Yellow stain on new external wall

[Sef1928172]

Hi.

I have a newly built and rendered external wall and one of the weep vents has some yellow staining below it. I was wondering what could be causing this? None of the other weep vents show similar staining.

Thanks in advance

 

[Nozzle]

That's disolved rust. There's perhaps a ferrous metal inside the cavity, and the residue is coming out the vent

 

[Sef1928172]

I see. So I assume that will be from a wall tie?

Is this considered normal and the weep vent doing its job, or does it indicate that there is more water in the wall than there should be and therefore needs investigating how/where?

Thanks again

 

[Ivor Windybottom]

More likely it's from the steel lintel, as there's no cavity tray over it.

The fix would involve scaffolding, props and rebuilding over the lintel. Possibly replacing the lintel if it's in a bad way (probably not though).

How recently was it built, and have you asked the builder about it?

 

[Sef1928172]

Only a few months old. Will ask the builder about it. Lintel is brand new.

Am noticing some faint water stains inside along steel beam, which extends back from this point too, so that is a bummer.

 

[Ivor Windybottom]

Definitely not expected. If they give you any waffle don't believe them.

Condensation within the cavity should be caught by a lintel tray, either ready-made or carefully crafted from a waterproof sheet with raised edges, and funnelled out of the weep vents without contacting the steel at all.

 

[noseall]

Condensation within the cavity should be caught by a lintel tray, either ready-made or carefully crafted from a waterproof sheet with raised edges, and funnelled out of the weep vents without contacting the steel at all.

cavtray2.jpg

• noseall
• 19 Jan 2024

Bolt4

• noseall
• 27 Apr 2022

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• noseall
• 14 May 2015
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[noseall]

Hi.

I have a newly built and rendered external wall and one of the weep vents has some yellow staining below it. I was wondering what could be causing this? None of the other weep vents show similar staining.

Thanks in advance

Unusual to see ANY water coming out of these weep vents, especially a building with waterproof render on it. Is there not an old wasp nest inside?

 

[^woody^]

Possible but unlikely to be a tie or the lintel. If it is rust, then unless its a steel beam, it is more likely a nail or such like dropped in the cavity.

You should not be getting that much outflow from a weep vent. Is the verge above properly sealed?
Treat it with a chemical rust cleaner to prevent permanent staining

 

[Ivor Windybottom]

Perhaps get the builder to take the edge off the roof and have a look down the cavity? If the insulation could be lifted out, which may or may not be possible depending on type. If there's a run all the way down from the top then you know where the problem is.

 

[Sef1928172]

Have raised with the builders and they are going to come and take a look. Definitely no wasp nest up there. Thanks all for your help. I’ll report back once we have solved it.