Window Sill Replacement - how to level

[CNSam]

Hi Folks,

So I'm in the process of replacing a windowsill in our kitchen which had basically every dent, chunk etc missing from it. It was a wooden sill which was coming away anyway.

I have taken the sill up today and noticed that below it is basically...bricks and mortar, however the plaster line is higher than the level of the brick (see pics).

What's going to be my best course of action here please folks? I'm thinking filling with something and levelling off or just using packing wood, but then how do I secure the new sill?

IMG_20200403_171107

• CNSam
• 3 Apr 2020

IMG_20200403_170307

• CNSam
• 3 Apr 2020

Any help would be greatly appreciated

Sam

 

[Deleted member 174758]

Dobs of compo (plasterboard adhesive) laid across the window opening and the window board dropped on and pressed down to the correct height and level OR two rows of packers at something like 300 to 400mm centres laid across the window opening an levelled (front to back and side to side). The window board is laid atop these, they are then drilled and counterbored before drilling through into the masonry of the wall beneath with an SDS/masonry drill (7mm drill bit, 7mm plugs, #10 or 5mm screws - often 80 to 100mm long to get through the board, packers/dabs and fix into the masonry below) and screwed down. If the wall beneath is a stud wall, then skip the masonry drill and brown plug and screw straight down. Packets can be of cuts of softwood or plywood or plastic window/door packers

After it has set (if using dabs), or been screwed down, fill the gap beneath the window board with plaster. Screw holes in the window board can be filled with 2 pack filler and sanded flush. Note that whilst PB adhesive is normally sticky enough to hold an MDF or softwood window board on it's own, it doesn't always work, so for a belt and braces approach add a few screws drilled and counterbored and long enough to fix into the wall beneath

Note the use of the term window board as opposed to window cill (sorry, but that's joiner-speak)

 

[Johnny Allround]

Hi Sam, fit soft wood window board and cap it ,finish off with a nice clean silicon line job done. Capping sits over existing calls when having upvc windows installed. Hope this helps.

 

[Johnny Allround]

Not calls I meant cills.