Damp on internal wall

[ihatehomeownership]

Just looking for advice. 1930s semi detached suspended timber flaws although I think there may be some concrete on top within the kitchen area. Terrible at DIY, but I at least want to diagnose it yourself so I can try and get appropriate solutions.

Found a tidal mark on an internal wall in front room, separating hall from front room. On opposite side of wall to a radiator which has had some flaking of paint underneath long term. This tidal mark as far as I know is new.

I looked under some floorboards which showed lots of rubble which was wet and then at the front of the house some standing water (pic attached). At the front of the house there is a downsloping drive with a small drain in the corner.

Got a damp surveyor in who suggested getting drain checked by water company due to its proximity to standing water. They said the joists appeared okay. Water company couldn't get camera in and when tried to jet it, more water entered house at front. Thought could be collapsed so came back to dig up, found drain discharging into ground with outflow partially obstructed by a brick but with no gravel etc. As not connected to mains not there problem but they kindly filled dug hole with gravel.

Spoke to a local builder who said a lot of these houses have damp subfloor voids.

This damp mark is diagonally opposite area.

I'm thinking of selling house soon so have the issue of wanting to get it sorted for next person but not wanting to pay too much if it can be helped.

My plan is to connect this drain to the main sewer (if allowed - I think my downpipe drains into main sewer), install an aco drain across the front of the house and dry out the wall (almost dry now I think but has a water mark) and hope that's the issue. I'm also not sure whether it's worth getting the under ground bricks repointed.

What I don't understand is why it is this wall in particular and is the pooling of water at the front a red herring/should I be looking for something else. A leak detection company came out and found no evidence of a leak from radiator or water supply. Not sure if it could be condensation related but seems unlikely to just be this wall rather than an external one. There are four air bricks at front and two at back. One also at side. The pool of water is now gone but the ground remains damp. I discovered this shortly after storm Ashley, not sure if relevant. House has had previous intervention for damp/rot by previous owners in this room although nothing to sort out poor drainage of drive (replacing some timber, installing another air brick).

Any advice appreciated.

Thanks.

 

[blup]

The tide mark is probably damp that rises from the pooling as the water hits the back wall, aided by the air bricks at the front. Getting a decent aco or similar drain at the front is surely the key to resolving the ongoing issue. Dig out the rubble and ensure the sub floor is adequately vented if this is a problem

 

[Ivor Windybottom]

More likely to be the radiator or other plumbing, it looks very wet - much wetter than the bricks under the floor.

It looks like there's a slate damp proof course, so it should be (mostly) stopped by that. Having flooding isn't good but not that rare. The symptoms will be rotting floors and high humidity in the house, not sopping wet walls.

 

[ihatehomeownership]

More likely to be the radiator or other plumbing, it looks very wet - much wetter than the bricks under the floor.

It looks like there's a slate damp proof course, so it should be (mostly) stopped by that. Having flooding isn't good but not that rare. The symptoms will be rotting floors and high humidity in the house, not sopping wet walls.

Thank you. Well there certainly has been rotten floor and we do get high humidity in the house.

Yeah I'm wondering if I should get a second opinion on the leak front. The wall pictured (front of house) is not the wall underneath the stained wall (side of room adjacent to hall, but that wall is presumably as dry or drier.

That wall is drying out now though which I guess would be a bit unusual for a leak, although the boiler pressure has dropped a bit and it could be pressure dependant.

 

[ihatehomeownership]

The tide mark is probably damp that rises from the pooling as the water hits the back wall, aided by the air bricks at the front. Getting a decent aco or similar drain at the front is surely the key to resolving the ongoing issue. Dig out the rubble and ensure the sub floor is adequately vented if this is a problem

Do you mean rising by condensation?

 

[blup]

Do you mean rising by condensation?

Rising by capillary action

 

[Ivor Windybottom]

It's not a very deep void. The guaranteed fix is to get rid the the lot and fill it with concrete and insulation, together with a damp proof membrane of course. You'd reduce your heating bills and make the place much more comfortable. It's DIY-able, with ready-mix concrete pumped in via a door or window.

