heat loss from uninsulated flooring

Uninsulated ground flooring results in about 10-15% of a typical uninsulated household’s overall heat loss.

Therefore, insulating any suspended timber or solid ground floors is recommended.

According to Building Regulations Part L, (approved from 15th June, 2022), insulated ground floors should have a heat transmittance, U-value, no higher than 0.25 W/m²K for an existing dwelling refurbishment (as opposed to new dwellings, built after 6th April 2008). 

An existing dwelling extension should achieve a floor U-value no higher than 0.18 W/m²K.

Insulating suspended timber ground floors

If you have an older property its more likely to be timber flooring or suspended timber floor. Insulating a timber floor generally involves taking up the boards and laying down mineral wool insulation between the joists.

This flooring can be fitted with breathable material like semi-flexible wood fibre insulation boards, which are less wasteful and more easily fitted than rigid, non-breathable polyisocyanurate (PIR) insulation board. PIR is difficult to cut precisely and fit snuggly between rigid wooden floor joist beams, often leaving airgaps and, therefore, enabling heat losses. 

However, if there is enough space under the entire suspended timber floorboards, then sheep’s wool attached by netting would be the most environmentally friendly material to use, otherwise mineral wool and battened in with more rigid, natural breathable insulation board that covers the floor joist beams, as these can also be a source of linear thermal bridging. 

It is important to allow enough sub-floor ventilation between the GFI and the ground in order to prevent mould and damp from occurring.

There is a new technology that involves a placing a robot under the floorboards and using it t spray the underside of the board with insulating foam. Q-bot have created this method in order to reduce the disruption and length of time of the processes.

Insulating solid ground floors:

Insulation applied on top of the existing floor will raise the floor level by the thickness of the insulation and it might require some extra works such as trimming door heights, repositioning skirting boards and other internal adjustments. 

Alternatively, it is possible to dig down into the solid floor and then build up with GFI and the final floor covering up to the original floor surface height. The installer will be able to advise on specific options, costs of each and materials.

Ground floor insulation (GFI) for all ground floor types, would be a perfect opportunity along with any plans for a heat pump and wet underfloor heating (UFH) pipe installation. This GFI should be installed just prior to any wet UFH installation. Insulation is an important consideration for UFH. 

There should be suitable insulation below the underfloor heating pipes to resist the heat going downwards, with as much heat as possible to flow upwards and into the room. The insulation level and fabric of the building should always be factored into an UFH design as it will impact on the heating system’s performance. 

GFI, along with other fabric insulation improvements around the dwelling, enables the central heating system to be designed to the lowest temperatures, which can be as low as 35°C, ideal for a heat pump system. This obviously saves both energy and money.

In addition to this you could use rugs to add some extra protection against heat loss.

Next steps to improving your floor insulation

To better understand the existing heat retention of your home and to identify opportunities for improvement we recommend a BHESCo Home Energy Survey. 

Please provide your contact details below and a member of our Energy Saving Team will contact you shortly.

Full details of our service and costings can be found at https://bhesco.co.uk/book-energy-survey.

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