Dam% Damp

[MorrisWoodman12]

Moved into a new home (for us) three weeks ago. What a lark! Vendor hadn't removed all his mother's goods (even longer story and had gone on holiday) before completion. Went over night before simultaneous exchange/completion to see how much was left, to be met by panic stricken estate agent. 'Burst' pipe had flooded two rooms upstairs, brought down the lounge ceiling and flooded downstairs. Having spent a year looking for a suitable home we went ahead with the purchase although at a suitably reduced price.
Three weeks later ceiling is cleared away, laminate flooring removed in most affected rooms and lots of damp floorboards dried out. The great majority of this work I'm doing myself.
Here's my question: there's a fair bit of green and black mould on the timber and on the garage ceiling plasterboard. What's the best way to deal with this? Is there a suitable liquid I can paint or spray on (although I don't have spray equipment)?
Thanks
Martin

 

[John Hall]

HG, do a lot of mould removing products, available in spray bottles and foam from B&Q etc…
My concern would be the cause of it…
Has the mould been caused by the leaking water?
Is the garage attached to house?…does it have any heating,…is there any ventilation..etc.
Borax Powder mixed with water is als recommended for mould removal..

 

[John Hall]

 

[Argus]

I'm not convinced that visible (and possibly extended) amounts of mould on structural wood can occur a couple of weeks after sudden wetness onto (presumably?) previously dry timber.............

 

[John Hall]

I'm not convinced that visible (and possibly extended) amounts of mould on structural wood can occur a couple of weeks after sudden wetness onto (presumably?) previously dry timber.............

I totally agree, but I was thinking maybe the leak has been there for some time….culminating in the final disaster…

 

[Adam W.]

I think that a picture of the disaster area is required.

 

[MorrisWoodman12]

Pictures as requested.
One of the general areas. This room is above the garage. Both are attached to the main house. I've no pictures of the lounge as that has had a dehumidifier running in it for several days and is now quite dry although some areas still have a degree of mold.

Detail from under the underlay. Note the green tinge to the mold - it looked a lot greener in real life.

Between the 8" joists after some of the chipboard and Rockwool removed. Rockwool was dripping wet on underside/only dampish on top.

The other side of the plasterboard in the garage. Didn't notice the mold a month ago when viewing the house.

 

[MorrisWoodman12]

I totally agree, but I was thinking maybe the leak has been there for some time….culminating in the final disaster…

About 10 days before the flood was discovered our surveyor had viewed the property. I would hope that at that time there was no leak. Although I expect he wasn't doing any electrical checks I hope he would have seen that one of the power circuits on the consumer unit had tripped if it had done so or at least mentioned it in his report. That circuit powers the macerator that caused the problem. (The 'burst' pipe I described earlier was short hand. I have not found what was running into the macerator system of toilet, basin and shower tray but with the macerator with no power to empty its system the shower tray overflowed causing all the issues). In the unlikely event that the surveyor had caused the problem then the water had been running around the house for no more than 10 days before it was discovered.

 

[MorrisWoodman12]

@John Hall I've used HG products before though just generally in a bathroom to successfully remove a small amount of mold. I'm not so sure about using them on large areas and wood and plasterboard. Does the bottle spray or does it just ooze a foamy mess? I thought/hoped there may be a more industrial product for applying to larger areas.

 

[Jameshow]

I'd be tempted to remove any damp plasterboard once it gets wet it losses its strength and the mold spores aren't good for your lungs either.

 

[John Hall]

It is a spray bottle, and will cover a decent area, but for a large area you may need something more heavy duty, like a hozelock sprayer…
I’d Google suitable solutions for killing the mould

 

[--Tom--]

If it’s damp and mouldy I’d replace it, any treatment is just a short term fix, much easier to replace now than in a year when you’ve decorated and moved furniture in

 

[thetyreman]

yes I'd also replace any damp or wet mouldy boards anywhere, you don't want to end up decorating and there is still damp there, could be worth hiring an industrial de-humidifier as well to dry it out.

 

[robotmannick]

I've tried several mould-killing/removing products, each with limited success. By far a better solution was just bog-standard bleach.

 

[Jones]

When plasterboard gets wet it losses most of its strength and may sag and crack in the future, also as it's above a garage it should be fire rated and may no longer perform as hoped. A further problem will be staining of the ceiling, you'll need a stain blocking paint before redecorating.
I would remove all and replace the boards and rockwool, if you're going to use the garage as a work shop putting resilient bars between the plasterboard and joists will reduce sound transmission.

 

[MorrisWoodman12]

Thanks everyone for your responses. I'll post again when I've decided what to do.
@Jones errr? Resilient bars? Please elucidate.
Martin

 

[Stevekane]

Mould can be a problem on boats, even on hard fibreglass surfaces and Ive tried various cures over the years, bleach seemed as good as any, but my last attempt was with some brickwork and patio mould cleaner, sprayed on with a trigger spray and this was possibly a bit more effective, Im afraid I cannot give you a brand as it was just a small amount a mate gave me in an unconnected bottle, but I think I would buy myself a pump up garden sprayer with a wand, only £10 or so and a can of the most visious looking mould patio cleaner you can find and once your woodwork and any mould is dry give it a good wetting with that. If you've cured the source of damp ( the leak) you would think you would be okay.
Good luck,
Steve.

 

[Jones]

Resilient bars are steel bars about 50x12 mm in a top hat section. You fix them to the joists at right angles and then screw the plasterboard to them. They introduce a gap between joist and plasterboard which reduces sound transmission between floors. They are widely used and available and any plasterers will be familiar with them.

 

[Limey Lurker]

About 10 days before the flood was discovered our surveyor had viewed the property. I would hope that at that time there was no leak. Although I expect he wasn't doing any electrical checks I hope he would have seen that one of the power circuits on the consumer unit had tripped if it had done so or at least mentioned it in his report. That circuit powers the macerator that caused the problem. (The 'burst' pipe I described earlier was short hand. I have not found what was running into the macerator system of toilet, basin and shower tray but with the macerator with no power to empty its system the shower tray overflowed causing all the issues). In the unlikely event that the surveyor had caused the problem then the water had been running around the house for no more than 10 days before it was discovered.

So does a macerator thoroughly cleanse itself after every use, or is there an amount of raw sewage left in the chamber? It might be that this is the cause of the mould.

 

[MorrisWoodman12]

@Limey Lurker So difficult to tell. I have no idea what was causing the leak only that is was into the macerator system and overflowing from the shower tray. It could have been the shower itself. When I removed and tipped water from the macerator the water looked clear and clean with no additional substances. I haven't taken it apart.