🚐 High Peak Conversions – Van Insulation Guide

1️⃣ Why Insulation Matters in Your Camper Conversion

A properly insulated van:

• Keeps you warm in winter

• Keeps you cool in summer

• Reduces condensation

• Improves sound-proofing on the road

• Makes the van feel more “house-like” and comfortable

Good insulation is one of the most important steps in a camper conversion — and also one of the most misunderstood.

2️⃣ Why We Recommend Foil-Backed Closed-Cell Foam

At High Peak Conversions, we avoid the usual multistep insulation method (sound-deadening + insulation + vapour barrier).
Why?

Because modern automotive foam does all three jobs in one product.

Our 10mm self-adhesive foil-backed closed-cell foam provides:

✔ Sound deadening

It reduces panel vibration and road noise without needing separate butyl mats for every panel.

✔ Thermal insulation

Closed-cell foam doesn’t absorb moisture and provides effective heat resistance.

✔ Vapour barrier

The foil backing stops warm, moist air reaching the cold metal and eliminates condensation inside the walls.

✔ Easy installation

Peel, stick, and you’re done. No messy sprays, no staples, no battens, no gaps.

👉 Product link:
https://highpeakconversions.co.uk/category/furniture-construction/thermal-acoustic-insulation/?v=7885444af42e

3️⃣ Why We Don’t Recommend Wool, Rockwool or Fibreglass

These traditional house insulations:

• Absorb water

• Cause mould

• Can sag inside cavities

• Require a separate vapour barrier

• Aren’t designed for a moving, vibrating vehicle

A van is not a house — moisture, movement, and temperature swings make these materials risky.

Closed-cell foam avoids all of these problems.

4️⃣ Where to Install 10mm Foam in Your Van

✔ Walls

Apply directly to the metal skin. Covers large flat panels easily.

✔ Ceiling / roof

Stops condensation forming overhead and reduces drumming noise.

✔ Floor (optional)

Foam can be applied under a plywood subfloor, though many converters prefer thicker boards for thermal performance.

✔ Wheel arches

Helps reduce road noise dramatically.

✔ Doors

Behind plywood door cards to eliminate rattles and heat loss.

5️⃣ How to Install It (Simple Step-by-Step)

1. Clean the metal
   Use panel wipe or isopropyl alcohol. Remove dust, grease and loose paint.

2. Cut foam to shape
   A sharp Stanley knife or scissors works perfectly.

3. Peel back a section of the adhesive
   Start small — don’t peel the whole sheet at once.

4. Apply from the centre outwards
   Avoid trapping air bubbles.

5. Press firmly with a roller or your hand
   Ensures maximum adhesion.

6. Overlap joins slightly
   For a fully sealed vapour barrier.

7. Repeat until all metal is covered

That’s it. No extra layers needed, although you can stuff the supporting framework and any hard to reach areas with ‘recycled plastic bottle’ wadding. You way also like to attach a layer of this same wadding over the foil backed foam, to give your self an extra layer of insulation.

6️⃣How Much Insulation Do You Need?

Each roll of High Peak Conversions insulation covers 10 m² (1m x 10m).

Here’s how many rolls you’ll typically need for different van sizes:

🚐 Small Vans (Berlingo, Caddy, Partner, Combo)

1–2 rolls

Covers the walls, ceiling, rear doors and sliding door.
Small vans usually have 10–15 m² of internal surface area.

🚐 Medium Vans – SWB (Transit Custom SWB, VW T5/T6 SWB, Vivaro SWB)

2 rolls

Enough for full interior coverage (walls, ceiling, doors and wheel arches).
Most SWB vans are around 18–22 m² inside.

🚐 Medium Vans – LWB / MWB (T5/T6 LWB, Custom LWB, Sprinter MWB)

2–3 rolls

Choose 3 rolls if you plan to insulate every cavity or want to include the floor.

🚐 Large Vans – LWB (Sprinter/Crafter LWB)

3–4 rolls

Larger panel areas and taller ceilings mean more material is required.

🚐 XLWB / High-Roof Vans (Sprinter Super High Roof, Crafter L5)

4–5 rolls

Longer vans with extra height can approach 40–50 m² total panel area.

🪵 Insulating the Floor?

Add 0.5–1 extra roll, depending on how much coverage you want beneath the plywood.

💡 Tip

It’s always better to have slightly more material than not enough — especially if you want to overlap joins or cover awkward shapes like wheel arches and door frames.

7️⃣ Should You Add Extra Sound Deadening?

Not always necessary.

Closed-cell foam already reduces resonance, but for those who want a super quiet build, you can optionally use:

• Butyl sound-deadening patches on large vibrating panels

• Then apply the foam over the top

This is completely optional and depends how quiet you want the van to feel.

8️⃣ Insulation Mistakes to Avoid

🚫 Leaving gaps
Every gap is a cold bridge.

🚫 Using wool/fibreglass without a vapour barrier
This causes condensation and mould.

🚫 Spray foam
It can warp panels and trap moisture.

🚫 Bubble foil without insulation
It reflects radiant heat only — it does NOT insulate on its own.

🚫 Blocking factory drainage holes
Vans must be allowed to breathe.

9️⃣ Why 10mm Foam Is Usually Enough

Some people think they need 25mm or even 50mm insulation.

In a van, thicker isn’t always better.
10mm is ideal because:

• It doesn’t interfere with panel trims

• It doesn’t bow the interior ply lining

• It gives excellent insulation for a heated, lived-in van

• It prevents condensation, which is the real enemy

Anything thicker often creates problems with fitting furniture and wall panelling.

🔟 Recommended Product

High Peak Conversions 10mm Foil-Backed Self-Adhesive Foam

The only insulation most van builders will ever need.

👉 https://highpeakconversions.co.uk/category/furniture-construction/thermal-acoustic-insulation/?v=7885444af42e

✅ Summary

If you want:

• Insulation

• Sound deadening

• Vapour protection

…without doing three separate layers…

→ 10mm foil-backed self-adhesive foam is the perfect solution.

Clean.
Quick.
Professional.
Reliable.