A well-planned oak frame extension can create a wonderful living space that not only transforms the way you interact with your living environment but can also add significant value. There are a number of things to consider before building an oak frame extension. Here are 15 things to know before extending your home.

1. Meeting Building Regulations with you oak frame extension 

The Building Regulations set out minimum requirements for structural integrity, energy efficiency, fire safety, damp proofing, ventilation and other key aspects that ensure a building is safe. Even if your oak frame extension can be built under Permitted Development rights and doesn’t require planning permission, work must get Building Regulations approval.

All new building work, including alterations and extensions will require formal Building Regulation approval. This includes replacement windows, under-pinning and rewiring. Some conservatories, are exempt provided they meet the following criteria:

• The conservatory is built at ground floor level and has a floor plan of less than 30m2
• It is separated from the house by external-quality doors
• The conservatory has its own independent heating system, separate from the main house
• Note that those conservatories exempt from Building Regulations approval still require any glazing and electrical installations to meet Building Regulations standards. Also any new openings formed to the conservatory will also require formal approval.

There are two main routes to securing Building Regulations approval for extensions:

Route 1: Full plans application

This is when the structural details for your oak frame extension are drawn up professionally and examined by building control before you actually start work.

An advantage to this route is the detailed drawings can be used to get accurate quotes that are easy to compare if you put the project out to tender. They will also be handy to refer back to during the construction process. For any extensions that are complex or high-value, a full plans Building Regulations application is usually the best route to take.

Route 2: Building notice

The second option is to serve a building notice 48 hours before work commences on site. This is often a quicker and more cost-effective option when tackling very straightforward projects, as it doesn’t require detail drawings.

In either case, the work needs to be checked at key stages by building control or an approved inspector. If everything is approved, you’ll be issued a completion certificate at the end of the project.

2. Does adding value matter?

If the property you are planning to extend is your forever home then this may not be a priority to you. However, if you are looking to add value with a view to selling the property later on, you need to make sure the value added is greater than the cost of the project for it to make economic sense. Finding similar local properties and seeing how much they’ve sold for can be a useful starting point

3. Bigger isn’t always better

The bigger the extension, the more it’s going to cost. Bigger is not always better when it comes to house extensions. There are often ways of creating the feeling of more space through clever design, without adding a huge extension.

4. Choose the right designer for your oak frame extension 

When it comes to designing your oak frame extension, there are a number of options you can choose from. Choosing an architect/designer who understands oak framing from the start can help avoid issues further on down the line. It will also ensure that you make the most of the oak framing structurally, aesthetically as well as taking into consideration scale and proportions. Clients often come to us with drawings that won’t work with an oak frame. It’s important that your designer understands oak as a construction material. Oak frame is often not as well understood by generalist architects and builders. At Welsh Oak Frame, we have an in-house design team who live and breathe oak frame design. It is these extensive skills that ensure we create a stunning oak frame extension that delivers your vision within your budget.

5. Are you extending on or near a sewer?

If your house extension will be built over or in the area of a sewer, you will need to contact your water board before work begins. If a sewer serving more than one property is within 3m of your extension, then a Build Over Agreement with your local water authority is likely to be required.

6. Planning in services

If you are adding an oak frame kitchen extension you will need to confirm the position of your units, cooker and white goods before work begins so that electrics, ventilation and plumbing can be planned in early on.

7. Can your existing boiler cope?

Adding an extension that requires heating or hot water will demand more from your current hot water system. Will your current system cope with this? It is important to work out what the new extension will need to be heated effectively. Can your current boiler can cope with this additional output.

8. Access restrictions

Logistics can be complicated when you’re dealing with an existing building – especially if you’re extending to the rear of a terraced property. Your contractors will need to get to and from the building area. They will also need to park vehicles and machinery near your house. If you live in a home with restricted access, then this may affect the options you have for your extension design.

9. How will you connect the old house and the new oak frame extension 

You will need to make a decision on whether you want the oak frame extension to complement or contrast with the main house. If you are aiming to match your house extension to the existing property then you need to source matching materials which can be a tough task. One mismatch can stand out like a sore thumb.

10. Does the Community Infrastructure Levy (CIL) apply?

If you are looking to build an oak frame extension that creates a new additional floor space of 100 square metres or more, or creates a new dwelling, then the Community Infrastructure Levy (CIL) may apply.

The Community Infrastructure Levy is a charge which can be levied by local authorities on new development in their area. It is an important tool for local authorities to use to help them deliver the infrastructure needed to support development in their area.

The levy only applies in areas where a local authority has consulted on, and approved, a charging schedule. This sets out its levy rates and has published the schedule on its website. Before embarking on house extensions 100 square metres or more you should establish if you will be liable to pay the Community Infrastructure Levy (CIL). Some developments may be eligible for relief or exemption from the levy. This includes residential annexes and extensions, and houses and flats which are built by ‘self-builders’.

To benefit from the self-builder’s relief the applicant does not have to physically construct the extension themselves but they must intend to live at the property as their main residence for a minimum of three years from completion.

11. Understanding the Party Wall Act

If your house extension involves building or digging foundations within 3m of the boundary, party wall or party wall structure, or digging foundations within 6m of a boundary, the work will require you to comply with the Party Wall Act. This legislation aims to prevent and resolve disputes.

A party wall surveyor may need to resolve any disagreements and set parameters to protect neighbours’ property. This is not a matter covered by planning or building control. The act does not apply in Scotland.

12. Planning rules in conservation areas

Permitted Development rights are restricted in Conservation Areas. Each local authority has its own policy for conservation areas, but generally the basis of the policy is to prevent the loss of character of the area. So, if you’re thinking about adding an oak frame extension in a conservation area, always contact your local conservation officer first.

13. You’ll need a contingency budget for your oak frame extension

You will need a healthy contingency budget to cover any unexpected costs. The start of work on an extension project can uncover problems with the existing house that need addressing, for instance. We recommend a contingency of somewhere between 10-20%.

14. Protecting trees

Some trees are protected by Tree Preservation Orders (TPOs). All trees within a Conservation Area are protected by legislation. They effectively have a TPO on them providing they have a trunk of diameter greater than 75mm. Altering a tree that is protected by a TPO is a criminal offence. It can result in substantial fines so take care if you are extending your home near to a protected tree.

15. You probably can’t claim VAT relief on your oak frame extension

Most oak frame extensions will be subject to VAT on labour and materials at the standard rate of 20%, especially if you use a contractor to undertake the work. If you use local trade­smen who are not VAT registered you can save the 20% VAT on their labour. You will still have to pay VAT on materials at the standard rate.

Some extension projects are eligible for VAT relief. These include work to listed buildings (zero rated), the conversion of an existing dwelling that changes the number of units (reduced rate of 5%) and work to a building that has been unoccupied for at least two years (reduced rate of 5%).

To benefit from VAT relief if you are extending a listed building or renovating an unoccupied home, you must use a VAT-registered builder. You cannot reclaim the VAT yourself.