damp dpc course

[forch]

hi
having a go at injecting a DPC course with chemical seems to b ok except a couple of holes i have drilled which are correct depth are just letting the chemical flood out of the mortar bed and using a rather alot of chemical and i am sure doing no good any advice cheers

 

[elephant]

The object of the exersise is to saturate the brick, not the joint. The procedure is to drill the brick about 60mm then put the lance in and turn the key just enough so that it wont move. Turn on the fluid (slowly to start) and let it run until you see the brick starting to get damp. At that point stop and move to next hole. 2 holes per brick. If the brick cracks or fluid starts pouring out, then stop. You do the outside from the outside and the inside from the inside except where it is not possible to reach, when you do the nearest one first then continue and do the further one. Stone and other materials have slightly different procedures.
It can take seconds or 4 or five minutes, depending on the brick.
Fluid should not be coming back out of the hole or out of the joints.

 

[noseall]

...........The object of the exersise is to let it run...........until you see the brick starting to get damp.

i thought it was to alleviate the damp.

 

[gregers]

The object of the exersise is to saturate the brick, not the joint.

depending on the requirements of the fluid used,over the years i have installed dpc's in the brick and the pug course.with the pressure ranging from 25psi(for water bourne chemical)-150 psi (for spirit based chemical-to the transfusion method (bottles that gravity fed the wall)

if its a cavity wall you do not need to inject the outside wall just the inside wall,just open up the cavity and clear out the silt/crud that has built up over the years.

 

[kevintaylore]

I'd always understood that the idea was to treat the brick and the joint. One way or another you want to form a complete barrier along the wall that is as close as possible to forming the type of complete barrier you would get with a physical DPC. One of the weaknesses of liquid DPC products is that they can often disappear down small cracks in the bricks and mortar which can leave small areas untreated. In fact this is one of the reasons why damp proofing creams are now so popular. If I was in your situation I would drill some extra holes a few cm away from the problem holes and try to reinject - probably using low pressure for at least a minute per hole - although if the fluid continues to go in very quickly you'll know you have hit another crack and will have to think again.