Wet cills

[Jimbo37]

Hi Self Builders
I need a steer, please

I have a new built masonry house, with a cavity and standard DPC window details. I had wet patches low down on the internal reveal - a wet quadrant from junction of window cill and window frame.

The builder resolved it with additional mastic around the frame on the outside, and it seems dry now.

My questions are

 - shouldn't the DPC have directed the wet out, before it got to inner leaf?

 - is mastic in this case a robust solution, or will it need replaced, maybe every 5 years?

 

[Mr Punter]

Normally you would have a cavity tray and weepholes above the lintel to sort out the top then a cavity closer at the sides and the bottom.  The main weather seal is between the frame and the outer leaf and is normally mastic or Compriband.  Any water getting past this should get stopped by the cavity closer and directed into the cavity.

[Jimbo37]

3 minutes ago, Mr Punter said:

Any water getting past this should get stopped by the cavity closer and directed into the cavity.

Thanks @Mr Punter - should I have expected the DPC to have prevented my inner cills getting, before the mastic was increased?

[Mr Punter]

Yes.  Do you have any photos of just before the window was installed?

[Jimbo37]

This is the best I have. Another row of blocks on the inside and alu window with alu cill.