FLOOR INSULATION

Floor insulation is one of the best forms of building insulation due to the fact that as much as 20-30% of heat, escapes through floor elements. Moreover, it is building material maintenance-free once installed. By installing floor insulation, you not only improve the thermal envelope of the building but also you create a complete seal around the building. At the same time you reduce the potential for heat to escape. As well as reducing heat loss, installing floor insulation can also help to minimise sounds created by floorboards, reduce drafts and create a warmer floor surface.

FLOOR INSULATION THICKNESSES

The building regulations require that floors achieve minimum thermal performance U-values and this affects the amount of insulation required. Achieving a U-value of 0.25 W/m2K or less would require at least 70mm of Phenolic high-performance foam insulation called Kingspan® K103, and 200mm of EPS100 polystyrene. In the case of PIR Rigid Insulation Boards, thickness of 120mm is normally used. In terms of XPS boards such as Soprema SL or STS, 50mm thickness is sufficient for the floor insulation. If you are concern about compressive strength of the floor insulation material, you should consider buying XPS extruded polystyrene board with the highest compressive strength ranging from 300kPa to 800kPa, followed by PIR rigid insulation boards (150kPa) manufactured either by Kingspan, Celotex, Unilin, Iko-Enertherm, Ecotherm or Recticel GP.

TIMBER FLOOR INSULATING

If your floor is above an unheated cellar or basement you will need to fit the insulation snugly between the joists and secure in place with netting if required. Solid insulation boards or rolls of mineral fibre can be fitted between the flooring joists. Plasterboard should then be fixed to the ceiling of the basement to provide fire resistance. If you have a suspended floor, with a small cavity below that is hard to access, you would normally have to take up the floorboards in order to fit the insulation. By correctly insulating suspended timber floors you can save money. As you keep more heat inside your home with floor insulation you’ll reduce the amount of energy you use whilst keeping your house snug. Where old floorboards are relayed or new ones installed, careful attention is needed to ensure that all joints between boards are adequately sealed. 

CONCRETE FLOOR INSULATING

If your home is newer then it is likely you have a ground floor made of concrete. You can still insulate them by laying a new layer of rigid foam insulation on top. Insulating your floor underneath the concrete slab can help regulate the temperature and prevent over-heating in rooms that are south-facing or occupied for long periods of the day due to the thermal mass of the concrete. The damp proof membrane can be placed above or below the concrete slab, depending on the particular product. If the membrane is placed above the slab an additional membrane may be required to protect the insulation from ground contaminants. In this case insulation can be added over the existing concrete slab or underneath a new one. Where insulation is placed above the slab, the rooms will warm up more quickly when the heating is switched on. High performance insulation panels or boards are often the best materials to insulate an existing concrete slab floor as they provide the best thermal performance at any given thickness. Keeping the thickness of your insulation to a minimum will reduce the likelihood of having to make costly alterations to door openings, stairs and other fixtures as a result of the increase in floor height. It is a good idea to lay a damp-proof membrane underneath the insulation. When insulating above the concrete slab, the floor finish over the insulation can be either screed or boarding. It is argued that a screed finish is more durable and can offer some thermal mass otherwise absent. Board finishes, on the other hand, can be quickly installed and provide a quicker thermal response time.

FLOOR INSULATING COST | UNDERFLOOR INSULATING | UK 

The total floor insulation cost has two parts. The cost of materials and the cost of installation. The average cost for suspended floor insulation is £155 per m2. Floating floor insulation costs are typically one of the cheaper floor insulation options. Naturally, costs will vary depending on the size of the room and the type of floor. As far as home improvement jobs go, this one is relatively reasonable regarding pricing. Prices depend on whether you do it yourself or get the professionals in. Having a timber floor insulated professionally, including filling the gaps between the floorboards and around the skirting, depends on the size and shape of the room and the insulation material used, but typically costs around £950. The cost of insulating a concrete floor can vary greatly, especially if the concrete is removed or additional works are done, but costs will probably start around £1,450. According to the Energy Saving Trust you could save between £40-£65 per month on your energy bill through floor insulation.

