Possibly damp outside wall

[Eliseboy]

Hi-not sure if I am seeing a problem that isn’t there but what do you think to the photo below?

We had the drive extended and in the process it has raised up in height - it used to be grass.

There are a couple of air vents low down and I think there is a semi-circular area at the bottom that looks darker than the rest of the brickwork. It doesn’t feel damp to the touch.

Could rainwater be pooling and not draining away and possibly entering the vents?

Any advice on how to see if there is an issue would be really helpful.

 

[KenGMac]

Eliseboy, good evening.

Can I suggest that in the next bout of heave rain you pop outside and check that the rain water gutter directly above this damp stained area is not leaking?

The shape is highly suggestive of a leak in a rain water gutter?? and the resultant splash effect on the wall.

Ken.

 

[Eliseboy]

Thanks Ken - good shout - will have a look then. In theory it ought not be a problem as that wall is a gable end and hence no guttering above but maybe something is going on. As you say, it’s an odd pattern.

 

[wedge69]

Is the TV aerial on that wall?

 

[^woody^]

Is the TV aerial on that wall?

There would be a load of bird's muck on the path if there was.

 

[wedge69]

There would be a load of bird's muck on the path if there was.

Very good, Sherlock

 

[Harry Bloomfield]

We had the drive extended and in the process it has raised up in height - it used to be grass.

There are a couple of air vents low down and I think there is a semi-circular area at the bottom that looks darker than the rest of the brickwork. It doesn’t feel damp to the touch.

The darker brickwork seems to be centred on those two vents, the blockwork looks as if it may drain towards the house, my guess would be heavy rain entering via those two vents, when rain water cannot get away fast enough.

 

[tell80]

Can you point out on your pic where your DPC bed is? Perhaps its buried?
Is the floor beyond that wall a suspended floor or a solid floor?


There are cavity tray weeps above both air bricks - are there any signs of damp or water damage at low level on the inside of that wall?


Does water ever stream in through the air bricks?

 

[Mr Chibs]

Outside ground level, ideally wants to be two courses (or more) from DPC... yours looks like it's only one now you've had new paving.

 

[Eliseboy]

It’s a suspended concrete floor and even when it’s been chucking it down recently I can’t see rainwater flowing in. I can also see through the vents and at least they are clear. I’ll have to have a look where the DPC is and will post up here.
Does look like I need to dig out the stones between the blocks and the wall and get some decent drainage going on.

The block paving is definitely higher than the grass that used to be there - never been that happy with the block paving it has to be said.

 

[tell80]

How do you know its a "suspended concrete floor" - if so it suggests a block and beam floor?

A little water entering the vents is no big deal unless the cavity is blocked with debris, and bridging the inner skin DPC.

Any signs of water damage inside the house?

 

[Eliseboy]

Hi- you are right, block and beam might be a better description - I guess it is suspended as when we had a water pipe moved in the kitchen they cut a channel in the floor and there was a void underneath so wasn’t solid.


The dpc is directly above the vents so there is one course of bricks on show underneath the dpc and unfortunately you can’t see the other side of the wall as there are kitchen cupboard all on that wall with solid backs.

We have had a leak there once before but it was a pain to get to as the plinth has a silicone bead on it securing it to the floor and I ended up taking out a cupboard and the fridge freezer.

I will see if I can get my borescope behind the cupboards some how.

Would it make any sense to take a vent or brick out to have a decent look in the cavity ?

 

[^woody^]

Does water ever stream in through the air bricks?

Lol. How is the OP going to get under the floor to check. Even if it did, it's not a problem.

BTW, the first photo shows air bricks, indicating ventilation to a floor void, and a suspended floor.

 

[tell80]

A Boroscope will typically go thro a drilled hole in the spot where the mortar bed meets the perp.
Whatever, removing a brick to have a shufti will work fine - and if the cavity is blocked and bridging then removing a few bricks for access is common practice.

 

[^woody^]

Cavity beach or drips from above splashing up the wall.

Or, you may have a cavity tray above the air brick, not just a DPC, and this could be sagging in the cavity and holding water.

Take out a brick or two centrally to the damp stain, on the course just above the air brick.

But check for drips first if this has just begun to occur after the paving was raised.