Garden RoomsInsulationSIP Panels
Garden Room Insulation Guide: Why SIP Panels Are Best in 2025
1 January 2025Benjamin Alder-Howe2 min read
Insulation quality directly determines whether your garden room is usable year-round or becomes an expensive shed. Here's why SIP panels outperform traditional methods.
Why Garden Room Insulation Matters
Winter Problems with Poor Insulation
- Freezing temperatures make the space unusable
- Condensation and mold issues
- Expensive heating bills
- Cold spots and drafts
Summer Problems
- Overheating makes the space uncomfortable
- High air conditioning costs
- Temperature fluctuations throughout the day
Insulation Options Compared
| Method | U-Value | Installation Time | Cost |
|---|---|---|---|
| SIP Panels | 0.209-0.264 | Fastest | Medium-High |
| Timber Frame + PIR | 0.20-0.25 | Moderate | Medium |
| Timber Frame + Mineral Wool | 0.25-0.35 | Slow | Low |
| Budget EPS Panels | 0.35-0.45 | Fast | Lowest |
SIP Panel Thickness Guide for Garden Rooms
72mm - Storage Only
Only suitable for non-heated spaces. Not recommended for garden rooms.
97mm - Occasional Use
Good balance for spaces used occasionally. Suitable for summer houses.
122mm - Daily Use (Recommended)
THE GOLDILOCKS CHOICE - Perfect for home offices and daily-use garden rooms. Best balance of performance and cost.
142mm/172mm - Premium Performance
For those wanting the best thermal efficiency and lowest running costs.
Installation Best Practices
- Level Base: Ensure your foundation is perfectly level
- PIR Splines: Use proper splines between panels to eliminate thermal bridging
- Comprehensive Sealing: Seal all joints with appropriate tape
- Rapid Weatherproofing: Get the structure weathertight quickly
- Mechanical Ventilation: Install MVHR or extract fans to prevent condensation
Common Insulation Mistakes
- Underspecifying Insulation: Choosing too thin panels to save money
- Ignoring Thermal Bridging: Using timber instead of PIR splines
- Skipping Ventilation: Airtight buildings need mechanical ventilation
- Poor Airtightness: Gaps and cracks that undermine insulation performance
- Inferior Panel Alternatives: Cheap EPS panels that don't perform
Annual Heating Cost Comparison
A well-insulated 12m² garden office:
- SIP Panel (122mm): ~£180/year
- Timber + PIR: ~£220/year
- Timber + Mineral Wool: ~£350/year
- Budget EPS: ~£450/year
Get Expert Advice
Not sure which specification is right for your project? Contact us for free advice tailored to your garden room requirements.