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What type and size timber for floor joist

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What type and size timber for floor joist

I am extending bathroom and replacing slab of concrete previously there with timber sub floor and in turn plywood and tiling .What size bearer and floor joists are necessary ?. The space to be covered is

1650 x 960. At the shortest point ,.i.e. 960 mm end, there is an exposed joist measuring 100mm x 50mm  where there is floor boards resting on it. Will be attaching another timber to the existing joist to support plywood flooring. The joists will be running the longer length.i.e. 1650mm. How many joists do i need for a 960mm distance to the wall ?

What size joists are necessary ?

What type of timber is needed ?

What spacing is required between joists ?

Is it okay to attach the bearer to the solid brick wall with Dynabolts ?

What size bearer is required for the job ?

Which type of timber is required for the bearer ?

Is it okay to attach the joists to the bearer using saddles ?

Thanks in advance. 

Bunnings Team Member
Bunnings Team Member

Re: What type and size timber for floor joist

Hi @bill2,


It's a good idea when considering building items like floors within your home to first consult some timber span tables and construction codes. These will be the guiding principles that you must follow and they include all the information you need. Some of the questions you have are quite difficult to answer without first inspecting the elements that make up your structure and seeing the constructing techniques used. 


Typically floors would be constructed from MGP10 H2 Pine or hardwood or laminated veneer lumber with a joist spacing of 450mm. A joist hanger can be used to connect to bearers. The spacing of joists, the calibre of timber and whether you can affix a bearer to a brick wall with Dynabolts are all items which you would need to check the Building Code of Australia for. You also need to take into account the weight the structure will be supporting including whether a bath will be in that area. 


You might wish to employ the assistance of an engineer who will be able to specify exactly how the construction should be put together.


You should find this step-by-step tutorial helpful: How to install a subfloor. You might note we have engaged the services of an engineer to draw up plans for us to follow.


Let me mention @ProjectPete to see if he might like to join the conversation.


Please let me know if you need further information or had any questions.







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