Damp in neighbouring property

Busybee0314

Our garden is laid to patio (it's a small terrace house/garden) and was done we believe about 15 years ago by a previous owner. The patio backs on to a neighbouring property and the owner has contacted us to say they have had a damp survey done and believe our patio is causing damp in their property. There are drains at the end of the patio by their wall and a very narrow soil/gravel strip. I'm surprised if, after 15 years, we are being told the patio is causing damp. We've never been told that before and are a bit nervous they are going to insist we tear our patio up! Has anyone any advice on this? Thanks

Apodemus

Sounds entirely feasible. Is the patio level above their floor surface level? Is it blocking any air vents? If the drains are at their end, then it suggests that the patio slopes toward their house. Are the drains blocked at all? Is the patio encouraging rain bounce up their wall? Is the patio preventing ground-water evaporation, leaving the surface water-logged? Lots of reasons why having a solid surface right up to a wall can be a bad idea.

Doesn't mean that it is causing damp, though, and given the abilities of most damp companies, they could easily be jumping to convenient conclusions.

moneyistooshorttomention

Perhaps suggest to the neighbours that you jointly employ a damp specialist and pay them 50/50 to work out what's what - ie the cause.

Whichever house turns out to be the "guilty party" then to reimburse the other house the 50% of that bill they paid.

So - if your house is the cause of the problem then you'd end up paying 100% of the bill.

If the cause of the damp is within their house - then they end up paying 100% of the bill.

Doozergirl

After 15 years, there's a chance the that there's a problem with the drain, but really, you shouldn't build anything directly up against and outside wall.

Taking your patio back by a few inches so that it doesn't touch the wall would be the considerate thing to do. Anything against the wall should be 150mm below the DPC. Airbricks should be plentiful, clear and no water allowed to run into them.

I'm sure your neighbours aren't making up the problem that's appeared.

Once the source of dampness is found and rectified, they really don't need to go through the usual 'damp specialist' thing of ripping off all their plaster, injecting a DPC and having the walls rendered etc.

If the patio causes a breach of the DPC, the DPC has not failed. A new one is not needed, it just needs to not be breached any more!
Time (plenty of it) should allow it to dry out. If the plaster is genuinely ruined when it is dry, then replaster.

teneighty

It is also worth considering where is the "natural" ground level.

It is not uncommon for older properties built into a slope to have a wall that is cut into the slope so the internal floor level is slightly lower than the external ground level.

In that situation it is the homeowner's responsibility to damp proof their own wall, probably by internal tanking. Not for the neighbour to reduce the level of their garden.

Obviously if the neighbour has raised their garden, possibly to create a level terrace/patio and built the ground level up against the neighbours wall then they should remove the offending raised ground. As Doozer suggested this can be a narrow strip along the wall rather than the entire patio.

Apodemus

moneyistooshorttomention wrote: »

Perhaps suggest to the neighbours that you jointly employ a damp specialist and pay them 50/50 to work out what's what - ie the cause.

Whichever house turns out to be the "guilty party" then to reimburse the other house the 50% of that bill they paid.

So - if your house is the cause of the problem then you'd end up paying 100% of the bill.

If the cause of the damp is within their house - then they end up paying 100% of the bill.

You might be supportive and help with any changes to your patio to help reduce any problems. But you definitely don't want to get into any suggestion of liability or any funding relationship over survey work or remedial work to the neighbour's property. Damp remediation companies can smell an open chequebook a mile off and before you know it you will be paying for all sorts of injected courses, plaster replacement, tanking, floors (and sub-floors!) and redecoration!