Cavity Trays

[Willa]

A little help/advice much appreciated please,
Do I need to install cavity trays over new windows.
Also if I am putting up a conservatory (making external wall now internal) will I need to install cavity trays above the conservatory in the existing wall? And will this not then come under Building Control? instead of just Planning. (under 30sq/m).
Thanks in advance

 

[horace1]

My house is 8 years old and only this year water started to urineate under the lintels of the windows i have installed-(what a ball ache) cavity trays refurbished type(-crew fix).
I am no 100% it will be succesfull but this wet weather will tell.
Use your own judgement as to wether you install or not, Is house new or old?

 

[Willa]

It is 18 years old. I will have pros in to do it. I will check with BCO on monday morning to get the full story.
Thanks for the reply.

 

[Nige F]

unless the wall is Leeward (sheltered ) you Need trays

 

[freddiemercurystwin]

You'll definately need trays above any new openings or at floor levels, above the conservatory roof is not so obvious, good practice would say yes, you can get ones as standard designed for retro fitting from various manufacturers.

 

[maggymay]

I would have thought any cavity wall above a lintel should have a cavity tray. Moisture will penetrate any 4" skin of brick work and will find its way to ground level to prevent moisture getting across to the inner skin of block work your brick ties have moisture barrier of some kind and the lintels have a cavity tray above them, either 18" felt or the propriety types you can buy, the felt is higher on the inner skin and any moisture is free to run out through the weep holes that you should have with the cavity tray.

 

[noseall]

there is a certain amount of driving rain that even the most porous of bricks walls can deal with before the inner face will show signs of water beading.

evaporation will occur as readily as saturation, so intermittent soakings aren't so troublesome.

persistent driving rain over prolonged periods, onto softer porous bricks however, can be a problem. certain areas of the country are especially prone to prolonged driving rain. i personally have known of only two instances locally where a cavity tray would have been useful.

above some upstairs windows, in particular where there is a soffit directly above, the need for a c.t. is not necessary. there has to be a certain amount of exposed brick work for a cavity tray to have a function.

common sense, and geography will often dictate when and where cavity trays should be installed. but if they are installed as part of an ongoing build then so be it. the costs aren't enormous. as for everyone rushing out to retro-fit cavity trays into already built scenarios, i should weigh up my options first to see wether it is definitely necessary.