DPC detail for stone cills

[ruggers]

I'm about to have my cast stone stooled cills fitted into the face brick exterior wall and I need to know if it's best to use 100mm DPC underneath, or a larger stepped DPC.

 

What are the benefits if any of the stepped DPC as per my sketch?

 

My partial fill cavity wall is

100 face brick, 50mm air gap, 100mm PIR, 100mm block. The cills are 65mm in height x 175mm deep so that i can have them set back into the cavity by 25mm, which then allows the windows to do the same. Rear of stone cill to front outer face of PIR=25mm.

 

I planned to install a trimmed cavity closer under the cill, so a stepped angled DPC would interfere with this unless folded at 90 degrees.

[torre]

Ask the manufacturer for an installation detail. Your stepped DPC is definitely approximately the right approach. 

 

Unlike plastic etc cills, stone or cast is porous so you need to prevent moisture getting through and behind it.

 

This is a decent starting point and also emphasises you may need to accommodate expansion/movement between the cill and brickwork, that's another point on which the manufacturer should be able to help

[torre]

Make sure your window supplier knows you're having stone chills if you want the frames to sit directly on them as you need to be sure any frame drainage will work. 

 

Quite often you'll see a stub plastic cill installed on top of a stone cill, which isn't quite such a clean look.

[ETC]

Wrap the cill.