Single Storey Extension Guide

Single storey extensions are highly popular and can include a rear extension or a side extension. People choose a single storey extension for a variety of reasons. They may want a larger kitchen and dining room or to create more space for a combined open plan living area. Extensions can help people gain a home office, utility room or playroom, while for some it’s the best way to build an extra bedroom with an ensuite bathroom.

The design and layout of any single storey extension will depend on your home’s requirements and your personal preferences. You will also need to consider: your home’s proximity to any neighbouring properties, especially if you live in a semi-detached or terrace house; the impact on the garden space; and if there are any restrictions on the land (e.g. greenbelt, open countryside or an existing covenant).

Benefits of a Single Storey Extension

Single storey rear/side extensions can often be the best choice as they can are versatile and serve various purposes, such as creating a larger kitchen, adding a dining room, extending the living area, building a home office or study, incorporating a playroom or family room, or even constructing a new bedroom with an ensuite bathroom. The design and layout of the extension depends on the specific requirements and preferences of the homeowner and it can add additional living space without too much disruption.

May fall under Permitted Development

Many single storey rear extensions fall within permitted development rights and can be built without planning permission. At DMA we always recommend that you obtain a Certificate of Lawfulness to ensure the extension meets the strict Permitted Development rights. DMA will be able to guide you through this process and advice you on the best course of action.

Speed

A simple single storey extension can be built in as little as three months. However the design, planning and building control process can take much longer. At DMA we recommend contacting us at least a year before you plan to build to ensure all the drawings are complete in a suitable time for a builder to quote for the work.

Caters to a variety of budgets

Single storey extensions are a great way to add space dependant on the budget. We work closely with our clients to ensure that where possible we design an extension within their budget and make them aware of any limitations at an early stage. We can also provide cost estimates at design stage before the client fully commits to a design.

Natural light

Bringing natural light and ventilation into our designs is a key consideration. For many single storey extensions we use a variety of fixed and openable roof lights or roof lanterns. We are careful to position the roof lights to not only bring natural light to the extension but also to bring natural light into the existing house.

Flat roof terraces and balconies

Flat roofs have historically been looked on less favourably than a traditional pitched roof. However with the advancements of technology flat roofs are coming into their own. Whether you want a roof terrace or a wild flower green roof, we at DMA can advise you on the best route to take and how best to navigate the planning system to achieve your dream roof.

Where to start

It’s best to keep an open mind when starting to plan your single storey extension. Many people gain initial inspiration from what friends and neighbours have done, but the more research you do the more ideas you will find. Engaging the professional services of DMA can be invaluable. We can assess the house’s existing layout, offer insights into potential design possibilities, and ensure that the extension harmonises with the overall aesthetic and functionality of the property. Our expertise can help the homeowner envisage the additional value that an extension can bring and walk you through the whole process with ease and clarity.

Types of single story extension

A single storey extension can come in many different forms and the options for any home will depend on its unique characteristics.

Side extensions

A side extension can turn a house into a home by adding a garage, utility, downstairs WC, study, playroom or extra bedroom. The list is endless as are the design possibilities. Like any project we are guided by the site constraints and the clients desires. Many people want to leave access down the side of the house and the boundary for maintenance, others would prefer the extra internal space. We work with each client to achieve the results you desire.

Rear extensions

Rear extensions are often used to enlarge an existing kitchen, replace a conservatory or add an additional room. We work with the client to design an extension that works with the existing house whilst maintaining garden space and opening  up the views from the house into the garden.

Wrap-around extensions

In some cases there is adequate space to build out to the rear and to the side with the extension wrapping around the house.

Stage 01 – Preparation and Brief

During this stage, we meet with the client to understand their requirements, analyse the site, and discuss their vision for the single storey extension. We will prepare a comprehensive brief based on our discussions and conduct any necessary initial surveys. This process enables us to understand how the client envisages the end result, what elements of the design are most important to them and if there are any limitations due to the site or location.

Stage 02 – Concept Design

Based on the brief from the client and our site analysis, we will develop concept designs that explore various options for the single storey extension. These designs illustrate the spatial layout, form, and overall aesthetic of the proposed extension. Where it is applicable we may produce more than one design solution for discussion. At this stage we can provide initial cost estimates in conjunction with a Quantity Surveyor. We will also review any planning constraints or building regulations that may have an impact on the final design.

Stage 03 – Design Development and Planning

Most house extensions require planning permission from your local authority. Although small single storey extensions often fall within ‘Permitted Development’ and can be built without planning permission. DMA recommends obtaining a Certificate of Lawfulness to ensure the extension meets the strict Permitted Development rights. For the planning application DMA will refine the drawings, complete all the application forms, prepare the site and location plans and submit the planning application via the planning portal. DMA will also handle all communication with the planning department regarding the application and make any necessary adjustments following feedback from the planning department.

