How big can you have a single storey rear extension?

[zippyswife]

I'm looking to purchase an end of terrace property. I would want to put a single storey extension along the full width rear of the property. As far as I'm aware although there has been a side extension there has not been a rear extension.

The garden is .25 acre and the house itself is quite small.

What kind of size extension could I ask for at the rear?

Although it was built in 1920s it is not listed. It doesn't seem like the adjoining property has extended although they have a conservatory.

I'm really new to all this so any pointers in the right direction would be appreciated.

Technically, you can ask for anything you like!

There's two ways that you can extend - by applying for planning permission or through permitted development. Permitted development basically means that there are certain kinds of extensions you can do without needing to seek permission.

For a terraced house, you could extend up to 3 metres beyond the rear wall as part of permitted development - but you'd have to consider all the other requirements too (for instance, you can't build on more than half of the garden - and the existing side extension will count towards it)

That doesn't mean that that's the biggest extension you could have - but anything bigger would need planning permission, which may or may not be approved.

We’d like to do similar but have been told we may have a Right to Light issue arising with neighbours

@AmberRoseGold is right to light an issue for single storey? I hadn't even considered that.

@PowerslidePanda thanks for the info. Is there an easy way of finding out whether I'd get planning for large extension before buying the property?

@zippyswife - No easy way to know for certain, but you might be able to get an idea by looking at the planning portal for the local authority. You'll be able to see what other houses on the street have applied for in the past and whether the plans have been accepted or rejected. Bear in mind that the rules have changed over the years though, so the further back you go, the less relevant the decision.

Yes it’s something to do with the angle of light coming to their window even on single storey. Definitely worth investigating as it is one of our local planning department’s Gotchas for planning applications.

Ah right. Had no idea. Thanks for that.

The planning portal website is good. You may also be able to get whats called pre-application advice from your local authority - give them a ring and ask them for some information.

What's on the side that you're not joined to?

On the side that you're joined to, you'll need to submit a party wall notice and follow the procedure for the Party Wall Act (your neighbour can nominate a surveyor but you pay for it) so you need to build that cost into your plans too.

One side is adjoined and the other side is part of my garden and then fields. I'll take a look at the planning portal. Thanks for the advice.

For a terraced house, you could extend up to 3 metres beyond the rear wall as part of permitted development - but you'd have to consider all the other requirements too (for instance, you can't build on more than half of the garden - and the existing side extension will count towards it)

I've seen the 3 metre rule for permitted development mentioned on here a few times recently. This has been extended to 6 metres (though requires prior notification) - much more detail in this article.

Great article @MsShopper I think I'll call their planning department just to check but potentially that could be a huge extension.

Is there an easy way to get a ball park on price for an extension?

You really need professional advice. Get an architect around for ideas and a quote.

If you have an existing extension it is likely you will need planing anyway but you need advice.

A note of caution..the planning rules are so complex now, even architects get it wrong. My neighbours had an extension and wanted an additional one which would have changed the original. Architect consulted with the LA who said permitted development but apply for cert of lawfulness. Came back after months as PP required and had to start the process again.

The architect now advises all clients to go for PP as the cost involved and time is barely more than a cert of lawfulness

Is there an easy way to get a ball park on price for an extension?

Not sure how accurate it is, but I came across this tool the other day!

Costs vary so much up and down the country. But as a rough ball park, use a figure of £2k per sq.m (£200 per sq.ft). This includes up to first fix and does not include your fixtures and fittings along with large bi-fold doors, rooflights, etc...

You may have moved on from considering this property but I came across this link recommended on another MN thread and thought it was useful Re: Right to Light

@AmberRoseGold

You may have moved on from considering this property but I came across this link recommended on another MN thread and thought it was useful Re: Right to Light

Not specifically mentioned or referenced to under the Town & Country Planning Act. LPA’s own policies normally provide certain restrictions.

@DevilDamo does that mean that right to light is not always a big deal then? We really want to do a side return extension but are concerned about the right to light being flagged as a separate issue to planning- which is what my basic reading around suggests. Talk of £100k compo which is not an option for us. Neighbours been there more than 20 years.

In all the years I have been involved in the construction industry, I have never known or been made aware of a Right to Light issue. That being said, doesn’t mean it won’t happen but in my opinion... is very rare. Formal Planning applications protect neighbours in some respect with regards to loss of outlook, privacy and daylight. These rules themselves give neighbours certain rights to light. It’s slightly different for PD extensions as those follow different guidelines.

There are also certain questions and tests that need to be carried out in order to ascertain if there has been a breach to Right to Light. Something that may put the affected neighbour off trying to seek or claim against it.