Building help - DPC and patio

[rossyl]

Hi

Not a car question, but I am hoping those experienced, or, those with more logic than me...might be able to offer a solution.

We would like to build a patio that is the same height as the internal floor height of the room that the patio will be adjoined to. The issue is that the DPC of the house is below the internal floor height. The DPC is approximately 2 bricks below the finished floor height of the house. In between the patio and the end of the house is an ACO drain running pretty much the whole length of the house.

Is there any way that we can build the patio to the height of the internal floor height, without creating damp issues?

Thanks
R

 

[Max Swell]

Go for decking maybe? You may struggle but I am no builder.

As long as you keep it clean decking is only slippery when covered in algae ie not pressure washed twice a year.

 

[CatmanV2]

Go for decking maybe? You may struggle but I am no builder.

As long as you keep it clean decking is only slippery when covered in algae ie not pressure washed twice a year.

Oh! Is *that* how you stop it. Looks like I've got a weekend planned out then.

C

 

[Max Swell]

As long as it involves a power tool or high pressure water it's a good weekend arrrfff arrrfff.

 

[Max Swell]

That's what my missus says anyway......

 

[safrane]

Its doable as long as there is a waterproof barrier created...just think about shops/office's etc that have a flat floor from the outside in.

You will need a builder who knows there stuff rather than a one trick pony type or you will have the damp you are not hopping for.

 

[Max Swell]

Deck

 

[CatmanV2]

That's what my missus says anyway......

It is better to ask forgiveness in this case, I feel

C

 

[andyp250f]

Another possible solution is to have a "moisture gap". This way you can create the same level as the internal floor, but the outside level has a gap between itself and the main building. dosn't need to be wide, just not attached. By installing a waterproof membrane between the two, you will keep the integrity of the DPC. pretty simple to do, and also might be worth asking your local building control/building inspector for advice. Although it woudn't appear you need building regs, building inspectors (at least where I live and do quite a bit of development) are not your typical civil service mandarins. "I could do with a bit of advise, I value your experience, How do you take your tea?" usually works a treat.
Hope this helps.

 

[Emtee]

You shouldn't (but in some circumstances you can) go within 15cms of the DPM. You can shorten this gap for steps and the such, but not really for patios.

The way around it is to leave a drainage gap of 20cm's, and on this point you mention the drain? I assume you won't build over the drain? In which case you would have a gap of at least 20cm's anyway?

 

[Max Swell]

Deck

 

[hodroyd]

Don't build up to the main building DPC, leave a gap, otherwise you will breach the DPC in that area. You can have quite a wide gap if you wish and cover that with a narrow steel grid running the length of the patio next to the building, this could also assist you with leaving access to the drain..!!

 

[2b1ask1]

Leave a gully or build in a line drain but leave a gap for airflow between the two structures that is deep enough to work, if you are slabbing the patio you can cantilever the slabs back over the gap to within maybe 30mm of the wall. That way there is no issue and you can use a blower or jet wash once a year to clear out the leaves etc. that will get in the gap inevitably :0

 

[rossyl]

Thanks for the advice ... I'm hoping the following makes sense.

This is my rough plan. Please suggect any changes that you see fit. I have not specified the distance down that the drain will sit, or the width of the gap. I would be grateful for your suggestions.

 

[safrane]

Only suggestion I would make is for the drop of the patio to be away from the house to ensue any blockage in the drain down does not force run in towards the house

 

[Max Swell]

I would suggest a deck

 

[Emtee]

Hi Rossyl, can I ask…..

You show door threshold and below that you show DPC along side the (existing/proposed??) ACO drain.

What is the current general outside ground level below the DPC?

Your drawing suggests that if the ACO drain is existing at outside ground level it's above the DPC? This would not be good at all. You'll be able to correct this in the areas where you're installing the patio, but elsewhere your outside ground level is above the DPC?

So I'm assuming that the ACO drain isn't installed yet and your drawing is a suggestion for the installation of an ACO drain to sit on current outside ground level protected against and above the existing DPC by the addition of a DP membrane?

If this is the case, why are you thinking to install an ACO drain? Just but the patio to the house, join the DPC to the patio, run it around the patio and reconnect to the house around the other side. Just be sure to have the correct fall on the patio.

Just my thoughts…...

Cheers, Miles.

 

[2b1ask1]

Hi Rossyl,

More or less as you have drawn it but taking on board Mile's comments. It is more important to maintain airspace above the DPC to this effect the aco drain needs to be below the DPC at all points. I would substitute gravel back fill for ballast rejects (larger stones screened out of ballast) or larger river rounded stones (cricket ball size) as larger stones will greatly improve airflow and are easier to lift out to clean.

 

[rossyl]

Thanks everyone for your comments.

I want to see what the builder proposes and then have some ideas immediately to hand if what I think they are proposing does not sound great. I'll have plenty to go on from the above so thanks very much

 

[hodroyd]

I sort of had a similar situation and filled with nice quality pebbles, they look nice, drain well and air can circulate..!!