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Bathroom ceiling black mould help really appreciated please

Postby daveforever » Thu Jan 28, 2021 1:54 pm

Hi all,

I hope that you are well,

I'm new to the forum and a relative DIY noob so I thought I would ask for a bit of advice please.

We've had a patch of black mould appear along one side of the en-suite bathroom ceiling. I've doused all the surfaces in the bathroom with mould killer (Cillit Bang).

However, it became clear that the mould had appeared because a bit of moisture had got behind the paint as some of it in that areas was lifting when wiped and exposing the plaster underneath.

I'd done a bit of research however some feedback on my project plan would be appreciated please. Any recommendations would be heartily appreciated. This is what I'm planning to do.

1. Use a scraper to remove any 'loose' paint until I get to a point where the paint seems to still be firmly stuck.

2. Sand the points where this good paint meets exposed plaster with 180 or 220 grit sandpaper (I'm not sure which would be best) to create a smooth finish.

3. Cover with Zinsser Bulls Eye 1-2-3 Primer-Sealer.
- Should I use a roller or brush for this? If a roller what size?
- Should I just focus on covering the areas with exposed plaster and a bit over the edge of paint. Or should I do the whole ceiling with primer?
- Do I need multiple coats?
- Should I water it down?
- How long should I leave the primer before first coat of Dulux?

4. Paint - minimum two coats - Dulux Easycare Bathroom Paint Pure Brilliant White.
- I understand the whole surface should be done in one go.
- Should I do edges first?
- With a cutting-in brush? What size?
- Then roller the ceiling (9" roller). Or roller first then edges?

- B&Q comments for this paint suggest that it is very thick. I saw someone elsewhere suggesting to water thick paint down 10% to thin it just a little bit. Is this a good idea?
- How long should I leave between coats?

5. Finally as the ceiling is going to be rollered edge to edge I am assuming that it is worth masking to ensure I don't get paint on the (fully tiled) walls. I was planning to go all round the edge with 75mm masking tape. Should I paint all the way to the top of the tile? Or leave a bit of a gap if there is any sealant/grout at the top of the tile e.g. not paint that?

Planning to get all the stuff from screwfix, most of the stuff from Wooster seems to have good reviews.

Thanks for taking the time to read. Any help appreciated.
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Simply Build It

Postby stoneyboy » Sat Jan 30, 2021 10:12 pm

Hi daveforever
Suggest you trace why you have a cold strip before you do anything more. Then do your stages 1 and 2, then mist coat exposed plaster and blind in the repaired area. Wait to see if the problem re-occurs.
Regards S
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Joined: Wed Dec 10, 2008 6:44 pm

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