Brick chimney arch - enough support as is or needs a lintel?

[Suzanne]

We took off old plaster in the kitchen to reveal a chimney that had been filled in with concrete (breeze?) blocks. We would like to reinstate the chimney, have removed crumbly mortar and will replace with lime mortar. We have also removed a few of the newer blocks below the arch (see photo) but are concerned that the arch doesn't seem to have enough of an angle to really support the stack above (its on the ground floor of 3). We'd be grateful for any advice on:

- the quality of the visible brickwork
- whether it seems able to support the stack
- if we can safely remove the new concrete blocks
- if we need to install a lintel


Thanks very much

 

[FamilyWiggs]

Experts will be along shortly, but in my non-expert opinion the arch was originally designed to support the stack. It does look fairly flat, but providing the brickwork is well pointed and the "angle" of the bricks in the arch properly prevents them dropping out, you should be ok. However, as it looks st the moment, it doesn't look like it would take too much for the arch to drop out... further, the pillars either side look rather narrow. I suspect that this arch has been messed around with a fair bit since it was originally put in.

Theoretically, the worst that should happen is that a trangle of brickwork drops out ... hard to tell the state of the pointing though. Looks quite poor.

Can you post a bigger pic - quite hard to tell whatis going on.

I would certainly suggest awaiting the input of experts before removing the supporting blockwork!

 

[skier-hughes]

A bigger picture would be better.
I think the arch may well fall down if the support is removed there doesn't appear to be much, if any radius, on the arch.
I'm wondering if this may even be a false front?
Can you post a side view.
I'm also a non expert
But have just done mine.

 

[MdB]

I'm with FamilyWiggs on this (and also not an expert). The shape of the lintel means that there will be a high sideways force at either side and it looks very thin at that point with the possibility of bricks missing. Larger / more pictures would help.

 

[skier-hughes]

Here's mine
http://www.myvideoproblems.com/testfiles/personal/kitchen/27-09-07_1142.jpg

 

[MattW]

My fireplaces also have a very flat arch similar to that image. In fact they look very similar to how many georgian window arches were constructed:

So I wouldn't be too worried by the shape of the arch - while there could be a very high sideways force as MdB has pointed out, the breast doesn't look like it has been narrowed at all, so presumably it was built this way.

The thing that worries me much more about that brick work is that it appears that the opening has been widened (for two brick courses on the right and most of the left... I guess you will need to reinstate these prior to removing the infill.

 

[Suzanne]

Thanks everyone so far - I've attached 3 more images - one of the side, two of the front. I'm concerned about the radius (thanks for the term!) and the removed original bricks on either side of the opening that are infilled with (breeze?) blocks.
Ive done some homework about getting supports to insert while removing the new blocks and inserting a lintel (after rebuilding the side walls back to 2 bricks wide), but as there was no lintel before (but who knows - maybe it was taken out) I am wondering if it can hold as it is

 

[MdB]

It looks to me as if it has been mucked about with enough that it isn't in its original state and hence it would be a good idea to get somebody in who knows what they are talking about to advise. Unlike MattW's pic, there is little to stop the sideways forces so that would be a likely point of failure.

 

[middi]

Those type of " straight" archways usually had a 1inch or 2 inch wrought iron bar set at the back of the archway bricks and resting on the first brick at either side of the piers, see if this is there.

If there isn't one remove the breeze blocks and fit one. Make sure that the piers are stabilised by rebuilding and repointing as required and the archways are repointed leaving a 1-1/2 inch gap at the edge of the top of the last bricks under the piers for you to insert the iron bar.

If you wish to fit a lintel stabilise the piers first then slowly remove the archway bricks( a few of the flat layed bricks above may detach) and make enough room to slide your lintel in position allowing for a supporting edge of at least 3 inch ( 75mm) at the edge of the piers.

Just do not keep your head under the archways whilst working ( dropping bricks give you a headache !!!)

