What Is a Caravan and Motorhome Damp Report? Understanding Caravan and Motorhome Damp Readings and What the Numbers Mean

What Is a Caravan Damp Report?

A caravan damp report is a detailed inspection that measures moisture levels within the walls, roof, floor, and structural areas of a caravan. The report helps identify water ingress, condensation issues, or hidden damp problems before they become expensive repairs.

Most professional caravan service centres perform damp checks as part of an annual service, and the results are recorded on a damp report showing moisture readings from various locations around the caravan. If you’re buying a used caravan, it’s also worth reviewing our Buying a Used Caravan: Essential Checks Guide.

Regular damp inspections are one of the most important maintenance checks you can carry out. Early detection can prevent thousands of pounds worth of structural damage.

Why Are Damp Checks Important?

Modern caravans are built using lightweight construction methods that often include timber framing, insulation, and bonded panels.

If water enters through:

• Roof joints

• Awning rails

• Window seals

• Marker lights

• Rooflights

• Service hatches

• Front and rear panels

  
  

it can become trapped inside the structure where it may not be visible until significant damage has occurred.

Damp can lead to:

• Rotting timber

• Delaminated wall panels

• Mould growth

• Soft floors

• Structural weakness

• Reduced caravan value

How Is a Caravan Damp Check Carried Out?

A technician uses a moisture meter to test multiple locations around the caravan.

Common test areas include:

• Front corners

• Rear corners

• Around windows

• Rooflight openings

• Around locker doors

• Under front windows

• Washroom walls

• Around wheel arches

• Near service doors

• Around external vents

The moisture meter sends a small electrical signal into the wall structure and measures the moisture content present.

The readings are then recorded as percentages.

Example Caravan Damp Report

“Below is a typical caravan damp report showing moisture readings taken around the walls, roof, floor and openings. Each number represents a moisture reading recorded during inspection.”

What This Report Shows

Most readings are healthy (8-12%), but the highlighted areas show elevated moisture levels. The reading of 94% would indicate severe damp requiring immediate investigation, while readings above 20% would normally warrant further inspection.

What Do Caravan Damp Readings Mean?

The percentage shown on a damp report indicates the amount of moisture detected in the structure.

0% to 15% – Excellent

These readings are generally considered normal.

Most modern caravans will show readings somewhere within this range.

No immediate action is usually required.

15% to 20% – Monitor

This area is often considered a caution zone.

Possible causes include:

• Condensation

• Minor seal deterioration

• Seasonal moisture

A technician may recommend checking the area again during the next service.

20% to 30% – Investigation Required

Readings above 20% generally indicate moisture ingress.

At this stage:

• Seals may need replacing

• Further inspection is required

• Water ingress is likely occurring

Repairs are often straightforward if caught early.

30% and Above – Significant Damp

Readings over 30% usually indicate an active water ingress problem.

You may also notice:

• Soft wallboards

• Discolouration

• Musty smells

• Loose wallpaper

• Internal staining

Immediate investigation is recommended.

40%+ – Serious Structural Concern

Very high readings suggest prolonged exposure to moisture.

Potential issues include:

• Rotting timber framework

• Wall delamination

• Extensive structural repairs

Professional assessment is essential.

Why Can Damp Readings Vary?

Several factors can affect moisture readings:

Weather Conditions

Testing after heavy rain may produce slightly higher readings.

Temperature

Cold weather can increase condensation levels.

Wall Construction

Different caravan manufacturers use varying materials that can influence readings.

Location of the Reading

A reading of 22% around a rooflight may be more concerning than the same reading in an area known to experience temporary condensation.

This is why damp reports should always be interpreted by an experienced caravan technician.

What Is an Acceptable Damp Reading When Buying a Used Caravan?

As a general guide:

Damp Reading	Buying Advice
0-15%	Excellent
15-20%	Usually acceptable
20-25%	Request investigation
25-30%	Negotiate repair costs
30%+	Proceed with caution

Always ask to see the latest damp report before purchasing a used caravan.

A caravan with a clean service history and consistent low damp readings is often a much safer purchase.

Can Caravan Damp Be Repaired?

Yes.

Common repairs include:

• Resealing awning rails

• Replacing window seals

• Rooflight resealing

• Locker door seal replacement

• Front or rear panel resealing

If caught early, repairs are often relatively inexpensive.

However, long-term damp can require wall rebuilds or timber replacement, which can become costly.

Signs Your Caravan May Have Damp

Watch for:

• Soft wall panels

• Wallpaper bubbling

• Black mould spots

• Musty smells

• Discoloured wallboards

• Soft floor areas

• Condensation between panels

If you notice any of these symptoms, arrange a professional damp inspection.

How Often Should You Have a Damp Check?

Most manufacturers recommend an annual service which includes a damp inspection.

You should also consider an additional damp check if:

• The caravan has been stored outside all winter.

• You discover a leaking rooflight or window.

• The caravan is more than 10 years old.

• You’re planning to sell it.

• You’re considering buying it.

Summary

A caravan damp report is one of the most valuable indicators of a caravan’s condition. Moisture readings below 15% are generally considered healthy, while readings above 20% should be investigated further. Early detection can save thousands of pounds in repair costs and help maintain your caravan’s value.

Whether you’re buying, selling, or maintaining a caravan, understanding what damp readings mean can help you make informed decisions and avoid expensive surprises.

FAQs

What damp reading is acceptable in a caravan?

Generally, readings below 15% are considered good, while readings between 15% and 20% are usually acceptable but should be monitored.

Is 20% damp bad in a caravan?

Not necessarily, but it should be investigated. It may indicate early water ingress or condensation issues.

Can caravan damp be fixed?

Yes. Most damp problems can be repaired if caught early before significant structural damage occurs.

Should I buy a caravan with a 30% damp reading?

Proceed with caution. A professional inspection should identify the cause and likely repair costs before purchase.

How much does a caravan damp check cost?

Prices vary but typically range from £30 to £80 as a standalone inspection, or it may be included within an annual caravan service.