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ICF / BUILDING METHODS

FEMA

unique situation. Some companies supply all the steel reinforcement cut to size ready for installation. � Good thermal performance. U-values can be as good as 0.11W/sqmK. The very nature of the system also means it is easy to make airtight. � Improved acoustics. The polystyrene formwork is intrinsically good at absorbing sound, and mass concrete reduces airborne noise transmission. People who live in ICF homes (especially those who have used it for middle floors), say how exceptionally quiet it is. � Fire-retardant. Although the polystyrene inner lining could, theoretically, eventually catch fire, even though it is treated with a fire retardant, normal plasterboard used in the normal way provides an excellent inhibitor in the first place. After that, the concrete walls cannot, of course, burn. Intermediate timber floors are still vulnerable. � Heat storage. If you use ICF for your internal walls you’ll find that they’ll act as thermal stores, giving off heat long after your central heating has turned off. � Flexible design. One of the best things about ICF is that it can very easily cope with curves, arches and all manner of odd shapes, provided they are planned for right from the start (see below). � Ideal for basements. Use water-resistant concrete and take advice about soil loadings if parts of the basement will eventually be covered with soil. � Chasing for services. The inner polystyrene leaf can easily be chased for electrical and other services. It’s wise not to chase the structural concrete element. Some companies offer different thicknesses of insulation that make this

chasing very easy and practical. With careful preparation it’s possible to pre-plan and create service voids within the concrete walls for say, rainwater pipes. � Can be clad externally with any material. This means that whatever external appearance you want, the underlying ICF can cope with it. You could, at this stage, add even more insulation, depending on the U-values you’re aiming to achieve, before your final cladding. The outer skin of the polystyrene blocks has to be clad (using built-in fixings or wall ties) with something – it can’t be left open to the elements. This outer skin can, though, be easily chased to make room for rainwater downpipes and even other utilities. � Very little waste. Because you order only the exact number of polystyrene units (and their accompanying accessories) you need, and the blocks are easily cut on site, there’s very little wastage. Concrete can then

be ordered in exact amounts per pour, a real plus if you have no room to store aggregates, sand and cement.

Disadvantages

AS Ballantine

Co Cork ICF build as seen in the Winter 2011 issue

� Poor image. In the UK and to some extent in Ireland there’s still some resistance to new construction methods. Many small builders especially seem reluctant to try new things. Because ICF can be done by anyone with a high level of DIY competence this also deters professional builders who pride themselves on their skilled, professional tradesmen. � Confusing choice. Because there is no agreed ‘best method’ in this market, the different types of products make it all seem more complicated than it is. Needless to say, every company boasts its superiority in one way or another and, in a world where there are very few ICF ‘experts’ it can be hard to know which way to turn. It’s probably best to discuss all this with your designer, then to talk with a proposed supplier to see if what they have to offer makes sense to all the parties involved. Different designs and technical specifications call for different methods. You may need to do your homework on several systems before deciding. 

AU T U M N 2 0 1 8 / S E L F B U I L D / 7 9

Selfbuild Autumn 2018  
Selfbuild Autumn 2018