Building a Floor

[Ninja14r]

Evening all  This is my first post.   I am looking to extend out the back of our existing concrete garage to build a workshop

My plan is to build a timber framed floor and lay ply sheeting for flooring.   I will then build timber framed walls with windows and doors.

The area is 3.6m x 4.7m and will be above exposed ground.   The longer side is the side butting upto the existing slab for the garage.

My query is what size timbers for bearers and joists including spacings for posts does the community recommend 

[MitchellMc]

Welcome to the Bunnings Workshop community @Ninja14r. It's brilliant to have you join us, and many thanks for your question about building a workshop.

You'll need to refer to timber span tables and the Building Code of Australia, then cross-reference that with your intended m2 load of the building. There are many variables to consider, mostly surrounding the weight and spans the timbers will be seeing. Everything that is going on top of these timbers needs to be considered, so without knowing the details of your entire plan, including wall cladding, roof sheeting and equipment being stored in the workshop, it would be hard to give a definitive answer to your question. Chances are that you'll need to submit plans to the council for approval, so you might like to employ the services of a qualified engineer to draw them up for you. They'll know what sized timber will be adequate.

If this frame is exposed to the weather, you'll need to use H3 treated pine. Depending on how many supports you intend to use, 190 x 45mm L/M Outdoor Framing MGP10 H3 Treated Pine for the bearers and 90 x 45mm Outdoor Framing MGP10 H3 Treated Pine for the joists would be in the ballpark. Post supports every metre along the bearers should be adequate.

You should find this step-by-step guide useful: How to install a subfloor.

Please let me know if you have any questions.

Mitchell

[Ninja14r]

Morning mate

It is a temporary room I am building for a workshop   it is located under the house and the ceiling will be gyprock fixed to the underside of the house floor laminated beams   walks will be timber framed with hardiflex external lining gyprock internal lining with earthwool within framing    will be mainly used as a storage room 

[MitchellMc]

Hi @Ninja14r,

The height you have to work within might be a limiting factor. If you're framing out the ground under your house for floor sheeting, then you can likely get away with a single-layer frame instead of joists over bearers. 90 x 45mm timber joists spaced at 450mm centres and supported on TuffBlock 300 x 300 x 90mm Instant Foundation System Deck Supports should do the job if this is a low-level frame. 

Mitchell

[Ninja14r]

Height no issue its 3.5mtrs from ground to bottom of floor beams under house.

Ground falls away slightly   so will build out from existing shed slab out towards middle of house to first row of steel posts

[EricL]

Hello @Ninja14r

It's great that you've received excellent advice from my colleague @MitchellMc. Just to add to the suggestions made, you've mentioned that it's under the house, for extra safety for the items in your temporary room. I suggest installing a vapour barrier both on the floor and walls, this will help with preventing condensation from diffusing into the wall in cold weather. 

Please keep us updated with your progress, we look forward to seeing the start of your project.

If you need further assistance, please let us know.

Eric