds 1/4"

  • Sealing before the frame has been properly shimmed and anchored

 

Summary of Best Practices

Application Area Recommended Product
Between frame and wall Low-expansion polyurethane foam
Exterior perimeter seal 100% silicone or hybrid sealant
Wide gaps (over 1/4") Backer rod followed by sealant

 

Questions or Jobsite Support?

We’re here to help if you need clarification based on your product line, wall condition, or site requirements.

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