Which is the Best Chimney Sealant – Silicone or Polyurethane?

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All areas surrounding the chimney and other flues on your roof must be watertight or you will start to notice water damage on the ceiling or walls inside your home. Two of the most popular sealants are silicone and polyurethane. Both work very well, but you still need to know the differences before making your decision.

Silicone and Polyurethane Similarities

Both silicone and polyurethane allow for up to 50% movement when dry. This makes them equally suitable for flashing that may try to bend or bow in time or with the weather. Both keep air and water out and give the flashing and chimney a nice, finished appearance.

Silicone Sealant

  • Cures quickly.
  • Cures to a soft finish.
  • Not good for high traffic areas.
  • Does not hold up to abrasion well.
  • Works best on metal, glass, and tile.
  • Can be used in any temperature, works well in cold temperatures.
  • 20+ year lifespan.

Polyurethane Sealant

  • Takes more than 24 hours to fully dry.
  • Cures to a hard finish.
  • Does well in high traffic areas.
  • Holds up well to abrasion.
  • Works best on wood.
  • Difficult to apply in cooler temperatures and does not make a permanent bond when cold.
  • 5-10 year lifespan.

When Sealant is Used

Any hole that is put into your roof needs to be sealed as quickly as possible. Rain, ice, and snow will get into them and cause serious problems to your home. A silicone or polyurethane sealant will seal the holes and gaps, and prevent water damage.

Fireplace Safety and Chimney Inspections in Ardmore

We have two CSIA Certified chimney sweeps standing by to assist you with your chimney needs. Give us a call at 610-626-2439 to schedule an appointment for a chimney inspection or cleaning. We provide chimney services throughout Ardmore and the Main Line region.

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