Existing Damp Proof Course – Benefits or Problems

[Matt Green]

Water rises in porous materials by capillary action- that's physics. If your definition of rising damp = capillary action (like the PCA) then there's no argument. Is rising damp caused by water rising in a wall from the soil with no other causative situation that could be addressed? Not often. Not often at all.

It's much like a chocolate covered ginger nut in that a lot of people claim to remember having seen one.


Matt.

 

[stuart45]

The claim the Netherlands does not use a DPC seems to come from Jeff's book, when he was on holiday in Holland. However when I worked in Holland and Belgium in the 70's a DPC was stuck into their walls, although it wasn't bedded on mortar unlike most of the UK.

The UK isn't the only country to see rising damp as a problem.
https://www.tudelft.nl/en/architecture-and-the-built-environment/research/research-stories/archive/2013/european-attack-on-rising-damp-in-buildings/
There are some materials that water will rise up through. I stuck an old Thermalite block in a inch of water yesterday and it's halfway up the block today.

 

[Westholme]

My 1894 house (nowhere near a marsh) has no damp-proof course but it does have one cavity wall. The mortar in this wall underneath the first course of bricks above ground floor level is very soft and dark brown. This could be an attempt at some sort of DPC and other walls might be the same. I need to replace some of the bricks and I'm wondering whether or how to recreate this mortar.

 

[MikeG]

......The mortar in this wall underneath the first course of bricks above ground floor level is very soft and dark brown. This could be an attempt at some sort of DPC.....

Personally, I doubt this very much. It would seem more likely that this is a mortar which has broken down. The only way of being absolutely sure of the make-up of an old mortar is to have it analysed in a lab.

 

[CliffordPope]

Didn't they add blood to lime mortar to make it less porous? That would presumably be darker?

 

[steveb]

Ah, nothing can beat a good sacrifice to ensure that the building stays dry

 

[88v8]

It frustrates me that it takes ignorance by two parties - both the owners and the workmen - to commit these mistakes!.

Alas, somewhere in a galaxy not far far away, that dynamic is active at this exact moment.
Most period-home owners are ignorant, worse, they don't even know what it is that they're ignorant about.
Equally, most builders don't know much about old buildings - after all, why would they when there are relatively few old buildings and most owners don't know nuffink - or the builders sort of know but don't care.

Before we bought our C17 cottage, we lived thirty years in a 1920 villa that we bought from the original owner. We always treated it well in decorative and architectural terms, but it had a dpc so no damp, consequently we happily DIYed, cemented and gypsumed in blissful ignorance and luckily did no harm. So we came to our cottage knowing nothing about lime, breathability, etc.
By good fortune and this forum which I found quite by accident, we have learned.

Most owners and most builders never will.

Ivor

 

[a twig]

It's much like a chocolate covered ginger nut in that a lot of people claim to remember having seen one.

I've got three packs in my kitchen cupboard