DPC - going from a suspended floor to a slab of the same height

[Wockawocka]

Hi,

I'm building a kitchen extension. Our existing floor is a suspended one meaning the DPC is two rows of bricks below the door thresholds.

The extended part of the house is designed to have a concrete slab, the final floor level of which is to match the level of the floors in the house.

How would I approach lapping the DPC? I've looked in various places online but I can't seem to find the answer, maybe it's the wording I'm using but I'm a bit stuck.

If anyone has done similar and has photos or diagrams to explain that would really help me to visualise what should be going on so I don't stuff it up.

Thanks!

 

[blup]

If it starts below and finishes above the suspended floor dpc, do you have to lap it at all as opposed to setting back in the plaster.

Blup

 

[Wockawocka]

If it starts below and finishes above the suspended floor dpc, do you have to lap it at all as opposed to setting back in the plaster.

Blup

Thanks for the reply, do you mean using the DPM of the new slab to run up and meet the existing DPC?

 

[SpecialK]

When you prep the main slab you will have thick plastic sheet under the concrete. This just sits against the existing house wall. You only need to join the new walls DPC to it. Well this is how mine was done! Have you got a building control person you can ask?

What I would do is to extend the insulation over the internal door thresholds so you don't end up with a cold spot.

 

[Wockawocka]

Have you got a building control person you can ask?

I do but they're out so often on inspections they take a while to come back to me, a few days for each email I send drags the timeline out by a lot, especially if the reply I get isn't clear and I have to email them for any further clarification.

Thanks for the tip on insulating the door thresholds! When you say to join the DPM of the slab to the DPC of the exiting is that an overlapped join with physical contact or just up against it?

 

[SpecialK]

I do but they're out so often on inspections they take a while to come back to me, a few days for each email I send drags the timeline out by a lot, especially if the reply I get isn't clear and I have to email them for any further clarification.

Thanks for the tip on insulating the door thresholds! When you say to join the DPM of the slab to the DPC of the exiting is that an overlapped join with physical contact or just up against it?

For the existing walls just have the poly sheet leaning up against it then lop it off when you are at finished floor level. For the new walls the DPC must be joined to the poly sheet. I have seen people use 300mm wide DPC (100mm under the wall and 200mm flapping in to the building) and tape the sheet to it rather than try to get both under the internal wall which is a pig to do.

With the poly sheet on the existing side use some old batons to secure it to the wall otherwise it will go all floppy when you dont want it to and tape never sticks well to masonary.

 

[Wockawocka]

For the existing walls just have the poly sheet leaning up against it then lop it off when you are at finished floor level. For the new walls the DPC must be joined to the poly sheet. I have seen people use 300mm wide DPC (100mm under the wall and 200mm flapping in to the building) and tape the sheet to it rather than try to get both under the internal wall which is a pig to do.

With the poly sheet on the existing side use some old batons to secure it to the wall otherwise it will go all floppy when you dont want it to and tape never sticks well to masonary.

Thanks for giving me the answers I needed!