18/08/2026
Rising dampness occurs when moisture from the ground travels upward through walls by capillary action, usually because the damp-proof course (DPC) is missing, damaged, bridged, or ineffective.
Dangers of rising dampness
Damage to walls and finishes
Continuous moisture can cause plaster, paint, wallpaper, and wall coverings to blister, peel, crack, or deteriorate.
Salt contamination
Groundwater carries soluble salts into the wall. As the water evaporates, salts crystallize and can cause staining, flaking, and deterioration of plaster and masonry.
Mould and unhealthy indoor conditions
Persistent dampness creates a favourable environment for mould and fungi, which can contribute to unpleasant odours and poor indoor air quality.
Structural deterioration
Prolonged moisture exposure can deteriorate mortar joints, masonry, timber elements, and other building materials. In severe cases, it can compromise parts of the building.
Damage to skirting and flooring
Timber skirting boards, door frames, carpets, laminate flooring, and other materials close to the floor can absorb moisture and rot or deteriorate.
Reduced property value
Visible damp patches, mould, peeling finishes, and recurring moisture problems can negatively affect the appearance, usability, and market value of a property.
Increased maintenance costs
Simply repainting a damp wall rarely solves the underlying problem. Without treating the source, the damage tends to return, resulting in repeated repair expenses.
Electrical and fitting risks
Persistent moisture around electrical installations can contribute to corrosion and deterioration of electrical components, particularly where installations are poorly protected.
Important point
Rising damp should not be treated by simply painting over the affected wall. The source of moisture must first be identified, whether it is a failed DPC, bridging, defective drainage, plumbing leakage, or another form of water ingress. The appropriate remedial system can then be selected.
For a waterproofing contractor, a good diagnosis is particularly important because rising damp, penetrating damp, condensation, and plumbing leaks can produce similar symptoms but require very different solutions.
Today 4:47 PM
Why it is important to involve a waterproofing contractor once you finish constructing the roof deck in a project
Involving a waterproofing contractor immediately after completing a roof deck is important because this is the stage where the concrete slab is exposed and accessible, making it easier to prevent water infiltration before finishes, ceilings, electrical installations, and other building works cover up potential defects.
Why it is important
Early detection of defects
A waterproofing contractor can inspect the roof deck for cracks, honeycombing, construction joints, weak points, improper slopes, and other areas that may eventually allow water pe*******on.
Proper surface preparation
Waterproofing systems require the concrete surface to be properly prepared. This may involve cleaning, repairing cracks, treating construction joints, removing laitance, and correcting defective areas.
Correct drainage and falls
The roof deck should have adequate falls toward outlets and drainage points. Standing water is one of the major causes of premature waterproofing failure.
Protection against leakage before finishes
Waterproofing the deck before internal ceilings, electrical works, plastering, and other finishes are completed helps prevent expensive damage caused by water infiltration.
Selection of the right waterproofing system
Not every roof deck requires the same treatment. The contractor can assess the concrete, exposure, drainage arrangement, movement requirements, and intended use of the roof before recommending an appropriate membrane or waterproofing system.
Treatment of vulnerable areas
Particular attention should be given to pipe pe*******ons, parapet walls, expansion/construction joints, drainage outlets, upstands, corners, and service pe*******ons. These are common points of water entry.
Reduced future maintenance costs
Waterproofing at the right stage is generally easier and less expensive than trying to locate and repair leaks after ceilings, tiles, insulation, electrical installations, and other finishes have been installed.
Proper testing and quality control
A professional contractor can carry out appropriate waterproofing inspections and water-testing procedures before the roof is handed over, helping identify failures while they are still accessible.
The key principle
A roof deck is not truly complete simply because the concrete has been cast. It needs to be properly inspected, prepared, waterproofed, drained, and tested before subsequent building finishes proceed.
The earlier the waterproofing contractor becomes involved, the greater the opportunity to prevent water ingress rather than spend money chasing leaks later.
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