Tips for Applying Plaster: Part 4
Vinyl Wallpaper, Paper Wallpaper, Fabric Wallpaper Gypsum Board Mortar, Concrete Existing Walls / Sand-Finished Walls, Fiber-Reinforced Walls, Kyoto-Style Earthen Walls Plywood, ParticleboardFor paper and fabric wallcoverings, the procedure for preparing the substrate is essentially the same as for vinyl wallcoverings.
The interiors of existing buildings—such as single-family homes, apartments, and stores—are almost always covered with vinyl wallpaper. You can tell the difference between vinyl, paper, and fabric wallpapers by spraying water on them with a spray bottle.
<If it doesn’t absorb water>◉ Vinyl wallpaper You can apply plaster over it. |
<If it absorbs water>◉ Paper or fabric wallpaper Please remove all the wallpaper. |
① If the surface is stained by cigarette smoke, incense, or mold, clean it with a neutral detergent or mold remover. |
② Press down with both hands to check whether the substrate beneath the wallpaper is sagging. |
③ If the substrate is sagging, secure it to the building structure by driving screws into it at 15–20 cm intervals. |
④ Check for any peeling areas, such as seams in the vinyl wallpaper. |
⑤ If there are any scratches or peeling areas, cut them off with a utility knife. |
⑥ Apply joint tape to the areas where the wallpaper has been cut or is peeling. |
⑦ Secure the joint tape with a staple gun. |
⑧ Secure the seams between the wallcovering panels with a staple gun as well. Space the staples approximately 15–20 cm apart. |
⑨ If any staples are sticking out, tap them down with a hammer or similar tool to securely fasten the wallpaper to the substrate. |
Tip! If paper or fabric wallpaper is peeling over a large area After removing the surface wallpaper, spray water on it to soften the backing paper, then slowly peel it off using a utility knife or metal scraper. |
In new construction and renovations, the substrate is almost always drywall, and a special installation method is used when applying a plaster finish. To create a plaster wall that is resistant to cracking, proper joint treatment and substrate preparation are of the utmost importance. Consult with a contractor or carpenter and have a professional handle the substrate preparation to ensure a wall that is crack-resistant and long-lasting.
◉ How to Install Drywall
Install the drywall using a “staggered pattern,” where the joints do not align. By avoiding aligned joints, you minimize movement when the boards expand or contract.
Since having a joint in the drywall align with the extension line of an opening can cause misalignment, cut the drywall to match the shape of the opening so that the joint does not fall along the extension line.
We recommend double-layering the drywall. Offset the joints of the top layer both vertically and horizontally relative to the bottom layer, apply adhesive over the entire surface, and secure it with staples or similar fasteners.
① Check to see if any screw heads are protruding. If they are, drive them in with a screwdriver. |
② Fill in the screw heads with spackle. |
③ Fill the seams between the boards with putty. |
④ Sand off any excess filler to remove unevenness and make the surface flat. |
⑤ Fill in the area with putty to eliminate all unevenness. |
⑥ Apply joint tape to the seams. |
⑦ Secure the joint tape with a staple gun. Space the staples approximately 15–20 cm apart. |
⑧ If any staples are sticking out, tap them in with a hammer or similar tool to secure them firmly. |
This is commonly seen in reinforced concrete (RC) structures, particularly on exposed concrete surfaces or where wallpaper has been removed. Any chipped areas or holes must be filled.
① For old walls, press down with both hands to check the wall’s strength and ensure it isn’t coming loose. |
② Use a damp cloth to remove any dirt, dust, or mold adhering to the mortar or concrete. |
③ Check for any chips or holes. |
④ If there are any missing sections or holes, fill them with putty. |
⑤ Sand down any excess putty to remove unevenness and make the surface smooth. |
Tip! If the wall is lifting during the strength check If the wall is lifting or sagging—as this can cause cracks or delamination—hire a professional to redo the substrate. |
These are commonly found in older homes. Since dirt on the walls can cause stains to seep through, be sure to apply a thorough coat of sealer before applying the plaster. In the case of severely deteriorated old walls, the old wall surface may peel away along with the plaster after application, resulting in cracks or the wall lifting.
① Spray water from a spray bottle near the edge of the wall to check the condition of the substrate. |
② Check for any areas where the wall is peeling or crumbling, such as in the corners. |
③ If there are any areas where the wall is peeling or crumbling, remove the affected sections using a metal putty knife or similar tool. |
④ Fill the areas where the wall has been removed or any holes with spackling compound. |
⑤ Scrape off any excess spackle to remove unevenness and make the surface smooth. |
Tip! If the substrate dissolves in water and turns into a gel-like substance either set it with wall adhesive, or moisten it by spraying water from a spray bottle and scrape it all off with a metal putty knife. |
Even if most of the substrate is drywall, plywood is often used for window frames. Since plywood tends to bleed, be sure to apply a thorough coat of sealer before applying plaster.
① Press down on the substrate with both hands to check for any sagging or lifting. |
② If the substrate flexes, the plaster is prone to cracking, so reinforce it by driving in screws. |
③ Unlike other substrates, apply sealer before securing the joints. |
④ Once the first coat of sealer has dried, apply another coat. Apply the sealer at least twice; three coats are recommended. |
⑤ Once the sealer is dry, use putty to fill in the screw heads and smooth the surface. |
⑥ Apply joint tape to all the seams in the plywood. |
⑦ To prevent the joint tape from peeling off while applying the plaster, secure it with a staple gun. Space the staples approximately 15–20 cm apart. |
⑧ If the stapler pins aren’t fully driven in, tap them in with a hammer or similar tool.
Tip! Secrets to a Beautiful Finish Since plywood and wood (baseboards) are highly prone to bleeding, thoroughly applying sealer to stop the bleeding is the most important step in preparing the surface. To achieve a beautiful plaster wall finish, be sure to apply the sealer at least twice, applying it thickly to ensure the bleeding is completely stopped. Even after applying multiple coats of sealer, the sap may not be completely sealed, depending on the plywood. |