This is a discussion, similar to my write up about "old wood". I want to talk about protecting wooden window frames, or any joinery for that matter, from the weather. Please be sure to treat these as my thoughts on the topic rather than a full technical guide. The reason I was prompted to write this was thanks to a recent window installation where old defective windows, beyond economic repair, were being replaced by some new windows that we had made. Firstly I was delighted to be commissioned to make some new windows, it's always a privilege that people ask us to make quality items that are sympathetic to their buildings. However I was saddened to see what was being thrown in our skip as the installation work progressed.
The stark reality is that any material will fail over time, wood, metal, plastic, they all have a life cycle. However, these windows we were removing could of easily lasted many more years with just a few simple steps. The key is to start on a good foundation, you'll notice from the photo above that there is no paint on the bottom of the casement, nor the edges of the casements that you can see below. This fist fatal flaw is at the heart of the problem. What I would want to see here is a full coating system and no bare timber exposed to the elements. Dry timber suitable for use by joiners will soak water up readily without coatings applied, this excess of moisture will then fester behind the painted faces and becoming a catalyst for rot. If that one step had been taken here I'd speculate another five years could of been drawn out from these windows.
Once you've chosen to start with a proper coating system, covering all surfaces you'll need to maintain it. The phrase "a stitch in time saves nine" immediately comes to mind. With my wooden windows at home I work this into regular cleaning cycle, I tend to clean the windows twice a year and use this time to look for any issues. I make sure things open and close smoothly, wipe the weather seals and look for any defects in the paint and make anything good with some paint or stain as required I also lubricate hinges and hardware. These steps are a wise move on a window made from any material. You can also choose to have you windows made from a very durable species such as Accoya, selecting a highly durable timber means that should an area of coating break down and go unnoticed, or a maintenance task slip then there is that extra fail safe of rot resistance below the surface.
By regularly cleaning and maintaining you'll soon see how quickly the paint finish breaks down. I'm very skeptical of advice given by paint suppliers who can quote up to 10 year gaps between reapplication of finishes. Every situation is unique and dictated by factors such protective roof overhangs, orientation to the sun, local prevailing weather etc. As a very rough guide I would look to apply new paint coating at 5 years and stains at 3 years. If in doubt seek the advise of a professional. With these simple steps the life cycle of external joinery can be dramatically improved. We've offered a painting service for some time now and would strongly encourage clients to have their windows full coated before installation. The cost of applying coatings will need to be factored in at some point, so why not have that process completed in our workshops before we install? That way your windows can look like the photo at the top rather than prematurely find themselves in the skip!