Decking over concrete patio

[HolyJoeMuttley]

Hi,

First post for me

I'm currently building a frame for decking which will be raised over concrete, but I'm struggling with how to go about levelling it. I haven't attached legs to it yet, but I'm concerned as some of the joists sag in the middle. The joists are 3.6m long (quite bad quality, but it seems it's all that's available at the moment) and I've started to place the noggins in between.

My question is, how do I rectify the sagging of the joists, should I be lifting the sagging joist and attaching the legs to it?

I'm completely confused on what to do so any advice will be gratefully appreciated.

Cheers

 

[HolyJoeMuttley]

It seems getting the noggins to sit perfectly square seems to help. I'm clamping the joists which is alleviating the twists in the timber while I fit the noggins. I didn't realise how important they are.