Laying on external metal mezzanine - Help with choices here

[r21442]

Newbie - first post though I've been a reader here 15 or so yrs.

I've a 1st floor balcony at my house. It is a galvanised steel frame with timber Joists, decking and balustrades. It is 20yo and the joists are beginning to go. I've asked a local mezzanine / balustrade installer to strip the timber and replace fully in galvanised steel with glass balustrades - all good, it's what they do.

For the surface I didn't want decking either wood or composite. We get a lot of rain in Scotland and the water runs off the ends or through the gaps mossing up the end walls or structural steel painted white. So they're going to lay a 4.5mm galvanised steel plate with the intention I put a solid, hard surface. I'm paranoid about drainage and they're going to put a gradient and have some channel system to route the run off - again all sounds good.

Now I need to choose a surface. Thinking either an impermeable resin or textured porcelain - Bradstone range looks decent and afaik a decent rep for quality? c. 26m2 to do and some stair treads. The questions are 1. any problems laying onto the steel? 2. Can a resin system achieve zero permeability? 3. Any gotchas with the porcelain option? 4. Any comments on Bradstone or alternates with a non-slip finish?

I'm doing the house up to sell so maybe I shouldn't care so much but I want a quality job to enjoy until it is sold!

[Tony McC]

Have you considered porcelain on pedestals? This is a fairly common option for deck/balcony/terrace paving and it solves the drainage issues by using the existing watertight 'deck' beneath.

[r21442]

Tony, yes, a pedestal system was uppermost in my mind initially. I've no experience so it made me cautious - concerns, maybe invalid, about solidity if the tiles are only bedded at corners and levelling of the pedestals then joining two contractors when I've had enough trouble finding one. In the interim, steel prices have shot up and some unavailable.

I'm going to go with the plan as is. I'm having to get thicker cold rolled steel joists at 400-500 centres and the steel plate deck has risen to 5mm. Having seen how well my existing galvanised frame has withstood the weather I don't see a problem and the only thing remaining to worry about is the adhesion, frost resistance & longevity of whatever is used putting the tiles onto steel plate but I guess that's been done before?

[Tony McC]

When tiles are directly bedded onto a steel support system, a specuialist adhesive is normally used, often a 2-part epoxy with all sorts of modifiers to enable it to cope with the variation in thermal expansion between steel and porcelain.

I'd be looking to the tile supplier for specific installation guidance. this is very much NOT an everyday task!