Dry lining fastenings rusting

[techno12]

Hi.

My semi-basement flat (it's about 2 feet below ground level, though there's a drainage channel a foot wide around 2 of the 3 sides) is mostly dry-lined.

Over the past year or so, the nails/screws have started to lump and become discoloured, mainly restricted to one side of the flat. What's odd is that they were fine the the previous 7 years I've been here so I'm unsure why it's occurring now. Maybe the fastenings have a finite 'anti corrosion' period and have all gone at the same time, maybe there's water ingress from a broken drain, or just moisture build up in the void. Maybe it wasn't done correctly back in the 70s when first converted.

The pic below shows the external wall that's closest to the worst-affected internal walls. That moss growth suddenly stopping and starting looks suspicious to my untrained eye.

The flat has always suffered from condensation issues (or possibly rising/penetrating damp) as I've had to run a dehumidifier but windows always soaking wet, despite each one having a vent-o-matic fan/vent in them, and mould grows on coats etc hanging in hallway after a few months. Walls have always felt bone-dry however with no mould.

Ideas/advice welcome.

Cheers!

 

[ree]

The external pic shows plastic plugs in DPC injection holes - DPC's whether injected, or as a mechanical barrier, are to stop damp rising not to deter damp from going down with gravity.

The pic also shows render touching the ground - it should be hacked off above any damp course to prevent capillary action bridging the DPC.
FWIW: chemical DPC's are often worthless, the injection holes simply disfigure the building surface.

The pic also shows the green algae resulting from splash water coming down from above somewhere - gutters, parapets? Clean the algae off the walls.
You should also clean off the surface of the ground "slab" and put a spirit level on it - i think that its ponding at the far end under the leaf debris.

What you do about the rusting fixings is difficult to say - you could remove them a few at a time, and make good the holes with silicone and a blob of finish. Thing is you dont know how the drainage/"tanking" and dry lining was originally installed eg. is there a sump pump in place? Are the walls tanked and is the floor membrane connected to any wall tanking?

Given the mold on the clothes, then you have an unhealthy problem which might require, at the least, an opening up of the dry lining to see whatever can be seen (often, not very much).

You might need powerful 150mm extractors in the kitchen and bathroom. Also pull all furniture away from the walls.

If you can control any penetrating damp and internal condensation and feel its healthy to continue living there then go ahead but, otherwise, its a complete rip out and renewal of the tanking installation.

 

[techno12]

Thanks for the reply!

Well, that area with the algae has suffered from a deluge of splash water on a few occasions, due to the guttering 20 feet above becoming blocked (it's an old Victorian house converted into 11 flats). This has been rectified for now, so that whenever it rains there's no obvious splashing.

The other side of the building looks like this..

I suspect some repointing is required, as floor level is at the base of the layer of bricks with the chemical DPC (floor tiles are salting in the kitchen internal to this wall) but surely water can get in the cracks in the layer below and beyond the DPC.

You're correct - I don't know how it was done back in the 1970s. A builder wanted to cut out some of the dry lining to see what is going on underneath so I may get him back to do this.

There are major works to be done to the building (scaffolding around it, repainting) and I'm trying to get a list of the issues that need to be rectified on the portion of the building that I'm in.

Thanks again!