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Tarmac driveway regards to drainage and dpc

Hi help please someone advise me.
My tarmac driveway was completed on friday and i`m concerned about the drainage is not sufficient. The highest point to the tarmac which meets the gable wall is just under the mortar line where the dpc level is. From this highest point a gradient was created to direct water to the gully on either sides of the gable wall. Is this sufficient drainage? It the highest point the tarmac against the gable wall is my worry as it just directly under the dpc mortar line however the builders assure me the slope gradient means water will be directed away. On either sides of the gable wall were the gully is the tarmac level falls to one brick course 75mm.
Please advise ? I worried about water penerating into the cavity water in causing damp to internal walls of the house.

4 Answers from MyBuilder Driveway Pavers

Best Answer

Definetley should be 150mm below dpc sounds like splash back from heavy rain could end up above your dpc in your home. Also you mention gully drains were they installed by the driveway people? If so do they run to a suitable soakaway and not into main drains as this is against building regs aswell. Really sounds like you need a meeting with them to explain a little more about why they have made these decisions.


Answered 2nd Nov 2017

You should really be 150mm minimum below the dpc. Regardless of the fall.

Good luck Alex


Answered 30th Oct 2017

As above the tarmac level should be at least 150mm below DPC. If the drive is sloping towards the house then they should put drain channels in and direct the water into these. These should then be fed into appropriate drainage or soak-a-way.


Answered 30th Oct 2017

i would request them come back out and talk to them. like the guys above have said, minimum off 150mm below DPC. if their professional, they would know this, and certainly not just do it under the mortar line!
if they have done that, i would be wary of thickness of the base & the actual tarmac. tarmac should be at least 70mm thick for domestic driveway. 40/50mm thick binding course, then 20/30mm of wearing course


Answered 31st Oct 2017

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