The following information is referenced from the Retrofit options study of a ‘typical’ home in Letchworth report, conducted by People Powered Retrofit for Letchworth Garden City Heritage Foundation (April 2025).

The information below provides some further information on the key steps that should be undertaken as part of a retrofit process.

If you wish to make external changes to your home as part of your retrofit plans then you need to apply for consent from Letchworth Garden City. As a first step, check out the guidance provided on “Altering your home“.

Making decisions about your project

There is no one-size-fits-all solution for retrofit. Some people employ professionals to oversee all their improvements; others carry out the work in whole or in part on a DIY basis. Some achieve everything at once in a ‘big project’; others work in stages.

All building projects face three main constraints: time, cost and quality. As a general rule, in a given situation, only two of these can be the focus. Quality is important in retrofit to avoid the performance gap and achieve your desired outcomes. This means that your project can either be delivered quickly at some expense, or more cost-effectively given more time (not accounting for any external effects due to inflation). You should try to be clear about where your priorities lie.

Logistics can be another major constraint that can influence your decision making. This is often about the order that you can do things in, and how you plan to tie retrofit into any other works you are planning such as extensions or repair and maintenance work. This requires some careful thought and will often differ from house to house and project to project depending on what your aims are, the availability of materials and labour and other works you have planned.

Getting your home ‘retrofit ready’

Before you carry out retrofit improvements to your home you should make sure it is in good condition and well-maintained. If you are considering major works you should carry out more detailed survey work. In particular you should check things like the condition of any existing cavity wall insulation, roof coverings and rainwater drainage. A structural survey may be needed, especially where there are any suspected problems or if you’re planning major alterations. You should resolve any problems with water ingress, condensation or damp before the retrofit work or as part of it.

Developing designs

You will need to consult with a retrofit advisor, designer or specialist contractor to help you develop your retrofit plans so they can be delivered. They can also help you with approvals like planning and building regulations – to make sure you have permission to build what you want and the designs are safe. Once you have detailed proposals you will be ready to start work.

Getting the work done

It is important to choose contractors who understand the work you want to do. They should be happy to take a ‘whole house’ approach that pays attention to risks in retrofit and work with you to achieve a good outcome. The type of contractor you need will vary depending on the scope, scale and the nature of the work. You might work with a small local building company for some parts, and a specialist retrofit firm for others – or do it all with one construction firm managing everything, including the design work. Finding the right contractor for the job may take time but in the long run it’s worth getting right. Whatever route you take it’s worth getting written confirmation of what you’ve agreed your contractor will do. Ideally this should be a standard contract form that is well understood.

Completion and handover

Once the work is complete you should obtain all the information from your installers and suppliers so you can look after your retrofitted home and maintain it. This is likely to include things like instruction manuals and guarantees and warranties for elements of the work. If you’re not sure about heating or ventilation controls or similar, ask your contractor to demonstrate them to you. Air pressure tests, thermal imaging and commissioning checks of heating and ventilation systems can help make sure everything is as it should be.

Monitoring and evaluation

It’s important to understand the impact your retrofit project has had on your home. This means looking back at your original aims once the work is completed to find out if they were achieved. For example, you can check whether your energy bills have changed or if you are more comfortable. Going further you can track internal temperature and other environmental data. This can highlight any tweaks that might improve things further, or spot issues before they become bigger problems.