I am currently building a two-storey extension to my cottage and there are two carriage arches in the new-build. Does anyone know how to build the perfect arch? Would I be better off using a curved steel beam with plates welded on? Or would you use a wood former and build the arches in brick then knock the former out after to use as a template for the frames. The width of the arches is 2500mm, one is a garage door and the other is door set into a frame. How are brick arches best built? Many thanks.
carriage arches
- Thread starter clarebear
- Start date
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H
hotrod
I watched a programme a few years ago with Fred Dibnah where he built some brick arches, supported by wooden formwork. He left the formwork in place overnight whilst the muck went off, then removed the supports the next day.
The programme was all about the tragedy of traditional engineering/building skills dying out and how things aren't built properly anymore. To prove the principle that an arch gains its strength from the supported load, he climbed on top of the arch. It collapsed
The programme was all about the tragedy of traditional engineering/building skills dying out and how things aren't built properly anymore. To prove the principle that an arch gains its strength from the supported load, he climbed on top of the arch. It collapsed
I would use a timber former, known as the turning piece. The best arches have the bricks cut and tapered, rather than tapering the joints, although on a large arch like this you can probably get away with the joints.
That's because he didn't buttress the bottom; had he have done so, it would have supported him.I watched a programme a few years ago with Fred Dibnah where he built some brick arches, supported by wooden formwork. He left the formwork in place overnight whilst the muck went off, then removed the supports the next day.
The programme was all about the tragedy of traditional engineering/building skills dying out and how things aren't built properly anymore. To prove the principle that an arch gains its strength from the supported load, he climbed on top of the arch. It collapsed
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If you know what the rise (vertical dimension between springing point and the underside of the crown of the arch) X is and you obviously know the width W. So the radius is [W²/(8X)] + X/2. Armed with that, you can make a former.
Noseall will give you all the griff
Noseall will give you all the griff
Carriage arch is vague, misleading term, and does not relate to the actual type of arch, but just to an archway for a carriage
Normally the arch will be segmental (long with just a slight rise), or it could be semi circular, or eliptical.
But more dramatic than a basic segmental arch, would be the three-centred arch, which looks a lot better.
Make the arch centre from two sheets of ply, with a thinner ply sheet bent around the top to lay the bricks on. Make sure the curve is smooth and even or else unevenness will show in the arch.
It's always better to work out the arch centre size on paper, or better still on a basic CAD program, and then scale this up to mark out on the board flat on the ground.
Normally the arch will be segmental (long with just a slight rise), or it could be semi circular, or eliptical.
But more dramatic than a basic segmental arch, would be the three-centred arch, which looks a lot better.
Make the arch centre from two sheets of ply, with a thinner ply sheet bent around the top to lay the bricks on. Make sure the curve is smooth and even or else unevenness will show in the arch.
It's always better to work out the arch centre size on paper, or better still on a basic CAD program, and then scale this up to mark out on the board flat on the ground.
H
hotrod
Aaaah it's coming back to me now! So you watched it then? He sat on it didn't he? He was a living legend our Fred. Don't make um like that no more.
RIP Fred - sadly missed
I've just done one using a wooden former and it looks pretty good. Mine's only about 1m across but I see no reason why the same technique couldn't work on a larger arch. Mine's in carved sandstone.
The trick is to ensure that the joints have a consistent mortar space between them (i.e cut the bricks) and that the keystone is dead central.
The trick is to ensure that the joints have a consistent mortar space between them (i.e cut the bricks) and that the keystone is dead central.
We use a ply sandwich with noggings between as Woods has said. There is no need for thinner ply across the top as the bricks will sit ok on the ply edge. It also allows the muck to weep and not smudge the bottom face.
We set out the radius using a type of compass. Lay the plywood on a flat lawn. Hammer a peg in the ground a set distance from the sheet. Decide on how much deflection you would want in the arch then use a notched strip of wood (roofing lath) as a guide for your pencil. One end of the notched lath with sit on the peg and the other notch holds the pencil.
Shortening or lengthening the lath will determine the radius or deflection from horizontal. For example a half round arch would just have a point directly at the edge of the ply sheet. A shallower radius will have the peg some distance away from the edge of the sheet.
Make one leaf of the former then use this piece as a stencil for the second piece. Keep the jigsaw smooth.
We set out the radius using a type of compass. Lay the plywood on a flat lawn. Hammer a peg in the ground a set distance from the sheet. Decide on how much deflection you would want in the arch then use a notched strip of wood (roofing lath) as a guide for your pencil. One end of the notched lath with sit on the peg and the other notch holds the pencil.
Shortening or lengthening the lath will determine the radius or deflection from horizontal. For example a half round arch would just have a point directly at the edge of the ply sheet. A shallower radius will have the peg some distance away from the edge of the sheet.
Make one leaf of the former then use this piece as a stencil for the second piece. Keep the jigsaw smooth.
You could also use a pair of trammel heads to form the arc. As it's a large arch I would consider getting a chippy to knock it up, as the arch will only ever be as good as it no matter how good the bricklayers are.
Cheers for the tips everyone.
Yeah, I remember that - he was emphasizing the importance of the keystone and how the greater the pressure, the stronger the structure. Its cos it was just an arch wi nowt round it. Funny tho
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