Terraced house extension plans and professional guidance for your home project

Below we have prepared answers to common questions about what detached, semi-detached and terrace house extension plans and information you will need to prepare for your home project.

Do you need planning drawings or building regulation plans for your terrace house extension?

The quick answer is yes, as a minimum you will need planning drawings and building regulations plans for your terrace house extension project.

The same applies to any type of house extension project, double storey extensions, single storey extensions, and whether the house is terraced, semi-detached or detached.

The idea is that house extension plans are prepared to convey the necessary information for the various approvals you will need to obtain for your home project.

Actually, “plans” is a shorthand for different types of drawings. “Plans” can mean floor plans, elevation illustrations, section cuts through the house, or 3D images that show the house from a bird’s eye view angle.

Terrace house extension planning drawings convey information to the planning officer to demonstrate two key things: a. what is there at the moment and b. what alterations you aim to carry out.

In fact such planning stage house extension plans come in two sets: as existing and as proposed. And the idea is that anyone can compare them to see exactly what the alterations and extension are and how such changes to the house comply with the planning regulations.

Typically such planning stage house extension plans include dimensions about the depth, width and height of the proposed extension. They also include information about the materials you propose to use, how new windows and door relate to the pattern of the existing windows and doors, and they need to demonstrate how your proposed extension impacts the neighbouring houses.

Building Regulations house extension plans are much more detailed and they include a larger quantity of construction information that is relevant to the current Building Regulations. For more information about what you need to include in these Building Regulations plans see Planning Portal – Building Control

Typically though the architect will prepare a set of technical Building Regulations plans and information for the Building Regulations submission. And a structural engineer will also prepare a set of structural Building Regulations plans an information to be also submitted to the Building Regulations Inspector.

The Inspector will check the technical and structural plans, request additional information if this is necessary and provide a conditional approval to these plans. Then the Inspector will visit the building site 4-5 times during the construction stage. At the end of the construction stage the Inspector will certify the building works and confirm that everything was built in accordance to the current Building Regulations.

For a fuller explanation of applications, assessment and timescales, read our guide to how planning permission works in London.

What type of double storey extension semi detached house plans am I likely to need?

Given that 7.8 million households (31.5% of all households) live in semi-detached properties, single and double extensions are one of the most common types of development to residential properties.

Typically there are two main types of double storey extensions to semi-detached houses you will need plans for:

Double storey side extension semi-detached house plans

Semi-detached houses often allow a gap between the side of the house and the side boundary. Georgian, Edwardian and Victorian semi-detached house layouts can easily be added to as long as this gap to the boundary is a minimum of 2.5m. This is true for both the ground and first floor layout. At the ground floor the plan of the semi-detached house will evolve to accommodate an additional reception room or guest bedroom at the front. At the rear of new extension the floor plan can develop to enlarge the kitchen area and to provide a new utility space. On the first floor the plan can be developed to add more bedroom and bathroom areas to the semi-detached house.

Double storey rear extension semi-detached house plans

A semi-detached house can be potentially extended to both the side and the rear of the house. When you have a chance to extend on two storeys at the rear, and this is subject to planning approval, you end up with a floor plan that works differently on the ground and first floor levels. In most cases a double rear extension will allow for an enlarged kitchen, living and dining area on the ground floor. On the first floor you need careful development of the design to create additional bedroom and bathroom areas. The reason for this is that the existing staircase or the existing bathroom might not be in an ideal position to allow for the double storey extension to your semi-detached house to create much or useful additional floor space.