Basement damp proofing advice please!

[pavsid]

Hi, we're in the process of purchasing a property where the ground level is at 1st floor at the front, and basement level at the back (so 2 levels).

We want to convert the basement to a liveable area, but two of the rooms, on the left side of the house, have damp issues to the exterior walls.

There is no access to the walls from the outside, as they are below ground (one completely, the other partially as it's at the back of the house).

A builder friend has advised first laying concrete down on the ground level around the property as currently it is slabbed and letting rain water through into the ground, and then sealing the interior walls in the basement with membrane.

My questions are:

1) Will this damp be affecting the structural stability of the house?
2) Is this the most effective way of damp proofing the basement? If not, what is?
3) Will that method maintain the structural stability of the house? I ask because surely the walls are still getting wet if the membrane goes in the inside?
4) What is this likely to cost? The walls are 11' and 14' wide, along the left side of the property.

Any help and advice would be massively appreciated.

Thank you in advance.

 

[freddiemercurystwin]

Proper tanking on the inside will thus not require any additional measures externally.

'Newlath' dimpled membrane systems and the like come to mind as the most effective in such situations.

 

[freddiemercurystwin]

//www.diynot.com/forums/viewtopic.php?t=275658

 

[pavsid]

Proper tanking on the inside will thus not require any additional measures externally.

'Newlath' dimpled membrane systems and the like come to mind as the most effective in such situations.

Thanks freddy So are you saying the "free to drain" method is best in this case? Described in the link you posted?

 

[freddiemercurystwin]

In this situation yes I would say so.

Alternatives are rendered systems but these will not withstand much in the way of water pressure and require absolutely meticulous preparation and execution.

Or otherwise there are the bituminous membrane systems but these need a masonry wall to hold them in position against the existing and again these are open to poor workmanship and failure.

However the dimpled systems are easy to install and the failure rate is low because of how they work ie a drained system rather than using a membrane as a barrier.

 

[pavsid]

That's brilliant, thank you.

Should I use the non-meshed membrane if I plan to put a stud wall over it? Or must it be "Newlath"?

 

[freddiemercurystwin]

Yes a dimpled system like Newlath, there are alternative manufacturers.

Don't know what you mean by a non mesh membrane?

 

[pavsid]

Yes a dimpled system like Newlath, there are alternative manufacturers.

Don't know what you mean by a non mesh membrane?

Ah, i just noticed that there are both meshed membranes and those without mesh - the meshed seem to be for those wanting to plaster directly on top of the membrane, and the non-meshed for those wanting to use insulation in a stud wall.