Reinstating stone window cills and Threshold Step

For discussions about topics related to Period Property in the UK

Moderators: Simon Wright, RobT

Post Reply
Bombay Redeye
Posts: 4
Joined: Thu 3rd Feb, 2022 11:59 am

Reinstating stone window cills and Threshold Step

Post by Bombay Redeye » Thu 17th Feb, 2022 11:42 pm

Hi all,

As part of the rendering process outlined in my other post, I need to reinstate 2 stone window cills and the threshold to the lower ground floor door.

These appear to have been removed when upvc windows were installed probably in the 90’s. The scars in the render where the original cills were are clearly visible and are consistent with the 2 original cills still in place. The windows and door are being removed and replaced, so that’s not an issue.

The house is an 1825-32 ish terrace with solid wall, 2 brick thick construction about 250mm thick.The windows needs to be set back from the wall face by 100mm (which they aren’t currently), leaving 150mm for window installation. The sash window frames will 130mm, leaving a 20mm internal reveal. Similarly for the door, 100mm external reveal, but only 70mm Frame, leaving an 80mm inner reveal. I am happy with the reveals.

What I would like advice on is how deep should the window cills and threshold be? From my research so far, cills could be full or half wall depth.

My current thinking is that the cills should be full depth (250mm plus 40mm overhang externally) with a 150mm flat for the window frame to be fitted onto. The door threshold slightly different in that it will not go full depth but 20mm deeper than the door frame so as not to create an extended internal step.

However, would this cause an issue with creating a path for water transfer from external to internal surfaces?

Should I install half wall depth and then brick internally to make up the remaining depth?

Am I overthinking all of this? Thanks

Gothichome
Posts: 253
Joined: Sun 13th Jan, 2019 12:35 am

Re: Reinstating stone window cills and Threshold Step

Post by Gothichome » Fri 18th Feb, 2022 3:55 pm

I may not be the correct fellow to answer your questions but I can tell how our 1880 Victorian home is built. The sills and threshold are made of a dense local sandstone, our home is also two bricks thick with an air space between. The sills and threshold straddle both brick walls and the wooden window boxes rest on the sill. The thresh hold reaches into the home only as far as the inner plane of the doors. There is an overhang of about 2 1/2 inches to the out side as a drip edge and both the sills and the threshold have a slight downward tilt to the exterior to discourage water creeping under sill or threshold.
I hope this helps
Ron

Bombay Redeye
Posts: 4
Joined: Thu 3rd Feb, 2022 11:59 am

Re: Reinstating stone window cills and Threshold Step

Post by Bombay Redeye » Fri 18th Feb, 2022 6:55 pm

Thanks Ron,

That pretty much ties in with my thoughts and research. Don’t think my walls have a gap though, but I’ll find out in a few weeks time!

The stone has arrived and the stonemason starts work on them next week.

Thanks Bryn

malcolm
Posts: 1166
Joined: Wed 18th Sep, 2013 6:21 pm
Location: Bedford UK

Re: Reinstating stone window cills and Threshold Step

Post by malcolm » Fri 18th Feb, 2022 7:30 pm

I made some notes when I went through this: https://www.the-salutation.co.uk/blog/new-sash-windows/ I think all of mine were flat sills the same width as the wall and offset outwards from the exterior surface of the wall by 50mm. The sash window balanced on what remained of the inner edge. I guess the reason was money saving. The cills need to fall outwards but not by much.

The inside brick opening is normally half a brick wider than the outside opening to provide space to hide the sash windows. Just in case it's been covered up by the UPVC people.

Post Reply

Who is online

Users browsing this forum: Bing [Bot], Google [Bot] and 20 guests