Floor heights

[bolst3r]

Hi,

So most of our internal extension (see below) is finished so i'm moving into the garden:

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• bolst3r
• 22 Sep 2009
• 1

We have a slate floor internally and the plan is to run exterior slate into the garden so when the doors are open the floor continues out. This however has thrown up a couple of questions. Below is the plan for the patio:

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• bolst3r
• 11 Jul 2011
• 1

I want to run the patio at the same level as the interior floor so there's no step but I want to make sure I take care of any damp issues that might arise from this. In this next picture I have illustrated how I plan to do this:

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• bolst3r
• 11 Jul 2011
• 1

As you can see the plan is to paint the exterior wall with synthaproof (SP) and then run a damp proof membrane (DPM) under the entire width of the patio and back about 2 meters. I then plan to layer my hardcore and concrete over the top and then set my slate tiles on top of this. Where my tiles reach the house I will make sure the DPM and SP are slightly proud then run a small bead of silicon between the tiles and house.

This shows the plan from a birds eye view:

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• bolst3r
• 11 Jul 2011
• 1

I know one of the main issues with damp is caused by capillary action so i'm hoping by using the methods i've described that this wont be an issue. I'm also going to put quite a hefty fall on the patio and as there's a 13" overhang on the back of the house.

I know in an ideal world there would be a step down to the patio but do people think the methods i've laid out are sufficient?

Thanks for any help or advice.

 

[Richard C]

I know in an ideal world there would be a step down to the patio but do people think the methods i've laid out are sufficient?

No. Similar topics have come up before & a search will give you more info but here are 2 previous threads;
//www.diynot.com/forums/viewtopic.php?p=1722069#1722069
//www.diynot.com/forums/viewtopic.php?p=1626084#1626084

External ground level is usually 2 brick courses below DPC & Building Regulations require a minimum of 150mm. Personally I think what your proposing is definitely not a good idea & will give you nothing but problems with damp ingress not just through capillary action either.

 

[bolst3r]

Thanks, I did try searching but didn't really find much. If this is a bad idea how about using a gully drain in between, like this:

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• bolst3r
• 11 Jul 2011
• 2

Only problem I have is the doors are set back an inch so what could I put between the door threshold and the drain as this would look terrible as it is?

Thanks

 

[bolst3r]

Think this needs a new thread on just the joining strip.

 

[Richard C]

The gulley drain will serve very little purpose as standing water will drain away from it. It’s not just standing water you need to take account of, the minimum height of 150mm is also there to prevent damp problems caused by rain splash back. Have a read of this;
http://www.pavingexpert.com/dpc01.htm
It's where the sketches came from in the previous link I posted.

You obviously don’t seem bothered about non-compliance with BR’s which may well come back to haunt you in the event of an insurance claim or when you come to sell up.

 

[bolst3r]

Hi Richard, thanks for the link and all your help, I do care about BR and damp and that's why i'm on here. I did read that site and it stated the 150mm is for commercial property so I wondered how other people out there do what i'm trying to do. I'm not trying to do anything dodgy I'm just trying to understand how I achieve what I want to do. Below are some images that show other people doing it.

Picture two on this page shows someone doing it:
http://www.bpmnet.co.uk/page/domestic_projects

http://www.airlite.com.au/timber/doors/bifold_d/

http://www.aluminiumtradesupply.co.uk/bi-folding-doors/

 

[bolst3r]

Right just called building regs as i've nothing to hide, they said the drain I'm proposing is fine in front of the the doors and I should just add a french drain of 4" either side of the doors so there is no splash back up the walls.

still no clear what I do with the gap between the doors and the drain though. Any ideas?

 

[r896neo]

i would try your luck contacting the mftrs of some of the fancy sliding doors as they might be able to tell you how they detail it. Better yet get one of them out to quote and pick his brains.

IT is of course possible but you might be into a situation of low level tanking to be sure.