Preparation and drilling
Preparing and drilling prior to drilling internally, all obstructions should be removed, i.e., plastering and rendering. Plaster/render should be removed up to a line not less than 300mm above the last visible signs of dampness and/or salt contamination (using an electrical moisture meter) or 1 m above the d.p.c. whichever is the higher.
The positioning of the d.p.c. is vital if the damp proofing works ate to be effective. The d.p.c. should be placed at least 150mm above external ground level. If the external ground level is above the internal floor level it is necessary to lower the outside ground (permanently) or to incorporate in internal waterproof surface treatment, such as SSDP Water Proofing Slurry to cover the gap between the inserted d.p.c. line and the floor.
Holes should be drilled using 16-18 mm drill bits at overall spacings of 110mm and at an angle of depression of about 30°, finishing in a mortar bed at the level of the proposed d.p.c.. In solid walls up to 460mm thick drilling from one side to the thickness of the wall (and at the 30° angle), should result in a hole terminating 50mm or so from the far side. It may occasionally be advantageous to drill from both sides i.e.,random stonework with rubble infill or thick walls. Drilling should stop just over half way through the wall, the holes being at staggered centres of 110mm.
Prior to application SSDP Injection Mortar all drilled holes should be flushed out with water to remove any dust. SSDP Injection Mortar should always be injected into damp holes.
In walls less than 120mm thick, rather than drill holes, the mortar bed as the desired level is raked out to between one third and one half its depth. The mortar bed should be flushed with water to remove debris and the injection mortar applied by trowel into the joint. The mortar should be made up to a stiffer than usual consistency. The joint should be filled to within 8mm of the front face. Re-point using 3:1 washed sharp sand : cement using Salt Inhibitor Render Additive.
Application of SSDP Injection Mortar
A hand caulking gun is used. The nozzle of the gun is inserted into the holes to the full depth and slowly withdrawn whilst filling the hole with SSDP Injection Mortar. SSDP Injection Mortar should be stopped approximately 50mm from the top of the hole. Once all holes are to this stage it may be necessary to top up due to SSDP Injection Mortar finding its way into any voids or fine crack. Once SSDP Injection Mortar has set, the holes should be plugged up with 3:1 washed sharp sand : cement, using Salt Inhibitor Render Additive.