Adding a two-storey extension to your home is a smart and practical way to not only add more space to your home but also save costs considerably since you won’t need to move.

A two-storey extension can be the perfect way to increase the living space in your home. You may have a growing family and an extension, in this case, can be a highly cost-effective solution.

Things to Consider When Adding a Two-storey Extension

How Tall Should it be?

The only real limitation of a two-storey extension is its height. Planning Policy warrants the extension’s height to go along with your existing house’s height – its eaves and ridges must be the same height as the existing roof.

Also noteworthy is the fact when it comes to extension heights, is that if your building generally has a low ceiling, it can be difficult to build a two-storey extension that has enough height to accommodate two full storeys – that’s 2.4 metres per story.

There are solutions though; e.g. going with a lower ceiling height in the new spaces, particularly at the first floor level or building the extension slightly down in the ground.

If your extension has too much height, one common solution is to add some flat roofing that’s concealed behind the actual pitched roof.

Is My Extension Footprint Too Big?

Neighbouring properties should not experience any loss of light, and therefore Planning rules limit how far your two-storey extension can span and how close it can be built to the boundary.

For example, it must not span any further than a boundary set 45 degrees horizontally, measured from the centre of your neighbouring windows – what’s referred to as “sight lines”.

Is There Planning Permission Required?

No Planning Permission is required as long as you comply with the following:

  • Your extension isn’t taller than the tallest point on your current roof
  • It’s built at least seven metres away from the boundary
  • It does not extend by anything over three metres beyond the rear wall
  • It is built using the same materials as your original structure

However, restrictions may apply if your home is in a conservation area, in which case you can get in touch with a locally based conservation office for guidance.

What about Building Regulations?

Getting approval on Building Regulations is a must. There are certain standards which must be met in terms of sustainability, energy efficiency, health, safety, hygiene, etc. You can either consult a certified building control firm or your local authority.

A Word on Party Wall Agreements

Neighbours who share a boundary wall with you – if they have no objections to your extension upgrade, you will not require a Party Wall Agreement. If they don’t give you consent however, a surveyor will need to be hired in order to arrange a Party Wall Agreement for you.

How to Find an Architect

You can Google this according to your local area, although certified bodies like RIBA allow you to find architects according to specific areas.

Always hire an architect who is well familiar with traditional as well as modern UK architecture, and someone you feel comfortable communicating with. Shortlist at least three and ask for written quotes. Additionally, you should also ask them to share examples of completed work from their portfolio.