Patio Level

kco3d

Hi,

Just looking for peoples thoughts on the following.

I've had 3 patio contractors out to give me estimates to lay a limestone patio (22 sq/m).

None of them seemed to be bothered about the TGD C regarding the damp proof coursing being at least 150mm above the finished patio level.

They all initially stated the entire patio level across the back of the extension (4.5m) could be up to the same level as the internal floor which is at DPC level so there would be no need for a step.

When I mentioned where the DPC was then they all said something along the lines of "Ah well then we'll come an inch or so below that point then".

With drainage handled by gradient away from the extension, is there such a low risk of damp due to splash-back that they are not really bothered about this guideline?

Would there be any implication when selling the house if a surveyor sees the patio level within the 150mm recommended distance?

Thanks.

sydthebeat

aco drainage channels.

kco3d

Many thanks for the reply sydthebeat but not sure I understand the purpose of this drainage channel in this case.

My understanding is that the purpose of the 150mm gap between the patio level and DPC is to prevent splashback from rain in that rain should not splash up to 150mm.

I thought a drainage channel between the patio and rear wall is only for the case where the patio cannot be slopped away from the rear wall for whatever reason.

Forgive me if I'm way off.

4Sticks

kco3d wrote: »

is there such a low risk of damp due to splash-back that they are not really bothered about this guideline?

Would there be any implication when selling the house if a surveyor sees the patio level within the 150mm recommended distance?

.

No. Yes.

sydthebeat

kco3d wrote: »

Many thanks for the reply sydthebeat but not sure I understand the purpose of this drainage channel in this case.

My understanding is that the purpose of the 150mm gap between the patio level and DPC is to prevent splashback from rain in that rain should not splash up to 150mm.

I thought a drainage channel between the patio and rear wall is only for the case where the patio cannot be slopped away from the rear wall for whatever reason.

Forgive me if I'm way off.

youre not way off...

the 150 distance IS for splash back, but this is significantly increased when there is rainwater flowing off a wall to the base which is then splashed back.

a drainage channel collects and drains this away, leaving what i would consider an insignificant splash back risk.

All front doors now must have level platforms with sloped access, this means by design that these platforms and sloops will be within the 150 DPC level. The industry standard detail here is to include drainage channels.

all you can do is lower the risk... be that by designing the patio away from the way (practicality and tripping risks?), designing in steps (practicailty and use?), or designing in drainage channels...

kco3d

4Sticks wrote: »

No. Yes.

Thanks 4Sticks

sydthebeat wrote: »

youre not way off...

the 150 distance IS for splash back, but this is significantly increased when there is rainwater flowing off a wall to the base which is then splashed back.

a drainage channel collects and drains this away, leaving what i would consider an insignificant splash back risk.

All front doors now must have level platforms with sloped access, this means by design that these platforms and sloops will be within the 150 DPC level. The industry standard detail here is to include drainage channels.

all you can do is lower the risk... be that by designing the patio away from the way (practicality and tripping risks?), designing in steps (practicailty and use?), or designing in drainage channels...

Cheers sydthebeat,

one last one, if it was you, and 150mm below dpc was the lowest level you could work with, would you

A) Start the slabs from the back wall (thickness ~30mm) therefore patio level is 120mm below dpc or,

Put in eco drainage channel (depth ~100mm) against back wall and have patio level 50mm below dpc

Appreciate your comments...

sydthebeat

B everytime

sydthebeat

B everytime