Plastering Rounded Corners: Forming Quirks around Staff Bead

[Brogden]

I hope no one minds me resurrecting this old topic, but I thought you might like to see what happened next . . .

After lengthy discussions with Terry, who has made plaster moulding for us before, we decided to get him to make plaster beaded corners for us rather than try to use wooden beads. This picture shows the construction detail. Because the plaster bead "embraces" the corner it can be made a larger diameter than a wooden staff bead, which would need some fancy machining to get the same effect. The bead has two flanges extended beyond the quirk to meet the plaster. The plaster float coat is run flush to the rebate and the joint covered with scrim tape and then the skim coat is run flush to the outside of the moulding. We are having the rooms traditionally wet plastered rather than dry lined.

Terry ran these on the bench in 3m lengths. You can see the larger bead, about 1.6" diameter, which makes the bead a visually more impressive feature when in place.

Charlie fixed the beads to the corners and then formed the birds beaks by hand in-situ.

This picture shows the beads around two of the doors, before the birds beaks were formed.

I hope someone finds this interesting!

Regards - Brogden

 

[Penners]

I hope someone finds this interesting!

Well, I certainly do, thanks Brogden.

I confess that my interest is largely academic, because I'm not sure that I shall find myself putting the techniques into practice, but any aspect of period property repair using traditional methods and skills is always a welcome addition to the fund of knowledge on this forum.

 

[chuckey]

WOW!, what a fantastic job, its great to see that there are people about who are prepared to use these traditional techniques to produce such a beautiful effect. Wish I had the time/experience to do the same.
Frank

 

[Flyfisher]

I hope no one minds me resurrecting this old topic,

Certainly not! Thank you for taking to time to post the update, it's always good to see how things work out, especially when it's such a good looking result. Congratulations.

 

[Schoolmarm]

So after fitting the mouldings, did you plaster using lime?

 

[Brogden]

So after fitting the mouldings, did you plaster using lime?

No, the plaster is a float coat of browning and a skim of multi-finish. The plaster beads are cast in plaster-of-Paris, specifically Formula Fine Casting Plaster with added Herculite for strength to better stand the inevitable knocks. The plaster-of-Paris beads have a high suction and the plasterer primed the surface of the beads with PVA to help mitigate the suction and strengthen the joint between the bead and the wall plaster.

As an aside, I was surprised to learn how little wet plastering with a float coat of browning is done these days: all new build is done with dot-and-dab dry lining with plasterboard, and a lot of renovation work as well unless it is making good old plasterwork. Finishing plaster specifically for browning is no longer made, and plasterers who can float and skim are becoming rarer as the older generation retire and the youngsters only learn dry lining. Peter our plasterer remarked that he couldn't remember the last job where the clients had asked for wet plaster. Dry lining has benefits in that it is quick to put up, dries out much quicker than wet plaster, and has better thermal insulation properties. But it just doesn't "feel" right for an old property, which is why we specified wet plaster where possible.

 

[AMc]

Dry lining has benefits in that it is quick to put up, dries out much quicker than wet plaster, and has better thermal insulation properties. But it just doesn't "feel" right for an old property, which is why we specified wet plaster where possible.

FWIW wet plastering is popular amongst the green self build community as it offers a much better seal for air tightness than board and skim - in combination with an insulated cavity wall. The danger with plasterboard dot and dabbed is that you can end up with air leakage behind the plasterboard through service inlets etc. and socket boxes. The carefully constructed insulated cavity wall contains a plasterboard tent liable to leaking heat every time the wind blows. The solution is to seal all the inlets properly too, but that kind of detailing is not always done.

If you comply with building regs for repairs over 25% of a solid wall then you need to insulate - at which point you need to use something like hempcrete to build up a thick layer on the internal surface or batten and insulate which is more easily done with board.