Thread: decking joists near pool H3 or H4?

Hi there, first time poster, have been a reader for a while - (great site!)

I am pulling down and replacing parts of a large decking area (80m2) around my pool. It is only 3 years old. It is a magnesium pool (chlorine basically), which has corroded some metal in the backyard, including the old metal c-section joists of the decking (previous dodgy builder used thin unprotected c-section which has rusted in 2/3 years - that is another story!)

I have taken the spotted gum boards off, chucked out the rusted c-section joists and I am about to put new treated pine joists in to replace the c-section metal joists. Then i will flip the spotted gum boards over and use the nicer looking side for my new look decking (holes will hopefully line up if I keep all things the same)


I am going to go with treated pine for the joists this time but I am not sure whether to use H3 or H4 treated pine. H4 is for use in the actual ground (which I wont be doing) and H3 is for outdoor use but not in the ground. The joists will go onto the old but perfectly fine, metal bearers (solid square metal tubing, freshly painted with rust paint - they never get water on them or in them) I am also going to run some thin rubber strips along the top of the joists, before the boards go back down, to help keep water off them.


I cannot source H4 joists in my country town, so I am leaning towards H3.


Will H3 be OK around a pool? I am thinking about painting some Diggers black protecta Diggers 4L Eco In-Ground Timber Protecta I/N 0960009 | Bunnings Warehouse on the joists closest to the pool (inside the glass pool fence where splashing occurs) Is this necessary? or will H3 be fine near pool water. NB: the H3 joists will not touch the ground at all

I will also use 316 stainless steel screws this time (square Robertson)

your thoughts / ideas ? thanks