Tanking slurry

My workshop is in a cellar of my Victorian house. It has two internal and two external walls, and the floor, which is 6" thick concrete on an impermeable membrane is about 6 feet below ground level. When I originally commissioned it I painted the walls with cellar paint - that was about 17 years ago. Over the years it's become apparent that one of the walls has succumbed to penetration damp. Some black mould has appeared on the lower sections and the mortar is bulging in some places. Things came to a head this year when the rise in the water table actually caused penetration and I found a shallow 3 sq mtr puddle in the workshop. Work with a mop soaked up about a bucketful of water and a dehumidifier has dried it all up. The cellar paint obviously didn't work the way I expected.

I need to tank the one wall to a height of about 1.5 mtrs. Will tanking slurry do the job? What preparation is required for it's application, and does it need to be covered afterwards, or can I just apply a coat of paint? It's only a workshop so aesthetics is not a requirement.

Hi Gary,

I've seen a product called SIKA work well in a similar situation. It was used to seal the walls of trenches, about 2m deep, in a car factory. This was just over 30 years ago so there may now be other similar products on the market. Our Site Foreman swore it was the best available product (at that time).

David

There used to be an effective cement additive called Pudlo.

If it has worked for 17 years first check if anything has changed outside. Cracked drain etc. Perhaps sink some boreholes outside and set up a sump pump.

Have a look at Sovereign Chemicals at Barrow-in-Furness they do all kinds of products for damp proofing, whether they have something suitable I don't know but well worth an ask. I do know they make and supply chemicals for injection damp coarse and it works vey well, daughters old farm house was done and very successful.

John

Gary,

Bayzle has a good point.

Consider your local rainfall, we had a fair soaking in Birmingham recently, but the rain only got 8" down. The Victorians wouldn't have dug a cellar if the watertable was normally that high.

I installed a chemical injection damp course about 30 years ago. Two holes halfway into each external long brick, record the time to saturation, then drill right through and halfway through the internal brick for the same length of time. Trouble was that the old Leamington bricks were very variable, with some saturating in about 20 secs, and some taking more than 5 mins. All except the wall that is now giving me problems were accessible via the old original cellars, so I lifted the floorboards of the room that is now above the workshop, and injected from inside. That's when I realized I could walk around in the void, and so decided to cut a doorway to gain access. 10 years later I did just that. I removed the earth floor, which was deeper than expected and, since there was no proper brick floor as per the old cellars, laid a membrane and poured a 6" thick concrete floor. I then repointed all the walls and applied the cellar paint. I wish I'd known about tanking slurry then, 'cos it's a big job to move the mill, work benches and and storage cupboards now.

The bus garage at Horsham was prone to flooding.

The solution was to bore a series of holes through the tiles lining the pit and inject a chemical to tank the pit.

It worked, but not when torrential rain caused the drains to back up and flood the pits from below!

Howard

When building cellars,they were lined on the floor with asphalt and the walls rendered the same.The floor was coversed with concrete to hold the asphalt down and block walls were built against the asphalt to prevent water pressure pushing it of.I realise that is not a solution for you, but for future reference, for anyone using the cellar for a workshop.A watertight cellar guaranteed.

Frank

An interesting thread. I used Pudlo about 50 years ago for a car inspection pit and it kept the pit dry. My Daughter has just bought a Georgian house with a small stream running through the cellar, I think it will be impossible the get dry.

News report today, wettest day for the UK since 1986 was on 3 October.

BBC news

Might be relevant, this was uneven rainfall so some parts got more than others.

Martin C

Echoing what Bazyle alluded to, Victorian surface water drains were often just land drains with no spigot and socket joints laid end to end, and they acted as a soakaway in light rain, and a pipe in heavy rain. I would say that the sudden appearance of a puddle is due to a build up of water outside the wall getting through. A friend of mine lived in a victorian vicarage with a very damp cellar, which dried out very well after the surface water drains, downspouts and gutters were all cleaned out and re-layed. Most of the underground drains and some of the downspouts were totally blocked and many of the gulleys were cracked and leaking. see if you can locate the dampest (wettest!) area then go look outside at the same point!

Edited By Phil Whitley on 16/10/2020 09:35:20