Hi Tony
Six years ago, a patio was laid against the back of my rendered house at the same level as the DPM. For the last two years there have been tidal marks and blistering paint on the wall of the house. The patio falls away from the house and the surface water runs into a narrow linear channel drain on the far side of the patio. See photos in following post.
I am thinking of having a trench dug against the house wall and a linear channel drain laid. From looking at the diagrams on the main website, I am wondering if it would be ok to lay this drain at the same level as the patio and therefore the same level as the DPM. This seems to be the neatest solution. But will this work? Or should I lay the drain 75mm below the patio and DPM? If the drain is lowered by 75 mm will I have a problem connecting into the surface water gullies?
An alternative but less neat solution seems to be to dig a trench and lay gravel at 150mm below the DPM (as per the website). I would consider this if the linear channel drain solution won’t work.
Thanks in advance
Patio at same level as dpm
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LindaE
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- Joined: Sat Jul 18, 2020 12:50 pm
- Location: Macclesfield
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Tony McC
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A retro-fitted linear channel would probably help but it will still take a while for the damp issues in the wall to resolve, and the 'tide marks' as you call them, may never disappear - just depends on their mineralogical make-up.
Do you know if any air brocks were covered up whne the Bozos installed this paving?
I'm wondering whether a deeper-than-normal channel would be required. I doubt the 'standard' 100mm depth channel would be adequate. A 150mm depth channel would put its invert at the 'proper' paving level, while a 200mm depth channel would push it beyond that.
I recently specc'ed a similar 'problem' where damp was a HUGE problem and the design incorporated a one-way drainage composite (https://www.pavingexpert.com/drain07 ) placed between linear channel and wall, and then linked to a land-drain to ensure any lingering water was escorted away as quickly as possible. That sort of notion could well be what's required for your project.
Do you know if any air brocks were covered up whne the Bozos installed this paving?
I'm wondering whether a deeper-than-normal channel would be required. I doubt the 'standard' 100mm depth channel would be adequate. A 150mm depth channel would put its invert at the 'proper' paving level, while a 200mm depth channel would push it beyond that.
I recently specc'ed a similar 'problem' where damp was a HUGE problem and the design incorporated a one-way drainage composite (https://www.pavingexpert.com/drain07 ) placed between linear channel and wall, and then linked to a land-drain to ensure any lingering water was escorted away as quickly as possible. That sort of notion could well be what's required for your project.
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