Waterproofing around decking posts....

[SteveBSL]

Hi, I have recently replaced the 50 year old handrails on my garage roof that forms a terrace.
The old handrails were steel box section shallow bolted into paving slabs that were on top of that.
I have used 82mm wooden posts and cut THROUGH the roof (complete with many layers of felt) and attached them to the structure underneath.
Around those posts I have installed new slabs.
I have put waterproof concrete around the posts where they pass through slabs.
But.... water is still passing down through the posts and dripping out the bottom into the garage....

Can someone advise how to waterproof?
I am now considering digging out the concrete and replacing with resin, or perhaps I should make rubber boots, or perhaps I should fabricate rigid plastic gaiters?

Clearly I have made a mistake by cutting through the existing waterproofing on the garage, but is there anyway to re-seal around the posts? and even if I make a perfect seal around the outside of the posts will water still come THROUGH the posts themselves??

Thanks for any advice..

 

[motorbiking]

A picture would help, but you need to create a flashing/boot like you say but it needs to cut in to the post. It won’t need to go in much - just 5-8mm. That needs to seat over the roof and be mastic or silicon sealed to prevent water ingress.

unfortunately due to capillary reaction the water was always going to run inside.

you could try marine mast boot tape. But tbh if you mastic it in and it’s recessed it will work.

 

[SteveBSL]

Thanks, I have thought about making mini flashings, it would be a fiddly job though on 14 posts...
Please see the photos that I have added showing the top and a typical bottom with the post bolted into the structure.
My latest thinking is to remove the lot and then concrete bolt-down post shoes into the void, then I can attach the posts on top of that and the wooded element would be completely separate from the concrete/slab/garage elements.
I'll have a look at the marine tape...
Thanks again!

 

[motorbiking]

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