Best filler for rotting timber windows?

[petermo]

What's the best procedure and products  to repair windows and sills that are rotten in some corners?   

I understand the approved approach is 

1. remove all rotten wood, (probably multitool or drill with grinder/file bit).

2. treat the solid with with wood hardener

3. fill with builders bog, or two-part-epoxy, or automobile bog 

4. sand/paint

It is point 3 I need guidance on... which product is best for this, I suspect it is one that's flexible to move with the wood, but dont know?

Thanks for recommendations

Pete

[JacobZ]

Hi @petermo,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

You're right on the money in terms of process.

Start by tidying it up and removing all the soft wood, then treating it with Earl's Wood Hardener.

Generally, Builder's Bog is what you would use, but the fact that it is in the corners makes me a bit wary because that is where you experience the most movement, and Builder's Bog is not flexible. Do you have any photos of the damage that you could share?

To be on the safe side, it is probably best that you use a flexible filler like this Nordsjo Professional Flexible Wood Filler.

Once the filler has set and is dry, you can sand and paint it as normal.

Let me know what you think.

Jacob