ICF Help & Advice

Our insulated concrete formwork help & advice centre has been created as a reference and information hub for designing and building ICF structures in general, and Polarwall in particular.

ICF Self Build

The question of “how much does it cost to build a house” is a huge topic with countless variables.  So there is not a simple definitive answer. 

But let’s look at the variables and try to give some guideline figures for consideration. 

Just finding a decent plot is difficult in itself, and a good building plot usually comes with a premium price. 

How Design Affects Build Costs

A new house can cost anything from £100,000 to millions depending upon the size and location of the build. How the design affects build cost is also something that can be huge.  

In terms of keeping costs down a small square or rectangular house will be the most cost effective. The build cost increases with the number of corners. However, more corners will generally make the design more interesting.

A 2-storey house provides better value for money than a bungalow for the same living area. The bungalow needs a much bigger foundation and a much bigger roof, which are both expensive items.

How Design Affects Build Cost

The house to the right is a relatively expensive build. It has a big roof area and two levels below ground built into the slope. It is also a complicated shape. Sloping sites are generally cheaper to buy than flat plots as there is an expense to building into the slope. Sloping land does make for good land to build a “walk-out basement” and maximise the living area.

Keeping the Architect Under Control

It is important to make sure that the architect is aware of your build budget.

To keep build costs lower, make sure the architect aligns the walls on the upper storey with the floor below. What might look architecturally interesting becomes expensive when the engineer has to add lots of steel support beams.

The fashion at the moment is for huge walls of glass. Nice in theory but always expensive and often impractical. The phrase “bringing the outside in” goes somewhat against the primary purpose of a house, which is to “keep the outside out”.

Obviously, the basement option can be a big expense but sometimes it is necessary and desirable. Cladding choices for roof and walls can also have a huge impact on the budget. Similarly, the type of window and its thermal performance can seriously affect costs.

Self Build Costs

The good news is that self-build project will typically save you around 30% on the build costs. This is compared to what you would have to pay for the same house from a developer. Also you’re in a position to build exactly what you want in the way that you want (subject of course to the dictates of the local planning authority). 

A good way to assess the feasibility of a self-build project is to start by planning your budget. Your cash resources, equity from sale of current home, and borrowing limits usually determine the available budget 

Developer Costings

Traditionally, a developer would work on 1/3 spent on the cost of the land, 1/3 on the cost of the build, and 1/3 would be profit. The scarcity of good single building plots in this country means that sometimes the self-builder may pay considerably more for the plot than the 1/3 mentioned above. 

Remember that there are other costs involved in the land purchase. These include the legal fees and stamp duty.  Some plots may require expensive connections from water and energy companies. 

The main portion of your build cost will be spent on the foundations and the superstructure. Superstructure includes the walls, the cladding, the floors and the roof. Typically this accounts for about 30% of the build budget. The cost of the superstructure will be determined by the size of the build, the construction system used, the amount of insulation within the various elements, and the cladding and finishing elements. 

As well as the superstructure, you also have to allow for drainage, electrics ,plumbing, heating, kitchen and bathroom fitting, plastering, decoration, tiling, flooring, and of course, the landscaping around the property.  

The figures that are provided in 2022 for building a house are between £1500 and £3000 per square metre of floor space.  The lower figure represents a budget house and the higher figure represents a house with a more luxurious finish. 

Further Reading on “How Much it Costs to Build A House”

For a full understanding of respective costs for self-building in the UK then do splash out on this book. We are happy to recommend this to people. It is the Housebuilders Bible by Mark Brinkley. For around £25 it will help understand where your money is going to go.

The only predictable thing with a build budget is that you will exceed it.

Have a look at our article Can Anyone Self Build a House? 


The various sections above cover the main topics for ICF construction both above and below ground. 

Do not use this as an alternative to what your chosen manufacturer recommends.  We can do things with Polarwall that ICF blocks can’t do and there may some things that you do with other ICFs that Polarwall can’t do. For example our instructions on vibrating the concrete may not be wise on some EPS block systems. 

We want to add to and develop this section, so we welcome all your questions, suggestions for topics and feedback.  If you want to go deeper into a topic please let us know.  This advice hub does not replace our training (or any other companies training) and you still need to avail yourself of our FREE training course.