Visible damp patch halfway up stone wall

[drpepe]

View media item 81707
Any idea what might be causing this damp patch to the left of the door halfway up? These photos were taken during rain but the patch remains discoloured even in very dry weather. You can also see from the photos it seems to be seeping into the mortar next to the door 'post'

(the picture doesn't really do it justice, but the discolouration is very obvious)

This area is complicated:

• 
  Drip from gutter? (but damp patch still visible during very dry spell in July)
  Block paving was installed above original DPC (but have removed a line of bricks and replaced with gravel)
  There has previously been a chemical DPC
  Next door at a higher level (but damp patch not 'connected' to boundary wall or floor)
  Gully drain for soil pipe and gutter downpipe located below the damp patch
  Bridging from boundary wall? (there is a slate layer where wall meets house)
  Interior of hall has damp soil and damp smell (we're getting a airbrick put in under the step).

A pic showing the guttering above the door
View media item 81708

 

[ree]

The boundary wall is possibly bridginging bridging any DPC(?), in spite of the slate barrier..
What kind of DPC do you have?

Perhaps you will post pics of the external ground level where all pipes enter, or gullies are located - including your neighbour's.

Detailed Pics of the interior wall will also help.

Is the floor suspended? Can you crawl under it?

Why is the neighbour's RWP discharging on your side of the garden wall - where does your gutter discharge to?

Stand in the rain and observe how water runs down the front elevation to your and your neighbour's house. Observe any splash or puddling on the stone "porch" cover, and any drips from pipes or gutters.

What is happening with the hose bib and its copper(?) supply pipe?

 

[drpepe]

The boundary wall is possibly bridginging bridging any DPC(?), in spite of the slate barrier..

That would be my guess as to one of the causes of the general dampness inside the house in that area - exacerbated by the fact we are downhill from the neighbour (about 30cm difference. Don't you think the pattern on the wall is puzzling though? i.e. it isn't 'connected' to the boundary wall and is higher

What kind of DPC do you have?

black (bitumen?) layer below the airbricks

Perhaps you will post pics of the external ground level where all pipes enter, or gullies are located - including your neighbour's.

i am away from home so sorry not a good photo of the drain area.
The 2 terracotta flower pots are covering drains into the gully drain underneath.

The gully has the rainwater downpipe, the 2 pot-covered drains (unused) and also the soil waste pipe heading into it from within the house.

I haven't a clue what the white plastic pipe is that emerges under the doorstep - it is open-ended about 10cm within the house and outside it turns towards the gully...

View media item 81789

Detailed Pics of the interior wall will also help.

View media item 77389Again not a good pic but the best i currently have - the outside wall (left of pic) has the gas/elec meter box on it (the foot of the open meter box is just visible). The top of the picture is a radiator on the party wall. The black soil pipe is visible under the floor. As you can see the wall plate is very damp - in this pic it had recently been excavated from under damp mud.

The interior face of the exterior wall doesn't really have any signs of damp, and the unfinished stone wall inside the meter box doesnt seem damp either.

Is the floor suspended? Can you crawl under it?

Yes it is suspended, but as you can see (and from the other pics in my diynot album library) there is very little space under the floor - the hall has the least space of the rooms on the ground floor, and is also the most damp. Other rooms have about 15-30cm, hall has 15cm in some places while other areas damp soil was touching the joists - until we dug most of it out this Spring.

Why is the neighbour's RWP discharging on your side of the garden wall - where does your gutter discharge to?

We share the rainwater downpipe (see top picture in my original post), which discharges into the drain on my side.

Stand in the rain and observe how water runs down the front elevation to your and your neighbour's house. Observe any splash or puddling on the stone "porch" cover, and any drips from pipes or gutters.

Very little rain runs down the house - the plinth/porch above the door protrudes further and gets soaked.

What is happening with the hose bib and its copper(?) supply pipe?

It is disconnected - an isolator under the doormat area.