Judging by your pictures I would have no hesitation to do as described ( bearing in mind I have not looked at the rest of chimney condition)

 

[Lime]

My opinion is as middi says.
I would not be happy with that fire opening at all.
The arch is ok in construction but it requires lateral support at either end which appears to be in a very poor/weak state.
I can't see if there is an iron bar support or not but it needs one.
Similarly the piers on either side of the opening look weak/unstable.
However no type of arch will support anything when the tops of the support piers are missing as they are here!

before any other brick/blockwork is removed the piers and the sides of the fireplace require to be rebuilt or correctly repointed to stabilise them together with the missing bricks replaced.

The breast also requires attention as the bricks appear lose but it is unclear whether simple repointing will be sufficient.

 

[Jon Maine]

Having a reconstructed a fair range of vaults which had failed this is a subject I know reasonably well.

As Middi says a reinforcing bar underneath is quite usual.

Firstly, the springing of the arch at each side, i.e. the top of each pillar need to be rebuilt. I would be tempted to either remove the concrete block and replace with a temporary prop or leave a small pillar of block in the middle.

Secondly if no bar is present I would be tempted to fit an angle iron on the back edge of the brick arch lapping up the rear side of the bricks. The arch is only holding a triangle of bricks more than likely so this will reinforce well. You will need to fit this probably before you insert the last bricks on each pillar.

Good luck.

 

[hoppy]

Million dollar question....

How old is the brickwork and how old is the blockwork
seems to me that the blockwork was installed just to close up the opening,,
if that arch has lasted the last 100 odd years who's to say it wont last the next 100

 

[Suzanne]

thanks so much for all the advice - we've seen there is no metal lintel or otherwise, so we will build up the piers (thanks for the new term!) and put in a lintel. If anyone knows of a company in South London or thereabouts that sells these we'd be really grateful. Hoping to get it done by Xmas (live everyone at the moment probably!).

 

[Penners]

Mine is another voice agreeing with Middi's analysis. Provided that steel lintel is there, then the lack of arching on the bricks is a good thing, because it removes the risk of outward stresses on those single-brick side-walls.

If the steel isn't present, then an angle-iron insert is needed. Plus a good rake-out of crumbly mortar and a re-point.

 

[Flyfisher]

Having opened up a few fireplaces, I've often wondered if the usual 'iron lintel' is really structural or just used as a former to hold the brick arch in place while the mortar sets? The one's I've uncovered have all been of the order of an inch wide and 1/4-inch thick.

 

[Stephen]

The arch is not working as an arch due to removal of the springing point on the left side. From your photos the blockwork is providing support and to remove it without installing some form of propping could result in collapse.

For a properly formed arch there is no need for a lintel as such as the arch itself will bear loads. However, for yours to work the left hand brick pier may well need complete rebuilding.

That is all one can tell from the photos. You really ought to get a professional to ahve a quick look and advise on waht works are needed.

Stephen

 

[middi]

Some of these suporting iron fitted on straight or arched chimney openings were purpose made whereby the ends were split in two,one end was laid flat othe first brick of the pier but the second carried throught to the ouside face of the stack and bend against it. Usually quite visible. Presumably to reinforce any side stress. The truth ( as realised by later applications) is that on a well pointed chimney and in good condition there is very little side stress, there is none at all if a lintel or iron bar is just resting on the piers.

These type of chimneys were successors of the inglenook.

 

[robgil]

is there supposed to be more bricks in the side piller things? it looks like half of them are missing.

 

[middi]

As Stephen pointed out, the left side pier looks as if part of the inner bricks are missing , these were probably in bad conditon or crumbling and were possibly removed when the breeze blocks were fitted, therefore removing these blocks without rebulding and stabilising the arch it may cause a lot of bricks ( if not the whole chimney!!) to tumble down.

Usually these side walls openings ( piers) were constructed with a single stretcher and two headers bricks ( 9 " wide).

 

[robgil]

ah , i need to pay more attention to the thread before posting. just spent 4 days up in suffolk living on pretty much a building site.
4 days without a shower , a proper bed or even a working phone. i cant wait to get into bed.