Galvanisation

[Ay8452]

Morning folks,

 

I have a couple of steel beams that I have installed as part of a double storey extension. Some of these the engineer has asked to be galvanised which we have done. A few other's he hasn't or at least his drawings were not clear. These are sitting in the inner skin on the warm side of the cavity wall insulation - see image attached. Cavity insulation is foil faced PIR board tongue/groove but also taped over all joints. Outer skin is going to have a silicone render. I only had red oxide protection on these steels and there seems to be mixed review on if I need to protect these steels with galvanisation. I have messaged the engineer and am awaiting a response, I am sure it will be best practice is to galvanise but feel its overkill here...

 

Can anyone share some guidance on this? Steels are already in and walls built to ground floor ceiling level.

[Mr Punter]

If they are already in it is tool late. They are on the warm side of the insulation anyway, sticking out into the room so should be fine.

[JohnMo]

4 minutes ago, Ay8452 said:

Steels are already in and walls built to ground floor

Well galvanized is out of the picture as the galvanize correctly the parts get dipped in a zinc bath.

 

Your ship has somewhat sailed already so you have what you have.

 

Although inside the heated environment, I assume the steel is attached to the foundation below insulation level, so will always be colder than the room. So will need to be insulated and boxed in. 

[Ay8452]

 

 

 

Thank you both, yes steel already installed. Should I try and get some galvanising paint on it, I can partially get my hand in and around one of the columns however the other one I have no access to...? And yes plan is to insulate/box in.

Edited June 17 by Ay8452

[Ay8452]

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Edited June 17 by Ay8452

[JohnMo]

54 minutes ago, Ay8452 said:

 

 

 

 Should I try and get some galvanising paint on it

Wouldn't bother

[Bonner]

Partially painting it is pointless. You will get a thin layer of surface corrosion but won’t affect the structural integrity or life time of the beam.

[SteamyTea]

The main thing to do is check the condensation risk.

Dry, unpainted steel will last well, but damp steel won't.

Some of the insulation suppliers have a condensation risk facility in their software packages. Run it though there and see what happens.

[saveasteading]

Can you see the outer face of the column still? That is the riskiest face.

That and the base.

 

Steel takes decades to degrade unless in a warm and wet environment so don't panic.

Paint what you can see, with any metal paint. Galv or other, or bitumen. 

Insulate wherever you can.

[saveasteading]

3 hours ago, saveasteading said:

warm and wet environment 

I'm now remembering visiting a paper mill that needed new machine plinths and water troughs . It's like an enormous sauna. The steel building structure, which other people don't look at,  resembles lace but still stood.

 

Your steel will be very slightly warmer than outdoors, but you can minimise this. An inch of eps around the steel before boarding, will reduce the heat, as will stuffing the gap with tocjwool or eps,  and a surround of membrane will keep even utility room dampness indoors.

And relax.