Damp proof courses (DPCs) are essential barriers preventing moisture from rising through walls and floors. They protect buildings from structural damage, decay and health hazards linked with dampness. DPCs come in various forms like physical barriers and chemical treatments.
What Are the Key Differences in Applying a Damp Proof Course to Internal vs External Walls?
Applying a DPC to internal and external walls requires different approaches.
Internal walls
- Often involves removing plaster to access the masonry
- May require careful consideration of interior finishes and fixtures
- Typically uses less invasive methods to minimise disruption
External walls
- Allows for easier access but may be affected by weather conditions
- Often involves drilling from the outside, which can be more straightforward
- May require consideration of external renders or cladding
Both applications need careful assessment of wall thickness and composition. Internal applications often focus on minimal visual impact, while external applications prioritise weatherproofing.
How Do DPC Liquid Products Compare to Chemical Injection Methods for Effectiveness?
DPC liquid products and chemical injection methods aim to create an effective moisture barrier but differ in performance. DPC liquids consist of silicone-based formulations that create a water-repellent barrier. They are easier to apply, offer uniform coverage and work by penetrating the masonry to create a continuous waterproof barrier.
Chemical injection, or damp proof course injection, involves cream-based or pressurised liquid solutions that are injected into pre-drilled holes. The active ingredients penetrate the masonry through several spaced injection points, spreading to form a continuous barrier. This method effectively treats thick walls or areas with severe rising dampness.
DPC liquids often work best in regular coursed brickwork and smaller areas requiring treatment. They're effective in situations where minimal disruption is desired. Chemical injection methods offer improved penetration in dense materials and irregular stonework.
What Are the Best Methods for Ensuring Proper Curing of a Liquid DPC After Application?
To ensure proper curing of a liquid DPC, think about the following best practices.
- Maintain appropriate temperature and humidity levels during curing. Extreme conditions may affect the chemical reactions necessary for proper curing
- Protect the treated area from rain or excessive moisture. Even small amounts of water can disrupt the curing process
- Allow adequate ventilation to aid the drying process. Good airflow helps remove excess moisture and promotes even curing
- Avoid disturbing the treated area during the curing period. Any physical interference can create weak points in the DPC
- Consider using temporary barriers to prevent premature exposure to moisture. These offer an extra layer of protection during the crucial curing phase
What Are the Potential Risks of Applying a New Damp Proofing Solution Over a Failed DPC?
Applying new damp proofing over a failed DPC can lead to several issues. It may trap moisture between the old and new barriers, provoking the dampness problem. This can cause further structural damage and promote mould growth.
The new solution might need to adhere properly to the failed DPC, limiting its effectiveness. It's crucial to remove or properly treat the failed DPC before applying a new one.
How Long Does a Damp Proof Course Last?
The lifespan of a DPC varies depending on several factors.
- Quality of materials and installation
- Environmental conditions
- Building maintenance
- Type of DPC (physical or chemical)
Generally, a well-installed physical DPC can last the lifetime of the building. Chemical DPCs may need reapplication after 20-30 years.