Two Storey Extension Guide

A two-storey extension can significantly increase a property’s space. It can enable you to gain additional rooms like bedrooms and bathrooms, as well as a larger downstairs living area. These house extensions are often used to accommodate a growing family’s needs. They can also create extra rooms for specific purposes, such as a home office, gym, or hobby room.

Benefits of a two storey extension

Two storey extensions can be the perfect alternative to moving house. Many people out grow their current home but love the location, neighbourhood and don’t want the expense of moving. By building a two storey extension you can add one or tow bedrooms, an ensuite or dressing room at first floor (dependant on the size of the plot and the existing house). At ground floor the kitchen could be increased in size or opened up in to a living/dining/kitchen area. There are many options and we listen to each client and their specific needs and requirements.

Footprint

Building a two storey extension means that the client is gaining significantly more space without increasing the overall footprint of the extension

Cost-effective

Although a two storey extension is more expensive than a single storey extension, it won’t be double the cost. You are only building one set of foundations and adding one roof so it can in the long run prove to be a more cost effective route to take.

Added value

A two storey extension will no doubt add value to your house when you come to sell it and for some people that is the main drive when considering a two storey extension. However, we like to emphasis the value that the client will benefit from while they live in the house, the larger kitchen, the much sought after utility room, a playroom for children or teenagers, a study that the door can be closed on at the end of the day. Making the most of your extension is our primary aim and we work closely with clients to establish their needs and preferences.

Where to start

It’s best to keep an open mind when starting to plan your two 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 two storey extension

You have a lot to consider when it comes to choosing a two storey storey extension, including the type of extension that’s right for your property.

Side extensions

A two storey side extension is often the most desirable as it has less impact on the back garden space. It often makes for a much more coherent layout at first floor but each house is of course different. 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

Two storey rear extensions can work really well with the right house and location. Proximity to neighbours, especially in a semi-detached house need to be considered and any planning constraints worked through at design stage. 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.

Wraparound extensions

In some cases clients incorporate a two storey and a single storey extension and create an extension that wraps around the property. We look at each house and the clients requirements and work with the clients to create the desired end result within the budget.

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 two 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 two 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 a small number of two storey extensions 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

A Schedule of Works is a document that accompanies the Technical Drawings but gives more detail of the materials, finishes and fittings in each room. They are more commonly used on larger and complex projects, which many two storey extensions will fall under. A Schedule of Works is beneficial when you want a more accurate price from the builder. It can remove the stress due to unforeseen costs.

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 Administration 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.

Paperwork & Insurance

• 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

Your building insurance company must be informed of any construction work taking place and it is your responsibility as the homeowner to tell them. You need to inform them whether you will be living at the property during the building work or if the house will be empty. The building insurance company will also want an estimate of how long the work will last. You should keep them updated if any part of the timeline changes and contact them again when the work is complete.