Insulating Concrete Formwork (ICF)

ICF (Insulating Concrete Formwork) is a sustainable, high performance building system which allows fast construction of buildings with low running costs and a long life.

The LEATHWAITE ® team have over 20 years experience as ICF Builders constructing using ICF and have worked on many successful ICF projects.

What is Insulating Concrete Formwork (ICF)?

ICF is based on hollow lightweight block components that lock together, to provide a formwork system into which concrete is poured. The blocks are made from expanded polystyrene panels fixed together with plastic webs (reducing thermal bridging) to create a formwork to which horizontal and vertical steel reinforcements can be easily added for extra strength. Once braced, concrete can be poured into the forms enabling fast construction one storey at a time. The expanded polystyrene panels stay in place, resulting in a super-insulated monolithic solid concrete structure.

Dependant on specification the U-value for ICF walls can be as low as 0.10 w/m2k which is ideal for achieving the Passivhaus Standard or EPC A Rating.

What are the benefits of using ICF?

High performance building envelope

If you are planning a Sustainable Building, regardless of the Energy Performance Standard that you are hoping to achieve, the two keys requirements for the building envelope are the thermal efficiency and equally important but sometimes less obvious requirement of air-tightness. ICF construction is an ideal build method to achieve both of these goals. As stated above very low U-values can be achieved with ICF. The air tightness of a building is critical in achieving a high energy performance and in particular if building to the Passivhaus standard. The fact that ICF walls are poured with concrete one storey at a time it creates a monolithic structure without joints which makes it far easier to achieve very low air tightness results than with other construction methods such as timber frame. There are also gains from the ‘thermal mass’ of the built structure helping to store and release heat. High levels of acoustic performance can also be easily achieved with ICF construction.

Fast construction

The ICF walls as soon as built are waterproof even before the external finishes are applied, allowing internal works to commence sooner. ICF construction is not impacted by adverse weather in the same way that traditional masonry is, cold temperatures do not affect progress. Services and cabling conduit can be quickly and easily chased into the interior of the ICF panels using a heat gun with plasterboard screwed directly to the panels leading to a faster interior fit out.

Ideal for basement construction

The combination of ICF and Crystalline Concrete Waterproof solutions is ideal for basement construction. The fact that the same ICF system can be used for both basement and above ground structures can result in cost and time savings on a project.

Flexible design

ICF systems are extremely flexible and allow Architects creativity in building design. Structures are not limited and can include curved or angled walls and overhangs. ICF systems can be clad externally with a wide range of finishes including masonry, brick slips, timber cladding, renders or other modern cladding systems.

Fire Resistance

ICF structures offer maximum safety with a fire protection rating of up to four hours.

Further information

Insulating Concrete Formwork Assosciaton

The Concrete Centre

Low Energy & Concrete Buildings

Amvic ICF