How to restore weathered window sills and attach mouldings?

KarenMM

A couple of window sills in my home are very weathered from sun damage and in a bad state with cracks in the wood.  The sills are not rotten (yet) and I would like to restore them before they get any worse. 

Should I use a detail sander or belt sander to remove/smooth the cracks?  Or, should I use a detail sander and multi-use filler for the cracks before painting?

Also, the mouldings on the edge of the window frame are not fully attached.  Do I attach the mouldings with liquid nails?  

Weathered window sillWeather window sillClose up of weathered window sillWindow Moulding with gap between frameWindow Moulding with gap between frame

EricL

Hello @KarenMM 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your windowsills.

I agree with your plan on using a detail sander, this will allow you to sand all the tight corners of your windowsill. You'll also be able to identify which of the timber surrounds are truly compromised. 

Once, you've finished sanding and have identified all the weak parts of the windowsill, I suggest spraying those parts with Earl's 250ml Wood Hardener. It penetrates into soft rotted wood fibres, restoring them to near original strength. This means you can repaint even the most damaged wood, ready for full restoration.

Once the wood hardener has cured, I propose filling the deep damaged areas with Turbo 175ml Builders Bog Flexipack. My best advice is not to add too much activator to the mix to prevent the bog from curing too rapidly. It's best to fill only to the original level of the timber so that you won't have to sand too much off.

In regards to the moulding, using liquid nails to re-attach them should be just fine.

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

Eric