WHAT IS DAMP PROOFING AND DPC?
Chemical damp proofing is at its simplest a method to prevent walls from acting like a sponge by drawing water up from the ground – a process known as rising damp. Modern buildings are constructed with a tough Damp Proof Course (DPC) sandwiched between the bricks all around the house just above the foundations.
This damp proofing course forms a barrier, preventing damp from rising up the walls. Unfortunately, however, many older buildings did not have a DPC applied during their construction or the materials originally used have broken down. In either case this allows dampness to penetrate through.
CHEMICAL DAMP PROOFING COURSE
This is where a Chemical DPC comes in. In simple terms bore holes are drilled into the wall and a chemical fluid is pumped in which reacts with the moisture to form a permanent water barrier.
everything from chemical damp proofing injection fluids and creams, to Damp Proofing Plasters and Renders, and even drills, injection Pumps and nozzles.
DAMP PROOFING YOUR HOME
Where rising damp is diagnosed, pro-point will install a remedial damp proof course using their DryWall Silane Diffusion system, the very latest in damp proofing technology. This involves the introduction into the wall of a concentrated thixotropic silane/siloxane ‘cream’ to form a barrier against rising damp. As the cream slowly diffuses, it also releases a silane vapour which reacts with the silica in the masonry to form a water repellent resin. No liquid is involved so the wall is quicker to dry out and it is not injected under pressure which means that there are no problems with party walls.
TANKING AND WHEN TO APPLY
Tanking is, as its name suggest a method of sealing a wall to prevent water ingress (think ‘water tank) often mis-specified as a cure for damp problems it is basically a waterproof cementious slurry (wet mix) that is applied to a surface to prevent water penetrating the internal surface of a building.. The idea is almost like coating the bottom of a pond to keep the water in but in reverse… it keeps water out.. example… an extreme one..
Lets just say the ground (not floor, ground is external) level of your house is above the dpc level by about 3 feet, and the soil is against the outside of your building. The wall is of 9″ solid construction. Now, the water draining into the soil is also soaking into your wall (its porous, see suction) and its coming through on the inside making your internal plasterwork bubble and bringing with it hygroscopic salts (that white fluff you see manifesting itself on the inside of damp buildings) there are 4 ways of solving this.. 1) lower the ground level below dpc. Problem solved. 2) install a membrane between the soil and the wall that allows water to drain away from the building. Expensive but technically possible, the membrane has an air gap allowing the wall to breathe. 3) move the soil away and paint a bitumen waterproof solution on the external and put the soil back. Doesnt let it breathe externally, whatevers in the wall is coming inside. 4) tank it. you’d coat the internal wall with a tanking solution up to and beyond the height of the ground level, this would stop water ingress wherever the tanking is applied.. you also kill all the suction so a basic render on top is gonna be hard work. What you dont do is stop the water thats already in the wall soaking upwards (capillary action, similar to what happens with a failed dpc) and manifesting itself above the tanked area. So, basically, tanking is NOT really a solution to a problem though in some cases its the only thing that will work e.g. differing FLOOR levels throughout a building, the lower level needing to be tanked up to the upper level where there is a dpc installed to stop moisture going any higher.