Anatomy of a DPC Cream – What makes Dryzone superior?
Forty years at the forefront of research and development in chemical DPCs have resulted in Dryzone Damp-Proofing Cream and Dryrod Damp-Proofing Rods. These silane/siloxane-based treatments are the most flexible and effective chemical rising damp treatments on the market today.
To truly understand their benefits, we must delve into the composition of DPC creams currently on the market. Only then can we see why Dryzone is the best.
How do DPC Creams work?
Silicone-based chemical Damp-proof courses (DPCs) work by diffusing into the pores of bricks and mortar. Once the active ingredient of the DPC has diffused into the wall, it chemically reacts with the minerals inside to form hydrophobic chains of molecules. With the correct amount of the right chemical, an unbroken DPC can be established across the whole length of the wall.
A hydrophobic barrier placed 150mm above ground level stops groundwater rising up through the ground via capillary action to cause rising damp. The 150mm rule is the best practice (according to Building Regulations Approved Document C) to prevent wind-driven rain splashing over the damp-proof course.
What is Silane?
A silane molecule
Silanes are members of the silicone family with very small molecules. Their size means that they can penetrate deeply into brick. Once inside, an alkaline environment (such as a mortar with portland cement) catalyses the transformation from silane to silanol. These silanol polymers then condense into polysiloxanes, where they bond to the surfaces of mortar pores. Once the bond has been formed, the surface becomes water-repellent.
In older brick walls bonded with non-alkaline mortar, pure silane cures into polysiloxane slowly. In walls with high alkalinity levels, there is a risk that silane-only treatments cure faster than they spread – resulting in a weak chemical DPC.
This means silane alone struggles to spread effectively enough to form a continuous chemical DPC.
What is Siloxane?
Siloxane (commonly known as silicone) is known for its low surface tension, high stability and ability to provide a low-adhesion surface. You probably use siloxanes in day-to-day life; they’re common ingredients of shampoos and conditioners. In the world of damp-proofing, siloxane polymers form the basis of the cream vehicle that carries silane into the pores of mortar. Siloxane can perform in walls with high and low alkalinities. However, it lacks the spreading power of silane.
Silane/Siloxane – the optimal team for chemical damp-proofing
A formulated balance of silane and siloxane increases the mortar compatibility of silane while maintaining its hydrophobic qualities.
In independent testing that measured the spread and effectiveness of injection products to stop rising damp in walls, silicone cream worked at 90% efficiency for spread and effectiveness. (from “Can a Wet Wall be Injected in an Effective Way?” by B. Lubelli, R.P.J. van Hees and A. Hacquebord in Hydrophobe VI, 2011)
In independent testing that measured the performance of the spread of different silane mixes (from “Reactive Transport of Silanes in Cement Based Materials” by Oehmichen, Gerdes and Wefer-Roehl in Hydrophobe V), the increase of surface tension in silane/siloxane injected into cement-based mortar resulted in further and faster spread. It is this quality that could lead to a stronger chemical damp-proof course.
In the German advisory board WTA (Wissenschaftlich-Technische Arbeitsgemeinschaft)’s advice on the water repellent treatment of porous materials, the advantages and disadvantages of each silicone-based Rising Damp treatment were outlined.
Cream-based silicone compounds (like silane/siloxane mixtures) had the longest list of advantages:
✅ High concentration
✅ Precise application
✅ Long contact time
✅ Defined applied quantity of hydrophobic component
Dryzone Damp-Proofing Cream was tested by the WTA as a rising damp treatment in highly saturated walls of up to 95% with alkaline lime-based mortar. It was proven to dry wet walls and keep water ingress at bay. Dryzone Cream surpassed the pass requirement of the standards set by these German regulations.
In 2000, Safeguard Europe pioneered silane/siloxane blends with Dryzone DPC Cream, and further refined their efficiency with Dryrod Damp-Proofing Rods. Let’s dig into that unique silane/siloxane formulation to find out why it works so well.
