Suitable mortar/filler for "pouring" against sloping window?

[Skånepöjk]

A somewhat strange headline...

but as you can see from the pictures, I've removed the old windowsill that was on old window brackets screwed into the wall.

I want to remove the slope and level it so I can place my new windowsill there.

It's up to 5cm deep and then it gets less and less towards the window.

I was thinking of mounting a plank over the hole and then adding/pouring some kind of compound.

But what? Self-leveling compound..? Gypsum? Fine concrete?

I would prefer to be able to sand it a bit if needed?

Any tips on what might be smart?

 

[Stuff]

Are you going to install a new wooden windowsill?
If the slope is relatively consistent across the width of the window, you could take a piece of wood and cut it into a wedge shape to compensate for the slope and then glue it to the underside of your new windowsill.

 

[Skånepöjk]

Is it a new wooden windowsill you're going to install?
If the slope is fairly uniform across the entire width of the window, you could take a piece of board and cut it into a wedge shape that compensates for the slope, and then glue it to the underside of your new windowsill

the new windowsills are in Stone

 

[useless]

Fill with any cement-based product... Fine concrete, plaster mortar B, house fix, tile fix, etc., depending on what is cheap and easy to find.
You may need to drill and insert a couple of screws or pieces of rebar to prevent the cast piece from coming loose and falling down.

 

[Skånepöjk]

Fill with any cement-based product... Fine concrete, plaster mix B, house fix, tile fix, etc depending on what is cheap and easy to get.
You might need to drill and insert a couple of screws or pieces of rebar so the casting doesn't come loose and fall down.

which option is easiest to sand? Wondering if gypsum might be a good alternative?

 

[TrädgårdsBjörnen]

Is it not a polished edge you can knock off?

 

[Daniel Barnaniel]

You probably won't find anything suitable that can be sanded if you're thinking paint-ready. Choose something in line with what useless suggests and fill.

 

[Skånepöjk]

You probably won't find anything suitable that's sandable if you're thinking of a paint-ready surface. Go with something along the lines of what useless suggests and fill in.

It'll be fine concrete! I'm familiar with working with that too

 

[Daniel Barnaniel]

Don't forget spikes in line with what useless wrote

 

[Skånepöjk]

Don't forget screws in line with what useless wrote

I pull in 3 screws straight down the concrete, let it suck in! Smart!