Restoring sash windows doesn’t mean replacing them. With the Sellaseal Premium Kit, you can upgrade cords, seals, and beads for smoother operation and improved energy efficiency. Your kit isn't the cheapest because we do not compromise on the quality of the products we supply or the methodology of draught sealing the window. This step-by-step guide explains the process, with added tips to make the job easier.
Step 1: Ensure Safety and Prepare the Space
Before you begin, secure the top sash to prevent it from sliding down and causing injury. If you’re unsure, screw it off at the sides. Be mindful of old paint layers, which may contain lead. Follow safe work practices and avoid inhaling dust when sanding or cleaning.
Step 2: Strip Out Old Components
Remove the staff beads, both sashes, and the parting beads. Clear out paint flakes, splinters, and debris from the grooves using a scraper or vacuum. This creates a clean surface for the new seals and beads.
Tip: Use a wide chisel to remove staff beads. Any stubborn nails can be cut with a multi-tool. Parting beads can be gripped and pulled out with pliers.
Step 3: Check the Timber for Repairs
Once everything is removed, inspect the timber thoroughly for signs of rot or damage. Any soft or decayed areas should be stabilised and rebuilt with the Sellaseal DT Epoxy range, which is designed to restore structural integrity and extend the life of your window frames.
Step 4: Inspect the Putty and Glass
While the sashes are out, check the condition of the glazing putty. Cracked, brittle, or missing putty can be quickly restored with Sellaseal Sash Glaze. It allows painting within a day and gives a clean, lasting finish.
Step 5: Access and Treat Window Balance Mechanisms
For windows with weights and pulleys, remove side pocket covers to access the weights. If your windows use springs, remove the spirals or balances. Clean the weight pockets thoroughly and lubricate the pulleys. Replace worn pulleys with new ones from the Sellaseal.
Step 6: Balance the Weights and Sashes
Check that each sash is properly balanced with its corresponding weight. A bathroom scale is accurate enough for this task. Balanced sashes ensure smooth movement once reassembled.
Step 7: Rethread the Sash Cords
Use quality waxed cotton cord with a poly core from the Sellaseal. Thread the cord through the pulleys and tie it securely to the weights using a figure-eight knot or clove hitch.
Tip: Use a smaller piece of builder’s line with a sinker attached to fish the cord through the weight box—this makes threading much easier.
Step 8: Install the Top Parting Bead with Seal
Measure, cut, and insert a new parting bead into the top groove. Insert the brush seal and secure the ends with a small dab of glue. Tap the bead gently into place and fix with nails.
Step 9: Rehang the Top Sash
Lift the top sash back into position and check that it slides easily past the new parting bead. Confirm that the seals are engaging properly and not rubbing.
Step 10: Fit Vertical Parting Beads with Seals
Measure from the top bead to midway down the meeting rail. Cut and fit new beads with seals on both sides, ensuring the seals face outward to contact the sash. Tap them into place with a rubber hammer for a snug fit.
Step 11: Seal the Meeting Rail
Use an 8 mm router to cut a shallow channel into the meeting rail and insert a carrier track with a seal. Clean and dry the groove before inserting. This creates a tight seal where the two sashes meet.
Step 12: Install the Bottom Sash
Rehang the bottom sash and confirm smooth movement. Measure, mitre-cut, and install staff beads with seals on the sides and bottom, leaving the top bead without a seal. Fit them around the frame and tap into place.
Step 13: Final Sealing and Finishing Touches
Check that both sashes move freely and that all seals contact properly. Secure the parting and staff beads with nails, avoiding nails that could interfere with the weights. Fill nail holes neatly and apply touch-up paint, avoiding the seals. Prime and topcoat exposed timber promptly to protect against moisture.
Why Choose the Sellaseal Premium Kit
The Premium Kit includes everything you need for a professional restoration—durable cords, seals, and beads designed for airtight performance. It improves comfort, energy efficiency, and preserves the authentic charm of timber windows without the cost of full replacement.