 

[ree]

Being on a hillside will increase any tendency towards water gathering in or "flowing" thro your sub-area. But this ground water will have no bearing on the mysterious wall patch.

I suspect that the patch could be caused by mainly the porch projection, and partly by the bridging wall.
By flashing the porch to divert water away from the house, and providing a high cover flashing (to guard against splash) you might eliminate much of the penetrating moisture.
Where necessary, raking out to 18mm and re-pointing in sand and lime will also help.

Is your gutter discharging into the hopper - i cant see a gutter outlet?

The white plastic pipe was possibly an outlet for draining excessive sub-area water.
By observation or report, has water ever risen to pond under the house? Dig out to where the pipe ends, if it enters the gulley check if vermin could access into it?

A shallow French drain, below the DPC along the front of the house, & filled with gravel might keep moisture back - only if you think it necessary.

Empty,clean,dry, & inspect the gulley for cracks. Seal any traps with water. Re-fit the gulley grill. The gulley drain should join your soil pipe drain in a manhole.

In time, the wall plate(s) in the sub-area will rot away, and rot the ends of the joists - at some stage, remedial timber repairs will be necessary. Good sub-floor ventilation is the best practice for the time being.

Edit: i've just seen your new pics and the in-situ french drain. Thing is, the surface level is still too high, and the vents are way too small - you should have 10" x 6" plastic vents to give far more effective ventilation. All the vent openings must be exposed.
Perhaps replace all the house vents with the above?

 

[drpepe]

I suspect that the patch could be caused by mainly the porch projection, and partly by the bridging wall.
By flashing the porch to divert water away from the house, and providing a high cover flashing (to guard against splash) you might eliminate much of the penetrating moisture.
Where necessary, raking out to 18mm and re-pointing in sand and lime will also help.

Is your gutter discharging into the hopper - i cant see a gutter outlet?

Both gutter discharge in to the hopper -with one shared downpipe into the gully. The picture below should make the gully area a bit more obvious.

The white plastic pipe was possibly an outlet for draining excessive sub-area water.
By observation or report, has water ever risen to pond under the house? Dig out to where the pipe ends, if it enters the gulley check if vermin could access into it?

Bloody hell i hope water hasn't risen that high as the white pipe enters the house only a few cm below the floorboards, but you may be right. The only 'flood' i know about is from a leaking shower upstairs - it did actually leak into the front hallway area and must have been quite considerable as the stairway party wall in the hall was re-plastered (this info is from the previous so may be suspect - i will question my neighbours more closely sometime soon).

Empty,clean,dry, & inspect the gulley for cracks. Seal any traps with water. Re-fit the gulley grill. The gulley drain should join your soil pipe drain in a manhole.

I'm not sure how to do this - when i removed the chippings and soil covering the gully (See pic) it revealed the brown ceramic that you can see, below that looks like a flat/curved piece of concrete that i assume *is* the drain - there is no removal inspection hatch or similar.

In time, the wall plate(s) in the sub-area will rot away, and rot the ends of the joists - at some stage, remedial timber repairs will be necessary. Good sub-floor ventilation is the best practice for the time being.

Yes the first part of the plan is underway to ventilate the area (scooping out soil and fitting a doorstep airbrick). I don't lknow how much room there is to fit such large airbricks - floorboards are very close to ground level and exisintg small airbricks are quite close to the footings.

Edit: i've just seen your new pics and the in-situ french drain. Thing is, the surface level is still too high, and the vents are way too small - you should have 10" x 6" plastic vents to give far more effective ventilation. All the vent openings must be exposed.
Perhaps replace all the house vents with the above?

The 'french drain' is simply me removing the first row of paving blocks, diggin about 20cm and replacing with weed membrane and chippings. TBH although an improvement, i don't think this is sufficient and still holds moisure against the wall - perhaps a proper 30cm wide & deep trench should be built to permanently remove any material from the DPM area.