After removing the fixed sidelights, it also became clear the Mullion was also kept damp and had started to rot into the sill.

We began be replacing the tenons of the mullions and jams.

Next, we moved onto the side lights and doors themselves. After ensuring everything opened and closed correctly, we re-puttied were necessary before giving everything a coat of breathable primer.

An honorable mention goes to the owners of the property who kept us fueled with a fine selection of biscuits! For those who haven’t tried the traditional way of enjoying a TimTam, you don’t know what you’re missing!

To replace the sill requires 7 precise measurements to be taken in a very specific way. A new sill can then be made which will fit perfectly. We opted for Accoya acetylated pine for this sill, for its dimensional stability and supreme 50+ year rot resistance.

With the new sill in place, we check the sashes open and close perfectly.

We removed the sill from the previous repair which had been glued and screwed in place. The previous repair re-used the original oak sill but the frame behind had rotten to the point where it would no longer support the sill. The oak sill was still in great condition, so we tidied it up to re-fit later.

We traced the rotten timber up the frame to good timber so that we could form joints for the repairs that would be carried out in Accoya. Using most of the clamps we had, the glue up for this job was worth a photo.

While the glue set, we go to work on the sashes, repairing the bottom rails and stiles and re-glazing and puttying where needed.

We try to identify the root cause of rot to windows where possible. In this case, the home owner had already identified and fixed a leaking gutter joint and had also noted the wooden lintel above the window was allowing rain into the brick work. We finished the window repairs by forming an Accoya drip the would keep rain off the timber lintel and help direct driving rain away from the window beneath.

It soon became apparent that the sashes themselves were in bad condition. As the property isn’t listed, we took the opportunity to improve on a few things that the homeowner had mentioned. First was the warmth in the room and the second was the seemingly low light levels.

After replacing the sills in Accoya, we made new sashes in joinery quality pressure treated pine. We fitted the latest argon filled double glazing with aged leadwork and welded joints to maintain the style of the originals, but opted for slightly thinner leadwork. This small detail, whilst seemingly insignificant, gives a much clearer view of the garden and the impression of much more light coming through the window.

The timber available during the 20s was typically slow grown and therefore is much more rot resistant and stable than the equivalents we see today. It’s therefore a good idea where possible to retain as much of that original timber as we can. Here, we were able to localise the repair only to the corner of the sill and bottom area of the weight box planks using Accoya with a minimum rot resistance of 50 years.

To complete the repair and ensure a long life for the window, we made a small repair to the bottom sash which also needed a little TLC.

Although a relatively straightforward job, the devil is in the details. With this style of beading where the bottom bead is larger and forms a drip, it’s essential to get the vertical beads just right. The Georgian style glazing bars add another detail in that the choice of pin length for fixed is critical.

With so many cuts to make, it’s important to get all these details ironed out so you can get in a rhythm and be productive.

We started with the repairs to the long drip beneath the arch. The drip was formed by an extra deep head on the casement windows so it was necessary to machine this back to good wood using a template, then form a groove for a tongue on the new Accoya drip to join into.

We started by repairing the damaged stile on the first sash before carefully and methodically freeing the remaining sashes from the bay.

With equal care, we removed and cleaned the hinges and tidied everything up before reassembling and getting everything working perfectly with the existing catches.

Whilst repair was still possible, the customer took the opportunity to upgrade to double glazed units. To achieve this, we opted for new sashes with slightly beefed up joinery to handle the additional weight.

Although it’s often possible to retrofit double glazing into an existing sash, the results are usually short-lived as the extra weight and shallow rebates are less than ideal for both the joinery and the double glazed unit itself. In fact, we often see the sashes and/or glazing fail within 10 years.

To incorporate the stronger sashes and their double glazing, we double rebated each sash to fit snugly into each original frame. This retains the flush appearance of the original design whilst also gaining some additional weather protection, useful in this relatively exposed position on the building.

Pressure treated softwood has superior rot resistance to hardwood and once decorated, it will far outlast a uPVC window.

To ensure the window was weather-tight against the tiles, we fitted rebated linings which seal the edges.