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
100mm Celotex GA4000 PIR insulation for floors-walls-roofs 100mm Celotex GA4000 PIR insulation for floors-walls-roofs is a general purpose insulation board for floors, walls and roofs. It has long been at the heart of the Celotex product range providing the user with a range of thermal insulation solutions. With low emissivity foil facings, GA..
100mm Dow FLOORMATE 300-A Styrofoam - Extruded Polystyrene Foam Insulation Board (pack-4)Dow Floormate insulation boards are manufactured using high quality extruded polystyrene used for insulating floors. This FLOORMATE 300-A board can be installed under or over the slab in ground bearing concrete floors. It is also suitable for use on suspended b..
VAT £93.72 INC VAT
Kay Metzeler EPS70 Expanded PolystyreneAn expanded polystyrene insulation board ideal for floor and wall insulation, Kay-Metzeler EPS70 provide a long lasting thermal solution. The polystyrene board is easy to cut to any shape making it ideal to fit to any space.Expanded Polystyrene (EPS) is proven in use over decades across the globe for const..
VAT £51.23 INC VAT
Kingspan Thermafloor TF70High performance floor insulation Kingspan Thermafloor TF70 is a high performance insulation with a fibre-free rigid thermoset polyisocyanurate (PIR) core.It used to insulate solid concrete and suspended timber ground floors, and has a thermal conductivity of 0.022 W/m·K.Thickness: 100mmAll thickness : 2..
VAT £63.22 INC VAT
100mm Kingspan Thermapitch TP10 pitched warm roof Insulation100mm Kingspan Thermapitch TP10 pitched warm roof Insulation is a high performance insulation with a fibre-free rigid thermoset polyisocyanurate (PIR) core.It is suitable for tiled or slated pitched warm roof spaces, and has a thermal conductivity of 0.022 W/m·K.Thickness: 100mmSize: 2400x..
100mm Knauf Earthwool Flexible Insulation Slab (pack-6)100mm Earthwool Flexible Slabs are high performance non-combustible Rock Mineral Wool slabs with flexible edges on all four sides, manufactured using our revolutionary ECOSE® Technology, and are designed for use in multiple applications. Product SpecificationsThickness: 40mm, 50mm, 60mm, 7..
100mm Polyfoam Floorboard Super Rigid Extruded Polystyrene Board (pack-4)Polyfoam Floorboard Super For high loaded floorsPolyfoam Floorboard Super is 100mm rigid extruded polystyrene (XPS) board with a Global Warming Potential (GWP) of less than 5 and Zero Ozone Depletion Potential (ODP). They are square edged boards that have very high compressive..
VAT £31.20 INC VAT
Polystyrene EPS Facade white External Premium (White) EPS Board is used for external wall insulation. It works well in conjunction with a finish of timber or plastic weatherboarding, tile hanging or any other cladding or reinforced-render systems. Thickness: 100mmLenght: 1000 mmWidth: 500 mmAvailable thicknesses: 10mm,20mm,30mm,50mm,80mm,100..
100mm Quinn Therm QF PIR Insulation Board - 2400mm X 1200mm100mm Quinn Therm QF PIR Insulation Board - 2400mm X 1200mm is a high performance, fibre free board, with a rigid thermoset insulation core and faced on both sides with a low emissivity composite foil facing.The high compressive strength of Quinn Therm QF enables it to withstand the dead an..
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..
100mm Ravatherm XPS X 300 SB Multi-Purpose Extruded Polystyrene BoardHigh-performance, multi-purpose extruded polystyrene (XPS) boards for the thermal insulation of domestic and industrial floors, basement and/or cellar perimeter walls.Ravatherm XPS insulation X 300 SB thermal insulation is manufactured by an extrusion process, which results ..
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..
100mm Rockwool RW5 Universal Insulation Slab (pack-2)An all round performer ROCKWOOL RW5 is a robust insulation solution for a range of general building projects as well as specialist specifications such as commercial, leisure, industrial and more. The insulation provides excellent acoustic, thermal and fire performance. ROCKWOOL RW5 has ..
100mm Soprema XPS SL Rigid Thermal Insulation Board100mm Soprema XPS SL Rigid Thermal Insulation Board is used in Floor Insulating applications and boasts a moisture absorption of around only 2% after long term use due to immersion, diffusion or freeze-thaw resistance. The benefits of the sheets are they can withstand heavy loads on top and are lig..
100mm Superglass Multi Acoustic Roll Mineral wool InsulationSuperglass Multi Acoustic Roll is a lightweight, non-combustible glass mineral wool insulation roll. The flexible roll is perforated at 2x600mm and 3x400mm widths to allow easy installation between common stud/joist spacings and minimum on-site cutting and waste. Manufactured at a minimum ..