Groundwork & Foundations

Is this a good way to raise the concrete level while preserving drainage?

Anonymous user 03/03/2024 - 3.25 PM

I'm renovating my ground floor bathroom. I have an area in the room below the typical concrete level which drains water out of the house via an open drain pipe on the floor. I also have penetrating damp, which cannot be resolved easily. I want to raise the concrete level to match the concrete level of the rest of the bathroom, yet allow penetrating water to escape the room via the drain. If I put a DPM down, and up the wall slightly, and then concrete on top of it, will this prevent water from draining under the DPM since the weight of the concrete will prevent water escaping? If so, is it then sensible to instead put down some gravel, and then a DPM, and then concrete on top of that? Water could escape, but there is no sand-based binding layer. I'm reluctant to use a sand-based binding layer because I'm worried about the sand falling to the bottom and then interfering with the drainage, since sand is smaller than gravel. Am I overthinking this, or is there a better way?

GJC Groundworks limited

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Wimborne

I think the first thing I would do is fined out where this water is coming from, you should not have water running under your floor.It’s possible you have a water pipe leaking or split that needs repairing or if it’s sink waste pipe or something not connected get it joined into the drain before you concrete the floor. It’s also possible storm/rain water could be running into your house through the blockwork under your house, there for you would need to put a land drain around the house to divert the water away. Once the water issue is sorted you could happily construct the new floor without any worries. Sand blinding, 1200 DPM, 75mm insulation,DPM then 75mm of concrete

Answered11 November 2019

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Anonymous user

Is there any reason why you can’t transfer the drain to the new level of concrete ? - if not use screed to up your level, and slightly slope the new floor to the existing drain to allow water to escape , or you could put a floating floor in to retain the void underneath to allow water to escape , just make sure you black jack the floor where the timbers will sit

Answered11 November 2019

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Anonymous user

I would no lay dpc on top stone or gravel as the weight of concrete would break the damp seal.i would use a strong concrete mix with waterproof retarder in .its defo a job that needs a solution. A dream channel could be the answer too

Answered11 November 2019

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Aaron Pugh Builders

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Ilfracombe

I would use a layer of pea gravel

Answered9 November 2019

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