Over the years I have worked with various plaster products and application techniques, with time spent Surveying damp, woodworm, and fungal decay of construction materials.
I have found that many issues with damp in properties are associated with Hygroscopic salt contamination of masonry walls, floors, and wall plaster finishes.
Most of the time you will encounter hygroscopic salts that have been introduced into the walls from rising damp. Commonly Chlorides and Nitrate salts were associated with dampness from the ground absorbed by capillarity into the base of the wall, subsequently accumulating at the surface of the internal wall plaster as evaporation occurs.
The salt deposits on the surface of the wall plaster will in turn absorb moisture from the atmosphere within the property, particularly in humid conditions. (Condensation).
This will restrict evaporation of moisture, and if associated with rising dampness the salt deposits will force the dampness to rise further up the walls.
CHIMNEY BREAST
Hygroscopic salts also appear on the surface of chimney breasts. Chimney stacks that are leaking or unventilated redundant flues which have interstitial condensation occurring and creating moisture will carry any salt deposits from the burning of fossil fuels (soot), into the masonry fabric of the chimney breast which will evaporate as hygroscopic salts on the internal wall surface. Noticeable by the distinctive brown staining on the plaster.
Hygroscopic salts can also be introduced into a building by penetrating damp from urban pollution and prevailing weather in marine environments carrying sea spray.
RURAL LOCATIONS & FARM BUILDINGS
In rural locations where old farm buildings, stables, etc. are converted into habitable living accommodation, the original masonry walls will have been contaminated with animal faeces and urine. Absorbed as ammonia which is eventually converted via bacteria to nitrates. The nitrates will migrate to the finished wall surface by evaporation. Nitrate crystallisation can be more aggressive in the spalling/delamination damage it causes to decorative finishes.
GET A SOLUTION
DON'T LEAVE UNTREATED
In all cases it is necessary to eliminate sources of dampness and remove any salt contaminated wall plaster. Clean down the exposed masonry and let dry for as long as possible. During the drying process the evaporation of moisture, will leave further deposits of salt efflorescence which can be brushed off prior to plastering.
Salt migration through masonry and plaster can only occur in solution, so the prevention of moisture movement will also prevent salt accumulations. Therefore, an appropriate plaster product or modified plaster specification should be applied to the exposed masonry substrate.
In conclusion EMC Surface Finishes can initially carry out a survey of the defective plaster to ascertain the cause of the dampness and provide an appropriate re-plastering specification.
AVAILABLE SERVICE
GET A SURVEY
In general, our plastering surveys and quotations are free as there is the realistic potential for our company to get work from competitive tendering against other companies.
For Damp /Condensation / Plaster defect surveys we will charge a fee. The price will depend on the nature of the problem, size, and location of the property. If the survey is to be disruptive by way of exposure works, this will incur additional costs. To further justify the survey fee, it must be understood that a qualified Remedial Surveyor will be carrying out a detailed inspection of the area they are instructed to look at and providing a thorough report. However, if there are repair works identified and our company is utilised to carry out the work the initial survey fee will be reimbursed in our final invoice.
The survey fee will be confirmed and must be paid at the time of booking the survey.