Front door sill - how to repair?

[Scaleybrat]

We have just placed an order for a replacement composite front door to be supplied and fitted. The property is over 100 years old and the door sill looks original. It is crumbling away despite some previous attempts to create some sort of repair and I’m now trying to create a solution before the new door is fitted. At first I considered replacing the sill with a hardwood version but that doesn’t appear to be easy with the current sill being of considerable size as you can see in the top photo.



There is an air grate under the sill for airflow under the floorboards. Ideally, I’d like to turn the whole thing into a small step by using a suitable cement type material but this would block the grate. If the grate has to remain, is there a material I could use to build up the sill back to its original profile?



Any ideas how I should tackle this? Clock is obviously ticking to get the repair done before the new door arrives in 8 weeks.

[wolfracesonic]

A suggestion, without being there; a piece 900x600mm piece of Indian sandstone bedded on bricks (or strips of Indian sandstone, not sure of heights), cut away enough of what’s under the existing door frame cill for the sandstone to slip under, ready to accept your new door frame. Leave a ‘tunnel’ under the step with a 215 x 65mm air brick at the front to maintain air flow.
Make the slab fall away from the threshold slightly.
Just a thought

[JoshSm]

In a similar situation I just got a whole new piece of stone, and swapped it out with the door still in place.

If you want a step without blocking the airbrick (and that lot looks like it needs excavating and redoing while you're in there) then you can always ventilate under the step so the air can reach the existing brick. At least that's how I did it.

[shtu]

As above really, new stone required. You can get stone repair materials like Lithomex, but I wouldn't bother for that job.

A mason would sort that out in no time.