Rising Damp Repairs: The Complete Methodology

I thought it would be useful to follow up on my earlier blog about rising damp repairs, because there is often a fundamental misunderstanding about the precise methodology that must be followed to ensure a good and lasting solution.

Recently, I was in touch with a long-time home improvement client also in Ekurhuleni, with a rising damp problem and, who believed that simply installing waterproofing rods would be enough to fix the problem. Despite my efforts to explain the full scope of what needed to be done, she remained fixated on the notion that the rods alone would resolve the issue.

That, however, is simply not the case.

In this blog, I will walk through the exact steps that must be taken to ensure any damp treatment process is truly effective. We will cover the critical aspects I discussed in the earlier blog and then drill down into the precise methodology for removing contaminated plaster and the correct replastering process – including what additives should be mixed into the mortar to guarantee a thorough, lasting job.

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Why Rods Alone Are Not Enough

Let me be clear: damp-proofing rods – such as the popular Dryrod system – can be an effective component of a rising damp treatment. They are designed to be inserted into drilled holes along a mortar course, where they slowly release a silane concentrate that penetrates the surrounding masonry and creates a water-repellent barrier. Some manufacturers even claim their rods outperform injection creams.

However – and this is a critical "however" – the rods are only one part of a multi-stage process. They address the cause of the damp (the absence or failure of a damp-proof course), but they do nothing to address the effects already present in the wall. Those effects include:

1. Salt contamination – The plaster and masonry have absorbed hygroscopic salts from the groundwater over years or decades. These salts attract moisture from the air and will continue to do so even after a new DPC is installed. 

2. Damaged plaster – The existing plaster has been physically weakened by salt crystallisation and moisture expansion.

3. Active moisture – The wall itself remains wet and needs time to dry out.

If you install rods (or any DPC) and simply replaster over the old, contaminated plaster, the salts will continue to migrate to the surface. You will see salt bloom (efflorescence), peeling paint, and eventually, the damp will appear to have returned – even though the DPC is working perfectly.

In short: the DPC stops new moisture from rising. But the old moisture and salts are still there, and they must be removed.

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The Complete Rising Damp Remediation Process

British Standard BS 6576:2005+A1:2012 (strange enough, it's the only industry standard that I could come across and, therefore, reference in my research for this iteration of the Blog on rising damp repairs process) provides the code of practice for diagnosing and treating rising damp in existing buildings. The standard emphasises the need to differentiate between rising damp and other causes of damp conditions before any treatment begins. Once rising damp has been confirmed, the following steps are essential.

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Step 1: Confirm It's Rising Damp

Before any work begins, proper diagnosis is critical. Rising damp is often confused with penetrating damp, condensation, or plumbing leaks. A thorough inspection should identify:

• Tide marks on walls rising no higher than approximately 1.2 metres.
• White, powdery salt deposits (efflorescence).
• Peeling or blistering paint near floor level.
• Rotting skirting boards.
• A persistent musty odour.

If you are unsure, engage a professional. Treating the wrong problem wastes time and money.

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Step 2: Remove All Contaminated Plaster

This step is non-negotiable.

All salt-laden plaster must be hacked off the wall – and I mean all of it. The industry standard, as specified in BS 6576, requires removing plaster to a height of 300mm above the highest visible tide mark – or to a minimum of 1 metre above the floor line, whichever is higher.

Why so high? Because salts can migrate upward through the plaster well beyond the visible damp line. If you leave even a strip of contaminated plaster, those salts will continue to attract moisture and ruin your new finish.

Take down skirting boards, architraves, and any other fixtures that might be in the way. The wall must be stripped back to bare brick or stone.

Well, I know – stripping off plaster, especially interior plaster, is messy. And I know my client (which is why her name has been withheld in this blog) is a smart and tidy lady who is not prepared to tolerate mess in her space. But unfortunately, there is simply no other way to fix this problem except through the full process I have tried to explain here. No shortcuts. No half-measures. Just the correct, proven methodology.

