Damp proof membranes on concrete floor - urgent help please

[Rslee]

Hi there
Can you please help - our builder seems to have little knowledge of buildings regulations so we are struggling with our extension/conversion.

We are converting part of an internal garage plus existing room into a new kitchen. Problem is there are 2 different floor heights for the new kitchen namely:

1. Most of the floor is block and beam - depth of 120mm below finished floor level
2. A small section of floor is the old internal garage floor so has a concrete slab on top of the block and beam - the top of the concrete slab has a depth of 50mm below finished floor level.

I need to lay damp proof membrane on top of the two different floor constructions. Do I lay membrane across the two different floor heights?

Also in the hallway there is a small part of the floor near the stairs where there is old screed which has been left in place because the stairs are resting on the screed. Below the screed there is some polystyrene foam insulation. How would Dpm cover this area? The hallway area around the small screed area is block and beam with depth of 120mm as in 1. above.

We we are planning on using wet underfloor heating (pipes in screed) then tiles where we have the 120mm floor depth.

Many thanks for for your help!

 

[ShaunCorbs]

" builder seems to have little knowledge of buildings regulations" this is a big big red flag maybe get building control involved or find a new builder

 

[Rslee]

We are a bit stuck at the moment as they are right in the middle of it and our buildings inspector is not much help and is on our builders side who is always trying to take the short cuts. I'm a mum of two small children with house in pile of rubble at moment so we are trying to do best we can by using forums like this.

 

[Chalked]

Block amd beam are normally sat on, or above dpc.

 

[snowhead]

If the builder doesn't have the knowledge he should be getting help from someone who is.
If he can't sort out Damp membrane he shouldn't be working as a Builder.

Is the Building control person an Approved Building Control Inspector being employed by the Builder?

What about insulation under the area that's having U-floor heating?

 

[Worcester]

Contract your own local council building control department yourself and get a DIFFERENT Inspector out to look. - see also responses to your post about Underfloor heating.

You may need to remove the existing screed that is on part of the garage floor, and you'll have to accpet a level change between the old and new, or else find a high performance insulation material - there are products that only 25mm thick are equivalent to 100mm double foiled celotex.

Also in the hallway there is a small part of the floor near the stairs where there is old screed which has been left in place because the stairs are resting on the screed. Below the screed there is some polystyrene foam insulation. How would Dpm cover this area?

There should already be a dpc below the insulation, any good builder will know how to ensure continuity. If he doesn't he isn't any good.

A lot of minor works / alterations builders are full of b***s**t and don't know the regs or ignore them if they thionk they can get away with it. - Don't let him do any more work until you've acted on my opening sentence.