Post-building works mould worries

Kaleosaurus

Hello,

We've had some substantial building work done over the summer. The plastering was finished almost 2 months ago but the walls haven't completely dried yet, we've had a dehumidifier running 24/7 for a month now. We've started seeing some mould appear in the skirting board joins, which were put there by our builder after replastering. We took them off this morning, and the boards are covered in mould, as is the plasterboard.

Our builder tells us it's not unusual to see some mould, but we are worried that the only way to fix this is to start from scratch, knocking the plaster off as the mould will be in it. Is that panic-fuelled overkill? Or the only way to make sure we've not wasted all our savings on fixing our damp issues, only to have bigger and worse mould problems in the future? We're getting rid of the skirting boards but are not sure what to do about the mouldering plasterboard.

TL;dr: once mould is established, is the only solution to replace the infested material? Or is that fungus hysteria-fuelled overreaction?

grumbler

Building work or just plastering? What sort of 'fixing your damp issues'?
If it hadn't dried yet, I think you have more serious problems than just mould. 

Kaleosaurus

grumbler said:

Building work or just plastering? What sort of 'fixing your damp issues'?
If it hadn't dried yet, I think you have more serious problems than just mold. 

Building work too, knocking the kitchen/dining room wall down. We knew the house had damp issues when we bought it and have been slowly working on them. there was a broken drain pipe under the floor that we fixed a couple of years ago, got gutters replaced, chimney stack re-pointed and stray tiles replaced which made a difference. This summer we had our suspended timber floor replaced as it was rotten, excavated under it and fitted new air bricks to improve airflow. There were also a couple of broken pipes in the kitchen which were just oozing water and saturating the wall, and also a blocked drain which was saturating the ground with water, these have also been fixed. We were thinking that considering the broken pipes and drain, and that the whole downstairs had been replastered meant that it's normal for there to still be so much moisture in the air, the relative humidity is still around 70%. 

Is it best to just focus on drying it out before we do anything further? We were planning on getting the floors done thinking that plugging the gaps in the floorboards might make it less humid inside the house (we noticed RH increases a fair bit when it rains). We've got our damp surveyor coming back (he doesn't sell anything and specialises in old houses, ours is an 1890s terrace) but he's not free til early November,  and we are wondering if we should just get on with removing any mouldy materials before it spreads further, as I believe the visible mould is just the fruiting body of the fungus which will have colonised the whole thing that is growing the mould? 

NeverTooLate

Are you confusing mould with dry/wet rot?

Kaleosaurus

NeverTooLate said:

Are you confusing mould with dry/wet rot?

Is that what the pictures look like? 😵‍💫

DRP

It’s mould on the back of that skirting not rot. 

you’re sure you’ve identified and stopped the sources of moisture? then it would make sense to let everything dry out before redecorating (plaster, carpets, skirting etcm))

how damp is the soil under the floorboards?

FreeBear

DRP said: you’re sure you’ve identified and stopped the sources of moisture? then it would make sense to let everything dry out before redecorating (plaster, carpets, skirting etcm))

And before the skirting goes back on, put a bead of expanding foam* in to the gap between floorboards & plaster. That will stop cold air circulating behind the skirting, kill any cold draughts from that area, and should reduce the chance of condensation.

*) Get yourself a cheap foam gun from ebay or amazon - You'll find it much easier to lay down a thin bead of foam (don't forget a can of gun cleaner too).

Doozergirl

If the plaster isn't dry then either you still have a leak or the leak you have fixed hasn't had enough time to dry.  

I would keep the boards off and put a dehumidifier in until you can be sure.  Mark the perimeter of the damp areas on the wall with a pencil and hopefully watch it shrink...