The Brew Cabin

Posted: **Wed Feb 02, 2011 9:13 pm**

Our old concrete patio slabs have been removed to show an uneven concrete layer below of unknown thickness. We want to lay a new patio (slate or sawn sandstone) to be 6 inches higher than this in order to be level with the internal floor.

Our contractor has suggested building the sub base on top of this old concrete to the required level before putting in the new slate/sandstone. We're concerned that water will get below out patio and have nowhere to drain to. Is it essential for us to dig out all the old concrete to get to the ground below?

Many thanks for any help with this.

Posted: **Wed Feb 02, 2011 10:17 pm**

The concrete could potentialy be a very good base to lay off as long as the levels didn't interfere with your dpc and the water is going in the right direction. If you want to check it's thickness drill a few holes in it. The paving is pretty water tight so don't worry about heave etc. If you lay it level with the internal floor then you'll probably be breaching your dpc and thats usually a big no no.

Edited By Pablo on 1296685296

The Brew Cabin

Building a subbase on old concretewe're laying a p