It is a widely held view that, after a wall has been treated for rising damp, it is always necessary to replaster the wall using a dense cement based render. There are two main reasons why this advice is given:
- Outdated methods of remedial damp-proofing are often not reliable enough to adequately stem the rising damp.
- The wall may be contaminated with groundwater salts that can leach into existing and new plaster, requiring a new surface which can resist them.
The former standard practice of replastering after every single rising damp treatment is time consuming, costly and creates a large amount of mess.
The Next Step in Rising Damp Treatment
The improved effectiveness of Dryrod Damp-Proofing Rods, compared with standard rising damp treatments, is such that it is not always necessary to render or plaster over the previously affected wall after treatment. Where Dryrods have been properly installed, the barrier that they create will sufficiently stop the rising damp.
Not having to replaster allows the property owner to keep any decorative finishes that were previously in place, if they so choose. It also allows the rising damp to be treated with almost zero disruption to the lifestyle of the occupiers of the property.
It is important to note, however, that although Dryrod will be able to sufficiently stop rising damp, it is sometimes still necessary to replaster.
Deciding Which Plaster Needs Replacing
No rising damp treatment, no matter how effective it is at creating a barrier to damp, will be able to undo any groundwater salt transfer damage to the wall or to existing plaster. In cases where groundwater salts have already caused decorative spoilage or created persistent damp patches it will be necessary to replaster.
It is possible to spot a wall that has been contaminated by salt, as a result of rising damp, by looking for the following signs:
- Paint blistering off of the wall due to salts crystallising underneath it
- Groups of visible salt crystals protruding from the surface of the wall
- Parts of the plaster that have been degraded by the salts can start to crumble
- Where the salts are hygroscopic, they can draw moisture from the air. This means isolated damp patches will appear even if other parts of the wall are dry
If the only visible problems on the wall are damp patches, a sensible course of action when using Dryrod Damp-Proofing Rods is to apply them and then wait to see if the decorative finish returns to normal.
It can take some time for a damp wall to dry out (approximately 1 month per inch thickness of wall, according to British Standard BS6576) but in cases where there is no salt contamination, it may return to normal. If the decorative finish does not return to normal and damp patches remain, it is time to consider replastering.
We would always recommend consulting with an experienced and qualified damp surveyor to properly confirm if a wall has salt contamination issues or not. Identifying which areas of plaster need replacing takes skill and experience.
The Most Effective Way to Replace Contaminated Plaster
The least disruptive method for replacing salt contaminated plaster is to use the Dryzone Express Replastering System, which uses a specially formulated salt barrier cream and damp resistant adhesive to adhere plasterboard to the wall.
The salt barrier cream helps stop salt from transferring through the adhesive and the adhesive leaves an air gap between the wall the plasterboard, ensuring any new decorative surface will stay unaffected by the salt.
Some people may wish to choose a sand and cement render, containing a salt retardant additive, to stop salt from transfer to new decorative surfaces. Whilst there are some situations where a sand and cement render is the most appropriate option, the Dryzone Express Replastering System is the quickest, most effective and least expensive way to replaster after rising damp.