Garden Room Insulation Guide: Achieving Year-Round Comfort

Garden room insulation directly determines usability and running costs. Minimum specification for year-round use: 100mm walls (U-value 0.18 W/m²K), 150mm roof (U-value 0.15 W/m²K), 100mm floor with 25mm insulated ply deck. Enhanced specification: 150mm walls + 200mm roof achieves Passive House standards. Insulation types compared: PIR boards (best performance per mm, £40-55/m²), mineral wool (budget option, £25-35/m²), spray foam (expensive but excellent for awkward spaces, £60-80/m²). Critical: thermal bridging at frame junctions reduces performance 20-30% if not addressed. Steel-frame systems need thermal breaks. Glazing accounts for 40-50% of heat loss: triple glazing (U=0.8) vs double (U=1.4) adds £2,000 but saves £150/year heating. Ventilation essential: MVHR systems (£1,500-3,000) recover 90% heat while providing fresh air. Real energy costs: well-insulated room £40-60/month winter heating (electric), poorly insulated £120-180/month. ROI calculation shows enhanced insulation pays back in 3-5 years.