Rising damp on ground floor?

Looks like the DPC is below the top course in the picture. Where is the floor level in relation to that - above or below ?

 

Hmm, summat weird here.

That's a chipboard floor - as you say, probably around 3/4" thick. For it to have such a localised damp patch, which looks as tho' it was created by an actual 'puddle' rather than a damp patch which slowly made its way through the chipboard, is unusual. It looks as tho' a quantity of actual 'water' came through at some point, as opposed to a slow ingress of damp.

What caused that? Well you're right - it ain't condensation. You say it also ain't a hidden pipe, or a faulty gutter. So that kinda does point to the setts lain against the wall - I wonder if somehow it allowed rain to 'pool' on its top rather than simply flow down the wall and away?

But, it's still strange - how did that water get across the cavity? It shouldn't have done so.

The outer DPC is above the floor level? Blimey. I'm guessing that the DPC on the inner skin must surely be well below the floor, so at a different height to the outer skin? Is that normal? (I dunno...)

So, best guess is that the setts allowed water to pool and get through that outer skin, perhaps even along the top of the outer skin DPC, and this water then crossed the cavity - perhaps using the newly-added insulation - to hit the inner skin at the same height, and that's above the floor level from what you say.

But, that is some water penetration...

With luck it won't happen again - at least not if it's the setts wot caused it.

 

I agree with devils advocate, you can see the outer brick is wet so the water has entered there, what came through should have condensated up the cavity. If you had granite there the water could have been just running into the wall.

The best solution is to see if the outer bricks dry now the granite has gone. If not I think is to check the drainage of the ground there, if the water is running to the house and not away?


are those stones on a damp proof barrier? if so the water isnt draining down into the ground. try digging up the ground and putting in some stones lower down so the water can drain down so the top layer isnt just soaked.

 

Yep DA, thats what I was thinking.

As the OP said, they had cavity wall insulation fitted a few years ago, so no cavity and any moisture may have tracked across a wall tie into the inner skin.

However, as you say the stain is unusual so I am guessing the cavity wall has caused a longer term problem and it may be just coincidence to that their was stuff piled up against the outer wall. I would cut out the marked section of the floor and see what is underneath

 

Dont dig out the floor yet. You should have an airbrick in the wall under the damp course since you dont have a concrete floor. Check the mud and shingle isnt blocking that,

 

With cavity wall insulation the air bricks are probably compromised with insulation

The floor is chipboard - easy to cut out inspect and replace if required and will help remove any moisture

 

No one's mentioned yet that the chipboard floor is of the water resistant type (green).

With cavity wall insulation the air bricks are probably compromised with insulation.
Unlikely due to the fact that airbricks are removed and a bottle brush type barrier is installed between the cavity around the air brick hole to prevent blocking the airflow prior to installing the cavity insulation.

 

Cut out a section with a circular saw I would say, BUT before that I would leave the trench open you have dug, & don't fill it in for a week or two, may help things to dry out

Out of intrest does the conduit run down the wall to that socket, or come up from below floor.

 

If as you say the air bricks have been changed you can be sure that a bottle brush type barrier has been installed.

 

Hi Nige.

I cannot answer any of your specific Qs above as I chust don't know.

Before cutting into your floor - which I presume you'd wish to avoid? - I think what I would do is to have a darn good pokie through yer air vents with a torch and a long thin thingy - see if there's a clear path right through to your underfloor area.

How high are these vents about outside ground level?

If it looks as tho' it's drying up, then I guess that could be a cause for relaxing - provided your air vents are clear. If they aren't, you will almost certainly have future problems, and they'll be worse than a damp patch - I'm talkin' rot...

If the vents aren't clear - ie blocked by insulation - then I'd have thought you could oblige the insulation peeps to sort it. You basically tell them to sort it or "you're putting them on written notice" than any future issues will be their responsibility.

What kind of insulation is it - a foam or poly beads or what?

 

Ouch - bad news, Nige. (Although, tbh, I would have been worried if chust placing a few slabs against a wall would be enough to cause water to pour through it...)

I think I'd go general builder route, but ideally one familiar with this age of property - what is it, 80's? Also, do you know if it was built by a local builder, or is it one of a number of similar properties built by a 'national'?

If you feel like it - and I suspect it's what a builder might do pretty much first off anyways - you could cut a section out of that chipboard sheet and have a gander.

Can you see where the fixing screws are? If so, that's where the joists lie, so you'd ideally want to cut along in the middle of that, and only to the depth of the floor itself.

The chipboard goes under the wall a wee bit by the looks of it? I think what I would do is to draw two straight lines, around one foot either side of that tape measure in pic one, and going from the 'horizontal' join line that's it front of that tape measure, to right up to the back wall where the water is coming through.

I would taper these lines slightly - perhaps an inch closer together where they hit the back wall, so's lifting the panel out should be easier.

You could use a jigsaw for this, but have it sitting on a wooden block you slide with it, so that the blade tip doesn't penetrate too far. Also carry out the usual checks for wiring, pipes etc using a detector.

Finally cut along that front joint line in between your two other cut lines - again you can carefully use a jigsaw, but held tipped forwards with the front of the guide plate held firmly against the floor, with the blade acting like an angled plunge saw only to the depth of the board. If you have 'orbital', turn this off...

In theory, you should be able to lift that cut panel up at the joint, and pull it forwards to disengage it from the back wall. (1.25"-ish screws driven in around an inch back from the front cut edge, then a claw hammer used to prise up the board.)

To reinstate, chust cut battens (3x2 or whatever) to sit half way under each cut lip in the floor, and glue and screw it through from the floor top. The removed panel should then drop neatly back into place and can also be screwed down.


What's the cause of this water (and I'm pretty sure it is 'water' and not 'damp')? I now wonder if rain is getting in further up, perhaps at the roof somewhere, and making it's way into the cavity up there, pouring down either on the inner or outer cavity skins before hitting the internal DPC and coming through?

The more I look at the damp pattern on the outside wall, the less it looks like normal 'rising damp' from the outside ground - if you look, there are very damp patches coming through the mortar lines in a few places. Yes, the bricks are very wet along ground level, but why these isolated patches further up? I mean, is the ground outside really that wet, to make the bottom row of bricks 'soaking'? It could chust as likely be water coming out from the internal cavity.

But that's all guesswork, of course.

Question: see the very damp row of bricks immediately above the ground level - is it the same all along that wall, or particularity obvious in this area? Also, see the damp patches on bricks and mortar lines above this, are these also present along the rest of that wall at chust below DPC level?

 

Agree DA, time to get the floor up & have a nosey.

 

It's a weird one - would you chust love to go there and have a look?!

I wonder where the OP lives - perhaps we could have a pint afterwards...

 

Ok, so the bottom row of bricks are likely to be chust 'rising', which is normal.

Good luck this weekend. I think I'd also write an email to either Mr Taylor, Woodrow or Wimpey. Tell them what style yer hoosie is, and explain the issues - attach the photos. I'm sure they'll try and offer advice.

Mention the cavity insulation too, see what they say aboot that.