Why Use the Dryzone Express Replastering System?
The Problem of Rising Damp
Rising damp is a common form of dampness, particularly in older buildings. It occurs when groundwater rises up through walls, floors and masonry via capillary action. Capillary action is the ability of a liquid to flow along narrow spaces, counter to the forces of gravity. Bricks and mortar can be very porous and contain many fine capillaries, through which water can rise.
Most modern properties are built with a damp-proof course, usually in the form of an impermeable plastic membrane, which is placed along a mortar line near the ground. Some properties, however, were built with no damp-proof course, or the original has failed, meaning that rising damp can occur and it is necessary to make remedial repairs.
Dryzone to the Rescue
When Safeguard Europe launched Dryzone Damp-Proofing Cream in the year 2000, the way that people treated rising damp was transformed. It is a special damp-proofing cream that is introduced along the mortar course at regular intervals by injecting it into pre-drilled holes. The Dryzone then diffuses before curing to form a continuous water-repellent barrier.
Dryzone provided a cleaner, faster and more cost effective treatment for rising damp than fluid pressure injection systems, which were the previous industry standard. This innovation transformed the industry, making damp-proofing creams the default method of treatment.
In the past, rising damp was treated using corrosive or flammable liquids, injected under pressure, to block the pores of brick, stone and masonry and create a liquid damp-proof course. This process took a long time, used hazardous materials and required costly electric pumps to get the job done.
Dryzone Damp-Proofing Cream solves many of the problems that were inherent in pressure-injection rising damp treatments. It requires no expensive specialist equipment to buy or maintain, the material itself is not hazardous or caustic and it does not require constant attention once the application has begun.
The properties of Dryzone Damp-Proofing Cream that are most valued by its users, however, are the speed of treatment and the consistent spread of active ingredient. Being able to apply Dryzone to a wall quickly, with the knowledge that the treatment against rising damp will be reliable and effective, means that jobs are completed in a short space of time with a permanently dry wall as a result.
At the beginning of 2014, Dryrod Damp-Proofing Rods were launched as the next step in rising damp treatments. They are patented fibre rods that are simply inserted into the wall along a horizontal mortar course. Once inserted, the rods will diffuse high-performance water-repellent ingredients into the wall, curing to form a barrier to damp.
Designed for ease of application and the reduction of wastage, the rods are even more effective than the high-performance Dryzone and has been proven to out-perform competing products. The exact amount of active ingredient is contained within each rod ensuring full treatment, no mess and no waste every single time.
Most rising damp treatments start with the areas of plaster that have been affected by the damp being removed. General industry guidelines suggest that it should be removed up to a height of either 1 metre from the floor or 0.3 metres above the highest point of the rising damp. Once the original brickwork or masonry has been exposed, it is then possible to proceed with the actual rising damp treatment.
After the initial treatment of the source of the rising damp has been completed, the traditional practice is to replaster the affected wall, using salt-resistant sand and cement render as a basecoat. This is often required because the groundwater that rises up a wall can contain salts that contaminate both the wall itself and the attached décor. The process requires two coats of sand and cement render, with a salt resistant additive, and a final coat of plaster.
Should I Replaster?
Once a wall has been treated, it will begin to dry out but if the wall has been contaminated by groundwater salts then complications can arise. The most common complication occurs when the salts are hygroscopic, meaning that they attract and hold moisture from the surrounding area, leading to the appearance of damp patches, on an otherwise dry wall. Other issues that can arise include efflorescence forming at the plaster surface, causing decorative spoilage, and salts crystallising just underneath the plaster surface, causing it to crumble and blister.
The sand and cement render, that is conventionally used to combat these salts, usually contains a salt retardant additive such as Renderguard Gold. This additive stops salts migrating from the affected wall and into the new plaster, which is applied on top of the render. The additive also provides additional waterproofing qualities to the render, helping to protect the new plaster from residual moisture in the wall.
Traditional advice says that every wall that has been subject to rising damp should be replastered. This is not always the case, however. Some walls that have been subject to rising damp do not suffer from salt contamination and eliminating the source of the moisture can sometimes be enough to see the wall drying out, with no ill effects.
This is especially true when a high performance damp-proofing solution like Dryzone or Dryrod has been used, where the treatment of rising damp is far more consistent and effective than what can be achieved by pressure injected fluids or low strength creams. Due to the superior performance of the damp-proof course, the extra waterproofing qualities of the sand and cement render are often not needed to cover less well treated areas of the wall.
We would always recommend consulting a professional before deciding if you need to replaster. There are many qualified damproofing specialists that can give their recommendation and our technical team is always available to help with the diagnosis.
Limitations of the Traditional Method
Although they are effective, sand and cement renders do have some significant drawbacks, when being used to replaster after a rising damp treatment.
As the traditional replastering method uses two separate layers of sand and cement render, followed by the skim plaster coat, it can be a lengthy process. Each layer of render must be applied, with considerable patience and skill, and then be allowed to dry before being keyed. Typically, one layer of render can be applied per day on a rising damp replastering job, meaning at least 3 visits to site for the contractor. Particularly saturated walls may slow the drying process of each layer even further.
