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Extending and converting a garage in stages - is this a realistic way to go about it

(16 Posts)
cavershamtights Thu 09-Mar-17 17:08:10

So, I'm house hunting and need eventually 5beds, but can do with 4 for the moment. I will also need a room in which to carry out my business, and so I'm looking at 4 and 5 bed properties with a garage that could be converted for the business.

I've found one I really like which has 4 beds but definitely scope to add a 5th over the garage at some point. The garage is a large double, so scope for 2/3 additional rooms in it, and I think I'd probably employ an architect to make sure that I make the best use of the space. I was thinking that I could maybe get plans drawn up for both the garage and 1st floor extension - with the plan being to do it in a staged way - garage first and 5th bed in a few years. Would it be a waste of money to get all the plans at once? Or sensible?

I haven't even bought the house but I'm super keen and would need a rough idea of costs so that I can make a realistic offer.

I don't want to link to the house because it's only just come on and in a super sought after location so I don't want to potentially alert the competition... (sorry - I hate threads where people won't link to RM)

CountMagnus Thu 09-Mar-17 17:21:50

You would probably be looking at around £15 to £20 k for converting the garage, depending on what you want to do with it (ie change to office and sitting room, or adding in bathroom or utility etc).

Not sure about costs for extending over the garage, usually around £1000 - £1500 per sq m.

BUT, whether you can extend above the garage would depend on whether the garage footings are suitable, if they aren't then you can't extend over the top.

So first thing would be to determine whether the garage is suitable for building above.

cavershamtights Thu 09-Mar-17 18:05:05

Yes, that is a good point. Would I need a surveyor to tell me about the footings, or a structural engineer?

cavershamtights Thu 09-Mar-17 18:12:38

Ah, just googled - seems I'd need to dig down to see how deep foundations are and 1m depth would be needed. I'll check if there are any flower beds around garage that would be easy to dig into without causing any damage (obv would need prior permission to do this smile)

CountMagnus Thu 09-Mar-17 20:59:47

Yes, a hand dug trial pit next to the foundations would tell you what you need to know. Structural engineer would probably give the most comprehensive advice covering other aspects of the build as well.

Good luck!

cavershamtights Thu 09-Mar-17 21:31:34

Thanks smile

cavershamtights Thu 09-Mar-17 23:33:15

Obviously I'll check before proceeding BUT - it's an integral garage, projecting out at the side and front of the house but partly under the first floor, and is original. Surely they would have just poured the slab in one go to a uniform depth for the whole place, would that not have been easier than farting around making it less deep for part? Or is that wishful thinking? It's a fugly 60s box house, complete with hideous felt tiles on the outside (space is the benefit that outweighs the fugliness).

Jaynebxl Fri 10-Mar-17 06:28:08

Definitely go for getting all the plans done and passed in one go. Then you're only paying once to get planning permission. You have a limited time in which to start the work once you get permission (can't remember if it is 3 or 5 years) but once you make a start on the work you don't have to complete it all in one go. We did similar. .. had three big jobs in mind to extend our house. Got all the planning permission in one go then had the first two jobs done. We can't afford the third yet but at least the permission is there.

CountMagnus Fri 10-Mar-17 07:37:30

Try giving Building Control a call, especially if any of the nearby houses have extended above the garage (assuming neighbouring houses are similar age and style)?

JoJoSM2 Fri 10-Mar-17 07:45:26

I think that a big one to double check - how likely it is that you will allowed to do the work. And how far the end of your house is from the neighbours- they could object to you building something right outside their window, for example

cavershamtights Fri 10-Mar-17 14:25:21

All good points. The road is a mix of 60s and 80s builds - all roughly the same style except all the 80s ones were built with the extra bit over the garage, so I would hope that would make it easier from a pp point of view. Only one relevant neighbour, and this house is slightly behind and to the north of them so I would hope it would not be a prob for them, as not blocking any light and not really in eye line. If I got the house they'd definitely be the ones for buttering up!

That's really interesting about pp time limit being to start of whole project, not finish date - that's great. Realistically I would prob be looking at 5-10 yrs to add the 5th bed. No way I could afford it quickly, and wouldn't need it sooner than that anyhow.

It is possible that the house was built on a cage (?), someone else who looked at a place on that road a few years ago mentioned that it had been and seemed to suggest that this would mean the foundations would be strong enough regardless of depth. No idea if that's true. I guess maybe the local building control or planning office might have details of that kind of thing and be able to advise? They're not hugely
Communicative though, if you don't pay them money...

CountMagnus Fri 10-Mar-17 16:51:57

Not heard of a cage foundation (unless they mean a large trench dug for concrete footings reinforced with a steel cage), could they have meant a raft?

VeritysWatchTower Fri 10-Mar-17 16:55:56

My house is exactly like you describe, one garage is integral with a bedroom above and then the other garage projects out to the side with nothing above.

We didn't build above but converted both garages into a massive playroom for the children with a store at the back. This just meant we had a wall built across the entire length with a fire door access.

The issue we had was some walls were double skinned (thermalite block and brick) and the other walls were single skinned - just brick. Foundations wise we are on a concrete slab foundation as we are on a hill.

I believe we were given 3 years from planning to actually complete the job, we submitted for an extension to the rear at the same time. We did the garage conversion first and then 2 years later did the extension.

CountMagnus Fri 10-Mar-17 17:55:06

one garage is integral with a bedroom above and then the other garage projects out to the side with nothing above.

Were the garages separated by a dividing wall, ie the gable end of the house?

SquidgeyMidgey Sat 11-Mar-17 14:32:37

Can you get in touch with your local building control office and ask their opinion on the locality and what is likely to be necessary? We're in the last stages of adding running water to a previously done garage conversion and when building control visited they said the foundation under where the garage doors had been wasn't deep enough and started talking about 2m foundations being necessary. Builder has got them to agree to 2x lintel in each doorway instead but it's still an expensive surprise.

cavershamtights Sat 11-Mar-17 18:04:16

So much useful info - thanks all!

count no, they don't appear to have ever been separate. They are actually slightly offset so that not all of the one side is under the house - more is not under it.

I will get onto the building control office next week and do some more investigation. smile

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