Shipping containers are made of corrugated steel — an excellent conductor of heat. Without insulation, a container home becomes unbearably hot in summer and freezing cold in winter. For year-round comfortable living in the UK climate, proper insulation is essential.
Preventing Condensation — The Biggest Challenge
Condensation is the #1 enemy of container homes. When warm, moist air inside meets the cold steel walls, water droplets form. Over time, this leads to rust, mould, and structural damage.
Insulation Types Compared
| Type | DIY? | Cost/m² | R-value/inch | Condensation Risk |
|---|---|---|---|---|
| Spray Foam (Closed Cell) | No | £50-80 | 7.0 | Very Low |
| PIR / Kingspan | Yes | £25-40 | 6.0 | Medium |
| Sheep's Wool | Yes | £40-60 | 3.5-4.0 | Low |
| Rockwool | Yes | £20-35 | 3.0-3.5 | High* |
*Rockwool requires perfect vapour barrier installation — high condensation risk if poorly installed.
Spray Foam Insulation (Closed Cell)
Closed-cell spray foam is widely considered the best insulation for shipping container homes. It's sprayed directly onto the steel walls, expanding to fill every gap and creating a continuous thermal barrier.
Advantages: Bonds directly to steel — eliminates condensation risk, highest R-value per inch, acts as vapour barrier, adds structural rigidity. Disadvantages: More expensive (£50-£80/m²), requires professional installation.
Recommended thickness: 50-100mm for walls, 100-150mm for roof/floor.
PIR / Kingspan Insulation
PIR boards are rigid foam boards with foil facings. They're a popular DIY-friendly option.
Advantages: Lower cost (£25-£40/m²), DIY-friendly, high R-value, widely available. Disadvantages: Requires careful sealing at joints, need separate vapour barrier, more prone to thermal bridging.
Sheep's Wool & Natural Options
For eco-conscious builders, natural insulation materials like sheep's wool are excellent choices. They're breathable, sustainable, and have good thermal properties.
Recommended thickness: 100-150mm for walls, 150-200mm for roof.
Step-by-Step Installation
Spray Foam (Professional): Clean walls → install timber battens → professional spray foam application → trim excess → install plasterboard.
PIR Boards (DIY): Install timber stud framework → cut PIR boards to fit → seal joints with expanding foam and tape → install vapour barrier → install plasterboard.
Cost Breakdown
- 20ft container: Spray foam £2,500-3,500 | PIR £1,000-1,800
- 40ft container: Spray foam £4,000-6,000 | PIR £1,800-3,000
- 2x40ft double: Spray foam £7,000-10,000 | PIR £3,500-5,500
Our container homes come fully insulated to UK building regulations. Contact us for a quote including professional spray foam installation.
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