House Extensions

Summit Builders specialise in the domestic building market and house extensions make up approximately 70% of our work. A house extension is the ideal (and often cheaper) alternative to moving into a new property if you find your family is outgrowing your home. A house extension can provide you with a brand new contemporary kitchen, a huge open-plan living room, a guest bedroom or a children’s playroom. Not only is a house extension the ideal way to create more living space but is a cost-effective way of adding between 10-30% value to the price of your property.

Summit Builders offer a complete house extension service, from consultation, to design and contacting your local authorities, all the way through to project completion. We offer a huge range of energy-efficient windows and doors and the employ the latest building and insulation technologies in all of our work. Summit Builders also understand the stress and disruption building work can cause to people living in houses while extension projects are in progress, so we take the utmost care on every project. We always clean up thoroughly at the end of each day and create as little disruption to the rest of your property as possible.



Summit Builders have created many types and styles of house extension in and around the Cambridge area; however, the most common extensions we build are:

Single storey extensions

A single storey extension is the most common type of house extension that Summit Builders are asked to build. They can be built onto any part (usually the rear) of a property where only a ground floor (including any basement space) is built. Planning permission may not be required for a single storey extension, but consideration must be taken into things like the extension’s impact on your neighbours and the position of flues and drains. Roofing designs for single storey extensions can vary, depending on the roofing of the existing property. Summit Builders can provide flat roofs, pitched tiled roofs and living green roofs that include decorative grasses, plants and shrubs.


Two storey or multi-storey extensions

Summit Builders can build, much like single storey extensions, two (or multi) storey extensions onto any part of a property. In some instances, it may be possible to build a two storey extension without planning permission, but this will depend on property type and design. Summit Builders can match the appearance of the extension to existing property, including building materials, roofing, the proportion of the openings and exterior finish and will not allow the overall size, shape and position of the extension to dominate the existing property. Summit Builders will also take into consideration any significant loss of light to the rooms or gardens of neighbouring properties when it comes to design and planning permission.


Over-structure extensions

This type of extension, as the name suggests, is an extension built over an already existing structure or part of a property, such as a garage, kitchen or living room. Over-structure extensions are not always as simple as it sounds because many garages are often built with single layer brickwork and are unable to support a room built above it, or the foundations of the garage may not be strong enough. If we feel this may be the case, we will dig an investigative trial hole to explore the foundations. A newly poured foundation may be needed, as well as the installation a new inner wall or blockwork piers and steel beams to support the weight of the extension above.



Porches are the smallest type of house extension that Summit Builders are asked to build. They are basic structures that are built over the entrance to the front, side or rear of a property and are ideal for leaving muddy boots, shoes or equipment in before entering the house. Porches are usually built with simple, single brick walls and columns and include a light fitting, windows and a door. If needed, Summit Builders can wire in an electricity point. Due to their size, most porches do not require planning permission.