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Step 3: Install the New Damp-Proof Course

With the wall exposed, it is time to install the new DPC. This can be done using:

• Chemical injection cream – Holes are drilled along a horizontal mortar course, typically 100–120mm apart, and a silane/siloxane cream is injected under low pressure. The cream spreads through the masonry and cures to form a waterproof barrier.

• Damp-proofing rods – Similar holes are drilled and the rods are inserted. They slowly release their active ingredients into the surrounding masonry.

Whichever method you choose, follow the manufacturer's specifications precisely. The success of the treatment depends on correct diagnosis, suitable wall conditions, and proper follow-up treatment.

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Step 4: Allow the Wall to Dry

This is where many jobs go wrong.

After the new DPC is installed, the wall needs time to dry out. Ideally, the new plaster should be applied to surface-dry walls. In any case, a drying period of at least 14 days should be allowed between the installation of the DPC and replastering, wherever possible.

During this period, moisture trapped in the masonry will evaporate. If you replaster too soon, you will trap that moisture behind the new render, leading to failure.

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Step 5: Replaster with Salt-Retardant Render

Once the wall is sufficiently dry, it is time to replaster. This is not the time for ordinary plaster.

Standard gypsum plasters – such as Carlite – should not be used on walls that have been affected by rising damp. Instead, you must use a salt-retardant render – a sand-cement mix that has been formulated to resist the migration of salts.

The render should be applied to a height of at least 300mm above the highest level of salt contamination and to a minimum of one metre above the floor line.

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Step 6: Use the Right Additives

To ensure the render performs as intended, you must add the correct additives to the mix.

Coprox Cement Additive is an excellent primary waterproofing additive that, when mixed with mortar, screed, or plaster, prevents rising, falling, and penetrating damp. It reduces water absorption and stops salt formation on finished surfaces.

Renderguard Gold is another high-specification salt-neutraliser and waterproofing additive specifically designed for replastering after rising damp treatment. It instils salt-retardant and waterproofing properties into the render.

Permaproof and similar products also provide the necessary waterproofing and salt-retardant properties.

The general mix ratio for a salt-retardant render is 3 parts sand to 1 part cement (preferably sulphate-resisting cement. There are a few options available locally but, I won't give them free advertising space on my channel), using gauging water that contains the chosen additive.

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Step 7: Apply the Render Correctly

The render should be applied in two coats:

1. First coat (scratch coat) – A relatively thin coat (around 10–12mm) is applied and scratched to provide a key for the second coat. This coat contains the salt-retardant additive.

2. Second coat (float coat) – Once the first coat has cured, the second coat (around 10–12mm) is applied and floated to a smooth finish.

Some systems, such as Renderguard Gold, are specifically designed for use in the first render coat to help prevent common post-treatment failures such as salt bloom or the reappearance of damp patches.

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Step 8: Finish with Breathable Paint

Finally, do not use standard emulsion paint. It will trap moisture and fail. Instead, use a breathable, moisture-resistant paint that allows the wall to continue releasing any residual moisture without compromising the finish.

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Why This Matters

My client who believed rods alone would fix her problem was not alone in that misconception. Many homeowners – and even some tradespeople – underestimate the importance of the full remediation process.

The reality is this: the DPC stops the rising water. The plaster removal and salt-retardant render deal with the legacy of that water. Both are essential.

If you skip the plaster removal, you are leaving a time bomb in your wall. Those salts will continue to attract moisture, and within months or years, the damp will appear to have returned. You will have spent money on a treatment that technically worked – but your walls will still look damp.

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Final Thoughts

Rising damp is not a mystery. It is a predictable process with a well-established solution. But that solution is not a single product – it is a system of steps that must be followed in sequence:

1. Confirm it is rising damp.

2. Remove all contaminated plaster.

3. Install a new DPC (rods or chemical injection).

4. Allow the wall to dry (minimum 14 days).

5. Replaster with a salt-retardant render containing the correct additives.

6. Finish with breathable paint.

If you follow these steps, your walls will be dry – and they will stay dry.

If you take shortcuts, you will be back to square one within a few years.

The choice is yours. But for my part, I will continue to do the job properly – every single time.

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