Possible leaking drain

Who do I need to get this checked out?

Sorry for long post.

House is 1910s / 1920s. Built on chalk hill, with a concrete path surrounding the sloping and down hill 3 sides the house. Cavity wall.

The sides of the house sloping downhill have had a plinth/cement join to the concrete base added at some point, I assume to direct rain water away from house

One sloping side of house has soil pipe and kitchen drain both connecting to an inspection chamber about 1.5m away.

The cement plinth has cracked through years of neglect and has had lots of plants growing through / breaking it. I've been doing regular treatments of Glyphosate and used today's sunny lunchbreak to dig them out and have a look



Ignore thee broken inspection cover, since been replaced. Just there to show the depth and type of drain. Private drain.

Anyhow under the removed plinth and around the soil pipe and sloping downhill its all rather wet soil and smelly. Not a sewerage smell but a rotten smell. It could just be the decomposing remnants of the plants I pulled (some stems as thick as cucumbers). Lots of woodlice.

I've lifted floorboards on the other side of this wall and no internal damp damage or rotten joists. Subfloor is very well ventilated. No smell internally underfloor.

So:

Is this likely a cracked drain, pooling water around the house? How do I confirm this/what trade do I need?

Is is possible its just ground water from rain? I dug a trial pit futher out in the garden. Soil at that depth was damp. Not as damp though.

Bonus question: should I reinstate the plinth? I guess this could be a divisive question. Accepted wisdom is to remove them. However, plenty of houses have render joined to a concrete base with no damp issues. There's no damp in this house.

Thank you

Drainage engineer with camera.

Andy

If it were drain water it would be grey or black and sticky/smelly.

You could dye test your drains to check for leaking.

Ian H said:

If it were drain water it would be grey or black and sticky/smelly.

You could dye test your drains to check for leaking

Click to expand...

Thank you.

Ill dig around, pun unintended, a bit more tomorrow. I did a few tests today (flushing the loo, running the sink) with the inspection cover up, and the water is fast flowing away / down hill.

I reckon if it's leaking, its a slow leak from baths/showers, so wonder if a dye test would show.

HERTS P&D said:

Drainage engineer with camera

Click to expand...

Thank you

I dug out the dead plants from the other side of the house, nowhere near the drains or potential runoff.

Just as damp and fetid smelling. However, pulling out large and decomposing rootballs so thinks its just rotting vegetation.

Gotta pull it all out and remove the cracked/broken plinth/path bits.

Still unsure if I should reinstate the plinth to direct runoff away from the foundations - as now, I've effective got a wee ditch that will fill into a moat when we next have a downpour

The concrete prevents moisture from evaporating = bad. Gravel or similar would be best imho.
Glyphosate has killed all the vegetation and now it's rotting.

Bullet-Proof_Biscuit said:

The concrete prevents moisture from evaporating = bad. Gravel or similar would be best imho.

Click to expand...

Agreed about concrete preventing evaporation. It doesnt appear to have caused damp issues inside though. The house's has remarkably windy subfloor ventilation, and airbricks venting the cavity, which is open in the loft.

Its a pity I dont know if the plinth and concrete was present when the house was built, or, added at a later date. And if added later - was it just to have a mud free path around the house, or, to combat a damp problem?

I assume the former - original plaster in the house and no damp or blown damage (apart from where some windows had leaked, nothing corresponding to the plinth or path.

I can see, after digging out more plants, the original render (unpainted) ending, and, bare bricks in the soil. Cannot see a dpc on the outside, although, inside cavity leaf has slate dpc visible when pulling flooorboards.

It terms of gravel - are you suggesting filling the dug out soil and plinth with gravel? Wouldn't this just channel runoff onto the foundations?

I obviously dont want to leave the dugout gap, but, unsure what's best to do.