Cost-Effective Ways to Build a House Extension – Wolfe Answers Questions from Ideal Home Magazine

While somewhat dependant on factors such as the size and design of the extension, from our experience block and brick is the most cost-effective and flexible for most projects, particularly when building a small extension. This being said, timber frame certainly works well for new builds.

For larger extensions, timber frame can be a quicker option, providing a sealed unit quicker than traditional approaches. It doesn’t suit every extension, however, with traditional block and brick methods often offering greater flexibility when attaching an extension to irregular profiles, such as period properties.

For larger projects, ICF blocks and pumped concrete can be a great approach, offering good thermal efficiency and build speed. We would still, however, favour a traditional approach to most extensions, but are always open to exploring alternative approaches if that’s the customer’s preference.

The key advantages of ICF blocks are build time, for larger-sized extensions, and increased thermal efficiency. The thickness of ICF walls does, however, reduce internal space within the extension. As maximising space is often key within these projects, this can be an important limitation.

Likely the most cost-effective build method for an extension is two skins of blockwork, cavity insulation and the exterior rendered. If using timber frame, exterior rendered blockwork is similarly most cost-effective.