Repair And Paint Sash Windows: A Step-By-Step Guide

Sash windows are a charming feature of many older homes, but they can be high-maintenance. Sash windows consist of one or more movable panels, known as sashes, framed in wood and operating by sliding vertically or horizontally. Over time, these windows may become difficult to operate or develop drafts that reduce energy efficiency.

This guide will provide a comprehensive overview of repairing and painting sash windows, ensuring a smooth process and a fresh look. Before painting, it is crucial to address any issues with the windows, such as broken sash cords, drafts, rot, or decay. The repair process involves removing the sashes, repairing or replacing damaged components, and reinstalling them.

When painting sash windows, preparation is key. Cover furniture and flooring, remove curtains and blinds, and scrape away loose paint. Sand the windows to create a smooth surface, and prime any exposed timber. Filling any holes or cracks and sanding them down is also essential.

The painting process itself should follow a specific order to avoid sticking. Start by painting the mullions, the thin central strip of the window, and then paint the frame of the lower sash. Paint the top section of the window frame, known as the rebate, without pushing the sash up. Repeat the process for the lower sash, ensuring access to all areas. Paint the frame casing and outer edges, followed by the cill, using broader brush strokes. Allow the paint to dry, and use a scraper to remove any paint on the glass.

Repairing and Painting Sash Windows

Prepare the window by removing any curtains, blinds, and locks

Preparing the window is a crucial step in the process of repairing and painting sash windows. Here are the steps you should take to ensure the window is ready for painting:

Remove Curtains, Blinds, and Locks:

• Take down any curtains or blinds that may obstruct your access to the window. It is essential to remove these items to prevent accidental paint splatters and ensure a smooth workflow.
• Remove all locks, handles, and catches from the window sashes and frame. This step will make the painting process easier and ensure a clean finish without paint on the hardware.

Cover Furniture and Flooring:

Invest in quality dust sheets to cover any nearby furniture and flooring. This step is crucial to protect your valuables from paint splatters and dust generated during the sanding process.

Prepare the Window Surface:

• Use a decorator's knife or scraper to remove loose, flaking, or chipped paint from the window. Pay attention to the nooks and crannies, ensuring you remove as much of the old paint as possible.
• Sand the entire window using medium-grade sandpaper (120-grit) to smooth out the surface and create a uniform finish. Get into all the tight spaces to ensure a consistent texture.
• Repair any damage, rot, or decayed areas. Dig out and clean these sections, sand them, and then fill them with a suitable wood filler. Allow the filler to cure completely before proceeding.
• Once the filler is dry, sand the filled areas again to ensure they are level and flush with the surrounding surfaces. This step will create a seamless finish.
• Vacuum the window to remove any dust generated during the sanding and filling processes. Follow up by wiping the window with a damp rag to eliminate any residual dust or debris, ensuring a clean surface for painting.

Sand the window to remove flaking paint

Sanding is an important step in the process of repairing and painting sash windows. It helps to smooth down the surface and remove any remaining loose paint after the initial scraping or paint stripping. When sanding a window to remove flaking paint, follow these detailed steps:

Protect Yourself and the Surrounding Area:

Before you begin sanding, it is crucial to take the necessary precautions to protect yourself and the area around the window. Put on safety goggles and a tight-fitting dust mask to avoid inhaling any dust particles. If you are working with lead-based paint, wear a NIOSH-approved respirator and consider covering the surrounding area with a waterproof tarp or drop cloths to catch paint chips and dust.

Choose the Right Sanding Tools:

Select a sanding block or sandpaper with the appropriate grit for the task. For wooden windows, a fine-to-medium-grit sanding block or sandpaper is recommended. If you are working with a larger window or extensive flaking paint, you may also need a disc sander with 60-, 80-, or 120-grit sanding discs.

Sand the Window:

Start by gently sanding the window, focusing on areas with flaking paint. Use smooth, even strokes and apply light to moderate pressure. Pay attention to the edges between painted and scraped areas, ensuring a smooth transition. This process is known as feathering and helps create a seamless finish. Be careful not to sand too aggressively, especially if your window has intricate carvings or details. The goal is to achieve a smooth, consistent surface without removing the original finish or carvings.

Clean the Window:

After sanding, use a microfiber cloth or a damp rag to wipe down the window, removing any dust or residue. Ensure that the window is completely dry before proceeding to the next step, which may involve applying a primer or new paint.

Additional Tips:

• If your window has not been maintained for a long time, be cautious about the possibility of lead paint. Take the necessary precautions, such as sealing the room, wearing appropriate protective equipment, and thoroughly cleaning the area after sanding.
• If your window has holes, cracks, or other imperfections, fill them with wood filler before proceeding to the next step. Allow the filler to dry, then sand it down to create a smooth, level surface.

