Wykamol Group | Damp Proofing
'DPC No.1' Damp Proofing Injection Fluid is an Organic Solvent-Based Stearate Resin (POAS) solution designed for the creation of chemical damp proof courses in walls above ground level.
Amorphous substrates such as solid chalk, (unfired) clay tec. may not be suitable for chemical damp proofing treatments. Stone walls filled with earth are similarly unsuitable.
All treatments should be in accordance with BS 6576:1985 (Code of Practice for the installation of chemical damp proof courses). In particular, the inserted DPC should be below the level of a timber floor unless prevented by structural considerations. Such floors should be inspected due to the risk of fungal decay.
Note: DPC No.1 is designed to control capillary moisture movement only. Walls heavily impregnated with microscopic salts or suffering from the effects of penetrating or condensation dampness may require further measures to create a dry internal environment.
Supplied in 25 Litre Containers, Ready-to-use Product.
Check and overhaul rainwater goods and soakaways to ensure that they are in good order and clean, repair or install drains to carry away surface water.
If the internal floor level is at or below external ground level, form trenches along the external face of the walls to at least 150 mm (6”) below the proposed DPC level. Do not excavate below footing level or affect the structural stability of the wall.
If this approach is not feasible the DPC must be placed at 150 mm above external ground level and the internal walls tanked below the DPC to prevent lateral migration of moisture/ salts.
Carry our any repairs or re-pointing and leave to cure (a minimum of 4 - 6 weeks) before installing the DPC.
Remove skirting’s, fixings and plaster to expose the line of the proposed DPC.
Plaster which may be affected by hygroscopic salts should be removed to not less than 300mm (12”) above the last visible signs of dampness or 1 metre above the proposed line of the DPC, whichever is the higher.
Check the removed skirting’s and, if required, put sound items to one side for reinstatement. Inspect other associated joinery and flooring timbers and if fungal decay is located take the appropriate remedial measures.
Ensure wall cavities are clear of debris. Remove all external render to expose the line of the proposed DPC. If it is suspected that the render is contaminated by hygroscopic salts and / or is physically unsound, it should be removed to an appropriate height.
In the case of semi-detached / terraced houses etc. Inform occupants of adjoining properties before treatments commence. The drilling of party walls in particular may cause disturbance to decorations and or ornaments.
Also, DPC No.1 may give off volatile vapours and it is essential that no fires or any other naked flames are present during and for up to two days after injection. Full ventilation must be provided during this time to both the treated and adjoining areas.
Cavity fill materials such as urea formaldehyde and mineral wool are not normally affected by DPC No.1 but may retain the solvent odour. Cavity walls filled with polystyrene must not be treated with DPC No.1. It may also damage existing bitumen DPCs and certain types of floor tiles, adhesives and polystyrene laid as floor insulant.
Select the course to be treated. This should be at least 150 mm (6”) above external ground level.
Where suspended timbers are present, the DPC should be formed below joist / wall plate level wherever possible.
In the case of solid floors, the DPC should be inserted as close to the floor as possible and, where necessary, linked to the floor damp proof membrane by the application of a suitable water-proof compound.
Vertical DPCs should be installed to connect staggered DPC levels and to isolate untreated wall areas, e.g. adjoining properties, fireplace and not treated due to lack of access and abutting garden walls. The vertical DPC should extend to at least 1 metre above the DPC level.
If very high levels of hygroscopic ground salts (chlorides, nitrates) are present in the property, our Technical Department should be consulted regarding suitable methods of treatment and reinstatement.
The spillage of DPC No.1 may present a contact hazard to unprotected persons. Soak up immediately or rinse away with strong detergent (as appropriate). Do not allow DPC No1 to come into contact with glass.
All treatments should be in accordance with BS 6576: 2005 Code of Practice for the installation of chemical damp-proof courses. Special precautions should be taken to isolate structural flooring timbers which will remain below the level of the injected DPC.
