Initial Design Considerations

The process of designing your building or conversion will naturally evolve from early sketch ideas to a final agreed layout suitable for a planning application and eventually to detailed building regulations drawings.
The first stage of any project is to obtain some initial design ideas, to find out any planning limitations and to obtain a budget cost for the work.

Even for straightforward projects, it is important to be sure that you have looked at all of the options open to you and gathered as much information as possible before you proceed with a specific design. It will cost time and money to change your design later on and, when all the work is completed, you should be satisfied that you have the best solution for your needs.

We would strongly recommend that you use an experienced architectural designer to carry out your initial scheme design as they will be familiar with the limitations that are imposed by planning and building regulations. They will also know how to make the most of the space available.

At the feasibility stage, you should be considering the overall design of your extension and not be overly concerned with details such as your choice of finishes.

The main considerations you will need to think about at this stage are listed below.

A. Your Requirements

Often know as the 'Client Brief', your first task is to define what you actually require from the building.

For garages, it is quite likely that you will be looking to park your car in it but will you require additional room for storage or a workbench?

If you are converting an existing outhouse or barn, the space can be quite versatile and multifunctional and may be used for a home office, games room or a granny annex.

Most designers like to have a clear Client Brief from you so that they can help you to create the space you need and give you an idea of furniture layouts. If necessary, create a list of priorities, dividing it into essential works and desired, but not essential works.

B. Position, Shape and Size

One of many decisions you will have to make is where you would like to build your addition (unless you are converting an existing building).

The overall size and position will be limited by boundaries, planning constraints and cost but does the extra space need to be a certain size for a specific reason?

If you are creating an office, for example, you will need enough room for one or more desks, chairs and storage. If you are planning to build a new garage, does it have to be big enough to suit a certain vehicle and are you planning to change your car in the future?

Our best advice is to plot furniture and vehicles on to your initial plans - if your designer is using a modern CAD package, this will be normally be easy to do or you could always use the cardboard cutout method!

The size of any new building will need to be in proportion to the hose and shouldn’t dwarf the original property. This is likely to be a condition imposed by the local planning authority.

Also, think about the shape of your proposed extension. Most will be rectangular or square, simply because this is easier and more cost effective to build. If you are thinking about a curved wall or an interesting shape, just be sure you are aware of any cost implications and make sure your furniture will still fit.

It is important to consider your neighbours and what effect your plans will have on them – they may lose sunlight or become overlooked. Try to minimize the impact and talk to them before you seek planning permission.

At the feasibility stage, your designer should carry out a measured survey of the property prior to preparing scaled plans for you but we would also recommend using a designer that can illustrate your proposal in 3D as this will help you (and your neighbours) to get a good understanding of how the proposal will look.

C. Light/Ventilation

This an area that your designer should be able to help you with but be aware of the Building Regulations limitations on glazed areas. You will generally be limited to an overall amount of glass so you will need to decide where this will benefit the design most. There are ways of compensating for excessively glazed areas but they can add to the cost of the works so get professional advice early on.

D. Structural Alterations

When carrying out your initial design, think about any existing structures you wish to demolish. Converting existing buildings can become expensive if there are a lot of new steel beams and extensive alterations so you may be better off trying to keep as much of the original structure as possible.

A well prepared feasibility study will give you a budget cost for the work that will highlight this area

E. Landscaping

Will your proposal involve felling any trees? The local council is likely to want to keep the landscape as similar to the existing as it can, so what might seem a small consideration to you – taking down trees or hedges – can be a major factor in your planning application.

If you can, when considering your home extension, try to minimise the number of trees and hedges you remove, particularly any that are near the boundary that faces onto the public highwa

G. Budget/Value Considerations

There is sometimes a reluctance to talk about budgets at an early stage, but this can often be the single most important factor that determines your final design.

Whilst you will be building the space for yourselves, we would always recommend that you consider the resale value that your proposal will add. It will need to blend in well with the existing and it may be worth asking a local estate agent about the potential increase in resale value.

H. Planning and Building Regulations

Once you have decided to proceed with the design of a project, you will need to finalise the design details and to obtain any formal approvals required.

Your designer should be able to advise you on this matter and, if planning permission is required, make sure you are aware of any local planning policies that may restrict what you can build

Planning Permission

Please refer to our factsheet on Planning Permission for Outbuildings to find out more about whether or not your proposal is likely to require planning permission.

If planning permission is required, it is a good idea to have an informal discussion with your local planning office prior to making any submission as they will normally be pleased to give you guidance that could save you time and hassle in the long run.

Before making the application, check that the overall dimensions give you the sized rooms you require and make sure you are happy with the elevations and layout. Check that the proposed materials are clearly shown as the planners will need to be certain that the extension blends well with the existing property.

If you are planning on felling any trees or hedges, make sure these are shown on the plans.

Your designer will usually deal with the application for you, acting as your agent and will ensure that the plans are to the correct scale and include additional information required for the planning submission such as a location plan, block plan and a design or access statement.

For  more information on this subject, please refer to our factsheet on Making a Planning Application.

Planning Permission Not Required

Where planning permission is not required, we would recommend that you obtain written confirmation of this from your local planning office as it may avoid any problems when you come to sell the property.
This can be done by obtaining a 'Certificate of Lawfulness' from the council and your designer should deal with this for you.

Further information on this subject is available in our factsheet on Permitted Development.

Building Regulations and Working Drawings

Conservatories are normally exempt from building regulations control when they meet a number of conditions. For more information on this, see our factsheet on Building Regulations Approval for Outhouses.

If building regulations approval is required, your designer will normally prepare building regulation drawings and submit these for approval to the council or to an approved inspector.

The drawings that are completed for building regulations approval are commonly known as the working drawings and these will contain all the information needed to ensure your proposal meets with the current regulations. They also need to be clear and have sufficient detail for your builder to be able to use to accurately complete the building works.

Other Approvals

You may need to obtain other approvals for your proposal and your designer will usually help you deal with these. You may need to involve your solicitor to check if there are any restrictive covenants and a party wall surveyor if your proposal is close to another property. We have provided factsheets on these issues below.
The Party Wall Act
Restrictive Covenants

Specification for Works

Once the working drawings are complete, we would also recommend that a written specification is also prepared for your project as this will minimize misunderstanding between you and your chosen builder/supplier.

There are many aspects of your project that will not necessarily be shown on your drawings (e.g. type of ironmongery, floor tiles, etc) but these need to be defined so that a builder can properly quote for the works. The specification will also usually form part of your agreement with the builder when works commence.