Cavity tray over bay window

Question

We have recently had a bay window installed from a flat window our house is 9”solid brickwork since then it has rained in terrible they said it isn’t their problem we need a cavity wall tray why didn’t it rain in before the new bay window was installed then and can we put a cavity tray in a 9inch solid wall with no cavity? Over this bay window?

Vito · Answer

The issue its just around the new window, for led flushing to window fixed ,and silicon, you cannot fit cavity try in solid wall ,

Charles · Answer

Rain didn’t get in before because the flat window had a sill and detailing that shed water differently. A cavity tray requires a cavity, so it can’t be added to a 9” solid wall. You’ll need alternative flashing or leadwork over the bay window to prevent leaks.

Kind regards, CB Builders & Son

John · Answer

Such cavity wall trays exist type C or E self supporting trays, however why was this not installed prior to bay window if they knew it needed one?

Matthew · Answer

Yes, you can and I would recommend having the tray installed with lead and weep holes, installing as a lead tray comming from the internal brickwork, across the cavity which has fill, down and through the external brickwork, 100mm lower than the internal brickwork where the lead tray starts, with weep holes either end of the window, all above the window head. With another lead tray across the window head from internal brick work across and through external brick work.

Stuart · Answer

You cant fit a cavity tray to a solid wall as there is no cavity. Sounds like the lead flashing isn't cut deep enough.

Kieran · Answer

If your house is solid 9-inch brick, there isn’t a cavity there in the first place.. so a traditional cavity tray can’t just be added in afterwards. That explanation doesn’t really fit the type of wall you’ve got.

If it didn’t leak before the bay window was installed, and now it does. That strongly suggests something around the new bay isn’t shedding water properly. When a flat window is changed to a bay, the structure and the external detailing are altered flashing, leadwork, brickwork, seals. If any of that hasn’t been done correctly, heavy rain will find a way in.

If you’d like, we can arrange to come out, assess it properly and give you a clear, honest answer on what’s happening and what it would take to fix it.

Scott · Answer

You cannot install a cavity tray in a solid wall  because there is no cavity to sit it in.

Cavity trays are only for cavity walls (two skins with a gap between).
Where the bay roof meets the brickwork, there should be proper stepped lead flashing chased into the mortar joints.

If: 
It’s surface stuck on
It isn’t chased in
It’s not deep enough
Mortar isn’t sealed properly 
Water will track down behind it.

There should be a DPC or cavity lintel tray equivalent detail above the bay opening even in solid walls, a physical water break should be installed above the frame.

If it only started after the bay was installed, that strongly suggests the installation has altered how water is being shed.

Amy · Answer

It would not need a cavity tray if there was no leaks before it would most likely mean that the window has not been sealed correctly

Mick · Answer

Cavery tray would prevent any mister leaking though

Cavity tray over bay window

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