Victorian terrace window - how to fix rot in bottom rail in lower sash?

[dzg]

Hello, our victorian terrace window is having some wood rot in the bottom rail. I'd prefer to fix it myself if possible rather than pay for replacement (unless it is reasonable cost). Does anyone have suggestions on how to fix? Rot appears to be both on inside and outside of the bottom rail mainly.

Thanks

[EricL]

Hello @dzg 

Please note that working around glass is dangerous as an accidental hit with a tool or when too much force is applied can make it shatter and cause injury.

To determine how bad the rot is, I suggest using a flathead screwdriver and pushing into the timber. If the screwdriver goes in deep, then it safe to conclude that the rot has travelled deep into the wood and it will be necessary to replace that timber piece. If, however, the screwdriver only goes in marginally, it might still be possible to patch the timber and repair it. 

If the timber is totally rotted, it will be necessary to remove the window from its housing and taken apart. A replacement piece which will need to be fabricated to the same dimensions. If you have the necessary tools and have some wood working experience, you'll be able to replace this piece yourself. If not, I suggest engaging the services of a handy person to repair the window.

If the timber only has surface rot, I suggest scrapping away the rotted portion until you reach the semi hard surface of the wood. I recommend spraying the surface with Earl's 250ml Wood Hardener to restore the timbers hard exterior. Once the wood hardener cures, I suggest filling the gap with Turbo 175ml Builders Bog Flexipack. My best advice is not to add too much activator to the mix so that you have time to level the surface of the timber. Once the builders bog cures, the next step will be to sand the surface until its level and then remove all the sanding dust prior to painting the surface.     

I also suggest having a look at this discussion - How to repair rotting timber window sill by @lilh 

Please remember to wear personal protection such as rubber gloves, goggles and a mask when working on your window.

If you have any other questions we can help with, please let us know.

Eric