WHAT INSULATION DO I NEED ?
When it comes to insulating floors, it can be tricky to know what kind of insulation you need, especially if you are tackling a renovation project.
Insulating floors is often trickier than insulating other areas of your home. The ground floor beneath a house is generally warmer than the air around it, and so it would perhaps be third on your list of priorities (behind walls and roofs). However, it makes sense to consider retrofitting, particularly if you have a suspended timber floor.
You can retrofit floor insulation on top of a solid concrete base, too, but this will have an impact on floor height build-up. And it’s only worth digging out the floor if you’re undertaking a major renovation.
The Importance of Insulating Floors
The limiting U value (the maximum U value that cannot be exceeded) required under current Building Regulations are:
- Roof: 0.20W/m²
- Ground floor: 0.25W/m²
- Walls: 0.30W/m²
INSULATING A SOLID FLOOR
Most modern homes have a solid floor, for example:
- concrete slab
- concrete planks
- block and beam
Insulation is laid on the concrete and covered with a screed. There will be a damp-proof membrane under the insulation and possibly a second membrane on top, depending on the type of screed.
In this scenario, a rigid foam insulation is usual, and as you’d want the same U value in the roof, we need the same thickness of insulation (180mm). Many builders will baulk at this figure — it was not long ago that installing 50mm of insulation in the floor was considered fairly advanced.
INSULATING A SUSPENDED FLOOR
A suspended timber floor tends to be cold and draughty because of the air circulating beneath it. Installing any amount of insulation will warm the floorboards and go a long way towards eliminating draughts. The effect is a greater sense of comfort and that, in turn, allows the homeowner to turn the thermostat down.
Achieving a U value of 0.25 would be a good target. That would need 90mm of rigid foam or 150mm mineral wool. A semi-rigid material is generally best as it can be cut very slightly oversized and squeezed in between the floor joists, thereby ensuring no draught-causing gaps.
VAT £39.98 INC VAT
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VAT £51.23 INC VAT
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VAT £63.22 INC VAT
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VAT £31.20 INC VAT
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100mm Ravatherm XPS X 200 SB Extruded Polystyrene Board For floors And WallsHigh-performance, multi-purpose extruded polystyrene XPS boards for the thermal insulation of domestic and industrial floors, basement and/or cellar perimeter walls.Ravatherm XPS X 200 SB thermal insulation is manufactured by an extrusion process, which results in a homogen..
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VAT £43.80 INC VAT
Recticel Eurothane GP PIR BoardEurothane® GP is a high performance PIR insulation board that is light weight, easy to cut, handle and install. Whether it’s a pitched roof, framed wall or floor, Eurothane® GP is the ideal solution amongst contractors and installer.Eurothane GP will not degrade or deteriorate due to moisture and therefore m..
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