New patio concerns

IvyFlood

I’ve just had a new patio installed by a firm that did some work for me in the past that was good, hence I had them back.

The patio they’ve laid is the same level as my DPC which from what I’ve read is against building regulations that state it should be 150mm below. They said that on digging they found an old clay pipe (still active) that ran under the house from one drain to another and this dictated their levels. They have said it’s ok because they’ve put a gravel channel in which will aid drainage and help with splash back. They also said it will be better than previous as I’ve got more drainage in the form of the aco drains (sometimes water did pool on the gravel). However I’m just not convinced!

Now here’s where it gets interesting! What was here when I bought the property was a mix of paving slabs (un grouted) and random concrete (see pic). And this was always extremely close to the DPC, it’s certainly never been 150 below. I’ve attached a close up of a bit of the concrete they didn’t get out so it can be seen how close it is. Three years ago I took up all the slabs and put gravel down as a low cost way to try and improve the area. It would have been too much to get rid of the concrete so I put gravel on top of this too. I remember seeing the DPC and arranging the stones purposely so as not to cover it, didn’t even give it a second thought!

I’ve never had any problems with damp with the slabs/concrete mix or the gravel and as far as the DPC is concerned nothing has changed, it’s still got gravel next to it at a similar height. So Im inclined to think it will be ok but I’m also paranoid about damp and the contractors want paying!

kipsterno1

https://forums.moneysavingexpert.com/discussion/6675316/patio-drains-at-damp-proof-course-urgent

stuart45

Because you have a cavity wall you might not get a damp problem inside. It's more common with solid 9inch brickwork to get damp issues with a high ground level. I've known cavity walls to have the ground level over the DPC and still be dry inside. However, it's normally better to have a lower ground level if possible. Modern new build houses often have the paving level with the DPC for wheelchair access, but they are designed with a tray at that level.

You might find that you don't get any damp inside. It depends on a few factors. if the wall gets a lot of driving rain penetrating the outer skin for example, it runs down the inside of the brickwork and below the DPC to the concrete infill. It then soaks through the brickwork and the sun and external air dry it away. If the ground is up against it the process is slowed down and the moisture can build up enough to get above the internal DPC. It's why on timber framed houses weep vents are important at DPC level. In theory they should be on cavity walls as well, but are generally not used.

stuart45

https://forums.moneysavingexpert.com/discussion/comment/82066619#Comment_82066619

Patio drains at damp proof course urgent! — MoneySavingExpert Forum

EssexExile

I had similar in my last house, it was fine. Against building regs but fine.

Jemma01

No idea, but it looks very nice 😍

Boohoo

The 2 things that concern me are the patio door sill end cap is missing next to the drain and the downpipe discharging next the the wall dpc and over the pebbles and where will the rainwater go as it looks like the piptis slightly off the ground so how will that pipes water get into the gully or french drain?

IvyFlood

@Boohoo there is a gully drain for the downpipe. And the DPC on that side of the patio doors is higher which is actually my garage. The patio doors join the garage to the house, it was done in the 80s and isn’t the best job!

Boohoo

https://forums.moneysavingexpert.com/discussion/comment/82070903#Comment_82070903

What mean an about the downpipe is there a drain underneath the where the rainwater comes out because it looks like it is not over the french drain and just discharges onto the pebbles.

Have you tried putting water in the gutter to see if the rainwater goes into a drain and not onto the pebbles and then runs over the patio and down the wall under the pebbles.

If there is a french drain running along the house under the pebbles that is fully connected to the gulley then you maybe ok but I wouldn't want pebbles over the drain incase they get into it and cause a blockage but if they are large I may not be an issue.

IvyFlood

Any more thoughts on this?

Boohoo

https://forums.moneysavingexpert.com/discussion/comment/82078927#Comment_82078927

Any answers to the questions I asked in the post above yours?

As there has been no heavy rain for weeks you won't know if the gutter works ok and if the patio will drain ok until it's too late.