Patio decking sub frame spec.

[carters]

I'm looking to put in some decking on top of an existing patio approx 3m x 4m.

I take on board idea of better to over engineer but is there any reason why I could not create the sub frame using 2x4 rather than 2x6 joists? Main reason for considering this is that 2x4s are available in the right lengths from local DIY. The available 2x6 joists would require a join.

any thoughts?

 

[WabbitPoo]

Nothing wrong with 4x2 per se, but it needs a lot more supporting piers than 6x2, and in any case, in my experience it still seems to fell a bit springy regardless of the number of posts.

 

[Thermo]

go to a timber merchants and get the lengths you need. it will be much much better quality and probably cheaper. most will deliver as well

 

[DCS]

Are you laying this deck directly onto the existing patio - if so I would strongly advice against this as the water will have know where to run-off and the decking will rot. If you are building a raised frame you should deinately use 6"x2" and as already said this will be cheaper from a merchants than the DIY stores timber anyway.
Also make sure you are buying tanalised timber and treat all the cut ends with a wood preserver before fitting

Good Luck

 

[Thermo]

nothing wrong with laying a deck on an existing patio. The water will still run on the falls of the patio to whereever it disperesed to before, unless it was a badly laid patio that had pools of water on. Ive lost count of how many we have done like this and gone back years afterwards with no ill effects.