Crafting Excellence: How our sash windows are made

Crafting sash windows at Sashwise is more than a process; it’s an art form. From taking careful measurements, selection of quality materials, the assembly process to the final quality checks, every step is infused with a passion for excellence. When you choose Sashwise, you’re not just getting a sash window – you’re bringing a piece of timeless craftsmanship into your home.

Here is a step-by-step process of how we make our sash windows:

1. Measuring

When measuring for a complete, new window, including the sashes and sash box/window frame , the dimensions of the external window opening are used plus any relevant sectional measurements. If the sashes only are being replaced, then the internal measurements of the existing sash box are used and again any relevant sectional measurements. These measurements are then used to create manual drawings.

2. Material Selection

At Sashwise, we source sustainable Accoya wood timber . This choice of material is crucial for ensuring durability, stability , resistance to weather elements, and a beautiful finish. Our skilled joiner then begins the process of preparing the timber. This involves careful milling, planing, and shaping to create the various components that will come together to form the sash windows. A full range of bench joinery tools are utilised in the process and a specialist CNC Router (Computer Numerically Controlled) is used for creating any difficult shapes.

3. Joinery and Assembly

The joinery process is where the magic happens…

• At the start of the process, full size working drawings are drawn out by a member of our machinist team and a cutting list is produced. The Accoya wood is cut to the various sections required and then machined to the exact width and thickness using a 4-sided planer.
• The horizontal sections of the sashes are cut to the exact length and the tennons are machined onto the ends to form part of the mortice and tennon joints.
• On completion, the internal moulding and glazing rebate is applied to all the sections using a power fed spindle moulder.
• All of the sections are then neatly stacked and handed over to the bench joiners for assembly.
  Referring back to the full-size drawings the mortices are marked out on the vertical sections of the sashes which are known as stiles. These are cut out with the vertical morticer, which are cut from both sides to avoid splitting.
• If decorative horns are required, a template is made and these are marked out onto the ends of the stiles and then cut and sanded.
• The sashes are then dry fitted together and the glass sizes are checked. Once we are satisfied that everything is correct, the sashes are glued using a polyurethane adhesive, clamped and checked for squareness, the joints are locked with stainless steel fixings and left to set.
• Excess glue is trimmed off, the ends of the styles are cut, and the edges are sanded clean. The faces are also sanded to a finish with 180g sanding pads.

• The surface finish is a key aspect of both aesthetics and protection against the elements. The sashes undergo a meticulous priming and painting process . The new joinery receives 3 coats of paint – applied by airless spray system prior to installation. Teknos paint is used, which is a micro-porous breathable paint of extreme durability and has a satin finish. Internal surfaces are finished using Little Green’s Intelligent Eggshell . A low sheen finish with exceptional durability that withstands staining and wear and tear and is also environmentally friendly. External surfaces are finished with Zinsser Allcoat Exterior Gloss which is an ultimate performance, mould resistant paint that offers supreme protection to exterior wood surfaces. We are also able to colour match our paint to any colour desired, should a custom colour be required.

• The double-glazed units are now installed with a hybrid polymer glazing compound. After this has set, the external putty is hand painted using a suitable primer and then the glass is cleaned and polished and they are ready for installation.

4.  Decorative Elements

If decorative elements have been chosen for the design of the sashes, glazing bars are bonded onto the glass and false spacers are added inside the double-glazed unit to provide the appearance of separate panes of glass. This allows us to retain the appearance of slim glazing bars.