How to fix window sill and window jambs?

[Marie11]

I have a window sill that is not level. The left side is pushed in/down and the right side is up. I will be getting new architraves surrounding the window which will be installed, but prior to installation I need to fix the window sill. The person installing the architraves will not fix the window sill. How do I fix the window sill?

Left sideRight side 

[JacobZ]

Hi @Marie11,

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

The main issue you will need to address is the gap between the sill and the jamb on the left side. You should be able to do this by packing underneath the sill, then refixing it with finish nails.

To do this, you'll have to start by removing the architrave. Architraves are attached with finish nails, so you can use a prybar to gently pull them off. 

Once the architraves are off, depending on how tightly the plasterboard was installed, you should be able to see where the sill sits on top of the timber framing, or at least see the bottom edge of the sill. You should then be able to lever the sill up using your prybar, then slip Window Packers between the sill and the framing beneath.

After packing out the sill, you should fire finish nails through the sill into the framing to lock it in place.

You would then fill the nail holes with Spakfilla and the seams with a bead of No More Gaps. Once dry, you would paint over the filler and caulk.

If you can work in with the architrave installer, that would make things much easier as many of the steps are similar to what they will be doing.

Let me know if you have any further questions.

Jacob

[Marie11]

Thank you so much Jacob. If I wanted to only use a varnish can I still use the spac filla and no more gaps? 

[JacobZ]

Hi @Marie11,

Is the plan to varnish over the existing paint? Or are you planning to strip it back to bare timber and then varnish it?

If you were varnishing over paint, functionally it would be fine, but you would probably be able to see it if you looked close enough. If you are keeping the paint, then it would be best to put a dab of paint over them before varnishing. It will look much more uniform that way.

If you were planning on removing the paint, then you'd want to use a timber-coloured filler like those from Timbermate. Pick the one that is closest in colour to your timber.

Let me know what you think.

Jacob

[Marie11]

Hi Jacob,

Thanks for the advice. I will be stripping the paint and sanding the timber before a satin varnish.