ICF Blocks: Standards and Requirements for Insulated Concrete Forms

There are dozens of manufacturers supplying the UK market with ICF blocks. The cost of blocks fluctuates massively. This is due, but not limited to the cost of storing and transporting blocks to the UK.  The UK market is not yet big enough for manufacturers to justify the cost of setting up factories locally.
So most, but not all blocks, are imported. ICF blocks come into the UK from Eastern Europe, Canada, the USA and Ireland. What is surprising is that the blocks coming from Ireland are surprisingly more competitive than the blocks made in the UK.

At ICF Structures, we can install any blocks you choose but the two blocks that we use regularly and recommend are manufactured in Ireland by Amvic and Altherm.
Although ICF is considered a relatively new MMC building system in the UK, it is important to remember that no matter what ICF block you choose, all ICF buildings must meet the same construction standards as all other building types.
And ICF manufacturers must conform to the same standards and requirements as all other building material manufacturers.

ICF Blocks Standards and Requirements

Insulation

The majority of ICF blocks are made from EPS Insulation and have a lambda value of 0.030 W/mK. The insulation thickness on the ICF blocks can vary from 65mm, 75mm, 85mm to 100mm thick.

Standard blocks come with 75mm insulation on either side and will achieve a u-value of 0.20. However, there is a ‘boost’ in the overall thermal performance of ICF buildings due to the fact that the internal and external layers of insulation run uninterrupted from foundation to roof level. The various thicknesses of insulation mean we can construct ICF Buildings that can achieve U-values from 0.35 W/m²K down to 0.12 W/m²K

Core Thickness 

You should think of an ICF building as a Reinforced Concrete (RC) building with insulation integrated into it. With that in mind, ICF blocks are available with either a 150mm core, or 200mm core. 

• 150 Core blocks are suitable for most house construction types. 
• 200 Core blocks are usually specified by an engineer where there is greater loading requirements - subterranean use, basements, buildings over 3 storeys, and where precast concrete or block and beam floors are being installed. 

So, as long as you think of ICF building as a reinforced concrete structure, you’ll understand why there are very few limitations on ICF. As the structural integrity of the building comes from the reinforced concrete core.

Reinforced Web

ICF blocks are made of an internal and external layer of EPS, separated by a web. The webs play a vital role in the strength and thermal efficiency of the blocks.

• Our advice is to avoid blocks that fold on themselves. Webs that fold are more compact for shipping purposes but are time consuming to install and not as structurally sound. 
• We would also suggest avoiding blocks with steel webbing. Steel is obviously extremely conductive and steel webbing lacks thermal efficiency over blocks made with plastic webs.
  

The plastic webs are usually made from a super strong polypropylene and each web is designed to withstand 500kg of force before it breaks. The integrated plastic webs that sit at 200mm centres through the block. This gives it the strength to withstand the pressure exerted on it during concrete placement. 

Straight Blocks and Corner Blocks

There are essentially only two components to ICF building blocks. A straight block and a corner block. 

• Straight blocks: measure 1200mm x 400mm (high) 
• Corner blocks: measure approx 800mm on the long side, 400mm on the short side and are also 400mm high. 

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To improve efficiencies and reduce waste on site, we recommend engaging with your design team early on and designing walls to meet the nearest 200mm.
We also recommend designing window and door openings in modules of 200mm. This is not a necessity, just a recommendation. We can build to any size, or shape and place openings wherever they are required.

Cavity Closers 

The best blocks on the market incorporate vertical and horizontal cavity closers. They are very easy to install and are inserted into the jams and heads of windows and doors to reduce thermal bridging and increase overall performance and efficiency of the building. 

Services, First Fixing and Plasterboard on ICF 

We usually allow for services and create openings in advance of pouring concrete. This saves core drilling the wall at a later stage which is both time consuming and messy. 

Internal finishing couldn’t be easier with the ICF Blocks we recommend and install. ICF blocks can be chased in seconds using a circular saw, making easy work of first fixing plumbing and electrical work.

Plasterboard can then be fitted directly to the face of the ICF block and screwed using standard plasterboard screws into the plastic web. Large, heavy fix items can be secured directly into the concrete core. 

External Finishing

The most cost-effective method for the external finishing of ICF is render, and the render needs to be approved for use on ICF. When thinking of render, people often think of pebble dashed houses from the 1950’s but renders have come a long way over the last 70 years.
Renders can be textured, coloured and mixed or matched with brick slips, or stone slip,  timber or metal cladding. Renders can be textured, coloured and mixed or matched with brick slips, or stone slip,  timber or metal cladding. 

You also have the option of finishing an ICF building with a traditional brick or natural stone. 

Building Height Limitations 

Since 2010 ICF is considered a standard building method. READ MORE HERE -LINK-

The only real limitation we have when building with ICF blocks is the building height. ICF buildings are currently limited to 18m which is usually 5 storeys. You can read more on the Limitation of ICF Building here

ICF Blocks can be used to construct houses, apartments, care homes, swimming pools and much more. You can click the link here to read more about our ICF applications.

Design Overview 

When designing a building using ICF blocks, remember it is simply a modern solid wall structure. It is extremely thermally efficient and very fast to build. Once we have built your structure you can get on with installing the roof, windows, and finishings, as per specification.

If you have any questions feel free to Contact Us, or check out our FAQs, or our service ICF Construction.