What goes into making a traditional timber sash and case window

12th of September, 2025

Making a traditional sash and case window is a complex joinery project. It’s the classic vertically sliding window used in Georgian and Victorian architecture, with counterweights and pulleys hidden in the cases.

1. Components of a sash and case window

Sashes: The glazed wooden frames that hold the glass. Typically two—one fixed (or semi-fixed) and one sliding. In a traditional setup, both can move.
Case (Box Frame): The outer timber frame that houses the sashes and contains the pulley stiles and weight pockets.
Parting Bead: A thin strip that separates the upper and lower sashes in the case.
Staff Bead: The inner trim that holds the lower sash in place but can be removed for servicing.
Weights & Pulleys: Lead or steel weights counterbalance the sashes, connected with sash cord.

2. Timber Selection

Softwoods like Redwood are great for working with and provide a good life span.
Hardwoods like oak or sapele or Accoya offer durability and weather resistance.
Ensure timber is quarter-sawn or stable, to reduce warping.

3. Making the Case

Cut stiles & rails: Typically 175–200 mm deep to house weights.
Rout weight channels: Hollow sections inside the pulley stiles for sash weights.
Install pulley stiles: Mortise for brass pulleys at the head.
Assemble the case: Traditional through mortise-and-tenon joints, pegged or wedged.
Cut weight pockets: Access hatches in the inside face of the pulley stiles.

4. Making the Sashes

Cut stiles and rails: Sized to allow glazing and sufficient strength.
Joinery: Through mortise-and-tenons (horns left long for strength).
Rebates for glazing: Cut to suit your glass thickness + putty line.
Glazing bars (if needed): Tenoned and shouldered into sash frame.
Dry assemble & test fit before final glue-up.

5. Glazing

Traditionally bedded in linseed oil putty, with sprigs or pins.
Modern options: Timber glazing beads with silicone or modern putties.
Allow for expansion of glass.

6. Balancing the Sashes

Weigh each sash once glazed.
Fit counterweights to match (a few ounces lighter than the sash for smooth operation).
Thread sash cord over pulleys and tie to weights and sash.

7. Finishing

Prime all bare timber (especially end grain) with an oil-based primer before assembly.
Traditional finish: linseed oil paint.
Modern finish: microporous exterior paint or high-quality exterior varnish.

8. Installation & Trimming

Fit the window case into the opening plumb and square.
Insert the parting bead to divide the two sashes.
Install the staff bead last, keeping just enough clearance for smooth sliding.

Edinburgh windows and doors use traditional techniques to assemble our windows and doors. They are not put into a machine and produced at the end of a production line. Our joiners are highly skilled and take the timber from batons to finished window. Putting love and care into each piece of timber at each step of the journey. Once complete we use high quality paint and some of the best spray machines and extraction fans on the market to ensure a top quality paint finish on all of our timber products.