Dampness in cavity wall help

ow9654

The house is built 15 years to specifications at the time, there is sheets of insulation 60mm thick and 40mm empty space in the cavity wall.
There are no leaks but there is a slight dampness above the damp coarse on the outer wall in the cavity
Could this be caused by condensation or any other reason?

Thank you.

BE_MIEI

Is the external ground level at least 150mm below the DPC level? Is there any dampness evident internally by the way?

ow9654

Yes the external ground level is 150mm below the DPC level.
There is absolutely no internal dampness.
Why I investigated the dampness was because there is some efflorescence salts on the outside wall which is pushing some paint off.
Thanks

BE_MIEI

If there is no dampness evident internally, I would say that that the wall is doing its job in keeping the moisture out. It sounds like there could be some latent defect causing the wall to take in water. Is the problem throughout the house or located specifically in certain areas, for example under windows?

ow9654

The dampness may have started 2ft under windowsill but now has spread to between windows and down to the top of the damp coarse at the back of the house only.
But the groove under the windowsill is clear.

BE_MIEI

The DPC could be missing from beneath the window sill allowing water to penetrate into the wall. You should be able to check this yourself. The DPC should be just about visible protruding slightly from the wall at the underside of the window sill.

ow9654

Thank you for your help,
But I still don`t understand how it would be damp in the cavity above the damp coarse, could this possibly be condensation?
Thank you.

bbam

I'd say poor detailing at the window sills is allowing rain water into the cavity rather than shielding it out. There may be no DPC, poorly fitted one or it may even have been punctured laying the sill in place.
The water is exiting the cavity at the DPC level.