Advice on paving that is too high

[amd1]

Hello everyone.

I just had a patio installed. The pavers agrgued with me at the outset when I told them that it must be a minimum of 150mm below the DPC. They said 75mm was sufficient, but I insisted on 150mm. Eventually they conceded and went ahead with the work. However, I did not know that there are two DPC's in the house and the 150mm that they measured down from was from the higher DPC and I've just discovered that the patio is just about level with the lower DPC.

There is an ACO drain against the house at around the same level as the lower DPC. I have no idea what to do. Can anyone please advise me?

Thanks.

 

[BathDIY]

I'm no expert on this but I had a house where the one DPC was at ground level, no way to alter the ground level without runoff rainwater going towards the house.

I did a fix which I found in my DIY book that called for a pea gravel trench around the property. I believe that this is a standard method and you should be able to find out more online.

My belief is that if you have 2 DPC's you're more than OK, I do wonder why you have 2 and I guess others in the forum may be able to shed some light on this.

Perhaps a fix is not required in this instance.

Hope this helps.

Justin

 

[amd1]

Many thanks for your reply Justin. As far as I know, the lower DPC is to protect the wall and the higher one is to protect the floorboards. There's a 'floating floor' downstairs in the house.

 

[^woody^]

Post a picture of the house and path in context.

 

[amd1]

Hi Woody. Please see attached.

You can just make out the thin line with appears to be the lower DPC, with the ACO type drain just below it.

I've attached another one so you can see the old air brick.

Thanks.

 

[oldbutnotdead]

What was on the ground before you had the paving done? Was that ACO put in as part of the patio work? Looking at the bottom course there's been water soaking into those bricks for ages

 

[amd1]

Hi. The ground level came up to the bottom of the subfloor vent and there was decking on top of that, level with patio door sill. It had been there for about 15 years or more, I think.

 

[^woody^]

The patio appears to be at an appropriate height.

By the time the walls are repainted then that will deal with any potential splashes. But the bricks appear damp in any case at ground level, but that is normal, and this could cause the paint to blow from the wall over time. Not a lot can be done about that.

A bit concerning about the argument with the contractor. The client is paying and should get what they want how they want it.

 

[amd1]

Hi Woody. The height may look ok, but the DPC is only a few mm above the ACO drain in the pictures. Building regulations state that the ground level and drainage should be a minimum of 150mm below the DPC.

 

[tony1851]

Building regulations state that the ground level and drainage should be a minimum of 150mm below the DPC.

No, they don't.

The relevant Building Regulation states:

"The walls, floors and roof of the building shall adequately protect the building and people who use the building from harmful effects caused by:
a) ground moisture;
b) precipitation, including wind-driven spray....."

There is no hard-and-fast rule that says there must be a dpc min. 150 above ground level. For example, if the house is on a dry, well-drained site, and the wall is covered
by a verandah or carport, and the bricks are reasonably frost-resistant, a dpc may not be necessary. There must be hundreds of thousands of houses which remain dry without any dpc at all.

 

[^woody^]

Hi Woody. The height may look ok, but the DPC is only a few mm above the ACO drain in the pictures. Building regulations state that the ground level and drainage should be a minimum of 150mm below the DPC.

But your floor is higher - 150mm higher?

You say you have two DPC's so the higher one will be presumably protecting the floor - which is more important.

You certainly don't want that paving 150mm lower as that will be a massive drop from the door for no reason.

BTW, the often quoted "150mm" is to reduce the effects of rain splashing up the wall above a DPC. Did someone mention previously up the thread that the paint will be protecting the wall?

 

[amd1]

Thanks for your replies all. The 150mm I quoted was what our surveyor told us was building regulations.

Woody, my next port of call was to ask what to paint the wall with. I was advised to paint 150 mm from the DPC upwards with bituminous paint. I’m wondering is that recommended or could I use something like storm dry, would that be any better?

Annie advice greatly appreciated.