How to convert garage into family room?

[westgan3200]

Our family has expanded by four(!) and we need more room, so proposing to make our garage under the main roof into a family area and office (for me), and a pull-out sofa bed for when the in-laws come to stay over and babysit.

• Garage Conversion for existing Two-story 4-bedroom house in SE Brisbane, built 1989
• Current garage 6 x 6m located immediately below master bedroom to be used for craft room and office.
• The floor of the garage is part of the main slab; council-approved plans show has waterproof membrane under the slab and original termite treatment.
• External Walls are brick veneer, with FC sheet lining, internal wall boundary to house. Stud spacing is 600mm
• Internal garage walls to house are also FC lined with stud walls at 600m
• Single existing window approx. 900 x 600mm in external wall.
• Height floor to ceiling is 2490mm. The ceiling is gyprock.
• Single entry door from garage to house with 75mm step up to kitchen/dining area.
• External drop from garage to path is approx. 25mm
• Two existing roll-a-doors 2410 x 2100mm will be replaced by aluminium sliding doors of the same dimensions, or fixed walls/windows to provide >>10% room area light into room.
• The house is on the high side of the street, and the driveway drops away rapidly from the front of the garage
• Networked hard-wired smoke alarms to be installed
• 3 to 5KW RC A/C to be installed for heating/cooling in this area (TBD)
• The existing area has four x 1200mm Fluro (LED) lights on the ceiling
• We have the original plans and approval file from Brisbane City Council

Not sure what to do about height of garage floor at current rolla door entry, as I think there needs to be a drop to the outside to prevent water entry. Could perhaps put a single brick height with damp-course and waterproofing at the bottom of where the existing garage doors are, and then either build a new wall/windows on top of that, or a wall with sliding aluminium windows in it.

Another option is to create a new floor in the garage to meet the existing floor height from the house. Could say, anchor 70x35 MGP10 H2 framing timber to the garage floor in a grid pattern (450mm centres?) and cover with yellow tongue flooring? Then have this butt up against the single brick barrier mentioned above?

Have I missed anything?

[MitchellMc]

Welcome to the Bunnings Workshop community @westgan3200. It's terrific to have you join us, and many thanks for your question about converting a garage.

I don't think there necessarily needs to be a drop from the internal floor to the outside, but you're correct that there needs to be some type of flashing or waterproofing to prevent water access. That would likely be designed into your walls when enclosing the doors. The two are not mutually exclusive, though, so you could still raise the floor inside and potentially insulate under the structural flooring if needed. 

If you do choose the bricks across the entry, you'll need to paint them with a waterproofing membrane to prevent water from seeping through. Once the waterproofing is done, you'll be able to frame and then clad over the opening.

You want like to have a read of this discussion: How to convert garage into a second living room? by @ivanptr. Hoping they can also provide us an update on their progress. 

Please let me know if you have any questions.

Mitchell
 

[westgan3200]

Thanks Mitchell