TYPES OF FLOOR INSULATION

There are 6 main types of floor insulation, with different production technologies and compositions. Some boards rely more on thermal insulation values, and some more on compressive strength, but in the end they all aim to maximize the temperature reduction on the cold side. The UK floor boards come in standard sizes: 1200mm x 600mm and 2400mm x 1200mm (8'x4').

 EPS

EPS sheet is one of the best-known floor insulation materials because expanded polystyrene board is a easy to install and have a high insulation value. Either Jabfloor or Kay-Metzeler range of insulation boards have been manufactured specifically for use with flooring. While EPS70 polystyrene is used to insulate floors between joists, EPS 100 is recommended to use under concrete, because it is a much denser material offering 100kPA compressive strength.

 PIR BOARDS

While EPS boards are budget friendly insulation boards, PIR Rigid Insulation Boards are most popular in the UK. Since the blowing agent evaporates during this reaction a rigid closed cell middle density insulation product is created. PIR boards offer compressive strength of 150kPa and are used to insulate the floor, because they come as rigid which means they are easy to cut into the shapes required. Additionally, PIR insulation boards are incredibly lightweight and relatively thin, whilst still providing high levels of insulation. There are a number of ranges of floor insulation boards available to choose from. Either Celotex, Kingspan or Xtratherm brands are the most popular polyisocyanurate boards used to insulate floors. Celotex offers TB4000, GA4000 and XR4000 PIR Boards range with compressive strength of 120kPa, followed by Xtratherm Thin-R PIR Insulation Boards with 150kPa, Kingspan offers ThermaFloor TF70 Floor Insulation Board with 140kPA compressive strength.

 XPS BOARDS

Xps insulation board is specifically designed for use with underfloor heating systems on concrete & wooden floors. In fact, it is a high strength (usually 300kPa) extruded polystyrene board suitable for any floor construction including below a concrete slab, below a screed and below chipboard. It is significantly denser than other types of insulation, which gives it a greater compressive strength. Its closed cell structure also resists both moisture and water vapour ingress. Due to its compressive strength, XPS is regularly used in applications where it is going to be under some strain, such as car park decks. It’s also great for use in basements. These boards are available in 30mm, 50mm, 80mm and 100mm thickness. Among widely available insulation materials, extruded polystyrene (XPS) insulation offers one of the broadest range of compressive strengths of 300, 500 or 800kPa. It is also one of the few floor products where manufacturers invest the time to test and declare compressive creep. There are a few main manufacturers offering XPS products. While Soprema offers an SL version with compressive strength of 300kPa, Kingspan with its Greenguard GG offers either 300kPa, 500kPa or 700kPa. On other hand Polyfoam offers square edged xps standard board that has a middle class compressive strength of 200kPa.

 PHENOLIC BOARDS

Phenolic board is a top shelf panel that can be used to insulate floors in both new build and refurbishment of residential, commercial and industrial buildings. As a part of Kooltherm range, Kingspan K103 Floorboard offers fibre-free rigid thermoset phenolic core with thermal conductivity of just 0.018 W/mK across all thicknesses. In fact, K103 is a premium product in terms of floor insulation. Product has been developed by Kingspan as a premium floor insulation board, providing high performing insulation with a thinner material than was possible before. K103 Kooltherm can be used on both solid concrete and suspending floors. Kingspan is followed by Unilin brand with SR/UF Safe-R Phenolic Floor Insulation Board. Unilin phenolic board offers thermal conductivity of 0.020W/mK and compressive strength of 150 (kPa).

 UNDER CONCRETE INSULATION

Cordek® company have created a wide range of Cellcore HX Plus void formers with an extra added insulation. This two in one solution is designed for use beneath reinforced concrete floor slabs to protect against the potential effects of ground heave with the additional Filcor EPS100 insulation layer protected by a ultra thin polypropylene sheet on top. HX Plus under slab is a combination product. In fact, it has a range of cellular legs with different depths of insulation glued onto the top of those cellular legs dependent upon the target U-value that you need to hit. It incorporates an integral layer of EPS insulation available in various thicknesses to meet thermal performance requirements. HX Plus is made in 25mm increments, which means insulation material ( Filcor ) is added.

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