How to attach a post to a metal railing for a shade sail?

[Kris_ben]

intending to install a 3 m x 4 m shade sail outdoors over a deck. In one corner I have post & rail fence, at the bottom of fence is wooden deck screwed into metal. Unfortunately the wood has been eaten or rotted away. I would like to attach a free standing pine treated wood post to this metal railing which is attached in concrete as per attached photo. Metal railing is 2.5 cm x 3 cm. How can I securely attach the wood and for it to not fall over? The other wooden posts will be secured into concrete. Any advice please? Also attached is a guide of the post size. Thanks 

  

[Jewelleryrescue]

Hi @Kris_ben 

Sorry  to point out your own instruction specify 100mm x 100mm by 3mm thick walls  steel posts all round Some solid wood  posts may work too but solid is the key message.  AS when the wind  catches the sail it is very powerfull lifting force  and may pull your 25mm x 30mm right out of the ground.

I tell you this for your properties safety. 

So see if you can install the strong posts

Australian Handyman Supplies Steel Shade Sail Post 100 x 100 x 3.0mm x 3.5m Classic Cream

I/N: 1143697

$247.80

[MitchellMc]

Welcome to the Bunnings Workshop community @Kris_ben. It's fabulous to have you join us, and many thanks for your question about installing a post.

There are not many options for installing a 100mm post onto a metal or concrete surface. Posts of this size are typically concreted into the ground, or a post support is concreted into the ground and a post connected to it.

Is there any space next to the slab that you could use for a concrete footer for the post?

Please let me know if you have any questions.

Mitchell