Damp and mould on exterior facing wall

readymix111

Hi All, i was just down in the folks house today and found bad mould in the front bedroom, on the wall, ceiling and even spreading to nearby bed and drawers. They got the front of the house sandblasted about 20 years ago but never got it sealed. The window is also in a bad state, condensation build up inbetween the glass and window sill board is rotten. There is also no ventilation in the room. What would be the best way to deal with this, i can put in a vent myself and i think ill get the window removed and replace the glass and it install back. Would the front of the house need to be sealed? Would i need to rip the plasterboard down and treat the wall from the inside?

Cheers

Right2Write

Fix up any obvious leaks and water ingress first. But mould growth is a result of various factors - insulation, temperature of the exterior wall surfaces, temperature in the room, sources of humidity in or near the room and ventilation. Raising the temperature in the room/ building will allow the air to carry more moisture but which can then condense on cooler walls etc.

So after the obvious, maybe look at what insulation is there and if it's cost effective to improve, ventilation and heating.

I think this is more an issue at this time of year as autumn can be damp but people often haven't got the heating going yet fully.

readymix111

Thanks for that, the room is a small one, with a radiator but no air vent in the room, im going to install one in the next few days. Would you think the plasterboard will need to be ripped down and new boards put up, would the mould be bad behind them? They were just thin boards put up originally onto the external wall, no insulation.

Right2Write

Putting an air vent in will increase the air exchange in the room, particularly if an upstairs room. It almost certainly smells musty. The room will also be cooler. This will probably be better health wise but may have minor impact on the mould growth. If the air in the room is moist, either from sources within the house or from outside ambience and you have cool walls, moisture will still condense then and mould will grow.

The usual approach is to fix all obvious leaks then a combination of improve the wall insulation, increase the heat and improve air circulation.

I've been there, done that as our house is a mixture of wall types and have experienced improving one part only to increase a problem elsewhere

In my experience mould growth is surface, you can get a bucket of warm water and put in a squeeze of bleach and clean it off. You mention plasterboard. Are your inside wall surfaces dry-lined? If you knock on them, do they sound hollow? Or is the plasterboard fixed solidly/ directly to the wall? You mention that exterior walls were sand blasted - what are they made of, brick or stone?

There are many factors at play and I'd be guessing that you want to come up with a reasonable if not perfect solution that doesn't involve too much hassle or expense.

readymix111

I had a fella in to have a look and straight away he blamed the windows and the fact that there is no ventilation. Im gonna core drill a 3" hole in all the 3 bedrooms and put vents in and then get someone to fit new windows on the front of the house. Cheers for your reply Right2write. hopefully this should put an end to the mould.