Soffit Insulation

Soffit Insulation


Thermal Insulation of Soffits

Isothane’s spray foam insulation system Pirthane® is the perfect soffit insulation solution. Soffits are the underside of architectural structures such as an arch, a balcony or an overhanging eave. By insulating these areas you can provide energy efficiency benefits to the structure and those using it.

Pirthane® is a closed cell polyurethane insulating foam and is used in conjunction with a waterborne intumescent fire protection coating which means that in addition to improving the thermal efficiency of the building or space it also offer excellent fire resistant properties. This combination of spray foam insulation and FPC complies with the requirements for a Class 0 surface as defined in appendix A paragraph 12 of Approved Document B ‘Fire Safety@ to the Building Regulations 2010. The combination of the two parts of the system is our product Pirthane® ‘0’.

The product is applied in-situ which gives it advantages over board insulation and other alternatives for insulating soffits. Irregular shapes are quickly and seamlessly filled and insulated. This means that it not only provides thermal insulation but also eliminates air leakage and drafts further reducing heat loss. The closed cell structure of our polyurethane foam soffit insulation means that it is water resilient, robust and weatherproof. This means that it has a long lifespan with low maintenance requirements.

Soffit Insulation using PIRTHANE in carpark Soffit Insulation





PIRTHANE® ‘0’ is used for thermal insulation and condensation control on:

  • Underside of concrete soffits or floor slabs for example in car parks.
  • Interior of commercial buildings.
  • Internal surfaces of marine craft.


Soffit Insulation with Pirthane:

  • Because Pirthane is applied in-situ it means irregular shaped soffits such as those which are ribbed or waffle shaped can be quickly and seamlessly insulated.
  • Because Pirthane has a low thermal conductivity value meaning you lose less head room than other insulation materials to achieve the same results.
  • It has excellent adhesive properties meaning it can withstand high wind speeds and vibration. It can be used on single skin substrates.
  • Low cost maintenance after the work has been completed.
  • It eliminates unwanted air leakage which can save up to 75% of energy costs.


Case Studies

Primark Grimsby Primark Extention, Soffit Insulation- Freshney Place, Grimsby

Clients Our approved installers Foamspray insulation carried out the works for contractor Harris CM undertaking a project for Grimsby Shopping...


Car Park Insulation of Soffits

Client: Ardmore Construction, Sovereign Quay, Eastbourne. Problem: How to insulate the car park soffit of these luxury harbour side apartment...


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