Considering an extension but don’t know where to start - and advice

[LouLou2020]

I’m considering having a 2 storey extension built behind and above the garage, including converting the garage into a room. Where do I start? How do I get a ball park figure of what it’s likely to cost to ensure it’s financially viable? I’ve tried to google and use online estimation tools but haven’t found one that works. TIA

Hi OP

Happy to share what I did, I hope it helps.

I also wanted a 2-storey extension plus a loft conversion. I looked around my town for houses that I thought had done something similar and I made a note of the addresses.

The planning section of my council's website lets you search for addresses to see planning applications (including drawings). I downloaded and printed a few out so that I had a good point to start discussions from, i.e. I could show my architect and builder an idea of what I wanted. This made it easier for them to provide me with estimates.

Online calculators will give you a rough estimate for the build per square metre, which you might find useful. Prices will vary a lot depending on where you live.

I think the key with any work is in choosing the right tradespeople. I've known my builder for years; he recommended the architect I used (he'd actually done the plans for my builder's own extension).

Again this is where having a look at your local council's planning section is useful because you'll see which types of feature get constantly rejected (getting your plans approved first time is obviously cheaper than revising/resubmitting them).

I hope it goes well for you.

Thank you. We don’t need planning permission as it’s covered by permitted development. Can you recommend a website to give a rough estimation?

OP I don't think two story is ever covered by permitted development?

I got an architect recommended by a friend, once PP had been secured I got a builder recommended by many friends. Builder found structural engineer, party wall surveyor, building control ppl for me too.

You will need to talk to an architect about drafting plans for the extension but you'll probably need planning permission, as 2 storey extensions are unlikely to fall within permitted development. Whereabouts do you live?

Might be useful to clarify PD - ecab.planningportal.co.uk/uploads/miniguides/extensions/extensions.pdf

VERY rough estimates for cost are 2.3 - 2.7k per new sqm. There are also online estimators such as this one www.homebuilding.co.uk/advice/extension-cost-calculator but I've not really ever used one.

I've had a good idea of plan, scribbled it down and spoken to builders based on a basic finish and standard construction