Insulation for Upgrading Concrete Slab Floors
For illustrative purposes only
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Start your U-value calculation >Converting existing unheated basements, garages and storage areas into habitable rooms is a popular way of increasing living space without constructing an extension. Such spaces typically have a sound, level concrete slab floor - but lack sufficient floor insulation to achieve the thermal performance targets for new habitable rooms.
If headroom is tight then the only option may be to break up the existing slab, dig further down and build up an entirely new floor. Where it’s possible to avoid that, however, upgrading the floor slab is a viable solution, adding a damp proof membrane (DPM) if not already present before installing the insulation.
Headroom is unlikely to be limitless though! So it makes sense to keep the make-up of the floor upgrade as thin as possible, which means using a high performance insulation product. Lightweight, rigid polyisocyanurate (PIR) foam insulation boards (such as Celotex GA4000 and XR4000) are among the most thermally efficient, commonly available insulation materials.
They are easily handled, meaning floors are quickly insulated ready to receive a light-gauge polythene separating layer and - depending on the height available - either a concrete screed or a thinner tongue and groove chipboard.
Where required, thinner polyisocyanurate (PIR) foam insulation boards (such as Celotex TB4000) can be considered for the perimeter upstand insulation.
Key Considerations
When using Celotex products, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions. In addition to the product datasheet, please refer to the following product documents:
- BBA certificates - where applicable to the application
- Declarations of Performance
- Health & safety datasheets
The building detail is for illustrative purposes only. It does not constitute advice and should not be relied upon.
Insulation products
| Product Name | Thickness Range | Sizes | Lambda |
|---|---|---|---|
| Celotex XR4000 | 110-200mm | Width 1200mm, Length 2400mm | 0.022 |
| Celotex GA4000 | 50-100mm | Width 1200mm, Length 2400mm | 0.022 |
| Celotex TB4000 | 20-40mm | Width 1200mm, Length 2400mm | 0.022 |