Does Roofing Tar Get Hard

November 29, 2025

2 min read

Yes, roofing tar does get hard. Roofing tar starts soft and sticky when it is hot, but it hardens as it cools down. This hardening process is important for your roof to stay strong and protect your home. Understanding how tar works helps you know when your roof needs care or repair.

How Does Roofing Tar Harden?

Roofing tar hardens through a process called oxidation. When tar is exposed to air and sun, it changes from a liquid to a solid. This takes a few days to a few weeks depending on the weather.

Heat speeds up the hardening process. On hot days, tar hardens faster than on cool days. Once tar is fully hard, it bonds to your roof and creates a water-tight seal that keeps rain out.

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Why Does Roofing Tar Get Hard Over Time?

Roofing tar hardens because it loses moisture. The sun and wind dry out the tar slowly. This is normal and expected.

As tar gets older, it becomes more brittle. According to RubyHome, asphalt shingles have a typical lifespan of 20 years, and the tar underneath breaks down during this time. Hard, old tar can crack and split. Cracks let water into your roof, causing leaks and damage.

What Happens to Tar When It Gets Too Hard?

When roofing tar gets too hard, it loses its flexibility. It cannot bend with your roof when the building moves or the temperature changes. This causes the tar to crack.

According to industry data, 33% of homeowners need roof replacement due to leaking. Many of these leaks start because old, hard tar has cracked. Once cracks form, water gets inside and damages the wood under your roof. This leads to rot and mold.

Hard tar also becomes less sticky. If you try to patch a roof with hard tar, the patch will not stick well. New material will not bond to the old, brittle tar.

When Should You Replace Hard Tar on Your Roof?

According to This Old House, most roofs last between 25 to 50 years. When your roof reaches 15 to 20 years old, the tar starts to fail. You should have a professional inspect your roof every year after it turns 15 years old.

Look for these signs that tar has gotten too hard:

Cracks in shingles or tar
Curling or buckling shingles
Water stains on your ceiling
Granules missing from shingles
Leaks during rain

If you see these signs, call a roofer right away. According to RubyHome, the average roof replacement cost is $9,526, with a range from $5,868 to $13,217. Waiting makes problems worse and more expensive to fix. Getting repairs early saves your home and your wallet.

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Contact a qualified roofing services for expert guidance on roof repair, replacement, or installation.