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How to waterproof double brick wall and concrete slab to covert garage to habitable room?

We are looking to convert the downstairs garage and utility space into a habitable room (bedroom, living, etc). The house is a late 1970s two-storey brick house in Queensland. The downstairs area has double brick walls and an original concrete slab.

Seeking advice on any DYI solutions to waterproof the double brick walls or make the concrete slab suitable for a habitable room.

Also interested in hearing from anyone who has undertaken a similar project. Thank you.

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Dave-1

Afternoon @nc

As soon as I saw your garage I thought of mine! 🙂

I have converted mine to a libary which could also be converted over to a workshop if I want to remove the bookcases.

Somethings I have found while renoing the garage.

1- Council rules, they arnt keen as to a garage become a room. Mostly because teh space for a car is then pushed outside and that space is pushed out onto the rd and then parking starts to become an issue (yes I did ask my local council 🙂 Its not a NO but a reasoning.

2- Garage floors slope towards the front 😲 lol and mine was a drop of 10cm over 5m

3 - Walls are not watertight, I have a single brick wall that was always dry until It wasnt. I ended up having to seal the outside of the bricks and fix the water issue there. There are always fine cracks in bricks/mortar.

4 - Services need to be worked out. Gas point/electricity and how they will run.

5 - False ceilings needed or not? your choice but there may be some adjustment needed with your rafters. (I left my exposed rafters as I really like the look)

Garage lining for stud walls stage 1

Garage lining for stud walls stage 2 (Cornice and skirting boards)

Bookcase retrofit to create a garage library

Garage converted into library room

The above are the projects related to the retrofitting of the room 🙂 It acme up nicely, and is warm in winter and cool in summer.

Dave

Hi Dave,

Thank you for your reply. It is much appreciated. Your library looks great! I love the big window and door you have used to replace the roller door. That is very interesting about the floor sloping and the brick columns not being vertical - I will have to check that out! What did you use to seal the bricks? Did you do anything to the concrete slab to prevent moisture from seeping up? Thank you.

Dave-1

Evening @nc

Thank you 🙂 I actually had a lot of fun retrofitting the room.

Now to answer your questions.

I sealed the lower bricks on the outside with a bitumen paint after digging the area out 😕 Gabion Wall to stop water ingress to garage

I ummed and ahhed over sealing the garage floor, in the end cost and lifespan of the sealing considering I did not know what was underneath the existing slab I decided not to seal it. I had never seen water or moisture come up through it and I was thinking of laying down a sheet of orange plastic first and then the carpet tiles. In the end I thought rubber backed floor tiles should do the job and so far there has been no issue even when water came in. The tiles are second hand and I got them for around $0.50ea so not a great loss if they were damaged.

Dave

EricL

Hello @nc

Thanks for sharing your question about converting your garage into a habitable room. Just a friendly reminder that Class 10a buildings (such as a private garage, carport, shed, or the like) are defined as non-habitable buildings in the National Construction Code (NCC) and are not permitted to be used for residential purposes without approval from the Local Government

I propose visiting your local council or their website and downloading a copy of the rules and regulations of converting a Class 10a building into a dwelling. Once you have an idea of what kind of plans and permits you need, you can then begin planning your conversion.

I recommend engaging the services of a builder that has done conversions before. This will make it much easier for you as they will have a general idea of what sealers to use on your wall, and what your options are regarding waterproofing your floor. I recommend getting a detailed quote for the materials and services they will provide so that you'll know what to budget for.

Here are some fantastic conversion projects our Workshop members have shared:

If you have any other questions we can help with, please let us know.

Eric

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