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Damp Proofing

Air vents or air bricks to prevent condensation and damp issues

Anonymous user 03/03/2024 - 3.32 PM

Hi, We’ve just bought a 1930’s 4 bed semi which was in a run down state with severe damp issues. To make matters worse it is rendered and that might be adding to the problems. We’ve had it re roofed as it was required n was told would help with most of the damp problems. However that did not help much as the chimneys were not repaired at the time by the roofer. However since re roofing we have now also removed the chimneys as a lot of water was coming through that and the room Below the chimney was most wet. The walls are starting to dry out now and we seem to be getting somewhere. We’ve been suggested to install one or even 2 air vents in each room for some air flow and condensation. My question is would 2 air vents in each room help with condensation n damp or will the rooms be too cold. Also what type of air vents should be used inside and outside the house and should it include ones with plastic wall pipe? Also can I install air bricks instead or air vents or may be in addition to air vent I should also install air bricks near the roof. Also in one room we seem to have like a wet patch on the wall on ground floor, we’ve checked with neighbours and they don’t have anything on their wall to cause it. Could it be salts trapped due to gypsum plaster as was reading that somewhere or something else. If it’s due to gypsum plaster what is the solution? Our cellar is having some standing water or small puddle at one point when it rains heavily but dries out on its own. Is that normal? Is there anythng we can do or needs to be done? All ur comments and suggestions would be appreciated. Many thanks Updated: sorry I’ve 3 people giving 3 different answers. Do I install air vents and air bricks as I thought that would help as the property is rendered because of which the bricks are not able to breathe and blocked and cause lot of issue with damp etc. Also if it’s the salts as mentioned what is the solution to it? Break the gypsum plaster and let it dry??

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4 Answers

Damp Cure Services

Rating: 5 out of 5
Cambridge
It seems to me you have been given the wrong advice and spent money needlessly. So this property you bought was in such a bad state that it needed a new roof and chimney removed?... Anyway the best answer you have on here is the one given by damp investigations. But honestly if you buy an old or aged property it was generally built to breathe and the fireplace would have been part of this ventilation. The walls would have lime mortar which evaporates moisture. If you are going to buy an older property I suggest you research there building fabric and design before you spend any money on modern inventions or materials.
Answered17 September 2020
8

Damp Investigations

Rating: 5 out of 5
Southall
Under no circumstances install air vents or air bricks to assist with condensation; the short answer is : they will make it worse ! I could write a book on this common misconception. You need a controllable air exchange . Very often the chimneys are not leaking but are contaminated with a natural salt called ammonia sulphate, this salt is hygroscopic and will appear wet . Big tip for you : measure the thickness of the plaster ( not render) if it’s thicker than 2-3mm , it is also hygroscopic and will display dampness or damp stains . Basements or cellars that are not for habitation may get puddles , if it’s not damaging anything, leave it alone .
Answered16 August 2020
6

Dovedale Dampcure Services Ltd

Rating: 4.9 out of 5
Hull
Your issues sound so familiar to me. You have a myriad of issues and to the lay person they all seem to be different issues, but the situation is that all of the issues you’ve described are all a consequence of one problem - VENTILATION!! There are essentially two type of ventilation, passive and active. Passive relates to such as trickle vents, wall vents, air bricks etc. These all have there place but are only of use in maintaining a dry home when there is no real condensation problem already active. When you have issues such as those you describe the only solution is active or mechanical ventilation. For a whole house large volumes of air need to be shifted which is why the way forward for you will most definitely be the installation of a PIV system. This will give you almost instantaneous results.
Answered16 August 2020
4

Promptfix Plastering and Building Services

Rating: 4.9 out of 5
Belfast
I would get trickle vents fitted to windows this helps with condensation and fit one vent in each room firstly and suggest air brick on the outside and adjustable on the inside allowing you to close in a real cold spell make sure that your external vents are angled downward on the outside and position is key here I would fit 8 to 12inches above skirting, and around 20 inches from corners of room if possible allows easyer air flow around the whole room. Cut out damp patch and make good with lime mortar and lime top coat finish that's premixed, wouldn't worry to much about your celler as I think that would be expected after heavy rain. Good luck
Answered16 August 2020
3