Help needed with concrete window sill repair!

Ardent

Was stripping paint on our window sill this evening and disaster struck - a section of it came away! See attached photos.

It looks like it was a repair job from the previous owner. You can also see the bar rusting inside the sill.

How do I go about repairing this? I'm thinking a piece of wood supported from beneath and fill in with either cement filler or repair mortar? Will it hold?

Has anyone any experience of this type of thing?

listermint

Drill a few holes first and put some small eye bolts into it to link the new concrete to the old.

But yes, wood form and concrete will fix. Can sand or grind back to finish smooth.

Ardent

listermint wrote: »

Drill a few holes first and put some small eye bolts into it to link the new concrete to the old.

But yes, wood form and concrete will fix. Can sand or grind back to finish smooth.

It's a pretty small area, can i get eye bolts that are small enough?

jimbev

I had similar few years ago because it was such a small area after a repair the filler would eventually blow out so for curiosity I tried car filler really sticky and has been there ever since

Lumen

I was reading about epoxy mortar yesterday, which is used for exactly this application.

There are preparation requirements, such as cleaning and priming the existing surface, but not inserting bolts. Listermint would know far more about this than I do, but nonetheless I'm going to gently suggest that they may be unnecessary, depending on what sort of product you're intending to use for the repair.

GottaGetGatt

Repaired concrete steps there in a building a few months back. Used car filler and sanded them afterwards with a Electric sander. Came out perfect. It'll be ideal for those sills.

Ardent

GottaGetGatt wrote: »

Repaired concrete steps there in a building a few months back. Used car filler and sanded them afterwards with a Electric sander. Came out perfect. It'll be ideal for those sills.

Got a link or name to what you used?

Maybe this stuff?
https://www.halfords.ie/motoring/paints-body-repair/fillers-preparation/u-pol-easy-sanding-body-filler

FMG

There might be an indent under the cill to form a drip so maybe use some polystyrene/wood dowel that can be removed after filler has cured.

Ardent

FMG wrote: »

There might be an indent under the cill to form a drip so maybe use some polystyrene/wood dowel that can be removed after filler has cured.

You're right, there is. I need to figure out the best way to preserve this.

Ardent

Lumen wrote: »

I was reading about epoxy mortar yesterday, which is used for exactly this application.

There are preparation requirements, such as cleaning and priming the existing surface...

PVA? I read another thread on here where the advice was to use PVA ahead of filler but not required with epoxy mortar?

Lumen

Ardent wrote: »

PVA? I read another thread on here where the advice was to use PVA ahead of filler but not required with epoxy mortar?

The best thing is to read the instructions.

For instance, this Weber stuff requires nothing but normal surface prep.

https://www.weber.ie/technical-mortars-solutions/products/concrete-repair/webertec-mortar.html

Since the repair isn't load bearing you probably just need to find something that comes in small containers. I image the epoxy stuff sticks like, eh, glue.

Ardent

Thanks for the help folks. I went with the car filler option (the stuff in my link above). So far so good - after sanding the filler flush with P80, adding stabiliser and a coat of paint, it looks very well and you wouldn't notice the repair job unless you were looking for it.

Might add some masonry sealer to the underside to increase the chances of it surviving freezing conditions.