Wallpaper not sticking to wall

Wallpapering over anti-mould or moisture-resistant paint often fails because these paints are designed to be slick, non-porous, and water-resistant—the opposite of what wallpaper paste needs to stick.

the mould needs completely eradicating prior to applying wallpaper.

You must take down the sections that are bubbling or not sticking, as the bond is already compromised.
Abrade the Surface: Lightly sand the entire wall with 120-grit sandpaper. This "keys" the surface, breaking the water-repellent seal and creating a texture for the adhesive to grip.

Before wallpapering over mold-resistant paint, make sure the wall is clean, dry, and free of any mold or dust. Lightly sand the painted surface to create a better grip, then apply a good-quality wallpaper primer or sizing. This will help the wallpaper adhesive stick properly and prevent bubbling. If the paint is very smooth or glossy, this step is especially important.

To wallpaper over mold-prone paint, you need to first address the mold issue and prepare the wall properly for a stable adhesive surface. Treat the wall with a mold-killing solution, remove any loose paint, and then apply a wall sealer or wallpaper primer. Finally, use a high-quality wallpaper paste and smooth out any bubbles or wrinkles during application.
Here's a more detailed breakdown:
1. Address the Mold:
Treat the mold: Use a mold-killing solution and ensure it's fully dry before proceeding.
Remove loose paint: Scrape off any loose or cracking paint to create a smooth, clean surface.
2. Prepare the Wall:
Sand the surface: Sand the wall to create a smooth surface for better adhesion.
Apply a primer: Use a wall sealer or wallpaper primer (like Zinsser Gardz) to create a stable, adhesive-friendly surface.
Consider lining paper: Hanging lining paper can help prevent the wallpaper from shrinking and create a more consistent surface, especially if the walls have imperfections or have had previous paint.
3. Hang the Wallpaper:
Use high-quality paste:
Ensure you use a paste specifically designed for the type of wallpaper you're using.
Smooth out bubbles and wrinkles:
Use a wallpaper smoother to eliminate air bubbles and wrinkles for a professional finish.
Important Considerations:
Anti-condensation wallpaper and paste:
In damp areas, consider using anti-condensation wallpaper and an anti-mould wallpaper paste to further prevent mold growth.
Moisture:
If the walls are particularly damp, use a dehumidifier to remove excess moisture before wallpapering.
Strong adhesive:
In damp areas, use a strong adhesive to ensure the wallpaper stays in place.
By following these steps, you can successfully wallpaper over walls with mold-prone paint and create a beautiful, lasting finish

Remove Loose Wallpaper

If the wallpaper isn’t sticking, take it down before proceeding.

Lightly Sand the Wall

Use 120–180 grit sandpaper to break the paint’s sealed surface and create a rougher texture for the adhesive to grip.

Wipe off dust with a damp cloth and let dry.

Apply a Primer or Sealer (Essential Step!)

Best option: Use a wallpaper-specific primer like Zinsser Gardz or Beeline Primer Sealer. These help the paste adhere properly.

Alternative: If you don’t have a primer, a thin layer of diluted wallpaper paste (a “size coat”) can work. Let it dry completely before wallpapering.

Use the Right Paste

Ensure you’re using a high-strength wallpaper adhesive

If using paste-the-wall wallpaper, make sure the wall is fully prepped as above.

Smooth Down Bubbles While Hanging

Use a wallpaper brush or smoother to push out air pockets.

If bubbles appear as it dries, they may shrink back, but persistent ones may need a small pinprick to release trapped air.

The best approach is to properly treat the mould and prepare the wall surface before attempting to wallpaper again. Here's what you should do:

1. Use a mould remover or a solution of one part bleach to three parts water.
2. Apply a mould-resistant primer or Zinsser BIN/Mold-resistant paint to prevent future growth.
3. Sand down any rough areas caused by mould damage or peeling paint.
4. Regular wallpaper adhesive may not work well on previously painted or mould-affected walls.
5. If the wall is still absorbent, apply a wallpaper sizing solution before hanging.

To successfully wallpaper over a wall with moldy, poorly adhering paint, you need to properly prepare the surface first. Start by cleaning the affected area with a mixture of water and white vinegar or a diluted bleach solution to kill any mold spores, then let it dry completely. Scrape off any loose or flaking paint and sand the surface smooth to create a stable base. If the wall has cracks or holes, fill them with wall filler and sand again once dry. Apply a mold-resistant primer or wall sealer to ensure proper adhesion before attempting to hang the wallpaper again. This will help prevent bubbling.

Wallpapering over a mold-affected wall can lead to issues like bubbling, poor adhesion, and mold growth underneath the wallpaper. To address this effectively and ensure a smooth, long-lasting finish, follow these steps:
Step 1: Identify and Eliminate the Mold Source

Locate the cause: Mold often develops due to moisture or poor ventilation. Address the underlying issue by fixing leaks, improving ventilation, or using a dehumidifier. Without resolving the source of moisture, mold will return.
Kill the mold: Use a mold-killing solution (e.g., a mixture of 1 part bleach to 4 parts water or a commercial mold remover). Apply it to the affected area and let it sit for 15-20 minutes before scrubbing and rinsing with clean water. Allow the wall to dry thoroughly.

Step 2: Prepare the Wall

Remove the existing wallpaper or peeling paint:
Scrape off loose paint and clean the wall thoroughly.
If there are remnants of wallpaper adhesive, use a wallpaper stripper to remove it.
Sand the wall:
Lightly sand any uneven areas to create a smooth surface for the wallpaper.
Focus on areas where the mold course paint might have created a rough texture.
Apply a stain-blocking primer:
Use a mold-resistant or stain-blocking primer to seal the surface and prevent moisture or mold from seeping through. This will also help the wallpaper adhesive bond properly to the wall.

