Floor insulation
Contents |
[edit] Introduction
In the average home, approximately 10% of the heat loss is through the ground floor. Therefore, insulation as a means of reducing heat loss is typically installed on the ground floor. However, it may also be provided in upper-floors between heated and unheated areas. In comparison with wall insulation or roof insulation, savings associated with floor insulation are more modest, but under some circumstances, installation costs can be lower.
The installed performance of an insulation product is dependent on:
- The performance characteristics of the insulation material.
- The suitability of the insulant to its installed location.
- Adherence to manufacturer’s instructions.
- Quality of workmanship.
- Defects, gaps in insulation, thermal bridging and moisture penetration.
Commonly-used floor insulation materials include:
- Cellulose.
- Cork board.
- Hempcrete.
- Woodfibre.
- Mineral wool.
- Extruded Polystyrene (XPS).
- Expanded Polystyrene (EPS).
[edit] Building Regulations
Legislation such as the building begulations part L has acted as a catalyst for insulation, along with advanced voluntary programmes such as the Code for Sustainable Homes and BREEAM.
The building regulations require that floors achieve minimum thermal performance values (U-values – a measure of how quickly heat will travel through the floor), and this affects the amount of insulation required. For example, achieving a U-value of 0.25 W/m2K or less. would require at least 70 mm of high-performance foam insulation, or 150 mm of mineral wool, (although this will vary depending on floor type, construction, shape and size).
Calculations by Kingspan have produced best starting point values that are thought to be suitable for common situations.
[edit] U-values for floors in domestic buildings
England – April 2014
- New Build: Best starting point (fabric only) – 0.11
- Existing buildings: Extension – 0.22
- Existing buildings: Refurbishment – 0.25
Wales – 31st July 2014
- New Build: Best starting point (fabric only) – 0.15
- Existing buildings: Extension – 0.18
- Existing buildings: Refurbishment – 0.25
Scotland – 1st October 2015
- New Build: Best starting point (fabric only) – 0.13
- Existing buildings: Refurbishment and extensions (where existing dwelling’s walls and roof U-values are worse than 0.70W/m.K in the walls and worse than 0.25 W/m.K in the ceiling) – 0.15
- Existing buildings: Refurbishment and extensions (for other extensions, upgraded existing thermal elements, non-empty conservatories and conversion of unheated buildings) – 0.18
- Existing buildings: Conversion of heated buildings – 0.25
[edit] U-values for floors in non-domestic buildings
England – April 2014
- New Build: Best starting point (fabric only) – 0.18
- Existing buildings: Extension – 0.22
- Existing buildings: Refurbishment – 0.25
Wales – 31st July 2014
- New Build: Best starting point (fabric only) – 0.22
- Existing buildings: Extension – 0.18
- Existing buildings: Refurbishment – 0.25
Scotland – 1st October 2015
- New Build: Best starting point (fabric only) – 0.15
- Existing buildings: Refurbishment, extensions and conversion of unheated buildings – 0.20
- Existing buildings: Conversion of heated buildings – 0.25
NB See PA ratio for more information.
[edit] Insulation methods
[edit] New buildings
[edit] Insulation above the floor slab
Insulation is placed above the concrete slab, along with a separating/slip layer and then a rigid floor which is generally either screed or boarding. The damp proof membrane (DPM), which can be either above or below the slab, must be continuous with the damp proof course (DPC) in the surrounding walls. The insulation boards must be tightly butted and sealed to limit air leakage.
Heating response time is improved by having the insulation above the slab, and the insulation zone can be used to run services and underfloor heating. However, when used together with timber-based flooring it may be unsuitable for use in rooms that may get wet such as kitchens or bathrooms.
[edit] Insulation below the floor slab
Insulation is placed below the concrete floor slab. There are fewer restrictions on the thickness of the insulation in comparison with above slab insulation, and there is less of an issue with point loading as the load is spread over the slab rather than the insulation. However, rooms are slower to heat by comparison with above slab insulation.
[edit] Timber floor
The installation process follows the same method as that detailed below, although the process is easier as there is no existing flooring to remove or gain access to.
[edit] Retrofitting existing buildings
[edit] Simple draught-proofing
Sealant or caulking can be used to fill the gaps between floorboards and between skirting boards and the floor.
[edit] Timber floors
Older homes are more likely to have suspended timber floors (with no ceiling below). These can be insulated by raising the floorboards and laying mineral wool insulation supported by netting between the joists. This process is relatively easy if there is a cellar or an access hatch allowing entry to the crawlspace (void) below the floorboards. If not, the floorboards will need to be taken up. It is important to consider the propensity of timber floors for air leakage. Attention is needed when relaying old floorboards or installing new ones, to ensure that all joints between boards are adequately sealed.
[edit] Upgrading an existing concrete floor slab
Newer homes are far more likely to have a ground floor made of solid concrete. The simplest method of installation is to add insulation and a new floor deck on top of the existing floor. However, raising the floor level will usually require floor coverings skirtings, radiators and electrical fittings are removed and re-fitted, as well as reducing the heights of doors.
[edit] Related articles on Designing Buildings
- Approved Document L.
- Ash deafening.
- Beam and block.
- BREEAM.
- Cavity wall insulation.
- Code for Sustainable Homes.
- Crawl space.
- Domestic floors: Part 1: Construction, insulation and damp proofing.
- Fire insulation.
- Flooring.
- Flooring defects.
- Hatch.
- Heat transfer.
- How to fit carpet.
- Insulation for ground floors.
- PA ratio.
- Roof insulation.
- Solid wall insulation
- Sound insulation
- Thermal bridge
- Thermal insulation for buildings
- Transparent insulation.
- Types of carpet.
- Types of floor.
- Types of insulation.
- U-value
- Vapour barrier
Featured articles and news
This weeks guest editor, Ankita Dwivedi of Firstplanit.
Fropm practice to research and the business of materials.
Terms, histories, theories and practices.
Types of work to existing buildings - repurposing of buildings
Alteration and everything else before demolition.
2023 HSE data on workplace injuries and ill health
And CIOB's response.
Building Safety Act and Secondary Legislation
Presidential update from CIAT's Eddie Weir PCIAT.
Starting pistol Statement for an election campaign?
Rates freeze, NI cuts, full expensing; early election?
Positive pressure or positive input ventilation
Could this be a remedy for condensation, damp or mould?
Unlocking a Healthier Tomorrow
Report on Social housing retrofit in Scotland 2023
Call for ministerial group and National Retrofit Delivery Plan.
The Great Transformation 1860–1920. Book review.
2023 Autumn Statement in brief with reactions
Including the devolved governments, CIOB, ECA, APM and IHBC.
Irish Life Sciences HQ, an exemplar of adaptive reuse
AT awards small to medium size project category winner.
Formal and informal adaptive re-use or new use of buildings.
Broken Record. Emissions Gap Report 2023
Temperatures hit new highs, yet world fails to cut emissions (again).
Environment Agency cuts waste red tape
No longer enforcing certain waste transfer documentation.
APM Project Management Awards 2023
Winners reactions during the event at the Park Plaza Hotel.
BSRIA Living Laboratory Innovation Challenge
An exciting opportunity for stakeholders to collaborate.
Discussing issues related to inside and outside air quality
Report from the BSRIA Briefing 2023, Cleaner Air, Better Tomorrow.