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Damp Proofing

Recurring mould issues even after the installation of a piv system


I moved into my ground floor flat in late 2015, it an ex council building built in the 50/60's I think.

In the main bedroom an area of the wall developed a large damp problem along with some smaller patches in the living room. We had the people who manage and maintain the flat fix the problem in that they removed all of the plaster off the wall and applied some sort of coating or sealant to the brickwork (I'm not 100% sure what it was but it was black in colour), they when re-applied the plaster to the wall which we painted over. The areas in the living room appeared to have just been painted over. They also installed a drainage system system around the outside of the flat where they put in some sort of membrane around the flat and dug a huge trench and filled it with rocks. In addition they done some re-pointing and repaired some of the guttering that was damaged.

I thought this would be the end of the matter but the mould in both areas then returned. In addition to the mould on the walls we were also seeing heavy condensation on our windows in the mornings. The managment company came out again and a internal moisture report was carried out and it was suggusted that the installation of a PIV system would solve the issues that we were having .

We then agreed to have a PIV system installed and painted the affected area of the walls with anti mould paint. This certainly reduced the condensation and the walls appeared to be ok, but we are now seeing again dusty black marks forming on the wall in the original problem area in the bedroom and white mould on some clothes, leather goods and some furniture (the underside of a ikea computer desk in the 2nd bedroom). There could be more mould that I have yet to discover and I plan to inspect more clothes and the cupboards in the hall for signs of white mould.

The people who installed the PIV are due to come around next week to check the operation of the PIV system, but if they advise that it all works ok I dont know how to proceed or who to turn to.

A bit more about the flat it is a 2 bed ground floor flat with 2 occupants, neither of us is there in the day and we'll cook in the evening and normally the shower is used one a day. We open the windows when cooking and when showering. The windows in the flat are UPVC but do not have trickle vents on them. There is a single ventilation brick in each room. Though in the kitchen the brick was covered up by a the installation of a fake ceilling. I no longer dry clothes indoors either. So I feel I'm taking all the required steps to reduce adding to the moisture in the air.

Any advice on how we can stop the white mold from forming and could there be an issue in the internals of the problem wall in the bedroom that may require a more invasive inspection?

13 Answers from MyBuilder Damp Proofing Specialists

Best Answer

It sounds like your wall insulation !!


Answered 23rd Aug 2017

It definitely sounds like an issue with the walls,either muck in the cavity or insulation in the cavity,the water ingress is most likely from the roof or the walls depending on the condition of the brick work. P.I.v. systems are ok to cure condensation issues but cannot stop water penetrating the building through poor or incorrectly carried out maintenance they don't stop dampness'. This is really only my thoughts on your issue as its impossible to be 100% sure without actually looking at the problem .
Good luck alex


Answered 7th Jan 2021

One word dehumidifier, and leave it switched on at 60% and keep emptying no matter how long, approx 30 days.


Answered 7th Jan 2021

In my opinion, you have problems with wall insulation and it is also possible externally that it needs to be checked or somewhere around the wall if water pipes and leaks pass.


Answered 7th Jan 2021

This is all about condensation and ventilation. Black mould will only grow in moisture. You have had a great many attempts to fix this - but - if you leave your doors and windows open and put the heating on full blast the mould will die and disappear.

I don't suggest that you do that for obvious reasons, but the root cause on these things are usually lifestyle choices in that it's cold outside so up goes the heating and all the windows are shut. Mould just loves all that still air, a bit of warmth and off we go :)

You just need to ventilate, get fresh air circulating and it will go away.

Hope that helps


Answered 7th Jan 2021

For me, I’d say it’s down to ventilation. I’ve had this before personally. All I was advised to do was to keep all furniture away from walls too allow the air to move more freely.
A simple thin bleach will wipe the mould spores away.... but unless the air flow is good/constant it’ll just keep happening.


Answered 7th Jan 2021

Insufficient ventilation More venting urgently required


Answered 7th Jan 2021

hi,get an independent damp specialist or 2 to give you an assesment.sounds to me like like they are trying to pee on a bonfire,wall may need isolating,much better air circulation and so say its ground floor flat,sure its not basement flat?


Answered 7th Jan 2021

from your description I cant work out is this rising damp or penetrating damp or possibly saturation from above either way unless you get an expert to look at this then you are going to spend a small fortune on lots of different solutions I would recommend getting a qualified survey carried out on the problem and then proceed with the recommendation


Answered 7th Jan 2021

Ventilation and you could try painting walls with Zinsser Guardzs this will provide a solid damp proof barrier that can be easily over painted, it drys quick and is a clear solution. Over paint with a tinted Zinsser perma white and the results should be excellent.


Answered 7th Jan 2021

Of day it's definitely lack of proper ventilation from my experiences


Answered 7th Jan 2021

Sounds like condensation to me
Ie. No or little wall insulation and a warm house
Is it worst in cold weather


Answered 13th Jan 2021

Could be dpc injection is needed and internal wall insulation to stop cold spots on external walls. Ground floor flats sometimes fail on dpc. If the wall is cavity and not insulated and the cavity is bridged by debris this can cause rising damp. If the mould is high up it'll be a ventilation issue. Low damp patches would suggest dpc.


Answered 20th Nov 2022

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