Air Brick needs a cavity tray ?

[BogBeast1]

Hi all.

I have an an end of terrace rental house that is suffering from mould. had it inspected and one of the suggestions was to provide additional ventilation into the cavity of the exposed end wall. Happy with that, fixing a couple of airbricks in the outer leave is not beyond me.

They also suggested additional ventilation into the house via airbrick. Bit more complicated, so I'll use a cavity sleeve as well.

Quite alot I have read indicates I need a cavity tray fixed over the sleeve. So a couple of questions:

> Is this really necessary?

> Never fitted one before, I am assuming that that the tray is fitted immediately above the airbrick by taking out the two bricks above?

Any advice greatly appreciated!

 

[r896neo]

As long as you have a slight fall towards the outer leaf i don't see the need for a tray?

 

[pinenot]

Quite honestly this is not the way to cure mould in my opinion. Can I ask is this mould on the internal or external wall? pinenot

 

[BogBeast1]

Thanks for the responses.. The mould is on the outside wall.

There were a number of other issues that were identified, principally a leaking gutter, a bathroom fan partially exhausting into the loft plus tenants drying clothes in the house without opening the windows. There are no trickle vents in the double glazing (yet, am about to fit, as well as the airbrick which should encourage additional ventilation in the house)

The cavity ventilation was simply an additional recommendation as it seemed to be holding moisture, the wall is pretty exposed and does get a rain blown onto it.

 

[pinenot]

This is a modern cavity build wall were talking about, yes? and if so are there any weep vents built in, or does it go back beyond this type of build technology.
Weep vent are fitted just above cavity obstruction to facilitate the cavity's ability to drain out any build up of moisture i.e. cavity trays (where fitted) pdc courses which bridge across the inner to outer cavity skins, where the weeps are spaced equidistant around the entire building. Retro fit of these is not all that difficult, but regardless this issue does not (moisture within the cavity, which is normal) give rise to mould on the external wall. I actually think your inspection/suggestions are a we bit ambiguous, if I may say. An air-brick through the cavity will vent the inside al right, cold air venting, better I would say, fit an extractor fan, but is there a moisture problem there as well? and worse does this stem from wetting of the external skin?? ...pinenot

 

[BogBeast1]

This is a modern cavity build wall were talking about, yes? and if so are there any weep vents built in, or does it go back beyond this type of build technology.
Weep vent are fitted just above cavity obstruction to facilitate the cavity's ability to drain out any build up of moisture i.e. cavity trays (where fitted) pdc courses which bridge across the inner to outer cavity skins, where the weeps are spaced equidistant around the entire building. Retro fit of these is not all that difficult, but regardless this issue does not (moisture within the cavity, which is normal) give rise to mould on the external wall. I actually think your inspection/suggestions are a we bit ambiguous, if I may say. An air-brick through the cavity will vent the inside al right, cold air venting, better I would say, fit an extractor fan, but is there a moisture problem there as well? and worse does this stem from wetting of the external skin?? ...pinenot

Its an early seventies build, so a reasonably modern cavity build wall, as an aside, a previous survey for cavity wall insulation determined that the cavity was too narrow for insulation. There are no weeps that I can see in the wall.

The gutter is leaking onto the outer skin of the house in the area where the mould is the worst on the inside wall, I don't know how long this has been happening but it seems to be the primary cause. Will be fixed this weekend

The house is empty at the moment and I simply want to knock down as many possible causes as possible to avoid repeatedly going back there (to clean mould/redecorate)....

Installing airbricks seems to be a bit belt and braces and fairly simple to do but I was unsure as to needing a cavity tray as if does seem overkill..