Can I build on top of a garage?

[TUS373]

Our house was built in 1968 and has a link attached garage that is not quite a double, but perhaps 1.5x the width of a single. The concrete floor in it is badly cracked and rather damp.

I am thinking that it may be possible to extend the garage width wise and also build another storey on top. I guess it will be down to what foundations exist as to what is possible, but they are buried under the concrete.

What type of trade can determine if it is possible to build on top, or whether the whole lot should be demolished and start from scratch? With builders, surveyors, building inspectors and architects all potentially part of the equation - who do I start with?

with thanks

[sfella]

Have a dig down the side of a wall on the outside, keep going until you get to the bottom of the footing and then measure to ground level. That will give you a good idea if what you have and what will be achievable

[TUS373]

Problem with that is that it will destroy the tarmac drive that goes up to the garage. I expect someone will have to dig out some concrete inside. But who is qualified to assess - 'yes, it will be OK to build on top'?

[Andeh1]

Builder for a few £100 to expose foundations. Couple days work, worse case scenario.

Expect the foundations to be insufficient! Full knock down, dig out & rebuild IMO.

[TUS373]

Question is....are builders always right? Are they 'qualified' to make that judgement? It would be a nightmare if they say 'yes, you are OK', then get plans drawn up, planning permission granted, then it all goes wrong and have to start from scratch when I may as well have done that in the first place.

[elanfan]

There was a thread here not long ago where a neighbour wanted to infill a link in a terrace. Basically had his arse handed to him.

[CharlesElliott]

Strictly they are not, but they probably have a very good idea. If you prefer, you can engage a structural engineer but their first step will be to ask a builder to dig down and see what is there already......

[TUS373]

Ah - OK. If it that is the way, I can dig down myself and find a structural engineer in. Again, do they need to see just one point or a point under each wall?

[TUS373]

elanfan said:

There was a thread here not long ago where a neighbour wanted to infill a link in a terrace. Basically had his arse handed to him.

Not sure what that means, but when I said 'link attached' I meant that the garage is kind of connected to the house, but only by a shared flat roof that goes over a passage and becomes the garage roof. We do not have a neighbour.

[Aluminati]

Highly likely that garage will be single skin built on a 4” or 6” if your lucky slab. So in short, I highly doubt it.

[CoolHands]

TUS373 said:

elanfan said:

There was a thread here not long ago where a neighbour wanted to infill a link in a terrace. Basically had his arse handed to him.

Not sure what that means, but when I said 'link attached' I meant that the garage is kind of connected to the house, but only by a shared flat roof that goes over a passage and becomes the garage roof. We do not have a neighbour.

I assume he means it was stupidly expensive. All builders taking the piss these days!

[Aluminati]

CoolHands said:

I assume he means it was stupidly expensive. All builders taking the piss these days!

Not all. I priced a loft conversion in Feb, 130k. Due to material increases, I advised client to hold off ( Leaving me with a hole) to see what way the market goes. The recommendation I will get from that will fill the hole.

Builders on checkatrade May be different…

[Sheepshanks]

TUS373 said:

I am thinking that it may be possible to extend the garage width wise and also build another storey on top. I guess it will be down to what foundations exist as to what is possible, but they are buried under the concrete.

If you're extending the width then you'll be digging new foundations anyway.

[foxbody-87]

Aluminati said:

Highly likely that garage will be single skin built on a 4” or 6” if your lucky slab. So in short, I highly doubt it.

My pal (who lived opposite me in my old place) had this, and one corner of the garage was basically sinking and all the brickwork coming away. Think it was a 4" slab with no other foundations.

[Terminator X]

You should be able to build a 1st floor on a garage no problem however ask an expert imho so a structural engineer.

TX.

[TUS373]

Here is back view. The walls are double. Red brick inside Marshallite outside.

[TUS373]

And the front

[TUS373]

And how it joins the house...

[iphonedyou]

There's almost no chance the founds and structure will support another storey.

Very slim chance whoever built it will have specified that it needs to support a future upwards extension and been willing to pay for that but I can't see it.

[Terminator X]

^^ engineers design to factor of 3 don't they so it should be able to support more load.

TX.