Step 3: Test Adhesion

Before proceeding with wallpapering the entire wall, test the adhesive by applying a small strip of wallpaper. If it adheres well without bubbling, you’re ready to move forward.

Step 4: Use the Right Adhesive

Use a high-quality wallpaper adhesive designed for challenging surfaces. For vinyl wallpaper, use a heavy-duty adhesive.
Apply the adhesive evenly, ensuring no dry patches are left that could cause bubbling.

Step 5: Wallpaper Application

Hang the wallpaper:
Apply the wallpaper from top to bottom, smoothing it out as you go with a wallpaper brush or smoothing tool to remove air bubbles.
Pay attention to edges:
Press firmly along the edges to ensure they adhere properly.
Trim excess:
Use a sharp blade or utility knife to trim excess wallpaper at the edges for a clean finish.

Step 6: Monitor for Issues

Check for bubbles as the wallpaper dries. Small bubbles may disappear on their own, but larger ones can be pricked with a pin and smoothed out.

Important Tips:

Avoid wallpapering directly over mold: Mold can continue to grow under the wallpaper if not fully treated and removed.
Choose breathable wallpaper: Non-vinyl or breathable wallpapers can help prevent moisture buildup.
Ventilate the area: Ensure the room is well-ventilated during and after wallpapering to prevent humidity from becoming trapped.

By thoroughly addressing the mold and preparing the wall properly, you’ll create a clean surface that allows the wallpaper to adhere well and avoid bubbling.

Wallpapering over a wall that has been treated with mould-resistant paint can be challenging because these paints often have a water-repellent or semi-gloss finish, which can prevent adhesive from bonding properly. The bubbling you’re experiencing is likely due to poor adhesion.

Steps to Fix the Issue:

1. Remove Existing Wallpaper:

Strip off any wallpaper that has bubbled or failed to stick properly.

Clean the wall thoroughly to remove any adhesive residue.

2. Prepare the Wall Surface:

Clean the Wall: Wipe the wall with a damp cloth and mild detergent to remove any dirt, grease, or mold residue.

Sand the Surface: Lightly sand the painted wall using fine-grit sandpaper (120–180 grit) to create a keyed surface that helps adhesive bond better.

Fill Any Imperfections: Use filler to patch cracks or holes, then sand smooth when dry.

3. Seal the Wall:

Apply a wallpaper primer/sealer (also called size) to create a uniform, adhesive-friendly surface.

A product like Zinsser Gardz or Beeline Primer Sealer works well to seal porous or painted surfaces.

Allow the primer to dry completely before proceeding.

4. Use the Right Adhesive:

Use a high-quality, heavy-duty wallpaper adhesive, especially if the wallpaper is thick or textured.

For difficult surfaces, consider a vinyl-to-vinyl adhesive if standard adhesive still struggles to bond.

5. Apply Wallpaper Carefully:

Smooth each section with a wallpaper smoother or brush to remove air bubbles as you go.

Pay special attention to edges and seams, ensuring they are well adhered.

6. Ventilation and Drying Time:

Ensure the room is well-ventilated to aid in drying and prevent further moisture buildup that could cause bubbling.

Final Tips:

If mould was present before, double-check for hidden dampness behind the paint, as trapped moisture can cause adhesion problems and bubbling.

If the problem persists, you may need to consider stripping the wall entirely, applying a liner paper, and then wallpapering over the liner for better adhesion.

Personally I would not wallpaper over mould until you have corrected the cause of the mould once you have done this I would then stain block the area with mould treated stain block then put the wallpaper on. If you don’t do this before putting wallpaper on you may get the mould come through the paper.

Bubbling paint over wallpaper can be frustrating, but there are steps you can take to address the issue:

Assess the Damage: Identify the extent of the bubbling. If it's localized, you may be able to fix just those areas.
Let It Dry: If the paint is still wet, allow it to dry completely. Sometimes, bubbles can resolve themselves as the paint dries.
Puncture the Bubbles: If the bubbles persist after drying, use a fine needle or pin to gently puncture the bubbles. Be careful not to tear the wallpaper underneath.
Smooth the Area: After puncturing, press down on the bubble with a clean cloth or your finger to remove excess air and flatten the area.
Apply Adhesive: If you notice that the wallpaper is loose, use a wallpaper adhesive or a mixture of water and wallpaper paste to apply a small amount under the bubble. Use a putty knife or a small brush to spread it evenly.
Repaint: Once the adhesive has dried and the area is smooth, you can repaint over it. Make sure to use a paint that is compatible with the wallpaper.
Consider Removal: If the bubbling is extensive or the wallpaper is in poor condition, it may be best to remove the wallpaper entirely before repainting.
Prevent Future Issues: For future projects, consider using a primer designed for wallpaper before painting to help prevent bubbling and ensure better adhesion.
If you’re unsure or the problem persists, it may be worth consulting a professional for assistance.

To wallpaper over mold-prone paint, first treat the wall with a mold-killing solution and let it dry completely. Scrape off loose paint and sand the surface smooth. Apply a wall sealer or wallpaper primer (e.g., Zinsser Gardz) to create a stable, adhesive-friendly surface. Use high-quality wallpaper paste and smooth out bubbles with a wallpaper smoother during application.

The issue is likely the mould-resistant paint creating a non-porous (not allowing liquid or air to pass through) surface. Here’s what to do:

1. Prepare the surface: Sand the painted wall to create a better base for the adhesive. Clean off any dust.
2. Apply a primer: Use a wallpaper primer to improve adhesion.
3. Check adhesive: Use a heavy-duty wallpaper paste suitable for non-porous surfaces.

If the bubbling continues, it may indicate moisture or underlying wall issues that need addressing before wallpapering.