Stage 04 – Technical Design

It is a legal requirement to obtain Building Control approval for almost all building work. DMA has the knowledge and expertise to produce a full set of technical drawings that comply with the current building regulations. We work with the structural engineer and other consultants to ensure all the information is available and coordinated for the building control ‘plan check’. DMA will submit the drawings to building control and make any necessary changes. Once the drawings have approval we issue a full set of Technical Drawings to the client to ensure the builder has all the information before they start work on site. Building control must be notified 5 days prior to any work starting on site by either the builder or the client. The fee for building control varies depending on the size of the extension.

Schedule of Works

For larger or more complex projects a Schedule of Works can be produced to accompany the Technical Drawings giving more detail of the materials, finishes and fittings in each room. This can be beneficial when you want to have a more accurate price from the builder and can remove the added stress on site due to unforeseen costs. However, many clients building single storey extensions can work through these details with their builder prior to work starting.

Tendering Process

The success of your project will be linked to the builder you choose to construct it and how your agreement is set up. We advise that you seek competitive tenders/quotes from suitable companies and we can manage that process for you, sending out the paperwork and checking tenders for you. We can also recommend builders we have worked with successfully in the past. It is also worth checking if your builder is a member of a suitable organisation such as Federation of Master Builders.

Stage 05 – Contract Admin and Site Inspections

Many projects have no formal agreement or contract in place before work starts, making disputes difficult to manage and resolve. We can assist you in choosing the right form of contract for your single storey extension. The contract between the client and the builder, sets out when they get paid and how much, how you deal with changes, what happens if the project overruns and how defects are dealt with. We offer a Contract Administration and site inspection service where we will prepare all the contracts, inspect the works on site on your behalf, checking for conformity with the contract drawings and that workmanship is to a suitable standard. We also liaise with the builder to make sure you receive the suitable certificates and paperwork at the end of the project.

Budget, Costing & Fees

Budgeting for your building project is important and the cost for a single storey extension can vary greatly. The area you live in, the materials chosen, and the size and complexity of the project will all have an impact.

We try to ensure you are aware of all the architectural services fees and associated costs from the beginning. Typically, these are approx.10% of the construction cost, but can vary from project to project. We recommend using the Love Renovate cost estimator to get an initial price based on the size of your extension.

Once concept design drawings have been completed we can arrange for a cost estimate. To get a full cost breakdown you can appoint a Quantity Surveyor to price the Technical Drawings prior to appointing a builder. Alternatively, most builders will give you a price for the works prior to appointing them.

Unforeseen costs can be one of the biggest stressors on a building project, so it is worth having a contingency fund. We recommend adding 5% to the contract value to cover these.

Keeping costs down

The areas where we often see costs rise are where high-end sliding doors and rooflights are specified. We all like the minimal lines of some of the high-end door manufacturers, but these types of doors can cost two or three times other options. Expensive kitchens are another budget buster, with some companies charging large mark ups for fairly run of the mill kitchens. Don’t discount using Ikea or Howdens and finishing it all with nice bespoke worktops. Flooring is another area that can mount up so shop around and make sure you have looked at quality as well as price. We can use our experience to guide you through options.

Process & Timeline

• Stage 1

  Preparation and Brief

  Day 1. First meeting with the architect, who will carry out a survey of the site

• Stage 2

  Concept Design

  Approx 4-6 weeks from initial meeting and survey

• Stage 3

  Design, Development and Planning

  Planning can take 2-6 months depending on the local authority

• Stage 4

  Technical Design

  Approx. 10-12 weeks to complete the drawings and coordinate with other consultants

• Stage 5

  Construction

  Varies greatly but a simple single storey extension will typically take 12-14 weeks to build

Snagging & Warranties

At the end of the project it is always a good idea to walk the project with the builder and note any points of snagging that need to be rectified before they leave. This could be as simple as a mis-aligned socket to a damaged door or window. Many issues will have been resolved on site during the build. If you have a contract in place then you will have an agreed period of time for the builder to rectify any snags. It is also good practice to get any warranties from the builder for windows, doors, new boilers, etc. DMA can assist with the sanggin process should we be required.

Paperwork

Both your planning approval and building control approval are legal documents and should be kept safe. Also all certificates from the builder need to be kept and some need to be shown to building control for the final certificate to be released. For example; commissioning certificates for a new gas boiler, electrical safety certificates, mechanical extract fan test results, fire alarm test and installation certificates if they have been upgraded.

Building Insurance

As the homeowner, it is your responsibility to inform your insurance company that work is taking place. They will want to know if you are going to remain living in your home during construction or if the house will be vacant. They will also need a rough idea of how long the work will take. It is worth contacting them again at the end of the construction phase to tell them the work is complete.