Prime the window to seal exposed timber

To prime a sash window, you must first prepare the window by removing any old paint and sanding the window frame. This will ensure the primer adheres properly to the surface. Use a fine-grade sanding block or sandpaper to smooth down the window frame, being careful not to sand too far back and remove any original carved details. It is important to note that if you are repairing very old windows, you should seal the room, wear protective equipment, and thoroughly clear all sanding dust from the room.

Once the window frame is smooth and free of dust, you can begin priming. Choose a primer that is suitable for wood and follow the manufacturer's instructions for application. Apply the primer to the entire window, including both the interior and exterior surfaces if you plan to paint both sides. The primer will provide a great base for paint adhesion and protect the wood.

After priming, you may need to sand the window again lightly to ensure a smooth finish. Use a sanding block or sandpaper with a fine grit, such as 120, to gently sand the primed surface. This will help create a smooth, level surface for painting. Remove any dust or residue with a damp cloth after sanding.

Once the window is primed and sanded, it is essential to allow sufficient drying time before moving on to the next step, which is painting. Refer to the primer manufacturer's instructions for the recommended drying time.

By following these steps, you will effectively prime and seal the exposed timber of your sash windows, ensuring a smooth base for your chosen paint to adhere to and providing protection for the wood.

Paint the mullions and frame

Painting the mullions and frame of a sash window is a delicate process, but with patience and the right tools, you can achieve a professional finish. Here is a detailed guide to help you paint the mullions and frame effectively:

Prepare the Window:

Before you begin painting, ensure your window is dry, and the wood is not damp. Remove any window furniture, such as locks and handles, to make the process easier. Use a decorator's knife to scrape away loose, chipped, or crumbling paint. If your window has not been maintained for a long time, be cautious of stripping previous lead paint. Seal the room, wear protective equipment, and thoroughly clean the area afterward.

Sand and Smooth:

Use a fine-to-medium sanding block or sandpaper to smooth the remaining paint and create a uniform surface. Be careful not to sand too aggressively, especially if your window has intricate carvings or details. The goal is to achieve a smooth finish ready for painting. After sanding, wipe down the window with a microfiber cloth to remove any dust or residue.

Fill and Prime:

If your window has holes, cracks, or imperfections, use wood filler to fill them. Allow the filler to dry, and then sand it down to create a level surface. If there are gaps between the window frame and the wall, use a caulking gun to apply flexible silicone. If you've sanded the window down to bare wood, apply a primer suitable for interior or exterior use, following the manufacturer's instructions. The primer will enhance paint adhesion and provide a smooth base.

Now, you are ready to paint the mullions and frame. Start by reversing the sashes. Lift the bottom sash as high as it will go and pull down the top sash. Paint the mullions first, as they are the division strips within the frame that hold the panes of glass. Paint carefully, but don't worry too much about getting a little paint on the glass.

If you are right-handed, start painting from the top left corner and work across to the right. You can paint one side of all the mullions first and then go back to paint the other side and the front. Alternatively, paint the left side of each mullion, then the right side, and the underside of each horizontal mullion separately.

After painting the mullions, focus on the face of the sash frames. Paint the structure that holds the mullions and glass in place, ensuring even and level coats with no runs.

Final Touches:

Once the paint on the mullions and frames is dry, you can reassemble the window. Carefully push the top sash back up and pull down the bottom sash. Clean off any dried paint from the glass using a window scraper or a razor blade.

Remember to allow sufficient drying time before closing the window or operating the sashes. If you need to close the window before the paint is fully cured, try to open it again as soon as possible to prevent the sashes from sticking together.

By following these steps, you will achieve a professional-looking finish for your sash window's mullions and frame.

Clean the glass with a glass scraper

Glass scrapers are an essential tool when it comes to sash window maintenance and painting. They are a cost-effective, yet highly effective way to clean paint off glass without causing any damage to the surrounding areas.

When painting sash windows, it is inevitable that some paint will end up on the glass. While it is tempting to try to avoid this, it is actually much easier to simply accept that it will happen and deal with it afterwards. Trying to avoid getting paint on the glass can slow down the painting process and make it more difficult.

A good tip is to use masking tape along the outside edge of the windows. This will help ensure that the walls remain paint-free. It is also simple to remove once the painting is complete.

Once the paint is dry, use a glass scraper to gently remove any paint from the glass. Hold the blade of the scraper against the glass and run it gently towards the mullions (the thin central strips of the window). Then, hold the blade vertically and run it carefully along the edge of each mullion where it meets the glass. This will cut through the paint, and when you scrape, the excess paint will lift off, leaving a clean edge.

It is important to be careful and gentle when using a glass scraper to avoid scratching or damaging the glass. Take your time and work in a slow and controlled manner.

Frequently asked questions