Building above garage not possible

[sparklewater]

We've just had our survey come back on the house we are buying and we asked them to check the integral garage as we want to extend above it.

Lots of other houses on the street have done it, so we assumed that it would be ok, just wanted to get the all-clear.

It's come back saying that it's a single-brick wall and unless the foundations are really deep, we'll probably need to knock down and start again.

Does anyone know what the price difference would be with that additional work? We wanted to get it done straight away but it looks as if we might have to save up and wait now!

I would want building regs on the orangery to ensure that lintel is up to scratch, if nothing else. The one holding up the back wall of the house...

I'd be surprised if you couldn't retain the garage walls, particularly if others in the road have done so, if it's just a simple room-in-roof with dormer etc you are planning in the roof space of the existing garage.
Or is it a flat roof garage of lesser construction?

But the garage is single skin. Habitable accommodation should have a cavity. If the foundations are not of a suitable depth, they will not carry the extra weight. At the very least an internal skin of breeze blocks must be used for the garage and then both skins would be built up to form the cavity required for habitable accommodation. It’s necessary to save heat, fuel and meet modern building requirements. The foundations for single brick thickness are unlikely to be sufficient.

You also need to consider how the 1st floor extension is attached to the house to avoid movement. This in part will be down to foundations and build quality. I wouldn’t cut corners because if you sell.......

Flat roof construction is neither here nor there. It’s the walls and foundations that matter. Plus modern building regs!

But the garage is single skin. Habitable accommodation should have a cavity

Probably the majority of new houses built today are single skin with an internal load bearing timber frame.

Is this a newish house? If it’s not it’s likely to be traditional build with breeze blocks and bricks. However to save money, some garages were just bricks. They were not designed for a 1st floor. Timber frame houses are common now but even 25 years ago they were not.

That's good to hear @reedwarbler, at least it won't add a huge amount of time onto the build. We just want a basic two-storey side extension with an en-suite above where the downstairs toilet is now, so won't be anywhere near your costs!

@Murmurur - that is my main concern as well!

@FurierTransform - it is a flat roof garage but we know it is single skin, so that's the main concern, as @Guymere says.

I don't know anything about timber frames etc. It would be great if that's possible I suppose, but I would rather do it all properly. No intention of cutting corners at all!

It's a classic 1930s semi, pretty solid, traditional build.

It’s highly likely to have cavity walls. Again your survey will tell you. There were no timber frame houses built then - unless a quirky cottage! Garages were an afterthought. Many people didn’t own a car.

So pay attention to foundations, how the extension will join the existing house to avoid movement and cracking and a suitable design to complement the original house.

130k? What have you been smoking?

What you need to do first is dig a hole at the side of the garage to actually see how deep and wide the foundations are ! Then it’s up to building control to say yey or nay. , if it’s yes then can leave the existing walls up and build another skin ( with insulation between) either on the inside ( lose a bit of floor space ) or on the outside. Then you just build on top.

As as you say others on the street have done it , if you look very closely at the brickwork on them you should be able to see if it’s the old bricks with new ones added on top or they are all new bricks. If they all have new bricks it probably means the foundations needed doing. Good luck.