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| The various methods applied for the protection of dampness in buildings are following: |
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| 1.Replastering |
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| 2.Knapen Tubes |
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| 3.Installation of a Physical Damp course |
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| 4.Installation of a Chemical Damp Course. |
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| 5.Chemical Impregation Under Gravity |
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| 1. REPLASTERING: |
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| The most common method is to scale the affected damp plaster back to the brickwork and replaster the affected area with a waterproof plaster or cement mixture. |
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| This may stop minor damp problems reappearing but severe cases tend to reappear some time later above or beside the treated area. |
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| Replace the entire surface with waterproof plasterboard. |
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| Others use a technique of attaching battens to the affected walls and nailing on plasterboard providing a gap of 5mm to 10mm between the old surfaces and providing ventilation slots for top and bottom. |
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| All timbers should be decay-resistant and rust resistant. |
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| 2. KNAPEN TUBES: |
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| Sloping holes are drilled in the affected area at skirting board level. |
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| Porcelain or similar tubes are inserted into the holes. |
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| Moisture in the wall drains into the tubes and evaporates (a sort of mini agricultural drain). |
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| 3.INSTALLATION OF A PHYSICAL DAMP COURSE: |
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| This method has traditionally been regarded as the most effective (also the most costly) cure for rising dampness. |
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| It involves removing a line of bricks close to floor level. |
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| Then a plastic sheet is inserted along the line and the old mortar is replaced with waterproof mortar. |
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| Each re-mortared section needs to set for around 48 hours before it can take the weight of the wall again. |
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| 4.INSTALLATION OF A CHEMICAL DAMP COURSE |
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| Pressure injection of a higher alkyl siloxane solution is the most widely used method. |
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| Holes are drilled into the bricks at regular intervals. |
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| The solution alkyl siloxane is pumped into the holes and permeates the bricks and surrounding mortar creating a broad band of water repellent brick work. |
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| Pressure injection into the mortar course only is less likely to be successful since the old lime mortar is very weak and often contains many fissures/that will cause the product to blow out before the new damp course is formed. |
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| 5. CHEMICAL IMPREGATION UNDER GRAVITY: |
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| Holes are drilled into mortar lines at regular intervals. |
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| Delivery tubes of specific design are placed in the holes and liquid is transfused into the wall under the influence of gravity. |
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| If sufficient liquid is transfused into the wall, it will form a horizontal water repellent layer in the bricks and mortar. |
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| The choice of solution is a higher alkyl siloxane in hydrocarbon solvent. |
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