ICF House Plans
This guide outlines the basic principles of using Insulated Concrete Formwork (ICF) to create your new house design plans. First and foremost, you will need to determine whether your project requires an Architect to produce the project drawings, but these ICF principles apply either way.
When do you need an architect to undertake ICF design for your project?
Permitted Development
Many simple ICF design projects can be built under Permitted Development Rules. These projects rarely need an architect’s services and we can provide all ICF home plans required for submission to your local council.
Standard House Plans
Do you know the exact design specification for your new house project? We can provide ICF designs for conventional domestic houses (up to maximum 3 floors, inc. basement) or rooms in the roof with dormers. We can provide drawings for planning application and building regulation approval.
Layout Guidance & Advice
If the required home design plans are complex or you need guidance on how to implement your design ideas, you should employ an architect to develop the concept of your ICF home plans and provide the planning application drawings.
Distinctive Concepts
Dramatic concepts or features such as large open spaces, bifold doors, swimming pools, curved walls or dramatic cantilevers can all be provided for your by your architect using the unique qualities of Insulated Concrete Form Design. We can advise them on the best methods for your particular project.
Let’s get your Home Design Plans approved and ICF ready!
Review our different design services in more detail and see how we can help get your project off the ground and built to the highest standard.
Basic Principles for ICF House Plans
Securing the Foundations of your ICF Design
In a typical ICF house, the most economic foundations include a conventional 1m deep strip footing incorporating a 400mm thick and 500mm wide C25 concrete footing. ICF is then used to bring the wall up to DPC (Damp Proof Course) level or just above it. This meets most Building Inspectors requirements and the extremely rigid rectangular box formed by ICF walls provides a structural system that is extremely resistant to cracking caused by foundation settlement.
As ICF walls do not transmit moisture by capillary action, DPC is not required. However, if a radon barrier is needed, it should be carried under the strip footing or fixed to the top of the footing inside the ICF wall using a suitable adhesive system.
When preparing your house plan drawings with ICF, the ground floor is an essential element to consider. It’s possible to use conventional beam & block floors but this is not optimal in an ICF house for 2 reasons:
The most cost effective and efficient design for house plan drawings is to provide an in-situ ground floor concrete slab over 100mm thick Jablite100 insulation. This can be poured during the same visit of the concrete pump as the 1st wall pour and will increase the thermal mass. If a radon barrier is required it can be placed on the top of the compacted granular material layers that will be needed underneath the layer of Jablite insulation.
In an ICF home design the first floor can be built using timber joists or posi-joists. The floor will need to be attached to the ICF type fixing supplied by Simpson (see here for more detail).
Alternatively, the timber bearers can be fixed using galvanised threaded rods that are placed in holes drilled through the bearers. After the concrete has been placed in the ICF wall and sufficiently cured, the nuts can be tightened to the required torque. A Structural Engineer will be required to design this system so that it suits the span of the joist or posi-joist floor. (See our structural design services for more).
The roof of your ICF house can be supported by wall plates fixed by resin anchor inserts into the concrete core of the ICF walls at eaves level. It is normally straightforward to provide structural steel supports bolted to the top of the ICF wall whenever the roof shape is complex but the Services of a Structural Engineer will be required.
Gable end walls can easily be built using ICF forms. The easiest way to do this is on a flat surface on the ground. After the ICF forms have been cut to provide the required slope and glued together using fire-resistant adhesive foam the gable end forms can be lifted into place by crane or by hand if they are small enough. If the roof slope is steep the gable end forms will need vertical boards fixed at regular intervals to retain the pumped concrete. The triangular voids can then be filled the next day, using a trowel, after the vertical boards have been removed. ICF Design allows for easy and quick gable construction that avoids all that brick-cutting by expensive bricklayers.
Basic Principles for Basements
When a basement is included in your house plan drawings the level of water-proofing required should be established using the following table.
There are two different options for designing a basement using ICF.
Retaining Wall Supporting Beam & Block Floor
When dealing with a large basement or where groundwater control isn’t practical, it’s often better to build an independent retaining wall with internal beam and block floors. This allows for an internal drainage system. The retaining wall can still be supported by a beam and block ground floor, though internal structural walls might be needed to hold up the far ends of the beams. This setup is called Type 1 in the sketch above.
Flat Slab Basement Construction
For smaller basements where you can control the surrounding water table, a Flat Slab basement is a great option. In this design, the ICF wall runs along the perimeter of the flat slab and is connected by starter bars cast into the slab. This is known as Type 2 in the sketch above. This design is particularly effective for ICF house plans with walkout basements, a common need when building an ICF home on a sloping site.
This structural approach is ideal in these situations because a beam and block floor at ground level can prop the basement wall. This significantly reduces the amount of reinforcement needed by up to 75%, provided the concrete blocks are grouted in place before backfilling against the basement wall.
As the demand for housing land grows in the UK, new house plans are increasingly being designed for steeply sloping sites. This has led to a rise in ICF house plans featuring “walkout basements,” which are perfectly suited for modern ICF home designs.
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