Insulated Concrete Formwork

The building technology used in a DLB Scotland home provides a more thermally efficient building, resulting in lower fuel bills. In addition they also have excellent sound insulation.

ICF or 'insulated concrete formwork' is an external wall system comprising of two layers of high performance insulation separted by 150mm which is filled with concrete once built.

The resulting wall is very strong, very thermally efficient, high in thermal mass which again helps thermal performance and also the wall is very air tight, no draughts get in and no heat leaks out.


Comfort with peace & quiet

When you walk around inside an ICF house, you notice that the temperature remains constant no matter what part of the house you're in. An ICF home stays cool in the summer and warm in the winter, with no cold or hot spots. The temperature is uniform throughout the house.

You will also notice how quiet an ICF home is. ICF walls achieve a sound transmission class rating that makes it one of the "quietest" building products on the market. In an ICF home you can turn up the volume on the stereo without bothering the neighbours. And the noise of a lawn mower outside will be reduced to the level of a whisper inside.

ICF graphicThermal Mass

Concrete construction naturally has a high thermal mass, which is the ability of a material to store excess heat energy during the day. This heat energy is then released back into the building at night as it begins to cool. The strength of an ICF construction allows for concrete elements to be used internally throughout, including all floors and internal walls, maximising the thermal mass available.

ICF is extremely airtight, with a typical structure experiencing less than 1 air change per hour (ACH). Because this is a poured concrete method of construction the structure is effectively monolithic, thus air-leakage is reduced to an absolute minimum.


An ICF house is built to last. Concrete is inherently durable, and when cast within the ICF system, it cures without suffering exposure to extreme temperature variances. This results in a far higher strength of set initially, but the insulation also permanently reduces the stress on the concrete caused by thermal expansion and contraction, enhancing its lifetime well beyond standard masonry construction and therefore timber frame also. Sustainability Concrete, a major element of ICF construction, hasn't traditionally faired that well in 'Eco' terms because of the high amount of energy needed to produce cement.

However, recent developments in concrete technology has changed this, for example, a typical structural concrete mix using 50% ground granulated blast-furnace slag as a cement replacement now has embodied CO2 in the order of just 12% of what would have been the original 100% cement figure. Similarly, expanded polystyrene (EPS), a natural by-product of the petroleum refining process and the other major element of ICF construction, when used for insulation purposes will recoup the CO2 generated during its production within the first week of the building's operation, simply by reducing occupant heating/cooling demands. EPS is also HCFC and CFC free.

Sustainability decisions must consider the lifetime of a building and not just the initial impacts. In the UK, 10% of our CO2 emissions come from the construction of our built environment. But a massive 50% comes from actually using our buildings, 27% of which is residential use. And this is where ICF construction really comes into its own, both in terms of its durability and its energy-efficiency, proving that it is a truly sustainable modern method of construction (MMC).