The Benefits Provided by Insulated Concrete Formwork (ICF) provided by PolySteel
Simplicity is a key strength of ICF. It only requires two main, common construction materials – the formwork and concrete. The formwork is created from two facing layers of expanded polystyrene (EPS) separated by a hollow core that is filled with pumped concrete.
Polybloks made by Polysteel are unique because they are made in the UK with steel webs and vertical ferrule strips that are firmly anchored inside the EPS foam side panels ensuring that Polybloks are stiff and very rigid.
The vertical ferrule strips lie 10 mm below the surface of the EPS side panels allowing the easy fixing of both propping timbers and any interior or exterior wall finishes with self-tapping screws.
They also have precision made vertical and horizontal tongue and groove interlocks that facilitates easy and accurate, installation of every Polyblok wall. The steel ties allow Polybloks to be fixed together with 4 steel clips that holds each block rigidly against its neighbour and ensures that the wall will not “blow” when being filled with concrete.
Steel reinforcement can be placed within the forms in retaining walls and the cantilevers that are often used by Architects in the more spectacular buildings. In dwellings reinforcement is rarely required.
These factors all make Polybloks simple to use and so highly suitable for newcomers to ICF building construction.
In a PolySteel ICF wall, the insulating formwork encases the concrete to enable it to cure very slowly and this increases its crushing strength. This and the steel web system reduces cracks to a minimum. ICF walls are several times as strong as walls made from concrete blocks with mortar joints and so are ideal for internal load bearing walls as well – and they are much faster to build.
The airtightness and continuous insulation of the structure prevents cold bridging and an ICF wall will not transmit moisture by capillary action leading to minimal risk of condensation or mould. Waterproofing membranes can be used to dampproof the floors and stop radon as in traditional construction.
The solid concrete core in an ICF wall creates an almost impenetrable shell that protects dwelling room and prevents fire from spreading internally or externally. PolySteel walls offer a fire protection rating of 4 hours and the EPS forms are treated with a flame retardant additive that stops them from burning even when directly exposed to flames.
PolySteel walls provide a solid wall construction that is a recommended method under the guidance standards for Flood Resilient Construction. The EPS material in the walls remains water resistant under flooding which avoids months of delays caused by drying out.
The BBA certification of PolySteel confirm that its forms will have “a service life of not less than 60+ years” – the same as traditional cavity wall construction. There is an abundance of statistical data and research papers that demonstrate the longevity, environmental benefits and disaster resilience of ICF.
ICF was approved in 2010 by the Valuation Panel of the then Council of Mortgage Lenders as a standard form of construction which is acceptable for mortgage purposes providing it has been supplied by a certified supplier like PolySteel. In other countries where ICF is more widely used, there is growing evidence of lower insurance costs and valuation premiums relative to other building materials.
Extending an insulated concrete formwork (ICF) building is not necessarily any more difficult when compared to traditional construction but does need planning. With modern concrete cutting tools it is not difficult to to remove panels of ICF.
ICF has increasingly become a competitive option following the rapid increase of the cost of timber frame and brickwork in the last few years.
Other cost savings are achieved when on-site because PolySteel can deliver a lorry load of ICF forms within 2/3 days. Labour costs are reduced due to ICF’s simplicity which speeds up the build programme. In fact It is possible to make a two storey dwelling weatherproof in a couple of months.
The houseowner also benefits from the monolithic concrete core that lies in direct contact with the insulating material of the block to create an airtight structure with exceptionally low U-values, excellent thermal mass and a consequent reduction in the energy used to heat or cool the structure.
The inherent strength in an ICF wall will require very little maintenance or repair over the lifetime of the property with possibly only the exterior finishes that may require attention over the long term.