open up chimney with brick arch

[weavy]

Hi folks

I'm in the process of opening up my Victorian chimney breast to install
my wood burner . Having taken off the plaster I have revealed a brick
arch above the infill . Had a feeling this may be there . What I want to
know is will it be safe to knock out the infil?l ,

The arch does have a steel rod 2 inch wide underneath it



Kind regards
Weavy




--
weavy

[Phil L]

Yes it's safe to knock out the infil - the steel bar was there for the
bricklayer to build his arch on, they never bothered taking them out even
though they could have once the arch had set.
If it's going to be on show, it'll need a good wire brushing and a coat of
high temperature paint, also, expect soot falls unless you intend putting a
'ceiling' above the wood burner - I used 'hardibacker' - a cement based,
15mm board available from b&q about 4X4 IIRC, still got half of it lying
around.
Don't use plasterboard as it won't last a fortnight - not even the fireproof
stuff.

[Tim Watts]

On Sunday 10 February 2013 20:10 Phil L wrote in uk.d-i-y:

> weavy wrote:
>> Hi folks
>>
>> I'm in the process of opening up my Victorian chimney breast to
>> install my wood burner . Having taken off the plaster I have revealed
>> a brick arch above the infill . Had a feeling this may be there .
>> What I want to know is will it be safe to knock out the infil?l ,
>>
>> The arch does have a steel rod 2 inch wide underneath it
>
> Yes it's safe to knock out the infil - the steel bar was there for the
> bricklayer to build his arch on, they never bothered taking them out even
> though they could have once the arch had set.

+1.

My fireplace "arch" is nearly horizontal and had no iron underneath. I added
a bit of 2" x 1/4" bar gently curved by standing on it across a couple of
bricks. It is let into the bricks about 2" either end.

It did not absolutely need it - but some of the mortar between the bricks in
the arch looked a bit dodgey.

--
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[Dave Liquorice]

On Sun, 10 Feb 2013 18:41:15 +0000, weavy wrote:

> I'm in the process of opening up my Victorian chimney breast to install
> my wood burner . Having taken off the plaster I have revealed a brick
> arch above the infill . Had a feeling this may be there . What I want
> to know is will it be safe to knock out the infil?l ,

It should be, the arch is there to take the weight of the stack and
transfer it into the ground via the sides of the opening. Assuming the
brickwork/mortar etc of the arch is sound the infill below it can be
removed.

> The arch does have a steel rod 2 inch wide underneath it

As has been said support for the bricky to build the arch on. It
shouldn't be doing anything significant to support the arch now.

http://en.wikipedia.org/wiki/Arch

--
Cheers
Dave.

[Tim Lamb]

In message <weavy....@diybanter.com>, weavy
<weavy....@diybanter.com> writes

I have done two here. Both having been reduced to an 18" opening with
the fireback gap filled with rubble.

In my case there is a steel strip following the shape of the arch and
supporting a row of *soldier* half bricks. The strip goes through the
brick columns and is split with each half turned back against the
brickwork.

Above the arch and inside the chimney, the brickwork is *corbelled*
(narrowed in layers) to form the actual flue.

--
Tim Lamb

[dennis@home]

It could be doing a useful function..

arches tend to push outwards and need something to push against.
the iron bar could be there to keep the arch from spreading if there is
not enough wall either side to resist the forces.

If the opening is in the middle of a wall the bar is probably doing nothing.
If the opening only has a couple of bricks either side it probably is
doing something.

[Dave Liquorice]

On Sun, 10 Feb 2013 20:29:30 +0000, Tim Watts wrote:

> My fireplace "arch" is nearly horizontal and had no iron underneath. I
> added a bit of 2" x 1/4" bar gently curved by standing on it across a
> couple of bricks. It is let into the bricks about 2" either end.

Unless the ends of that bit of strip are really unable to move outwards
it's going to be next to useless should the arch start to collapse. In
fact it may make things worse by pushing the tops of the side walls
outwards.

You bent it by simply standing on it, how heavy is the triangle of stack
above the arch?

--
Cheers
Dave.

[Tim Watts]

On Sunday 10 February 2013 20:54 Dave Liquorice wrote in uk.d-i-y:

> On Sun, 10 Feb 2013 20:29:30 +0000, Tim Watts wrote:
>
>> My fireplace "arch" is nearly horizontal and had no iron underneath. I
>> added a bit of 2" x 1/4" bar gently curved by standing on it across a
>> couple of bricks. It is let into the bricks about 2" either end.
>
> Unless the ends of that bit of strip are really unable to move outwards
> it's going to be next to useless should the arch start to collapse. In
> fact it may make things worse by pushing the tops of the side walls
> outwards.

They are unable to move outwards and there's a foot thick of solid masonry
either side of the opening.

Don't forget that it's basically only supporting the triangle of brickwork
over the opening - this iron's job is merely to stop the odd brick dropping
out.

>
> You bent it by simply standing on it, how heavy is the triangle of

<insert> single brick leaf at the front of the </insert>

> stack
> above the arch?
>

Probably a lot less than me! And 1/4" bends easily when the ends are free :)

[RobertL]

On Sunday, February 10, 2013 8:10:39 PM UTC, Phil L wrote:

> weavy wrote:

> > I'm in the process of opening up my Victorian chimney breast to
> > install my wood burner . Having taken off the plaster I have revealed
> > a brick arch above the infill . Had a feeling this may be there .
> > What I want to know is will it be safe to knock out the infil?l ,
>

> >The arch does have a steel rod 2 inch wide underneath it
> Yes it's safe to knock out the infil - the steel bar was there for the
> bricklayer to build his arch on, they never bothered taking them out even
> though they could have once the arch had set.

Are you sure the rod isn't there to take the spreading load from the arch? An arch exerts an outward push on the brickwork each side.

Also, if you are reopening a chimney you'll need to have building control approve it anyway. They'll give advice on the steel rod as part of that.

Robert