Attached garage / DPM detail

[23vc]

I’m about to start my attached garage having spent the last 2.5 years building the house extension, any chance of people’s thoughts on how I’m proposing to do the oversite/DPM detail? I’ve knocked up the following work of art, happy for it to be ripped apart if incorrect tho! All advice appreciated as ever.
PS it’s not actually big enough to ever have a car in it, despite the pic.

 

[Bonni]

Building regs wouldn't be bothered with a DPM in the garage although I still fit them. If the concrete floor is longer than 8m, I would sit steel mesh in the floor with ST4 concrete mix to help avoid cracking. Rather than a solid wall, I build with a 50mm cavity.

I would have the DPC on the outer leaf 6" above finished ground level, so step up/down where necessary. DPC on inner leaf 6" above floor.

 

[23vc]

Thanks. Sounds like I am on the right lines, I’ll do as you say re. dpc levels but for my setup with the dpm lapping across the inner skin blockwork I didn’t think I needed an inner skin DPC.

 

[^woody^]

There are several issues with that drawing

On the house side you are showing that the new DPM is not connected with the house DPC. There is a route to dampness there.

With the floor slab, it's likely that the slab could settle and so that detail may not accommodate that and there is potential for the DPM to split at the wall junction.

You have no provision to stop moisture coming down and across the wall from above that DPC above the ground.

 

[23vc]

Ta.
Yep agree with both of those issues, can’t do a lot about the house DPC as the house is already built. Also, you’d end up with an exposed DPM surely if you tried to link it with house DPC?
If you’ve got any better ideas for the garage DPM setup then it’d be muchos appreciated, guess I could blackjack the outside face or summat...