DPM

Question 1

When your building utilises underfloor heating where should your DPM be placed in relation to the concrete slab?

Answer 1

Under it

Question 2

What is one advantage of having the DPM under the concrete slab?

Answer 2

It will be protected from damage during subsequent building operations.

Question 3

What is one disadvantage of having the DPM under the concrete floor slab?

Answer 3

It will delay the drying out of the concrete as the concrete will only be able to lose moisture in the upwards direction

Question 4

What must the materials in a DPM be impervious to? (resistant to)

Answer 4

Water in both liquid and vapour form

Question 5

When using a DPM under the concrete slab it should be laid on what to prevent puncturing from the hardcore?

Answer 5

A bed of sand

Question 6

Where the level of the DPM is below that of the DPC in walls it is necessary to do what?

Answer 6

To turn the DPM up against the side of the walls so that it can overlap the DPC (forming a continuous barrier against moisture)

Question 7

What is a DPM impermeable to?

Answer 7

Water in both liquid and vapour form

Question 8

Can a DPM be laid directly on top of hardcore?

Answer 8

Yes. But only if it has been thoroughly compacted first.

Question 9

DPC’s should be placed at least how high in cavity walls?

Answer 9

150mm