Ask a Tradesman
Damp Proofing Question
Rendering over dpc.
I have a house that was built around 1890 and is of brick construction with a rendered band running around the base which also forms square edged columns around the front door. Until recently the house had a concrete front garden that met the building at the level of the base of the grille ventilating the ground floor cavity.
I have removed the concrete slab as it was falling toward the building and was, I thought, too high in relation to the ventilation grille. Removing the concrete slab exposed the DPC visible at the level of the base of the grille. To be 'belt and braces' I removed the render one course above the dpc and injected Dryzone into the mortar joint.
My questions are
- if i lower the new front garden level to 150mm below DPC im going to be very nearly on top of the brick tier foundation, is this a problem
- I want to reinstate the render band as all the other houses have them and it also forms part of the elevation detailing around the front door, but have read that the render shouldnt go past the DPC. If i stopped the render above the DPC and dropped the ground 150 i'd be left with a band of fairly tatty looking bricks that have been underground for the last 40 years. How could I finish this without compromising the damp proofing?
- should I install a french drain of some kind?
Many thanks for your help!
You could fix a bell cast bead just on the dpc then render above and below this is to stop you bridging the damp course keeping both renders separate,use water proof render on both levels sika water- proofer.
Answered 8th May 2013
Hi, you should use Stainless Steel Render Stop Beads to construct a horizontal expansion joint at the DPC, and either leave it clean (ensure no bridging) or Mastic Fill in a colour to suit your finish.
As Trident suggest use Sika1 as additive to the render(both coats)
Answered 20th Jan 2015