Damp help advice please

[Flynnwood]

A friend has discovered damp under some old boxes in his garage (1st pic). It appears to be coming in from the outside wall where the rendered wall joins his neighbours drive. (2nd and 3rd pics).

The DPC runs the whole length of the wall behind the rendered part and seems fine.

How best to seal the gap please?

Some sort of silicone? ... or dig out and re-concrete that 3 inch wide section of the neighbours drive? or ... ?

Thanks!

How to seal this gap?

 

[lincs1963]

Gap should not be sealed, render needs chopping off to above the DPC. Damp will track past the render and up above the DPC. Common problem found inside many houses where the plasterer has plastered all the way to the floor.
Also the reason why any external paths or patios should be kept two courses below damp.
Apologies if I have mis-interpreted the pictures.

 

[blackrodd]

Gap should not be sealed, render needs chopping off to above the DPC. Damp will track past the render and up above the DPC. Common problem found inside many houses where the plasterer has plastered all the way to the floor.
Also the reason why any external paths or patios should be kept two courses below damp.
Apologies if I have mis-interpreted the pictures.

The plastering is not the problem, as you can see the dpc is working, 'cos it's dry above.
Just goes to show what's happening inside you're wall cavity at ground level, without the under slab polythene, etc.
The damp ingress is from the wet ground below.
If this wall was built on the edge of a "slab" then capillary action will pull damp/wet through.
The builder should "scratch" down 50mm or set a length of timber to form a rebate, which will stop this happening.
The path has failed likely through not compacting the base, or the stone forming the base.
Path should be laid to take surface water away from a building when at all possible, helps stop frost damage.
Regards Rodders

 

[Flynnwood]

Gap should not be sealed, render needs chopping off to above the DPC. Damp will track past the render and up above the DPC. Common problem found inside many houses where the plasterer has plastered all the way to the floor.
Also the reason why any external paths or patios should be kept two courses below damp.
Apologies if I have mis-interpreted the pictures.

The plastering is not the problem, as you can see the dpc is working, 'cos it's dry above.
Just goes to show what's happening inside you're wall cavity at ground level, without the under slab polythene, etc.
The damp ingress is from the wet ground below.
If this wall was built on the edge of a "slab" then capillary action will pull damp/wet through.
The builder should "scratch" down 50mm or set a length of timber to form a rebate, which will stop this happening.
The path has failed likely through not compacting the base, or the stone forming the base.
Path should be laid to take surface water away from a building when at all possible, helps stop frost damage.
Regards Rodders

Rodders - thanks for your response. Can you clarify this bit for me please:

"The builder should "scratch" down 50mm or set a length of timber to form a rebate, which will stop this happening."

 

[blackrodd]

Common practice for a garage base was to dig down for the footing/foundation, shutter the outside and form the outside of the base or slab, in 1 pour of concrete.
Then build the walls above the deeper foundation, on the floor or base.
With or without dpc under the first brick or block, this draws moisture and damp in to the building at floor level.
If the builder had laid a 4"x 2" on it's flat where the wall is to be built, the top being the floor level, this would help stop capillery action drawing damp/moisture in, as it would form a rebate.
More recent regulations stipulate footings should be 500mm below ground for frost damage prevention.
This means that the wall will be built to a dpc level, allowing any finished paths to be a minimum of 150 below dpc and you prepare the inside floor level this time using the correct grade of polythene, up to or over the dpc level.
Done properly there is no damp. As the house is built today.
Looks to me as if the path outside in pic is higher than garage floor?
If you ever see the literature for a pre-cast, sectional garage, somewhere you will see mention of extra cost of a cement fillet to the inside at floor level.
This is probably you're best solution, a cement fillet and then paint possibly with Wicks roof repair that works in damp application situations. Regards Rodders