Saltpetre
Possible cause(s): Rising damp
White, powdery efflorescence on your walls: the most common sign of active rising damp.
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Understand before treating
A damp wall can have several causes.Do not treat only the symptom.
Saltpetre, mould, flaking paint or a damp band: a visible sign is not always enough to draw a conclusion. MURSAIN analyses the causes before proposing the suitable solution: HYGRO, air treatment or drying after water damage.
MURSAIN method
- Observe visible effects without rushing to a diagnosis.
- Link symptoms to possible causes.
- Guide towards the solution suited to the building.
Direct answer
The three main causes of a damp wall are rising damp, condensation and water damage. The same building can combine several causes: the diagnosis helps avoid confusing the visible effect with the origin of the problem.
Start from the symptom, then verify the cause
These cards are for guidance. They do not replace analysis of the building: some signs may be linked to several origins, or appear together.
Peeling wallpaper
Possible cause(s): Rising damp or water damage
Moisture migrates into the partition and lifts your wall coverings from the inside - any renovation remains futile without prior treatment.
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Flaking paint
Possible cause(s): Rising damp or water damage
Paint blisters and flakes under the effect of evaporating moisture: a symptom to treat, not to hide.
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Crumbling plaster
Possible cause(s): Rising damp or water damage
Plaster gradually disintegrates into powder or comes away in patches, weakening the wall structure.
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Grey / black mould
Possible cause(s): Condensation
Black marks in corners or behind furniture: condensation creates the ideal conditions for their development.
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Damp band at the base of walls
Possible cause(s): Rising damp
This damp line at the base of the wall marks the level where capillary water stops, at that moment.
Understand this symptom →Compare the possible origins before choosing a treatment
Low walls, salts, damp band
Rising damp
It can be the cause of saltpetre, a damp band at the base of the wall, and contribute to deteriorating finishes.
See the HYGRO treatment →
Humid air, corners, mould
Condensation
It often appears in corners, at the top of walls, behind furniture or in cupboards, and can be worsened by other sources of moisture.
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After leak, incident or infiltration
Water damage
After water damage, structures can remain saturated: they must be dried before decorative renovation work.
See drying after damage →Get oriented without over-diagnosing
The markers below help prepare your request. They indicate a possible lead, not a final conclusion: only an examination of the context makes it possible to choose the right response.
Why this caution?
Flaking paint can come from rising damp or water damage. Mould can be worsened by a wall that is already damp. The aim is therefore to connect the signs together.
Low wall, damp band, saltpetre
Possible direction: rising damp
The HYGRO solution is considered after analysis of the causes, especially when the signs are concentrated at the base of the wall.
Grey / black mould, corners, top of wall
Possible direction: condensation
Air treatment may be relevant when air moisture and ventilation are involved.
After leak, incident or saturated wall
Possible direction: water damage
Structural drying should be considered before paint, plaster or wallpaper.
What moisture can damage
For the building
Saltpetre, damp bands, crumbling plaster, flaking paint or peeling wallpaper signal deterioration that must be understood before renovation.
For indoor comfort
Air that is too humid encourages discomfort and mould growth. Treatment aims to restore a healthier, more stable indoor environment.
For the works
Repainting, replastering or papering a support that is still damp exposes the finishes to fresh deterioration. The cause must be treated before cosmetic improvement.
Go deeper or request guidance
Symptom articles
Go deeper into each visible sign: saltpetre, mould, paint, wallpaper, plaster or damp band.
See the resource →Techniques and expertise
Understand the three treatment families proposed by MURSAIN after analysis.
See the resource →Frequently asked questions
Find short answers about diagnosis, HYGRO, causes and works.
See the resource →Free diagnosis
Describe your situation to be guided without reducing the problem to a single symptom.
See the resource →Next step
Several possible causes? Let's take stock.
Describe the visible symptoms, where they appear and the context in which they occur. MURSAIN will guide you through a diagnosis before proposing a treatment.