You look closely at your roof and notice small raised bumps across several shingles.

They almost look like bubbles.

Are they hail impacts?

Heat damage?

A leak?

Possibly none of those.

You may be seeing shingle blistering.

GAF describes shingle blisters as small raised, pimple-like bumps and identifies trapped moisture or excessive roofing cement beneath shingles among common causes.

What Causes Shingle Blisters?

Potential contributors include:

Moisture in the roof deck

Wet decking beneath roofing materials can contribute to trapped moisture.

Attic moisture

Improper attic conditions can allow excess moisture to affect the roof assembly.

Moisture trapped in roofing materials

Although less common, moisture can sometimes be trapped within materials themselves.

Excess roofing cement

Too much roofing cement beneath shingles can also contribute to blistering.

Are Blisters the Same as Hail Damage?

No.

This distinction matters.

A blister is typically a raised area.

Hail impact is caused by an external strike.

Once a blister breaks, however, the remaining spot may be mistaken for impact damage.

That is one reason post-storm roof assessments should consider the complete pattern rather than identifying every small mark as hail.

Do Shingle Blisters Mean the Roof Is Leaking?

Not necessarily.

GAF’s technical guidance notes that blistering itself should not automatically cause leakage.

But the condition still deserves evaluation because the cause may involve:

• Moisture
• Installation
• Roof assembly conditions

A symptom does not need to be an active leak before it becomes useful information.

Should You Pop a Roof Blister?

No.

Do not intentionally puncture roofing material.

Walking on the roof or trying to investigate individual bumps yourself can cause additional damage and creates unnecessary fall risk.

Photograph the roof from a safe position and let a roofing professional evaluate the surface if blistering appears extensive.

When Should You Have It Checked?

Arrange an assessment when:

• Blisters cover a large area
• They are opening or losing granules
• The roof is also cracking
• The attic has moisture
• You recently experienced hail
• The roof is already showing significant age

NanoTech’s assessment process is intended to distinguish between localized repair needs, aging shingles that may still be serviceable, and roofs that have progressed to replacement-level failure.

Don’t Diagnose a Roof From One Bump.

A blister may look dramatic without being structural failure.

Or it may be a clue that moisture or another roof-system problem needs attention.

Seeing unusual bumps, blisters, or surface changes? Have NanoTech assess the shingles before assuming the roof needs replacement.