How to repair window architrave?

KTC

Hello, I’m wanting to fix some window architraves which have been ruined by weather over time. As you can see in the photo, it’s the inner part that needs replacing. My questions are,

1) is this part still an architrave?

2) how should I go about replacing this? 
Thanks

EricL

Hello @KTC 

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

The damaged portion of your window is not part of the architrave. It would be the interior sill of the window that needs repair. I'm surprised that MDF was used for that part of the window, usually it's made of timber.

Due to the extent of the damage the MDF will need to be totally replaced. In this particular instance, I suggest engaging the services of a builder. I suspect that once the damaged portions are removed there might be more damage underneath and extensive repairs will be necessary. 

However, if the damage is limited to the top area, then the repair should not be too in depth.

Generally, the builder will take the window frame apart and will make their assessment on which parts need to be replaced. 

If you need further assistance, please let us know.

Eric