Jack Barber / Website Design

Dealing with Mould and Condensation in a 1920s Semi

Nearly 3 years ago we moved into our home - a 1920s semi in Whitby. We immediately undertook as much decorating as we could manage, and subsequently replaced the kitchen and bathroom.

Even more recently we have slightly altered upstairs - removing a toilet and enlarging a bedroom as a result.

We've really enjoyed making our home more practical and functional - suiting our needs as a busy family of 6.

However, our progress has been marred by the common problem of dealing with mould and condensation. Now well on the way to dealing with it effectively, I wanted to share some tips which have really helped us get on top of the problem.


Cavity Wall Insulation - It's (Probably) Not The Cause

Our house has cavity wall insulation. If you Google something like 'cavity wall insulation condensation' you will get lots of results - mostly featuring home-owners who believe that their cavity wall insulation is the cause (or at least a highly-contributing factor) of their condensation issues.

We were the same.

However, having asked the cavity wall insulation guarantee people round to inspect the work, we were assured it wasn't the cause and should look at all the other contributing factors first. Only then could we be sure that the cavity wall insulation was the cause of the problem.

Here are all the things we have done to deal with our condensation issues.


1. Got a Tumble Dryer

Our condensation issues are (hopefully were) always much worse in the winter. And it's obvious really - drying loads of washing inside is always going to result in a build up of moisture which has little chance of escape.

Our house has double glazing, and is fairly draft-free. Drying washing in un-ventilated rooms is a serious mistake. Each load of spun washing still contains a considerable amount of water so if you're drying indoors without good ventilation it's going to cause problems.

We got around the issue by buying a tumble dryer. It is amazing. We immediately saw the benefit, with the amount of early morning window condensation being reduced dramatically.

Yes it's an expense. But rather pay a few hundred pounds now for a device which could save thousands in building and decorating repairs later on!


2. Installed a Proper Kitchen Extractor

This is fairly obvious too. We have an extractor hood over our hob. But because the extractor is on the same wall as our boiler there is nowhere for the extracted fumes to go - so it's just cycling the air.

We installed a new extractor fan (like a bathroom one) on another wall. This fan has a humidistat in it which senses humidity in the air and extracts until the humidity is back to normal.

Boil a kettle, the fan comes on. Cook some veg, the fan comes on. On a damp day, the fan comes on. It's a machine, designed to remove moisture from the house and it's working at it 24 hours a day.

Our fan cost around £60, and installation was a bit more. But again, well worth the time and expense to know that every time you're creating moisture something's working hard to remove it.


3. Increased the Bathroom Extraction Time

We already had a bathroom extractor fan. The kind which is triggered by the light pull. However, because the noise is annoying, I'd reduced the time it's 'on' for to the minimum (about 2 minutes).

To help remove more moisture I simply increased the 'on' time to the maximum - now about 30 minutes. And I may well replace it with a humidistat version at some point - so it won't turn off until it's happy the air is dry.


4. Opened Up Our Air Bricks

During decorating we'd blocked up a couple of air bricks. I didn't really appreciate what they were for. Now I do.

If you have any blocked up air bricks, un-block them. Also, avoid leaving furniture in front of them. This may not always be possible as they're usually on flat walls where wardrobes go, but try and leave a decent gap if you can.

They allow air to flow in and out of the house. Yes, that means some damp air can get in, but it also means moist air can escape which really helps prevent condensation on windows.


5. Added Some More Loft Insulation

We added some more loft insulation (and I still have some more to do). This prevents 'cold spots' on ceilings where moist air likes to stick. This is generally the cause of black mould on ceilings.

It's definitely worth the itchy-scratchyness of dealing with fibreglass to add some more loft insulation if you can. Fill in all the gaps between the joists - and get some expert advice if you want to know more!


6. Kept the Trickle Vents Open

Like the air brick tip, if you have trickle vents on your double-glazed windows, leave them open. This allows air to circulate, enabling moisture to escape.


7. Dealt with a Damp Chimney Breast

We had some damp on a chimney breast. We had the chimney re-leaded and slates etc. checked on the roof which prevented any more moisture entering the brickwork. But unfortunately, due to the building methods used by previous owners, the damp was stuck inside the chimney with no way of escape.

Eventually we took all the plaster off the chimney and let the bricks dry out for a few weeks (probably 3 months) before having the chimney and surrounding walls insulated and plastered (see below).

If you have any damp in your house it's probably a highly-contributing factor to condensation and mould and needs dealing with before you can work out where else the damp air might be coming from.


8. Insulated the Walls

Our builder recommended using insulated plasterboards on exterior walls and chimneys. We took his advice and had a couple of exterior walls insulated and plastered as part of some decorating work we were doing.

The walls felt instantly warmer - as you'd expect. Because of this, those black mould patches which can appear behind furniture or pictures hung on an exterior wall should be a thing of the past.



In short, there are lots of relatively easy things which can be done to remove the problems of condensation and mould in a home. We now have to wait until the autumn again before we'll see if they've worked or not. I'm quietly confident they will have.

Mostly it's down to ventilation and extraction. Houses of this age were built before double glazing and efficient insulation - enabling them to 'breathe' more easily.

If you found this post because you're looking for answers, I hope it's been helpful!