damp-proofing solid stone walls with A "cream"-bas

[martinrich]

Hi UHM,

I just about to embark on renovating an old sandstone Victorian house and I have been advised by a damp company to have a "cream" based injection DPC, with a 3:1 waterproof render on the inside of the wall, prior to wallboarding. Im not convinced an injection course will work in this kind of solid wall and I have had problems with injection DPCs in solid walls failing in the past. Does anyone have a view on modern "cream" base DPCs and if they would be suitable?
Otherwise any recommendations?

There is only the front and back walls which make contact with the ground, the rest of the internal walls in the living space sit above cellar walls (front is 2 storey, back is 3-storey, with the cellar out into the garden). It seems that the surveyor also detected high damp readings on all living room walls but clearly it cannot be rising damp as they are 1st storey. The house has never had heating in it - could it just be a damp cold cellar where moisture just rises up through the walls over 100+ years?
Thanks for your help in advance.
Martin.

[Deleted-user-3]

Cream is supposed to work by following the water in the substrate where it crystalises forming a waterproof barrier...
in theory this will work fine, wherever it comes into contact with moisture within the wall, the reaction takes place..
high pressure silicon injections rely on the substrate being sound enough to support the pressure of the injection where it permeates the substrate a bit like forcing water into a sponge...
the problem with this is if the substrate is unsound or has a multitude of gaps then the fluid just doesnt get where its needed.. no good for loose built walls, works ok on sound brickwork..
cream doesnt need pressure...
youre going to need to get an insurance backed guarantee and as youve had experience with solid walls before, never mind sandstone / rubble solid walls youll know how things can go wrong...
maybe once its injected a tanking system might be a good idea, render applied, then tanking, then more render...
first thin coat of hard render to fill any gaps -give a backing to the tanking..
tanking to seal the walls
second coat of render to hold the tanking in place..
final coat of skim...

theres electo osmosis too, ive heard people recommend it for solid walls of this type but ive had no dealngs with it personally..

[Sir Harry]

Contrary to popular belief DPC injection creams do not form a physical damp proofing barrier. Silane / Siloxane damp proofing creams work by migrating through the mortar bed structure to line capillary bores with a silicone resin rather than to block them. The creams have an excellent record of treating damp in traditionally built solid and cavity walls.
However if you have rubble filled stone walls, damp proof injection is entirely inappropriate as it is not possible to provide a continuous pore lined section through the wall structures and through the random rubble between.
Perhaps you should consider active electro-osmosis damp proofing. This process involves installing a series of positively charged anodes (+) in a wall and a cathode (-), at lower level in the ground. A tiny electrical unit powers the system and free water molecules are repelled from the anodes and are attracted to the cathode.
Electro-osmotic damp proofing is the only remedial damp proof system that can be installed into a wall above flooring timbers that has the capacity to drive dampness down beneath them to protect the timbers and provide a vital requirement of any damp proof course.

[martinrich]

Thanks once again for all the information fellas!

I do have to replace 3 joist ends which are rotten. Fortunately access is good as they form the cellar ceiling! I am though very interested in the electro-osmosis option, as a cream DPC would be injected above ground level and the joist ends actually sit either at ground, or just below it, looking at the cellar. If the moisture can be driven below the joists it sounds like it maybe a better option then? Any guesses as to how far the moisture can be driven below the wires?

I'll try to work out if they are rummble filled walls as well.
Cheers
Martin.

[martinrich]

Oh.. forgot to ask, is is possible to put the electro-os wiring in the cellar next to the joists or does it have to be above them? Would be tucked out of the way in this case.
Thnanks again
Martin.

[Sir Harry]

The line of anodes needs to be above the outside ground level. Accordingly the anodes can only be beneath the joists if the joists are also sited above ground level.