Replacement cavity tray width

[Moonshine]

I am looking to replace cavity trays on my house where it's suspected that the tray (bitumen I think) has failed.

 

I am looking to use 450mm type E trays, which, you only need to take 3 bricks out at a time to fit.

 

The question I have house far over the window do they need to go. E.g a 900mm window, does the length of cavity tray need to be min 100mm longer either side (1100mm total)

[PeterW]

150mm is the norm but tend to go up to a brick further. 

[nod]

I did them on one of our rentals and hired a brick saw for the day from Smiths rather than using an angle grinder Cuts through like butter 

Less mess and much quicker and neater 

[Mr Punter]

You could try just painting the wall above with StormDry, which is supposed to last 25 years.

[Oz07]

Those saws are supposed to be the mutts nuts for patching