DIY Doctor

Main navigation

air bricks

Postby marcus » Tue Jan 01, 2008 6:00 pm

hi all have moved into a new house in the summer put all the furniture in and settled down for christmas rather than a spring clean we went into a chritmas clean ready for the parents and friends, during this we moved some cupboards away from corners and found that the walls had black mould rising up the walls in the corners of two of the ground floor rooms the house was built in the late seventies and has no air bricks it also has a solid concrete ground floor. i gather that this happens due to bad circulation in the room can this be solved with air bricks and if so do you install at the top of the wall or at the bottom? and how far apart do they need to be ?
would really appreciate all advice.

p.s happy new year to you all!!!!
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Tue Jan 01, 2008 5:37 pm


Simply Build It

Postby rimexboy » Thu Jan 03, 2008 9:37 pm

Hi Marcus
your right this could be due to bad air circulation if you have double glazed windows why not just try them open all the time on the night vent and see if that solves the problem.

cheers simon
Rank: Labourer
Progress to next rank:
Posts: 3
Joined: Thu Jan 03, 2008 8:30 pm

Postby marcus » Sat Jan 05, 2008 11:24 pm

thanks very much for coming back to me simon. the windows are double glazed, but they don't have vents on them, lomger term is there another way of solving the problem, air bricks or other and if there is an other would appreciate any solution (the mould has been cleaned downa few times nowmother in law not to impressed with the property purchase lol)
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Tue Jan 01, 2008 5:37 pm

Postby BevBunny » Sun Jan 13, 2008 4:03 pm

Hi Marcus, I've lived in houses with a similar problem ie condensation/mould issues but no ventilation because of the type of windows. I bought a dehumidifier and found this this stopped the mould from coming back. The longer term solution would be to change the windows or get into the habit of opening them as often as possible but obviously this isn't always possible. You can buy a pretty decent dehumidifier for about £80 and this should sort the problem. cheers Bev
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sat Jan 05, 2008 12:55 pm

Postby Lin » Sun Mar 16, 2008 1:26 pm

marcus, have u installed air bricks into your property yet? Im hving the same problem in my ground floor flat .. and not always possible to leave windows open due to the cold and security. Ive had companies advising me to install air bricks to get rid of the moulds. Im confused !! Shd i hv air bricks at the bottom nearest to the mould to increase circulation or shd i just hv it near the ceiling, hoping the warm air would go out?

If u've had yrs done, can u advise me please?

Rank: Labourer
Progress to next rank:
Posts: 4
Joined: Sun Mar 09, 2008 6:35 pm

Postby Perry525 » Sun Mar 16, 2008 7:27 pm

The problem is due to humidity/water vapour that you put into the house and your handling of the heating system.

Every person breaths out water vapour! You must have breathed onto a cold window as a child and seen your breath condense on the glass as a grey wet patch.

Our breath is total saturated with water vapour. Every person breaths out roughly 46 grams of water per 24 hours.

Every one of us creates about 2.5 litres of water vapour that enters the air in our homes every 24 hours.

That comes from breathing, sweating, washing, drying towels and things on radiators, cooking and things like opening the bathroom door and kitchen doors while the air is still damp in these rooms. Leaving the doors open with wet towels drying on the towel rail.

You will probably be surprised to learn that children produce more water vapour than adults, because they are so active.

On this point dogs also throw out a surprisingly large amount of water vapour, even when asleep.

Every time you turn the heating down or off, you unbalance the humidity/heat relationship.

For every temperature there is a specific amount of water vapour that is held in suspension.

Each time the temperature drops, its ability to hold water vapour diminishes - that water has to go somewhere, usually it will condense onto the nearest cold surface, a window. In your case its an already damp cold wall, behind a cupboard, where there is little or no air circulation.

Before you get noticeable condensation on your windows, it is already moving into your bed and bedding, making the bed feel cold when you get in, and your clothes feel cold in the morning.

To quickly solve your problem, you need to buy a de-humidifier and keep the de-humidifier on 24 hours a day remembering to empty the tank.

Then hold the same temperature 24 hours a day.

Walls become damp because rooms are warm, and the outside of the wall is cold, possibly freezing.The water vapour you and your family put into the home, rushes towards the nearest cold thing.Usually, this is a window the coldest spot in most rooms.

Installing double glazing alters the rooms balance, modern argon filled windows are warmer on the inside - the walls are now colder and the moisture/ water vapour looking for the coldest nearest spot moves inside the walls and condenses there.

Walls that have a waterproof render outside, tend to be wetter.
The condensed humidity inside the walls can freeze and over the course of a cold winter will move back and forth as ice inside the walls.

As is often the case, the coldest part of a wall is the render on the outside the ice tends to form there pushing the render outwards, leading to cracking and separation.

Because the rooms are always warmer than the outside air the condensation is trapped inside the walls.

This is when the de-humidifier comes into its own, utilizing water vapour other important feature.
Water vapour will also automatically move into a dry patch, so the de-humidifier will firstly attract the moisture in the air and the air drying out will lead to a drying of the walls, beds, furniture and clothes as the moisture therein moves out.

De-humidifiers are good. They reduce the moisture in the air and
in so doing lower your heating bill, dry air costs less to heat than damp air. Dry walls are a better insulation than damp walls they too save on heating costs.

You will save far more on your heating bill using a de-humidifier, than it will cost you to run it.

The alternative, you will have to wait for the summer to dry you out.

The sun shining on the outside of the walls, heats the walls forcing the damp to seek a colder place indoors, if the rooms are cold enough the water vapour will move back into the rooms.

Mold spores are in the air at all times looking for somewhere to settle and grow, their favorite is damp patches.

In normal conditions you only require a full air change in the house every two hours. If more fresh air is required then open a window.

Don't for heavens sake, make holes in your walls!
All this will do is make you cold. Yes, some water vapour will move outside, as its colder and drier most of the time, but not always, however, your expensive heat will also disappear outside and there is no point in letting that happen.
Rank: Site Agent
Progress to next rank:
Posts: 734
Joined: Fri Jul 06, 2007 7:35 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics