Window refurbishment (before it’s too late!)

A wooden window needs some sort of coating to keep the rain and sun out. But sometimes painting gets neglected and when decay sets in a repair is needed.

I was once speaking with a Swedish painter, and asked “all your houses are made out of pine, don’t you have problems with rot?” To which the answer was “Sweden may be cold, but it is not as damp as England”.

I’m afraid it’s true, warm soggy weather is a wood-eating fungus’ best friend. And our habit of installing pine windows into masonry walls, slathering them (walls AND windows) in impermeable plastic paint, and then neglecting to repaint when cracks appear that allow water to enter the wood. This water then cannot escape and the rot begins…. It’s amazing that wooden windows last as long as some do.

Resin Window Repairs

These giant oak sash windows have sills that are starting to rot. It is a durable hardwood, but even oak will rot if it stays wet for long periods of time. Previous holes have been filled using a polyester “car-body-filler” -type of filler. This is often used on exterior wood repairs, but tends to get cracks appearing where the filler fails to bond to the wood properly. Water enters through the cracks, cannot escape again, which leads to the rotting process.
So…… first job is to get rid of the old filler and decay to get back to sound, dry wood. (Bit like being a dentist but on a larger scale!)

Grind out rotten wood

The epoxy resin system starts off with a primer to create a firm foundation for the next layer of filler.

paint on epoxy primer


Mix filler


The main epoxy filler comes in two types: a quick setting resin for minor repairs and wood splicing; and a slower setting resin for deep holes – the type I’m using for this job.

Once the epoxy filler is mixed up, I’ve formed a “dam” out of acrylic sheet to create a straight edge at the front of the repair, and the filler is “buttered” firmly onto the primed wood and smoothed off.

Mould filler in place

The resin sets in a few hours, but for sanding it is better to leave it longer.

Sand filler and paint

The result is a strong – but flexible – filler securely bonded to existing, sound wood. I think it is important to prime the sanded epoxy filler with a high quality oil-based adhesion primer before repainting the whole window as normal.

Large sash windowThe result: paint-spots removed and panes cleaned

Published by: Colin Taylor on: October 28th 2016

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