High strength is best
When considering a chemical damp-proof course, always ensure that the cream is a high-strength silane/siloxane formulation.
When comparing Damp-proofing Cream strengths, there are 2 separate elements to consider:
- The overall strength of the active ingredient in the wider formulation
- The composition of the active ingredient itself
A 100% active silane formulation inhibits the formulation’s ability to cure – leading to compatibility issues with pre-1940 housing stock. Conversely, a predominantly siloxane solution will struggle to effectively waterproof between injection points, leading to DPC failure and rising damp.
Only high amounts of the correct blend of silane/siloxane can establish a strong and resilient chemical damp-proof course.
The false economy of low-strength silane/siloxane creams
We have successfully identified the silane/siloxane blend as the best chemical composition for an effective remedial DPC. The market agrees – since Dryzone blazed a trail in 2000, silane/siloxane creams have become the preferred choice of damp-proofing contractors worldwide.
The Dryzone formulation of 63% silane/siloxane (by weight) has been expertly calculated for maximum spread and performance across all ages and types of property. Since then, lower-strength competitor creams have been brought to market. They seem to have the edge on price, although performance is much to be desired.
There are low-strength products on the market that contain only around 15-20% active ingredient and yet pass BBA certification. Although these products tend to cure slowly and spread throughout the wall well, they may struggle to establish a strong damp-proof course in saturated environments like Dryzone is proven to (as per WTA testing).
Low-strength silane/siloxane creams tend to cure slowly and spread throughout the wall. However, they lack the strength to successfully establish a chemical DPC.
Brick "burgers", showing saturation levels in high active ingredient, low active ingredient and no DPC treatment
The University of Portsmouth produced a report on DPC Cream effectiveness. They pitted Dryzone against competitor products that contained 15-20% (per weight) active ingredient. Researchers prepared five lime mortar ‘burgers’, each with a hole in the centre. After 4 weeks left to dry, each mortar piece was injected with one of the DPC treatments. They were left to cure for a further month. After regular measuring by weight to check water absorption, each ‘burger’ was split in two to reveal the extent of the waterproof zone. Their research found that low-strength creams caused the brick to gain up to 14% in weight. Dryzone weight increase topped out at 4%. This significant difference in weight proves that low-strength silane/siloxane creams are ineffective at stopping rising damp.
Independent figures (From “Silane Emulsions as Masonry Water Repellents” by Dr Michael Wilson, published in “Silicones in Coatings Conference Papers”, 1996) on water repellency versus active ingredient concentration in “Mortar Water Sealers” found that higher strength concentration damp-proofing creams reduce weight gain through water absorption. Not only that, but high-strength creams performed higher amounts of reduced weight gain as the experiment scaled up from 2” mortar cubes to 4” mortar cubes.
Only high amounts of the correct blend of silane/siloxane can establish a strong and resilient chemical damp-proof course. That’s why Dryzone Damp-proofing Cream is the optimal choice for anyone who needs to establish a remedial chemical damp-proof course.
Damp-Proof Courses: The Next Generation
Safeguard Europe is continually focused on innovation and improvement for the built environment. Dryzone damp-proofing creams have been tested around the world. We believe that they’re the best-tested DPC cream on the market. Time and time again they’ve withstood the best that the world’s scientists have thrown at them. We understand you’re attached to damp-proofing creams. Back in the 1990s, the damp-proofing industry swore by dangerous solvent-based liquids.
Let us introduce Dryrod Damp-Proofing Rods.
We’ve optimised the Dryzone silane/siloxane formulation into a unique and user-friendly format that makes establishing a strong chemical Damp-Proof Course quicker and easier than ever before.
In rigorous laboratory tests, Dryrod Damp-Proofing Rods have been proven to outperform all tested competitor damp-proofing creams. They perform in a wide range of wall conditions:
- Saturated walls (up to 95%)
- Low and high alkalinity mortar
- Low and high porosity mortar
- Lime-based or cement-based mortar