Slate DPC...

24 May 2019
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United Kingdom
Have a double course slate DPC, about 15mm deep, on a 1930's house that we're adding a double storey extension to. To keep the brick course continuing through around the extension we need to build up in a similar manner. Apart from using slate are there any other similar materials with same compressive strength that can be used. I was thinking porcelain tile as this works out cheaper and is much easier to score and snap with a tile cutter. Thoughts please. Thanks, Ernesto.
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Hi Ernesto, what does building control say, i can't imagine they will allow anything other than the plastic dpc? Do you have a pic?

He was round today funny enough. I forgot to mention that we would be using a normal dpc... the proposal for the porcelain tile was to get over the difference in height of brickwork. The double layer slate dpc is about 20mm high so to keep the courses level we need to build up same amount on the extension. hope that makes sense.
Building inspector seemed ok although he said he’d never come across the situation before or my request for using porcelain.
As far as im aware, when you bed plastic dpc it should be between two beds of about 7-10mm ( feel free to correct me if im wrong anyone) if that's the case the difference would be very little. I work as a stonemason by trade mainly in newbuild and architectural restoration, we use roofing slate alot as a dpc under steps first course etc, could you run a course of slate then plastic if iv pictured this right in my head
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Thanks for that Nikolas. What my builder is proposing is a normal dpc, another bed of muck and then 10mm of porcelain tile. This would make up the height we are trying to achieve.
sounds good to me, there's no need to have similar compressive strength to slate, you just need enough to keep your house up (which is actually not that much, even those 2.7n/mm blocks that are like rice crispie cakes are fine)
I'm not a builder though.

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