Side Abutment Cavity Tray Position

[LA3222]

 

Just drawn a rough sketch quickly, as seen.

 

My question pertains to the location of the stepped cavity trays in relation to the lead flashing for the roof tiles. My walls are blockwork and will be rendered, this means that the lead will be chased into the blockwork in a straight line rather than coursed in step with the blocks. The cavity trays though are stepped and run with the blockwork coursing.

 

So where do this cavity trays sit in relation to where the lead is chased in?

 

On the left of the image the stepped cavity trays (shown in black) stop at a line parallel to the roofline. The lead flashing is chased in and touches the corners of the cavity trays, the issue here is that there seem to be lots of little white patches which are not protected by lead flashing or the cavity trays?

 

On the right of the image the stepped cavity trays are pulled closer to the roof line, then the lead is flashed in at the correct height. This means the channel chased for the lead cuts through the cavity trays but in this instance all exposed surfaces are protected.

 

Which is the correct way to do this?

[Mr Punter]

I would avoid damaging the cavity trays when chasing in the flashing.  The very small amount of residual exposure on a rendered wall will not be enough for any water to penetrate.  So the left hand looks good.

[nod]

What I normally do is tack the lead to the block work and run a diagonal bead over the lead trapping 

Not the correct way but I always hated beading and rendering in and out of the stepped lead 

With the advent of fibreglass 

Nearly all roofers leave the FG  flapping in this way when we are rendering 

[LA3222]

13 minutes ago, nod said:

What I normally do is tack the lead to the block work and run a diagonal bead over the lead trapping 

Not the correct way but I always hated beading and rendering in and out of the stepped lead 

With the advent of fibreglass 

Nearly all roofers leave the FG  flapping in this way when we are 

AIUI the lead will be chased in as a straight run and then the renderer will bring his bead just past that in a straight line giving a clean finish?

 

I think I'm overthinking this one as those spots I mentioned that are neither protected by a cavity tray or lead are unlikely to have anything come through anyway - it's a silicone render which should be a fairly effective barrier against anything but the harshest wind driven rain?

[nod]

That’s all I did on ours 

I let it in 40 mil Lead silicones the joint and stuck a bead over it 

[LA3222]

6 minutes ago, nod said:

That’s all I did on ours 

I let it in 40 mil Lead silicones the joint and stuck a bead over it 

Makes me laugh reading some of your comments at times - I always have to take a minute and decipher what you are saying! So, the lead sits in the blockwork by 40mm, silicone over that, bead on top. Jobs a fish!

 

Cheers?

[nod]

1 hour ago, LA3222 said:

Makes me laugh reading some of your comments at times - I always have to take a minute and decipher what you are saying! So, the lead sits in the blockwork by 40mm, silicone over that, bead on top. Jobs a fish!

 

Cheers?

Comes of typing on my phone

Loads of suggested typos 

[Brickie]

2 hours ago, LA3222 said:

I'm overthinking this one

Yeah,but only a bit. For me,those zones you’ve mentioned won’t exist in reality-you’d overhang the end of the previous tray further than you’ve drawn,so any penetration or condensation will not have a route past the tray system. As for the diagonal cut-you’re only cutting in what-20-30mm? So long as the tray in the actual cavity is intact,that’s what matters.