Archway over brickwall

[eemgee]

OK fellas,
SWMBO has declared she wants the brick arch covered in plaster, Just doesn't like the look of the brick and also reckons it creates dust all the time.
I have done archways before but always on timber walls and I've always put metal angle on the corners cutting one side and then bending carefully to create the curve.
I've battened the brick arch with 10mm battens on the inside of the arch and am setting all sides of the arch with 10mm plaster direct on to the walls using cornice cement and intend to use 6mm plaster on the inside of the arch. The archway is 1100mm wide so I should be able to bend it OK by dampening the rear side.
Now the question do I still use the metal corner angle or is it OK to joint with paper on the corner and wet plaster, will this be strong enough
Wayne

[b1ueshift]

I would have thought a steel edge was the way to go for any exterior angle. Won't chip if somebody knocks it and gives you a sharp edge to work to.

[journeyman Mick]

Wayne,
you can save yourself a fair bit of work and buy "arch bead" instead of the normal angle. It's already notched to enable easy bending in archways. There is a psecial plasterboard sheeting that bends (relatively) easily, otherwise wetting the outside of the curve and applying pressure can work, but you need to have multiple goes at it for tighter curves.

Mick

[eemgee]

Thanks Mick,
I hadn't heard of the "Arch bead' before , sounds exactly what I need,
And thanks b1ueshift I do like the idea of having a hard corner especially when the grandkids decend on us.
Wayne

[rod@plasterbrok]

eemgee, There is a plastic arch bead that performs much better than the steel bead. The steel bead has a very small lip that can allow a fine hairline crack to appear. The plastic archbead has tabs the same width as the other side of the angle. This reinforces the joint much better.

You will also need to use the plastic externals so the profile matches.

If you use the metal arch bead I suggest you paper tape the edge first to help avoid cracking.

When I was working as a plasterer we had a lot of call backs for fine hairline cracks on arches even when paper taping first. Once we started using the plastic angles we never had a call back. We only supply the plastic angles to our contractors for archways or curved bulkheads for this reason.

Also 10mm board will do the bend ok. We have a section on curved walls on our web site. when you wet the strip lean it against the wall for a bit or drape it over a couple of tressels. Dont force it.

Cheers

Rod Dyson

[eemgee]

Thanks Rod, the plastic bead sounds the way to go, I have started on the arch I'll post some photos in the next reply, I have made one blue when cutting the side sheets but i could overcome that by using the plastic bead, can it be bought from either LaFarge orBoral who are the two suppliers here in Hobart
Wayne

[eemgee]

Here are the photos of what I have done so far.
Had to find out how to reduce the photo's size before I could post them.
Wayne
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Attachment 29157

[rod@plasterbrok]

One side looks like it has render with a sand finish? did you intend to stick plaster direct to the brick and match to the render or batten and plasterboard that wall as well?

The inside sheet should go on first normaly and cut the face sheet by running a series of saw cuts up and then cutting the back with a trimming knife. This way if you use a metal angle the shorter leg will not leave the "JOINT" exposed, as it would the way you have done. Like you say the plastic bead will fix that problem.

If they don't have the plastic bead in stock they will get it in for you. If not the lagarge store in Hobart will.

If you can't get plastic and have to use metal make sure you cut the inside sheet the full width and trim any overhang, then paper tape the "joint" before fitting the angle.

If you get the plastic angle start the arch bead about 100mm below the point where the arc starts. Tack that end then push it hard into place from the other side and tack that end. If you push it firmly up it will form the arch without any flat spots. Then you can tack it at 300mm centers from the first end. Sometimes you may have to release the second tacks as you come around if you hadn't set it quite right.

I find it best to only put temporary tacks in untill you are satisfied that the angle is set up right then mix up some plaster and fill a small section 100mm long on each side 300mm apart. When it sets the bead will be exactly how it was when you pinned it. Then remove the temporary tacks, scrape back the spots where you filled and fill the angles as normal.

It is a bit slower that way but the end result is much better as it is easier to adjust things perfectly without banning around with a hammer.


Cheers Rod

[eemgee]

Thanks Rod,
Boy without your input I'd have made a lot more mistakes as I went along,
I hope I speak for all those of us non tradesmen of limited knowledge on this forum in thanking you for your input and your willingness to impart your experience to us all. It gives us the confidence to have a go.
Thanks again,
Wayne

[eemgee]

Here are 2 more photos of where I'm at, ready to put the beading on,
I've rung Lafarge & they said that they have it here in Hobart.
As you can see I've plastered the wall after sanding the paint back to bare render in the spots where I put the cement, Yes Rod you spotted my blue of putting the inside sheets on last, only noticed it myself after cutting the panel on one side so I had to continue as is.
Thanks again Rod.

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Attachment 29267

[rod@plasterbrok]

Cheers Wayne,

Its looking good.

Well done.

PS. If Andrew Arnott still owns the lafarge store down there tell him I said hello!