Garage conversion now & building on top in the future

kakalokia

Hi everyone.

Just looking for advice around garage conversion & building on top of garage.

We currently have a garage (attached to the house) that is in a relatively good condition, and we're thinking of converting it to an extra room. We're also thinking of building another room on top of the garage itself.

We want to do the garage conversion now, but postpone the building of the room on top of the garage to the future, mainly due to finance.

Is it possible then, to carry the garage conversion now, and not have to knock it down when the time comes to building the room on top? Basically I don't want to waste money converting the garage now only to have it knocked down later when we wish to extend further. I'm hoping I can carry out the conversion now in such a way that all the foundation/groundwork is there for future extensions, without affecting the garage/new room itself. Is there any way to ensure this? If there is any way to do it, would I need to get an official approval of some sort now (i.e building regulation, etc) so that in the future I'm covered in terms of building on top of the garage without knocking it down?

I went through the proposal with two builders that we know, and got mixed responses. One builder said we can dig in the garage now and lay the foundations so that we can build on top in the future without any issues. He mentioned we can take videos of the process as future proof to building control that we have all the foundation for building on top. The other builder said we either do everything in one go now (conversion + building on top), or we carry out the conversion only but will have to knockout walls/ceiling for building on top in the future.

What's people's thoughts/experience around this?

For reference, we're in the Kingston Park area of Newcastle upon Tyne.

Thanks.

SHAFT

So you'll covert the garage to a room and it'll have a finished ceiling supported by ceiling joists which are not designed to and will not take the weight of the floor you decide to put above it later.

Mojisola

We had friends who did this and it was cheaper to do both levels at the same time, although the upstairs room was left unfinished inside for the best part of a year until they saved the required money.

Belenus

Does your existing garage have single brick outside walls? If it does, you may need to add another skin or an insulation layer if you are converting it to a habitable room.

If it is single skin then, as far as I know, you won't be able to build on top of it, either now or in the future, without making it double skin.

Skin may be an incorrect term. I refer to a wall that is one brick thick versus a wall that has two vertical layers of brick separated by a cavity.

kakalokia

Mojisola wrote: »

We had friends who did this and it was cheaper to do both levels at the same time, although the upstairs room was left unfinished inside for the best part of a year until they saved the required money.

Thanks for your reply.

If you don't mind me asking, do you know how much approx it costed them to do both levels?

By unfinished, do you mean it was just a skeleton?

Thanks.

kakalokia

Belenus wrote: »

Does your existing garage have single brick outside walls? If it does, you may need to add another skin or an insulation layer if you are converting it to a habitable room.

If it is single skin then, as far as I know, you won't be able to build on top of it, either now or in the future, without making it double skin.

Skin may be an incorrect term. I refer to a wall that is one brick thick versus a wall that has two vertical layers of brick separated by a cavity.

Thanks for the reply.

I'm terrible with these kind of things, so I honestly don't know if it's single or double skin walls. Below are pictures of the outside of the garage:




Looks double to me, but honestly not too sure.

Belenus

You need to measure the thickness of the outside garage wall away from the door area. That will require some careful measuring as you are working a bit blind. You need to measure from the outside of the wall to the inside of the pillar by the door and then subtract the distance from the inside of the pillar to the inside of the garage wall.

If it is about 300cms then it is probably double skin.

FreeBear

Belenus wrote: »

If it is single skin then, as far as I know, you won't be able to build on top of it, either now or in the future, without making it double skin.

One method of construction is Structural Insulated Panels clad with an outer skin of bricks. It may be possible to convert the garage withs SIPs and then add a second floor if the foundations are adequate.

An alternative is to use piles at strategic points and then construct a steel framework to support the second floor.

Both options are expensive, and building regulations may change by the time the OP is ready to add a second floor. The most pragmatic answer would be to demolish the existing garage and build the two storey extension now. Planning permission would be needed regardless of which route is adopted.

You do realise that planning permission and building control is required before converting a garage in to a habitable space.

kakalokia

FreeBear wrote: »

One method of construction is Structural Insulated Panels clad with an outer skin of bricks. It may be possible to convert the garage withs SIPs and then add a second floor if the foundations are adequate.

An alternative is to use piles at strategic points and then construct a steel framework to support the second floor.

Both options are expensive, and building regulations may change by the time the OP is ready to add a second floor. The most pragmatic answer would be to demolish the existing garage and build the two storey extension now. Planning permission would be needed regardless of which route is adopted.

You do realise that planning permission and building control is required before converting a garage in to a habitable space.

I read that building control is required, but not a planning permission, from the following link:
https://www.planningportal.co.uk/info/200130/common_projects/25/garage_conversion

Thanks.

Mojisola

kakalokia wrote: »

Thanks for your reply.

If you don't mind me asking, do you know how much approx it costed them to do both levels?

By unfinished, do you mean it was just a skeleton?

I don't know - but it was some time ago so prices wouldn't be relevant.

The upstairs room had a window but the walls weren't even plastered and I don't think there was a floor for some time, either.

Doozergirl

kakalokia wrote: »

I read that building control is required, but not a planning permission, from the following link:
https://www.planningportal.co.uk/info/200130/common_projects/25/garage_conversion

Thanks.

A two storey extension is not a garage conversion. It is a two storey extension.