Boxed in on three sides - Boxed in and trying to get out.

[matt_north]

Hi all

I have an issue with a patio fall. One of those issues where when you solve one issue it raises another.

As you look at the soon to be patio area i have the house to the right, to the left a low wall and a high wall to the back. The patio area is raised 1500mm above the garden all back filled with clean rubble and topped with type1. The patio area is 6m (width) and 5.5m (deep). The builder has left the patio area LEVEL and the height to the DPC is 200mm.

My issue is i cannot do a complete fall from right to left as there is a low wall on the right and i can't do a fall from back to front as i would need to raise the back by over 100mm (i can't reduce the height at the front as the fill retaining wall is there) which would reduce the gap from the patio slabs to the DPC to about 25mm (with slab and mortar included).

The only way i can think of is to slope away from the house, right to left for 2m then after this slope from back to front over the edge of the patio. But obviously this causes difficulty at the point the two falls meet.

If anyone can think of a better solution it would be greatly appreciated. Patio is going to be Indian Stone with Rompox Easy.

Regards
Matt

[Tony McC]

You almost have the solution..... slope away from the house, install a linear drainage chanel, then on the other side of the channel, have the fall reversed so that section, too, falls towards the linear channel.

Does that sound feasible?

[matt_north]

Hi Tony

Thank you for taking the time to reply. Definitely feasible, in that scenario i was thinking a slit drain rather than a full Aco drain. Do you have an opinion on slit drains?

I have thought of another solution which would enable the preferred front to back slope. On the back right hand side create a potted herb garden corner on some decorative aggregate to where the patio doors begin then for the length of the patio doors i won't have a DPC problem so can accommodate a higher patio. Then all i have to worry about is the front corner of the building (about 1200mm from end of patio doors to corner). Considering the back of the patio needs to be 100mm up on the front of the patio, by the time the patio makes first contact with the wall of the house (after patio doors) i will only need to be 45mm up.

The only issue is, my eyes must have been painted on when i took the measure of 200mm to DPC, it's actually only 150mm (it was dark)!! But i was thinking i could get away with creating a 150mm wide sunken splash strip for the remaining 1200mm wall to keep the 150mm DPC to floor.

Your opinion would be greatly appreciated, it would basically mean a patio floor level to DPC distance of 105mm sloping to approx 130mm along the length of 1200mm with a 150mm wide sunken splash strip between the wall and the patio maintaining a 150mm splash to DPC distance.

I hope that made sense and i look forward to your opinion.

(I know this has been said many times before but the website is fantastic. I don't think i've come across a website before with so much useful and usable information- thank you very much).

Kind Regards
Matt

[Tony McC]

Slot drains (not "slit") are all well and good as long as they are properly maintained.

Every time I see a failed slot drain, it's clogged up becauyse no-one has cleared onstructioons from the slot and no-one has run a rod-and-plunger through it to clear any silt.

With 'standard' linear channel drains, any onstruction or blockage is obvious becaus eit can be seen from the surface, but with slot drains, the problem often lies unseen below the surface, so never gets fixed.

When they are looked after properly - and all it takes is a once-a-year check - they are a great option for discreet drainage, and that's half the problem: they function so well (at first) that they get overlooked and forgotten.


Splash strips: I know they have their admnirers but I have never, ever liked splash strips. They do have their uses - as a 'drain' for single flag paths, f'rinstance, but when I see them used for draining entire patios or driveways, I know it's only a matter of time before the problems start, be it damp on the wall, incresed salt bloom on the masonry, failed render coats, saturated sub-layetrs or, most commonly, ponding becaus ethe damned things haven't been properly constructed.

When there is no alternative, then I'll give a grudging nod to a splash strip, but I'd always look for an alternative, any alternative, before considering their use on one of my projects.


Thanks for the kind words!

[matt_north]

Thanks for the reply Tony, a choice to be made! Looks like i'm going to have time to think about this one looking at the forecast