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Raising ground level close to air brick and DPC

Discussion in 'Building' started by GettingOnWithItAll, 12 Aug 2019.

  1. GettingOnWithItAll

    GettingOnWithItAll

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    My head is swimming after hours spent researching my best options and would appreciate your opinions. See below for some background info.

    1. Air Brick. I have a double height air brick with its top level with the DPC. The ground level is up to the bottom of the brick and I’m considering making the ground level higher. The NHBC standards have a 600mm clear space 75mm below the level of an air brick, and I can get nowhere near this and pleasing SWMBO. I could fit something like a Snorkelvent (https://www.snorkelvent.co.uk/shop/snorkel-vents/1-standard-model.html), move the air brick higher up using a periscope or block in the lower half of the vent and put in another air brick or 2 further along the wall. The Snorkelvent is certainly the easiest, although I question it straddling the DPC. The periscope may be a lot of work. The extra air bricks are work but may be a good improvement, I have relatively easy access to the inside wall and if I’m putting in one then a second isn’t that much extra work. The image shows the brick with the ground dug out for a base and sub-base.
    AirBrick_1.jpg

    2. Ground level within 150mm of DPC. Although much of the proposed path will be more than 150mm below the DPC, the left-hand end will be less than that in order to get a drainage slope. I've spent ages on PavingExpert. I can probably keep the DPC at least 75mm above a 100mm deep ACO drainage channel with grille, which I think meets the standards. However, I’d like to have the level at the porch to be close to the level of the DPC and avoiding having a step means part of the drainage channel being less than 75 below the DPC. I could have a small gap, say 10-15mm, between the ACO channel and the wall, either with a bottom of earth or a mini drainage channel.
    PorchImage_1.JPG

    A bit of background

    I intend to fit a fill-in porch and raise the level of the front drive/pathway to my 1930s cavity wall semi. The ground slopes 8% (1 in 12) towards the house and 4% (1 in 25) down to the right, giving a difficulty with levels and making drainage crucial. The drive to the right-hand corner is 2 brick levels (150mm) below the DPC. I’ve removed the flower bed next to the front wall that was causing efflorescence on the brick work and partially blocking the air brick.

    SWMBO wants me to build up the level of the front with slabs over the old flower bed and existing concrete path, which is in good condition (ignore the weeds in the bodge where the internet cable runs). This makes a lot of sense as it would fit the revised step at the porch, avoid the existing step where the angled path meets the drive and make better use of the triangular flower bed.
     
  2. GettingOnWithItAll

    GettingOnWithItAll

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    I emailed my questions then spoke to someone from my local Building Control. He said that the drain coming close to the DPC wasn't a problem and didn't/couldn't specify a minimum distance. I did, though, get the impression that he was a little vague or unsure. I'm also wary of its being raised as an issue by a surveyor. I will therefore probably have a small gap, say 10mm, between the drain and the wall, with the intention of filling it in later if weeds become a problem.
    Thanks to all who showed an interest by looking.
     
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