Insulation & waterproofing

Insulation and waterproofing: how to choose and buy at a good price

Updated 20 October 2026

Choose the material for the place, not for the price

Basalt mineral wool does not burn and lets vapour through, so it is often used for facades under plaster, framed walls and attics. Polystyrene (EPS) is lighter and cheaper, but more vulnerable to fire and rodents. XPS (extruded polystyrene) hardly absorbs any water, so it goes under a screed, on a plinth and on a foundation. PIR boards give high heat resistance at a small thickness. In hot regions the same boards are also used on terrace roofs to keep the heat out.

Waterproofing differs too: bitumen rolls and coatings for foundations and flat roofs, membranes for roofing, and a vapour barrier for an insulated attic or a framed wall.

What to put in your request

• What you need — mineral wool, EPS, XPS, PIR, membrane, bitumen roll, coating.
• What it is for — facade, roof, attic, floor under a screed, foundation, inner walls.
• Thickness in mm — for example 100 mm for a facade.
• Density or grade — facade wool 135 kg/m³, EPS 25 kg/m³.
• Area or quantity — sq m, cubic metres, packs or rolls.
• Make — if you have a preference.
• Delivery — unloading, carrying up, address.
• Budget, if you want to name it.

Example: “I need 2,000 sq ft of 100 mm basalt mineral wool, density 135 kg/m³, for a facade under plaster. Nagpur, delivery with unloading. Budget up to Rs 330,000.”

How it works through BlaBlaPrice

You write one request, and building materials sellers in your region answer in the chat with the price per pack or sq m, terms and delivery. Each seller sees where their offer ranks and can improve the terms. So the price often turns out better than after calling around warehouses. It is free for the buyer, and contacts go only to the seller you choose. More in how it works.

How to compare offers

The biggest trap is the price “per pack”. A pack can hold a different area, so convert the cost to a square metre and a cubic metre at the same thickness. Check the density: a board of 30 kg/m³ and one of 135 kg/m³ are different materials, although they look alike.

Ask whether the material has a certificate, whether the wool got damp in storage, and whether delivery is included. For polystyrene, check the stated grade and thickness, because sometimes “100 mm” turns out to be less. Ask separately whether the needed fixings and adhesive are available and at what price.

Typical mistakes

• Taking the same density for a facade and for a floor: the loads are different.
• Saving on foundation waterproofing: putting it right later is the costliest.
• Forgetting vapour and wind barrier films when insulating a roof or a framed wall.
• Not counting an allowance for cutting and waste.

For the finish on top, see finishing and cladding materials, and for fixings, look among fasteners and hardware.