Insulation — Complete Guide

Insulation reduces heat transfer (thermal) & sound transmission (acoustic) through walls, roofs & floors. In India's hot climate, good insulation dramatically cuts air-conditioning costs & improves comfort; acoustic insulation creates quiet, peaceful interiors. This category covers all major insulation materials — from fibrous wools to rigid foam boards, reflective foil & spray foam.

Insulation follows IS 8183 (mineral wool), IS 4671 (EPS), ASTM C578 (XPS) & ECBC 2017. Top brands: UP Twiga, Owens Corning, Rockwool, Supreme, BASF, Lloyd, Aerolam.

Materials in this Category

Material	Best For
Glass Wool	Thermal + acoustic, HVAC ducts
Rock Wool	Fire + acoustic + high-temperature
EPS / Thermocol Sheets	Economical thermal, cold storage
XPS Boards	High-strength thermal (roofs, podiums)
Reflective Foil Insulation	Radiant heat (roofs)
PU Foam	Highest R-value, cold storage, gaps

How Insulation Works

Heat moves three ways — conduction (through solids), convection (through air), and radiation (infrared). Different insulation tackles different modes:

Bulk insulation (wool, foam) resists conduction & convection — rated by R-value (higher = better)
Reflective foil reflects radiant heat — needs an air gap
Best results combine both — reflective foil + bulk insulation

Insulation Comparison

Material	Thermal k (W/m.K)	Acoustic	Fire	Best For
Glass Wool	0.030–0.040	Excellent	Non-combustible	Thermal + acoustic, HVAC
Rock Wool	0.034–0.044	Excellent	Up to 1000 °C	Fire + high-temp
EPS	0.033–0.040	Poor	Combustible (FR)	Economical thermal
XPS	0.028–0.035	Poor	Combustible (FR)	High-load thermal
Reflective Foil	Radiant barrier	Poor	Foil non-combustible	Roof radiant heat
PU Foam	0.020–0.025 (best)	Moderate	Combustible (FR)	Cold storage, gaps

How to Choose

Thermal + acoustic (general): Glass wool
Fire-rated / high-temperature: Rock wool
Economical roof / wall thermal: EPS
Load-bearing / wet (podium, roof): XPS
Roof radiant heat (hot India): Reflective foil + bulk
Highest performance / cold storage: PU foam
Acoustic walls / studios: Glass / rock wool

                For hot Indian roofs: Combine reflective foil (blocks radiant solar heat) with bulk insulation like glass wool / XPS (blocks conduction) — plus a cool-roof reflective coating on top — for maximum heat reduction & AC savings.
            

Cost Overview (Approximate, 2025-26)

Material	Cost (per sqm)
Glass Wool (50 mm)	Rs 35 – 140
Rock Wool (50 mm)	Rs 60 – 300
EPS Sheet (50 mm)	Rs 60 – 180
XPS Board (50 mm)	Rs 220 – 420
Reflective Foil	Rs 20 – 140
PU Foam / Panel	Rs 250 – 2,200

Best Practices

Choose density / type per application (thermal / acoustic / fire)
Use FR-grade EPS / XPS / PU for buildings
Combine reflective foil + bulk for hot roofs
Don't compress bulk insulation (reduces R-value)
Keep insulation dry (wet = loses performance)
Use foil-faced for vapour barrier
Seal gaps for continuous insulation
Wear PPE handling wool (skin / respiratory)
Provide fire barriers for combustible foams
Follow ECBC for building envelope insulation

Applicable Standards

Standard	Description
IS 8183	Bonded Mineral Wool (Glass / Rock Wool)
IS 4671	Expanded Polystyrene (EPS)
ASTM C578	XPS / EPS Thermal Insulation
ASTM C1029	Spray PU Foam
ASTM C1224	Reflective Insulation
ECBC 2017	Energy Conservation Building Code

Conclusion

Insulation is one of the highest-ROI investments — cutting AC costs & boosting comfort in India's hot climate, while delivering quiet interiors. Glass wool is the all-round thermal + acoustic choice; rock wool adds fire / high-temperature; EPS / XPS are rigid thermal boards; reflective foil tackles roof radiant heat; and PU foam gives the best R-value. Combine reflective + bulk for hot roofs. Explore each in detail: glass wool, rock wool, EPS, XPS, reflective foil and PU foam.

See all categories on the construction materials page.

Insulation