Microjet DPC is a ready mixed solution to be injected into masonry walls under low pressure to form a chemical damp proof course.
Microjet DPC Damp Proof Course
Antel’s Microjet DPC is a ready mixed solution containing multi functional siloxanes. The material has been especially formulated for use as an injection fluid for the formation of a chemical damp proof course. The process involves the saturation of a selected course of brickwork by pressure injection. The material provides for excellent penetration similar to spirit based injection fluids.
2. FEATURES, BENEFITS
Safer to use and handle
No odour transferred through to attached buildings or party walls
High alkali resistance
As a chemical damp proof course
4. TECHNICAL DATA
Microjet can be applied by pressure injection (5– 50 p.s.i)
5. INSTRUCTIONS FOR USE
ACTION WITH RESPECT TO FLOORING TIMBERS
5.1 Where a suspended timber floor is independently supported on sleeper walls, with an effective damp proof course, these need not be treated.
5.2 Where a suspended timber floor is supported on joists and/or a wall plate bearing on or embedded in the wall, there is a possibility of decay, particularly where concealed timbers are in contact with the wall. The condition of these timbers should be ascertained and remedial action taken if necessary.
5.3 If damage is limited to the joist ends, the floors may be reformed using sleeper walls or joist hangers to isolate the timbers from the damp wall.
5.4 If the timbers are sound, the existing floor may be retained, provided the injected damp proof course is formed below the timber joists and/or wall plates
6.1 The course to be injected is chosen so that the position of the horizontal damp proof course complies, as far as is practicable with BS 6576:1985
6.2 Internal walls on solid floors are injected as close to the floor as possible.
6.3 Complementary vertical damp proof courses are positioned, where necessary, to isolate treated walls from the effects of rising damp in adjoining walls to maintain continuity between horizontal damp proof courses at different levels.
6.4 Internal plastering affected by hygroscopic salts is removed from the area to be treated to a height of 300mm above the maximum level of the rising damp. Internal skirting, flooring etc are also removed, as necessary, to expose the area for treatment. Externally, the proposed damp proof course line is exposed by removing any facing material.
INJECTION PROCEDURE FOR BRICKWORK - HIGH PRESSURE
6.5 Two 10mm holes are drilled to predetermined depths along the selected course. Two holes are drilled in each stretcher and one in each header at an average spacing of approximately 120mm and maximum spacing of 150mm. If a brick course proves too dense to allow adequate penetration of fluid, drilling may be carried out in the adjacent mortar courses.
PROCEDURE FOR DIFFERENT TYPES OF WALLS
a. Walls 115mm thick are injected from one side only.
b. Solid walls of 230mm thick are normally injected from both sides. If access is restricted they may be drilled progressively (using a sequence of drilling, injecting, re drilling) to deepen the hole by 100mm to 120mm and re-injecting.
c. Solid walls of greater thickness can be treated from one of both sides. In each case the progressive injection technique is used.
d. Cavity walls are normally treated from both sides, but if the thickness of the individual leaves permit, the progressive injection technique is used from one side.
6.7 The solution is injected at normal pressure of 700kPa. Nozzles fitted with pressure tight seals are inserted into the drilled holes and injection is continued until complete saturation is achieved and the fluid begins to exude from the substrate. The nozzles are removed and subsequent holes are similarly injected.
INJECTION PROCEDURE FOR MORTAR - LOW PRESSURE
6.8 Holes are drilled at 150mm to 170mm spacing and the fluid is injected at a pressure in the range of 150kPa to 350kPa.
INJECTION PROCEDURE FOR SOLID STONE
6.9 In solid or cavity walls of conventional construction in block work or stone the drilling and injection procedure
is adjusted to accommodate variations in the density, porosity and structure, but in each case the procedure chosen ensures a continuous unbroken band of impregnated material along the length of the wall.
7.1 Untreated walls are isolated by injection of a vertical damp proof course throughout the thickness of the wall.
7.2 Treated walls are left for a period of at least 14 days to allow initial drying out. Internal plastering is applied, using a sand/cement mix incorporating Antel Rendermix (See Replastering Specification)
7.3 Particular care is taken to avoid bridging the injected damp proof course, both internally and externally. Where external rendering has been removed, it is restored, ending in a bell casting above the injected damp proof course.
7.4 Holes in the external wall surfaces are plugged with sand/cement mortar or preformed plastic plugs coloured to match the existing wall surface.
7.5 In buildings with a history of penetrating damp, a spray treatment of surface water repellent is applied to prevent recurrence
8. HEALTH & SAFETY
Precautions are necessary in handling and injection, to avoid bodily contact due to splashing, spillage or leakage. The normal precautions (use of goggles/visor, gloves, protective clothing and the prompt removal of contaminated clothing) should be observed with particular rigour. Should the fluid come into contact with the skin it must be washed off promptly. If it comes into contact with the eyes they should be flushed with cold water for ten minutes and medical attention should be sought. If ingested seek medical attention immediately. To protect third parties from contact with the fluid, the working area must be tightly screened off during treatment from the public highway (e.g. terraced houses abutting the pavement).