New Damp course position

[trevorbayliss]

My house has a DC which is one brick above the finished patio area.

When i build the new extension do i continue with this current damp course line or raise it one course as new DC's have to be a minimum of 150mm above finished ground level i think.

 

[Blagard]

The external DPC should be 150mm above ground level so do that using suitable bricks below the DPC. Consider lowering the external ground levels if that is practical. Stepping the DPC is normal practice where the external ground level slopes. Your internal DPC level may well be different. Avoid a situation where external ground levels are higher than internal floor levels as that brings potential for other problems that need to be accommodated by building additional detailing.

 

[trevorbayliss]

Ok i think my internal and external will be similar, but not worked this out yet fully.

I am doing a suspended timber floor. Does the DPC have to be under the joists and hanging brackets. I am going to use masonry brackets so the timber will sit with the wall behind its back. It will also be treated timber. I think this DPC will have to go on the line of these brackets or above. Is this ok.

 

[^woody^]

The DPC is normally dictated by the floor level

 

[Blagard]

With a suspended timber floor just make sure the timber is in contact with areas protected by DPC's the joist hangers are better fitted above a DPC to reduce risk of corrosion. You will probably need the stepped ducts to get your airbricks in. The external DPC at 150 above ground is because that 150mm is where the bricks get saturated due to splashing rainwater. The internal DPC does not have to be 150mm above the outside ground level and in your case may well be lower to protect internal walls.