How much value does a double garage add to a house?

[ToExtendOrNotToExtend]

I have bought a house with a 35-40 year old double garage in bad condition which takes up 1/3 of the garden in London. It will cost min £5.5k to fix up and I am not sure if it's worth it. Some people argue garages, especially double ones like ours can add much value to the house. How much value do you think it can add if in usable condition?

The most urgent work needs doing is to replace the leaking and peeling asbestos roof. I have been quoted £4.5k for this.
On top of this, I will still need to replace 1 or 2 steel joists for the roof at extra cost, replacing the rotten wooden door to the garden and replace the broken windows and repaint. I estimate it will cost £5.5k to make it ok usable for storage, £6k to make it look nicer.

My roofer said the walls were constructed by concrete sheets and not strong. The company who quoted to replace asbestos by steel roof says the walls were built by large concrete blocks and the structure is sound which I don't fully believe.

The garage backs on to a not well maintained service road with right of access. A couple of old neighbours store their cars in the garages and trim grass, bushes in Summer. They say sometimes they get blocked in. I have no plan of using my garage for cars and I don't feel I need a double garage for storage.

Another option is to remove the whole garage, estimated cost is min £1.5k to remove asbestos and £1.5k to remove the rest of the garage. New fences and gates will be needed at the rear, is £1k enough?. I can build a single wooden garage later on if I need it. Is £2-3k enough?

What would you do? I am open to all kinds of ideas.
The asbestos roof got to be removed quite soon and I don't have the money to build a garden office/gym sort of thing.

Thanks a lot.

If its a garage on the side of the house, you can pretty much bake in 40-50% of the value that a double height extension would add.

If its set back and detached, probably not much.

You can remove corrugated asbestos roofing yourself. No need to pay through the nose for it.

Plenty of info out there on how to do it safely.

Good luck.

The garage is at the bottom of the garden.

Do you have off street parking at the front of the house? If so for how many cars?

We have to park on the street because our row of terrace is built on a slop. One neighbour has turned their sloped front garden to a two car driveway and it costed £20k.

Most of other neighbours built on flatter land (opposite side) have 1-2 car driveway.

I think in the future we will have to pay the price and covert our slopped front garden to a drive with a private electric charging point. It's better than parking in the garage (not blocked in, better road conditions). I want to start saving for it, that's part of the reason why I don't want to spend too much on the garage.

Bump, still looking for advice

Would knocking it down add space to the garden? That would add more value for me.

Could you knock it down and make it into a garden office?

Could you knock it down now, and then consider replacing at some point in the future?
Would give you some thinking time, and be better from a cash flow perspective.
You could use it as extra garden space (but hopefully not spend too much money), then at some point in the future you might realise you need the storage space, or want a garage for a vehicle etc. Then you could spend the money to put either a single or double garage in.

I'd ask the estate agent who sold you the property if they can give you an idea of the difference in property value with/without a double garage.