Drill the selected course. Spacing should be 120mm to 150mm apart. (2 per stretcher, 1 per header) to an average depth of 75mm. The diameter of the holes should be between 10 -15mm dependent on the injector rods used.
Single skin (115mm) walls are drilled from one side (avoid percussion drills). Solid walls (230mm or more) should, where possible, be treated from both sides.
If access is restricted injection can be carried out from one side. The first brick is treated normally. A hole is then drilled through into the next brick skin and injection undertaken using the time taken for successful treatment of the first brick as a guideline (see illustrations). Walls of greater thicknesses may be similarly treated in an incremental manner.
Treatment may be carried out into the mortar course if required using a similar drilling pattern (maximum 100mm spacings). The course selected should allow reasonable pressure retention during injection and a lower pressure and longer injection times used to achieve good continuity of treatment (see ‘Injection’ below).
A combination of mortar joints and brickwork can be treated by using the brick drilling pattern above but drilling at an angle (ca. 45º) to end in a mortar joint at the level of the proposed DPC (in such cases, for walls of greater than 340mm depth, special drilling patterns may be required).
Treatment of solid stonework should be carried out in a similar manner to ‘Brickwork’ with adjustments being made to the drilling pattern to take account of the construction.
Both solid external skins should be treated in a similar manner to ‘Brickwork’. One set of drill holes can then be drilled through into the centre of the wall and the rubble infill treated.
Injection is carried out by inserting injector rods into the pre-drilled holes and forming a seal. In brick / stone DPC No.1 is injected at an approximate pressure of 500-700 kPa (70-100lbs/in²) until a continuous band of treatment is visible on the face of the wall. If treatment is being carried out into the mortar joints the pressure should be reduced to approximately 200-350 kPa (30-50lbs/in²).
3-4 litres per metre based on 225mm (9") solid brickwork (or pro rata). In other words, a 25 litre container should cover around 6.25 to 8.25 linear metres on a standard 9" thick brick, depending on porosity of substrate.
Take the usual labour hygiene into account.
PPE should be worn during application. See our Safety & PPE Products.
Consult label and material safety data sheet for more information.
On external faces of walls, drill holes can be re-pointed using a matched mortar or can be plugged with DPC Injection Plugs (Available in a variety of colours, suitable for 10mm - 12mm wide Drill Holes).
Usually within 2 - 7 days of installation depending on the thickness of the wall. Very low temperatures which slow down solvent evaporation will extend curing times.
The removal and replacement of internal salt contaminated plaster is an important part of an effective damp-proof course. Salts left behind by rising damp are hygroscopic and can cause future staining independent of any issues with structural dampness.
It is therefore essential to follow specific re-plastering guidelines drawn up for dealing with the particular challenges posed by damp / salt-affected surfaces.
It is advisable to leave walls injected with DPC No. 1 to dry for as long as possible, and for at least 14 days, before removing excess salts and commencing replastering.
It should be noted that whilst insertion of a chemical DPC inhibits further moisture from rising up into the wall, the moisture present before the DPC will take time to dry out.
A damp wall takes time to dry out. As a general guide, the drying rate is given as 1 month for every 25mm of wall thickness (BRE Digest 163, ‘Drying out buildings’). Thus 230mm will take approximately 9 months to dry. However, the drying processes depend on conditions, ventilation and the type of masonry, so drying may take considerably longer.
Due to the potential prolonged drying of the wall, the following must be considered:
Delay any decoration for 4-6 weeks following re-plastering and allow for good natural ventilation to enhance drying. Do not apply heat or accelerated drying methods.
Do not use wallpaper for at least 12 months (longer on thick walls).
Redecorate using a non vinyl based emulsion.
Maintain good ventilation around walls.
Note: The initial decorations should be regarded as temporary, the final decorations not taking place for at least 12 months after completion of the damp proofing and ancillary work.
Where appropriate, external renders should be applied in accordance with BS 5262:1991 and terminate in a bell mouth just above the DPC level.
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