Insulating concrete forms (ICF) is a system of construction, used normally for the exterior and party walls of buildings. The resulting walls form a monolithic reinforced concrete structure. 

Fire-retardant insulation used in the manufacture of the formwork is then retained to provide thermal insulation for the building. Certified interior and exterior finishes are applied to the surface of the insulation to complete the buildings.


Altherm ICF is certified by the NSAI Irish Agrément Board for buildings up to six floors, 18m in height and for fire and sound rated walls. The certificate specifies the conditions and detailed installation requirements under which the products must be installed and finished to meet or exceed the requirements of the building regulations, including those for fire protection.

The certification process requires periodic audits by the certification body to confirm compliance with the certificate requirements and international ISO standards.


The material used in the manufacture of Altherm ICF is a flame retardant Expanded Polystyrene (EPS). EPS is a certified insulation solution for buildings of all types, the world over. In all cases the EPS used by Altherm ICF, delivers a certified minimum compressive strength of at least 129kPa.

This is well in excess of the compressive strength of 70kPa specified for typical external insulation systems, and thus forms a much stronger substrate for finishes.

External finishes

The exterior finishes used must be certified by NSAI Agrément, this includes strict specifications for weatherproofing, longevity, fire safety and impact resistance. For ICF construction the renders are certified and applied to comply with CAT 1 of ETAG 004.

This is the highest impact category corresponding to heavy non deformable objects hitting the surface of the render and is a standard of impact resistance common to all construction methods. Only finishes with a reaction to fire classification of Class B-s1, d0 or better are ever used.


The concrete core of the systems provides a certified structural resistance to fire in excess of 60 minutes. Longer stability periods can be achieved by the installation of additional reinforcement to the structure as required.

In all cases the EPS used is a fire-retardant grade, this means in practice that the EPS will not sustain a flame and will extinguish upon removal of a flame in a fire situation.

Surface spread of flame is addressed by the internal and external finishes specified to Class O, or better, resistance to spread of flame. The EPS substrate in conjunction with the base coat and the finish coat gives a reaction to fire/ spread of flame as Class B-s1, d0.

The flame-retardant EPS is thus encased in an inflammable Class 0 concrete core on the inside and a Class 0 render system to the exterior. This ensures that the requirements of Technical Guidance Document Part B for fire safety are met or exceeded.


Although it is considered a modern method of construction in Ireland, insulating concrete forms have been used in residential construction the world over for many years. ICF as a construction method is approved by certification bodies in all major jurisdictions and is a popular and growing method of construction worldwide.

  1. Altherm ICF is fully Irish owned and Irish based, and is committed to delivering high-quality, durable and safe homes.
  2. Altherm ICF is certified by both NSAI Agrément and the British Board of Agrément.

For more information about the quality and compliance of the Altherm ICF product range please click here.