Really big extension

[Hoolahoophop]

Has anyone doubled the size of their house through extending?

House we are buying is aprox. 2000sq ft.

1st Floor: 4 x bed, 2 x bath (1 family, 1 ensuite) big landing and a decent sized airing cupboard.

Ground Floor: Living room, dining room, wc, big entrance hall, small kitchen and small utility.

This is smaller than our current house, but much better location and garden.

We would like ideally,

1st Floor: 5 bed (two with ensuite) family bathroom, and home office.

Ground Floor: Living room, dining room, music room, walk in pantry, bigger utility, gym, and the kitchen to be a kitchen/breakfast/family space.

So quite a lot of work, the ground is a huge slope, currently not utilized so we could dig down and put a 3rd floor at the back that opened onto the lawn and extend above in the ground floor.

But this seems a huge amount of work, has anyone done anything like this and survived, any tips.

This will cost way more money than buying a house the size that you want. Renovation costs are really high at the moment.

Also groundworks, i.e. Digging down are really, really expensive.

Agree with pp that it's hard to see how this would be cost effective plus you may have issues getting planning permission if they consider it to be overdevelopment.

Lots of people have doubled (or close to) the size of their houses by extending (particularly the myriad bungalow conversions that are everywhere now), but in your case it's so unlikely to be cost effective that it's not worth it unless you want to live in it forever (and not many people do want to live in a massive 5 bed house forever).

I have a family member that did it.

A det 3-bed on a good sized corner plot, they doubled the footprint and upstairs made a huge master bedroom & en-suite (with the en-suite being bigger than the family bathroom).
Although it was generally ok (certainly looked good from the outside, you would never have known it was an extension) it did not flow well on the ground floor. Instead of knocking through and opening up, they just made a single opening which meant the ground floor felt like two completely separate spaces.

The location/plot is more important than the house, so we wouldn't consider the finished ideal house in another location. Would rather compromise on what we can do with the one we are buying.

We have spoken to the local authority and they have said planning would most likely be granted, so not worried there.

We bought very much under budget mortgage free so do have some money to play with. However We do understand that the investment we make in the property to make it our home probably will not be financially sensible and we will likely not recoup it if we did need to sell. However we do not see it as an investment, but as a home so don't mind if it does not pay back.

We absolutely would not be stretching ourselves to achieve what we want, if the plans suggest that is case we would scale back. Lifestyle, work life balance, holidays and experiences are too important to us to sacrifice them for the perfect home. We don't want to compromise on location though.

If money is not a massive issue then why not just move out somewhere else during the building work?

We definitely could consider that @Reallybadidea so long as we could find somewhere very close by. Better for the children to continue to be walking distance of their friends and school. We wondered about phasing the building work if we can, but that might end up with more of a hodgepodge renovation as @Nourishinghandcream described.

If you’re making such a huge change, you should consider or at least scope out knocking the current house down and rebuilding from scratch. New homes get significant tax breaks on the builds - labour and materials costs are zero rated, so saving you at least 20%.

@dreamersdown that would probably be the most sensible option. Seems a shame though as the current house is only 30 years old. So a relatively modern property in excellent condition. Survey was excellent. We would just like a bit more space to get it back to the size we are used to!

I did also consider an annex, so keep the house as it is, or a tidy extension just to increase the size of the kitchen, then a second building for home office, music studio, gym and guest bedroom at the end of the garden. Possibly partially underground to level up the garden and hide it from view. But again that could be expensive, less disruptive though and we could continue to live in the house while it was done.

I've done a lot of renos and lived in the house through all of them. It's tough! It's not for the faint hearted. The only things I really have to add is that I've always tried to get the kids rooms done to a reasonable standard, even if they're moving rooms, as a first priority....I've always felt that it's not the life they've chosen lol so at least try and get their space sorted. Similarly I've tried to get one "area" sorted for me/the family. I really struggle with the renos, whereas although my husband does, he's overseeing it, talking to builders etc...to have one room for me, or for all us,at the end of the day which is "done" has made a real difference....especially when the rest of house is cold/open...and your stuff is in boxes....just have one adult living room that's relatively tidy, is warm/got a fire, a few of your "bits" out, makes such a difference!

I've never done it in phases. I'm kinda an all in gal. I couldn't bear to rip open the house, do a bit...put it all back.. .live in it, accumulate stuff etc....just to go back to square one and rip it all open again....I'd rather live through the mess/the cold/the dust rather than keep ripping the plaster on and off so to speak

Another vote for demolish and rebuild if location is the most important thing. You'll never get exactly the house you want by extending and a basement will be much cheaper to include in a new build property (we've done this). You'll also be able to make your home energy efficient and include all modern technologies. An annexe with lots of glazing is a great idea for a gym and spa room especially if you have great views.

I don't think most extensions really need an architect but it sounds as though you could do with one for this, to explore all the options. They'll come up with layouts you'd not thought of. Obviously an architect design service isn't cheap but you'd need one technical plans drawing up (architect or technician) and a structural engineer for calculations anyway.