Are your walls suffering from blistering, damp stains, peeling paint and salt efflorescence? When you search for a solution online, two products keep coming up: damp-proof paint and damp-proof plaster. They may sound similar, but what they actually do is completely different. The wrong choice means the same problem returns within a few months, worse than before. In this guide we clearly explain the difference between the two, which one really works and how a permanent solution to wall damp is achieved.
The short answer: paint covers, plaster solves
Damp-proof paint forms a thin film on the wall's surface and tries to keep water outside. But the source of wall damp is usually on the inside; rising damp travels upwards from the ground, while condensation collects on the surface. Moisture whose source has not been cut off becomes trapped behind the paint and, under pressure, blisters and peels it away. In other words, paint hides the problem but does not solve it.
Damp-proof plaster works on a different principle: thanks to its porous, breathable structure it allows the moisture in the wall to evaporate in a controlled way, while trapping harmful salt crystals within itself. This keeps the surface healthy, lets paint adhere and stops the stains from returning. In short, plaster manages the problem, while paint merely covers it over.
Damp-proof paint versus plaster: a comparison
| Feature | Damp-Proof Paint | Damp-Proof Plaster (HydroFix) |
|---|---|---|
| Function | Coats the surface | Manages moisture + restores the surface |
| Breathability | Low (forms a film) | High (porous structure) |
| Salt efflorescence | Builds up behind it and lifts the paint | Traps it within itself |
| Durability | Months, if the source continues | Permanent (once the source is cut off) |
| Application layer | Decorative top coat | Load-bearing intermediate layer |
So is damp-proof paint never used?
It is — but not on its own. Paint is the very last and most decorative step of the process. Once the source of the moisture has been cut off and the surface has been restored with a breathable plaster, a breathable interior paint can be chosen as the top coat. If you reverse the order (paint first), both money and effort go to waste.
The permanent solution for wall damp: the right 2-step order
1. Cut off the source of the moisture
If the problem is rising damp (moisture that climbs from the base and concentrates in the lower 1–1.5 metres of the wall), no matter what you do to the surface, the source continues. This is where the DampStop injection barrier comes in: injected through holes drilled into the wall, it stops the capillary rise of moisture with a chemical barrier. You can find out whether the damp really is rising damp in our what is rising damp article and on our Triple System page.
2. Restore the surface with a breathable plaster
Once the source has been cut off, HydroFix Damp-Proofing Plaster is applied so that the moisture remaining in the wall is released in a healthy way. This two-component, polymer-reinforced, cement-based plaster breathes thanks to its porous structure, traps salt and ensures that the paint applied over it lasts. For application details, take a look at our how to apply HydroFix guide.
How much material do you need?
To estimate the quantity you need, measure your wall area. If you are not sure, fill out our Request a Quote form and our technical team will recommend the right product and quantity for your specific structure.
Conclusion
Damp-proof paint and damp-proof plaster are not alternatives to one another — they are different layers of the same solution. For a lasting result the order is clear: first cut off the source of the moisture (DampStop), then restore the surface with a breathable plaster (HydroFix) and finally apply the decorative paint. Painting alone does no more than postpone the problem by a few months. For a root-and-branch solution to the damp in your walls, get in touch with us.
Looking for a permanent solution to your damp problem?
Dry your walls out for good with HydroFix and DampStop.