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Can You Put Plaster Over Damp Surface (Walls/Paint/Bonding)? (How To)

Damp surfaces are common in homes. Dampness can make the property unwelcoming, unhealthy and be a perfect breeding zone for mold. Plaster is a great option to consider when you have a damp surface. This section will guide you if you have a wet surface and are wondering if you can plaster it.

Generally, you can put plaster over a damp surface, but you have to treat the surface first. Remove the damp surface, treat the surface, and then apply a fresh plaster layer. Your new plaster will last when you solve the underlying damp issue first.

Old wall with dirt and stain

Plaster is a durable and robust finish that adds to your house’s elegance. Plastering works well on interior and exterior walls, but inspection is needed before starting the process. For instance, if the walls are damp, you need to understand the source of dampness before you decide to re-plaster. You should seal the source entirely so it doesn’t persist and damage your new plaster coat.

Should You Put Plaster Over Damp Surface (Walls/Paint/Bonding)?

Putting plaster on the wall

Plaster is an excellent house finishing option and can work well over dump surfaces. However, plaster should only be the last step after a series of activities involving examining the damp area, treating it, and sealing well before plaster. This section discusses the main problems to look out for before putting plaster on a wet wall or paint.

Plaster is porous and easily allows moisture in. Look for the primary source of dampness in your property. It could be faulty plumbing, leaking gutters, downpipes, small gutters, or poor insulation. Stop the sources, and apply your new plaster well. The new plaster coat should not leave any cracks.

Plaster can last for years but can also be damaged easily, thanks to its porous nature. Expert plastering is required on damp surfaces to ensure the existing moisture does not cross over to the new plaster. When applying plaster on wet surface/paint, carefully clean the surface to remove anything that may cause dampness to your new plaster.

Dampness in properties may be caused by faulty plumbing, leaking gutters, poor insulation, and condensation. Plastering can only last long when the surface is clean and free from moisture. Seal any moisture source, treat, and only apply plaster on a clean, damp-free surface.

Plaster installation can be complex when the surface is damp, so expert input is needed. Proper installation ensures the new plaster does not bulge, crack, or bubble. A plastering professional should carefully clean your wall, mix the plaster mixture well and gently apply it.

What Tools Do You Need To Put Plaster Over Damp Surface (Walls/Paint/Bonding)?

tools for plaster

You may require multiple tools to apply plaster over a damp surface effectively. Some tools remove the original wet surface, while the rest apply the new plaster. You can readily find the tools at your nearby home improvement store or online.

Plastering over a damp surface requires a paint scraper, mold remover, sealant, utility knife, window and finishing trowels, mortar stand, brush, and a plaster coat. Other helpful tools are a spackle knife and a bucket.

A paint scrapper removes your old paint/plaster before you apply the new one. A mold remover should eliminate the moldy patches and give your surface a newer look. A damp sealant is used explicitly on wet surfaces to protect them against possible future dampness.

A utility knife helps remove damp surfaces in areas with cracks. It removes debris and other particles for easy sealing and plastering. A finishing trowel helps create a smooth surface when plastering, while a window trowel is for plastering along the windows.

A brush facilitates the cleaning when you are done with the process, while a plaster coat polishes the surface and makes it waterproof. Ensure you have all required tools at least a day before the plaster project commences to save time.

What Preparations Do You Need To Put Plaster Over Damp Surface (Walls/Paint/Bonding)?

Putting plaster on the wall

Plaster is durable and can leave your house looking elegant for a long time. However, the plastering results heavily rely on your preparations before the actual process. This section discusses the main things you should do to make your process easier and improve the project’s success.

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Get the necessary tools and keep them clean. Remove any objects like baseboards and wallpapers from the surface. Dry the surface for at least one week before plastering and seal any cracks.

Getting the right tools is the key preparation step for plastering. You need to ensure you have everything, so you don’t break from work to find the tools. Clean the tools to get rid of debris or mud from the previous project. Existing dirt on tools may sometimes reduce the efficiency of your new plaster.

Once you gather tools, remove baseboards, wallpapers, and paintings on the damp surface. Ensure the surface is dry. Depending on the level of dampness, you may use a humidifier or fan for drying. The key is to ensure the surface is dry before plaster, so you should leave the surface for at least a week before the actual plaster day.

Fix any holes or cracks on the damp surface once it’s dry. Cracks, especially when they are big, may be hideouts for insects and can allow moisture in. Use your scrap knife to clean them, and fill them before the plastering day.

Damp is the main setback for a plaster project. Ensure the surface has no dampness before plaster. You may schedule an inspection for moisture testing if you need clarification on the damp condition. When putting a plaster on damp surfaces, preparation takes time, but the step increases the plaster’s success rate.

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How to Put Plaster over Damp Surface (Walls/Paint/Bonding)

confused man standing

Putting plaster over a damp surface is a straightforward process once your remove damp, block its source, clean and treat the surface. Here is a step-by-step guide on applying plaster over a damp surface.

Step 1: Prepare the surface by confirming that no debris, particles, or dirt is present. Confirm that the surface doesn’t contain moisture.

Step 2: Apply PVA to seal any small holes and cracks. PVA will also ensure the surface dries out equally ahead of the plaster application.

Step 3: Mix plaster in a bucket. Follow the manufacturer’s instructions on mixing cement for plaster, and wear protective clothing. The right plaster solution should be thick, with no lumps or visible particles.

Step 4: Apply plaster on the surface. Scoop plaster from your mixing bucket, use your trowel and distribute it evenly on the surface. 

Step 5: Polish your plaster. Chances are your first layer of plaster will develop small bumps after thirty minutes. Use your trowel to smoothen the applied plaster to ensure its smooth and evenly distributed across the surface.

Step 6: Apply a second plaster coat. This step is optional, and the cement should be slightly thinner than the first.

Step 7: Polish, paint, and clean. Polish your plaster to ensure all edges are equal. When the plaster dries, you can decide to paint it. Clean the surface when done.

Putting plaster over a damp surface is straightforward with the right tools. Clean the surface, mix the plaster well, and carefully apply it on the surface. Avoid excessive pressure when polishing your plaster.

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