But if you're selling you'd never get the investment back. But if the reason you're selling is the damp then it definitely can be fixed.

But I still don't think the sort of damp you're showing on that photo is rising damp from the ground, it's sopping wet so is more likely to be from something within or above it.

 

[Harry Bloomfield]

Any advice appreciated.

You first need to locate the source, cause of that water, and fix it. Standing water, under timber floors is never good. Even if you concrete under that floor, then the water could still collect on top of the concrete.

How high is the ground around the house, compared to that rubble floor below? Have you any eternal photos?

 

[ihatehomeownership]

That rubble floor is maybe a foot below the outside ground. I'm fairly sure the standing water coming in from the front is coming from the drive, a mixture of standing water on the drive where it meets the house and the drain which basically just empties into the ground with no french drain and was partly occluded by a brick. I'm hoping a combination of connecting this gulley to a drain and an aco drain backfilled with gravel will resolve that. Not sure if the subground brick needs repointing also.

I have attached a pic of the outside opposite the collection of water. The downpipe doesn't really drain much just a very small flat roof from a bay window.

I have noticed today lots of condensation around joist ends and floor close to wall presumably due to cold weather and high humidity from being generally wet down there. I'm wondering whether the stain on the opposite wall could anyway be condensation related against the pipes that feed the radiator. It's kind of flummoxing me as it's like 10 foot away from this pooled water.

Thank you.

 

[ihatehomeownership]

You first need to locate the source, cause of that water, and fix it. Standing water, under timber floors is never good. Even if you concrete under that floor, then the water could still collect on top of the concrete.

How high is the ground around the house, compared to that rubble floor below? Have you any eternal photos?

Sorry forgot to quote reply you.

 

[Harry Bloomfield]

I have attached a pic of the outside opposite the collection of water. The downpipe doesn't really drain much just a very small flat roof from a bay window.

That area looks very wet, and that looks as if the black painted area, might have been an attempt in the past, to resolve that very same issue. It might help a little, if that fall pipe actually discharged all the way into the drain, rather than just flowing over the top. You could easily extend it, for a few pounds.

 

[ihatehomeownership]

That area looks very wet, and that looks as if the black painted area, might have been an attempt in the past, to resolve that very same issue. It might help a little, if that fall pipe actually discharged all the way into the drain, rather than just flowing over the top. You could easily extend it, for a few pounds.

Yeah I'll get that discharging into the drain once the drain goes somewhere and also move the virgin box so it isn't occluding the vent. Every little helps, although whether it will help that wet wall I'm sceptical.

 

[Harry Bloomfield]

Yeah I'll get that discharging into the drain once the drain goes somewhere and also move the virgin box so it isn't occluding the vent. Every little helps, although whether it will help that wet wall I'm sceptical.

It might also be worth digging a sump, and adding a sump pump, if only as a temporary measure.

 

[Ivor Windybottom]

You wouldn't get condensation on radiator pipes if the heating's on. You get it on cold pipes in damp rooms - usually the cold feed and toilet header tank get a good coating that can often look like a leak.

If the air in your house is exceptionally damp AND the heating's off and stone cold then it's possible it's condensation. But I still find that theory unlikely given that it's wet enough to make the paint darker.

Does your heating system require manual top ups via a filling loop? If so then do you find it loses pressure and needs topping up regularly?

Do you have a water meter? If so then take a reading down to the very last digit and arrow position, ideally take a photo, before you're next about to go out for a day trip. Check when you return, if it's moved then there's a leak.

Measure the humidity with a decent meter. If it's above 60% at a reasonable living temperature then it's too wet. Above 70% is definitely a problem.

I still think it's way too severe to be rising damp, but you're guessing unless you get the floor up at the bottom of that wall and have a proper look.

 

[Harry Bloomfield]

Measure the humidity with a decent meter. If it's above 60% at a reasonable living temperature then it's too wet. Above 70% is definitely a problem.

I would qualify that a little - My indoor humidity at the moment is RH 63%. Checking back through my records, it twice exceeded 73%, yet there are no leaks, no damp at all here. What really matters is the average humidity, over say a week or so, rather than an instantaneous reading, then panic if it's over 70%.