Is this ok to be left out in freezing temperatures overnight before application?

probably not, and is not recommended in the application specifications either. Read the specification sheet for the product on the amozon site or on the product site. I will say the product was VERY easy too use.

Should I seal up larger cracks before or after applying this?

I would suggest sealing the crack before applying the final top coat of this product. I did that let the sealed crack dry and then did an overall coating with this. Came out great.

How long will this last on my chimney crown? Can you be more specific than just “years”? (Other products say 15 years.)

couldn't tell you, ask me in 15 years.

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Chimney Crown Sealer - Brushable Waterproof Sealant Prevents Leaks - 1/2 Gallon

Product ID: 228360427

Details

Brand
Item Form
Paste
Material
Elastomeric
Style
Compact
Water Resistance Level
Waterproof

💧Elastomeric waterproof membrane

⏱️Fast drying & curing

🖌️Brush-on easy application

$138.14

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Description

🛡️ Seal leaks today, protect your home tomorrow!

RAPID DRY CURE TIME - Touch dry in under an hour, fully cured in 2-4 hours for quick project turnaround.
FLEXIBLE WATERPROOF SHIELD - Creates a durable, crack-resistant barrier that flexes with your chimney.
LONG LASTING LEAK PROTECTION - Stops water infiltration fast, preserving masonry integrity season after season.
OPTIMIZED COVERAGE EFFICIENCY - Covers up to 20 sq. ft. per ½ gallon, maximizing value and minimizing waste.
EFFORTLESS BRUSH ON APPLICATION - No primers needed—just brush on two coats and save time on repairs.

MasonryDefender Chimney Crown Sealer is a brushable elastomeric waterproof sealant designed to protect concrete chimney crowns from water damage. It forms a flexible, durable membrane that resists cracking and chipping, dries quickly within 2-4 hours, and covers up to 20 sq. ft. per half gallon. Ideal for minor crack repairs, it requires no primer and offers long-lasting leak prevention to maintain chimney integrity.

Specifications

ASIN	B08F7ZKG7H
Best Sellers Rank	#82,265 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #278 in Hardware Sealers
Brand Name	MasonryDefender
Color	Light Gray
Compatible Material	Concrete
Customer Reviews	4.7 4.7 out of 5 stars (543)
Item Form	Paste
Manufacturer	SaverSystems
Material Type	Elastomeric polymer
Number of Items	1
Style Name	Compact
Surface Recommendation	Chimney Crown (Concrete)
UPC	709057000918
Water Resistance Level	Waterproof

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$138.14

Duties & taxes included

In stock

Sold byAmazon USADelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

Buyer Protection · Full refund if your order doesn't arrive as described.

Desertcart purchases this item on your behalf and handles shipping, customs, and support to USA.

Secure transaction

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TrustScore 4.5 | 7,300+ reviews

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Fantastic and great service. Shipping was faster than expected.

1 week ago

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Great price for an authentic product. Fast international shipping too!

3 weeks ago

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