Once it has cured, a sand and cement render is a very hard surface, often harder than surfaces to which it is applied. Although this means that the render itself is very hard wearing, which is a useful quality, it also means that removing the render without damaging the wall beneath becomes very difficult. In historic buildings especially, the preservation of the original walls is always a major concern, for both the property owner and heritage surveyor.
Because they are very dense, sand and cement renders are generally very cold, especially in comparison to plasterboard and modern insulating plasters. A cold material is obviously going be harder to heat than a better insulated one. Apart from the possible increased cost of heating, a cold wall is more likely to be affected by condensation and, as a consequence, black mould.
Our Research and Development Department wanted to bring the quick, clean and cost effective qualities of Dryzone Damp-Proofing Cream to the replastering process. The overall goal was to allow a wall with rising damp to be treated and replastered within a single day, this lead to the development of the Dryzone Express Replastering System.
The concept that our laboratory team developed was, in effect, a variation on dot and dab plasterboard application. The idea being that, if plasterboard could be adhered to a wall in such a way that no salts could transfer to it from the wall, the plaster coat could be applied almost immediately.
A system of this nature would require a salt and damp resistant adhesive, for use between the plasterboard and the wall, and a salt resistant cream that also acts as a primer for the adhesive. As long as the plasterboard is not in direct contact with the wall or the floor then no salt or damp contamination will be able to affect the new plaster.
All the materials used in the Dryzone Express Replastering System have been chosen specifically to work with each other. Numerous laboratory tests were performed to find the best formulation of salt-resistant cream and plasterboard adhesive. We have produced a full laboratory report of the Dryzone Express Replastering System tests along with an abridged summary of the methods, results and conclusions.
The Modern Method
The Dryzone Express Replastering System comprises of three main stages, which are Dryzone Damp-Proofing Cream or Dryrod Damp-Proofing Rods, Dryshield Cream and Drygrip Adhesive. More detailed information on all products can be found on the Dryzone System product page. The process for using the system is as follows:
- Hack off contaminated plaster, back to the original brickwork or masonry, and apply Dryzone Damp-Proofing Cream or Dryrod Damp-Proofing Rods. This part of the process remains identical to previous damp-proofing cream treatment methods.
- Apply a single coat of Dryshield Cream to the area that is intended to be replastered, using a brush or roller. The cream must be allowed to sink in to the wall for at least 30 minutes before moving on to step three.
- Measure and cut plasterboard sections to fit the area being replastered and then apply dabs of Drygrip Adhesive, at a regular spacing, to the back of the board.
- Offer the plasterboard up to the wall and tap into place, using Dryzone System Positioning Plugs and plastic Wedges to make sure that the board is touching neither the floor nor the wall. Apply all plasterboards in the same manner, until full desired coverage has been achieved.
- Leave the Drygrip Adhesive to cure for 1½ hours and then apply skrim tape and plaster as per normal plastering procedure.
Why Choose the Dryzone Express Replastering System?
The Dryzone Express Replastering System holds numerous advantages over the traditional sand and cement render method of replastering after rising damp. The most obvious being the time reduction from the start of the job to the finish.
A job using Dryzone Express Replastering System can be completed comfortably within 24 hours, or one day’s labour. A professional using sand and cement render could only complete a rising damp treatment and replastering job in a minimum of 3 days, with multiple returns to site.
Due to the efficiency of the Dryzone Express Replastering System and the lack of material preparation needed before application, in comparison to the mixing of sand and cement render, the material and labour cost is low. Our estimations show that a typical sand and cement render job costs, on average, 47% more per m² than a job completed using the Dryzone Express Replastering System. This saving includes average costs for both materials and labour.
Because the Dryzone Express Replastering System is a damp and salt resistant form of dot and dab drylining, it has all the same benefits that a drylining system holds over traditional renders. Sand and cement renders are prone to cracking during the drying period, are very difficult to take off if complications occur and can be very uneven if they are applied by an inexperienced plasterer. Dryzone Express Replastering System cannot crack, can be removed if further renovations are required and, if desired, will always present a flat surface.
Most types of plasterboard are suitable to be used with the Dryzone Express Replastering System, including insulated plasterboard and foil-backed plasterboard. This gives the user a large amount of control over insulation properties, breathability and plasterboard thickness, the choices available to someone using sand and cement render are far more limited in this regard.
All choices regarding the type of system to use with any individual job, however, should be made with the advice of a professional. Certain jobs may be inappropriate for the Dryzone Express Replastering System, or for certain types of plasterboard. It is important to choose the correct materials and methods for each individual job.
Our technical team are able to advise on all types of damp-proofing systems and will be able to help you to specify the correct materials for the property you are working on. We can also put you in contact with independent surveyors or contractors to carry out the works to your specification.
Where to Get the Dryzone Express Replastering System Products
All the products mentioned in this article can be purchased directly from Safeguard Europe. Call on 01403 220120 to order by phone or order online at www.safeguardstore.co.uk. We have select international distributors, of which contact details are available upon request.
We are always available to answer any questions you may have regarding technical queries, shipping details or business enquiries. Just call us on 01403 220120.