How to replace plasterboard window sill?

[maddison1]

   

Hi there,

I have had some water damage from a window not being sealed properly in the bedroom. The window has been resealed and fixed, however the water has caused damage as seen in the images.

Wondering the best way to fix this would be? Under the plaster it is double bricked.

Thanks!

[EricL]

Hello @maddison1 

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

I suggest removing all the loose bits that are coming off the sill. However, any part that is still in good condition is best left in place. I propose looking for a bit of offcut timber that can go in between the sill and the brick wall. This is to reduce the height of the gap between the brick and window sill.

Once you find a suitable piece you can either wedge or glue it into place using liquid nails. Once the glue cures, I recommend filling the gap with Builders Bog. My best advice is not to add too much activator to the mix so that the bog will not harden too quickly. 

I suggest spreading the bog with a UNi-PRO 50mm Real Good Paint Scraper. Your goal is to fill the gap to the same level as the sill. This will save you from having to sand too much of the bog back down. You can apply the same repair technique to the damaged vertical portion of the sill. 

Once the bog cures, make sure to sand it down so that its nice and level. Wipe off all the sanding dust away before painting the surface.

Here is a handy painting guide: How to paint like a professional by @Peggers 

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

Eric