Puzzled over damp proof course

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Currently having an extension built and just a bit worried about the way they are doing the damp proof course.
We were under the impression that it needed to be a continuous membrane that would run under the concrete slab and then go upwards slightly and then under the layer of internal breeze blocks.

They have already built the breeze blocks with dpc in, but the membrane is not able to link to it and will apparently just go over the floor and then up the sides and not link with the dpc. Is this allowed under building regs? Has anybody seen this method done?

DPM (floor) should link to the DPC (wall.) If there's a gap then damp could penetrate.

Hello @wineymummy this is exactly what we are querying with them. They say that they'll be no gap as the floor membrane will go up the bricks passed where the dpc has been inserted, but everything I read says it should be one continuous piece rather than separate

The picture on the left is what we expected, the picture on the right is what they are planning

The picture on the left is the correct usual way of doing it , I think the other way would be fine too , but it’s up to the building inspector at the end of the day , wait to see what he thinks ?

Thanks @Chumleymouse
Think we might have to do that. I'll ask when they are coming next.

Just make sure your there when he comes and point it out to him with any concerns you have.

In my experience they are there to help and are usually fine .
Only people trying to cut corners and save money/work have anything to fear from building control 😀👍

Imagine if water ( damp) was rising up from underneath. In your right hand sketch the water could in theory creep between the inner block work and the slab DPC.

However there would have to be flooding for that to occur, in which case it would rise up the cavity and leak through in any case.

I wouldn't in my (professional) opinion suggest the builder is doing this to save time or money and would be surprised if the LA Surveyor would have a problem with this solution. Also, unless this is your builders first 'job' then he will have used this method in previous builds and already know the surveyor accepts it as satisfactory.

However, you are paying both of them and if the surveyor says s/he wants it addressing, then the builder will have to conform.

I think you are right, I cannot find any image that shows how they are suggesting it can be done.

It looks to me that there is a potential issue of damp creeping between the two if it is not continuous.

I would raise it now with the building inspector - it could be a costly mistake to rectify.

Perhaps they have done it incorrectly and are trying to fob you off?

Thanks for the replies. We have contacted the council team so are just waiting to hear back.
They are doing it this way, as they can't get the floor poured yet, but wanted to carry on with the brickwork. Builder is a lovely guy who has been in the industry for a long time and has done other work for us, so I don't want to believe he would bodge it, but it just seems to be different from the information we can find about it

Another image, it states DPM to lap under DPC.

this one from...
www.labcwarranty.co.uk/blog/8-handy-hints-for-installing-horizontal-damp-proof-course/

(I'll be interesting to know the outcome - the information on the internet is quite often out of date, and sometimes wrong!)