We've got 24 photos of this project in our portfolio Refurbishment Extension and Loft Conversion East Finchley

It appears to be single skin (walls aren't thick enough to include insulation). If this is the case you will only be able to call it an outside room such as a garden room and so it won't add to the value. To strip out the old kitchen, replaster, redecorate, new flooring will likely cost £2,000. If you knock it down a replacement extension will cost about £1300 per square metre so I estimate that this space will likely cost £15/17k to rebuild.

Wow, just wow! This looks amazing, well done.

Hi @Emma CW If it's any use as a very rough comparison, you can see our project here: https://www.houzz.co.uk/discussions/5865541/utility-kitchen-design-feedback As we've come closer to obtaining quotes (planning with our council took 6 months due to Covid delays), it seems we're likely to be looking at £125k (or about £2500 per square metre), excluding kitchen. Our U-shaped kitchen, which fills a space roughly 4.5 X 3.5m is looking like an additional £20-35k fitted (range based on direct-from-manufacture web retailer, to bespoke local supplier), with mid-spec appliances and sourcing our own quartz worktops. No idea how one might get a high spec kitchen for £5k as suggested by Base 2 (- appliances alone could easily cost this). Do note that we require demolition of two existing structures and we have limited side access to our property (i.e. little room for machinery to excavate foundations). Of course, interior furnishings, landscaping and contingency costs will all be in addition to the above estimate. When we went into this project, after reading years worth of home building/renovation magazines, we thought we'd be able to realise our plans for under £100k. Unless we were going to actually do the work ourselves, it quickly became apparent this wasn't realistic when ringing around for quotes on some of the big ticket items (e.g. glazing, kitchen, groundworks), so my main advice would be to speak to your architect/designer about probable costs based on comparable projects they've worked and ask a couple of local builders to give you a rough guide from your plans.