Damp Proof Course Too Low

[Georgie73]

Hi

We have just bought a new house which was originally built in 1939. There are two relatively new single storey extensions to the front of the house. On the inside of these extensions the skirting board is rotten and crumbles.

It appears the damp proof course has been put in at ground level - ie, level with the ground outside is the same level as the floor inside the house. I'm thinking the DPC should be placed about two bricks higher.

What do I do to resolve the issue?

Many thanks

 

[noseall]

Lower the ground outside.

 

[Georgie73]

Really? Is that all?

I can see over time, raised paving has been put in place - it all needs replacing so simply take it out and excavate down at least one brick level?

 

[tony1851]

Lower the ground outside.

I'm not sure that would be the whole solution.
If the extensions are 'relatively modern', they would be of cavity construction, and too-low a dpc on the outer skin would not usually cause dampness on the interior.
As well as the ground being too high, I suspect the bottom of the cavity is filled with rubble, allowing damp to rise past the inner dpc (if there is in fact an inner dpc?)

 

[noseall]

DPC is typically fitted at internal floor level.
External ground level should be 150mm lower than DPC.
Whether your high external ground level is causing rotten skirting internally is debatable. Is there any DPM under the floors?

 

[Georgie73]

OK. Good to know its at least at the right height internally.

The ground floors of the house are solid concrete. I'm assuming there must be some DPC within the concrete or there would be damp residue visible?

The skirting board crumbled to powder with a squeeze of the hand.

 

[noseall]

I'm not sure that would be the whole solution.

Me neither. Great minds eh.

 

[kazuya]

i was going to say just fit plastic skirting, then sit back and wait for the **** storm lol
but actually id lower the ground level like noseall says first and see if it does the trick before i tried anything else.

 

[Georgie73]

Yes, we will do that.

Many thanks

 

[^woody^]

If the cavity is clear, then it should not matter where the ground level is, and in any case damp should not be getting from the outside to the inside, or from below the floor to the skirting.

The actual problem may be more than just the ground level, but the ground level may be highlighting a problem.

Lower the ground or from aa 150mm trench along the wall. If this is not desirable, then you'll need to remove a few bricks to investigate the cavity and DPC/DPM arrangement.

 

[Georgie73]

Hi
We are at the new house for a few days. I can definitely see the flags/paving stones have been raised over the years. There isn't any actual damp coming in at all so we won't make it such a priority to lower the outside yet (loads to do before hand!)

Many thanks
George