Self Diagnosis

Damp problems in your property can be caused by a number of things. In this useful damp table we highlight the main symptom, cause and treatment of damp in your home.

1. Presence of Efflorescent (white) salts on walls to a height not more than 1.2m above ground level Rising Damp 1. If no dpc, fit a chemical dpc using Dryzone Cream. 2. If external plaster to ground level, remove plaster to not less than 300mm above contamination or 2 brick courses above dpc, whichever is higher, and treat walls with 2 coats of Latseal Slurry mixed with diluted Bondaid Plus prior to re-plastering. 3. remove contaminated plaster on inner surface of walls and re-plaster using Renderguard Gold (a salt retardant) in the new plaster mix.
2. Damp appearing on internal walls Possible failure of dpc or failure to fit dpc under floor slab 1.Remove contaminated plaster. 2. Fit a Fillet Seal at all wall/floor joints. 3. Drill and inject a chemical dpc in all walls. 4. Treat the floor slab with either ECS Epoxy Floor Coating/Latseal Slurry/Vandex Super/Vandex BB75 after having removed all fittings on the floor slab (built-in cupboards, kitchen counters etc), lapping the walls by one brick course above the new chemical dpc.
3. Damp in floor carpets, warped wooden flooring, white salts between tile grouting Possible Rising Damp through floor slab - failure or absence of dpc beneath floor slab As above
4. Blistering of paintwork 1. Possible Rising Damp. 2. Water penetration of walls from cracks in external plaster. 3. Water penetration through brickwork or mortar. 4. Failed joints between windows/doors and walls. 5. Leaking roof 1. Treat as above. 2. Repair cracks using a latex-modified plaster. Remove contaminated plaster and replace with plaster containing Renderguard Gold in the new plaster mix. 3. Treat exterior walls with Storm Dry or Raindance/Raincheck (water repellents) after thoroughly cleaning walls and repairing any holes in the mortar. Remove any contaminated plaster on internal surfaces and replaster using Renderguard Gold. 4. Rake out joints and fill with an expandable polyurethane sealant. Remove and replace damaged plaster as above. 5. Fix leak. Remove and replace damaged plaster as above.
5. Damp in walls beneath a balcony 1. Failure to turn up waterproofing at side walls. 2. Lack of waterproofing beneath sliding door track. 3. Failure to water proof tops of parapet walls. 4. Failure to seal balustrade fittings or outlets 1. Remove skirting tiles and tiles at edge of walls. Complete waterproofing, lapping side walls by a minimum of 150mm. Replace skirting/edge tiles. Remove and replace damaged plaster in room beneath balcony as above. 2. Remove door frame and adjacent tiles and waterproof from balcony waterproofing to at least 100mm in from door frame. Re-fit frame ensuring that track fittings piercing the waterproofing are properly sealed with either epoxy or a polyurethane sealant. 3.Remove all damaged plaster and allow walls to dry out before re-plastering. Seal tops of parapet walls with membrane soaked in Acryl Seal or apply 2 coats of Acryl Fibre lapping the edges of the wall. Remove and replace damaged plaster in room beneath as above. 4. Remove balustrade. Ensure fittings are properly sealed with an epoxy or polyurethane sealant. Ensure waterproofing to outlets is continuous from the slab waterproofing to well inside the entire outlet. Remove and replace damaged plaster in room beneath as above.
6. Damp in middle of ceiling beneath a flat roof or balcony 1. Possible failure of waterproofing. 2. Possible movement in a pre-fabricated slab(rib and block etc) damaging acementitous waterproofing 1. Where necessary repair damaged waterproofing. 2. Where possible replace cementitous waterproofing on all pre-fabricated slabs with torch-on membrane. This will depend on there being a sufficient threshhold between the slab and adjoining rooms.
7. Damp in walls between split levels Failure to dampproof from slab to slab Remove plaster from lower floor level to 2 brick courses above upper slab level. Fit a Fillet Seal at the lower wall/floor joint. Check for presence of dpc sheeting at upper slab level. If no sign of dpc sheeting create new chemical dpc at upper slab level. Apply 2 coats of Latsea Slurry mixed with diluted Bondaid Plus to the exposed brickwork and re-plaster. Create a vertical dpc using Dryzone Cream at all off-leading walls from lower floor level to the height of the upper floor slab
8. Black mould on ceilings in bathrooms, shower room or kitchen Condensation Ventilate room. Open windows or fit an extractor fan. Clean off mould with an anti-fungal wash or Jic
9. Horizontal cracks in walls beneath a balcony Possible movement of the slab Fit an expansion joint at the slab level and fill with an expandable polyurethane sealant
10. Plaster damage on base of boundary walls Absence of dpc sheeting in walls (National building standard) Remove contaminated plaster from ground level to 1.2m above highest ground level on either side of the wall. Apply 2 coats of Latseal Slurry mixed with diluted Bondaid Plus and re-plaster. Start new plaster a few cm off ground level to prevent ground water ingress.


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