Fireplace lintel

[kevhill]

Does any one know if this fire place needs a lintel under the curved bricks if I remove the blocks? There isn't one in place as it is now. Thanks in advance

 

[malcolm]

All of mine are held up by brick arches without lintels. The arch only supports the bricks in a 45 degree triangle above. Yours isn't the best example of an arch but the ends have a good angle so as long as the mortar is OK you should be good.

 

[Cubist]

Hi Kev,
Arched brickwork like that is intended to be self supporting and relies on the transfer of weight/pressure to the columns on the sides. Best to check that some clown has not cut into the vertical sides of the opening to make room for the blockwork. If they have then you will probably need to install a new lintel.

From the pictures the mortar between the bricks of the arch has failed and one or two of them have slipped downward. There also appear to be some cracks in the brickwork above with cracks forming a rough 'V' pattern. Before you do much more you need to stabilise the brickwork above the arch by pointing between all the bricks with a suitable mortar. The mortar must be pressed firmly into the spaces between the bricks and as far back as is needed to fill the voids. Remember, you may need to root out some of the existing mortar between the bricks to a depth of about 20mm so that the new mortar can form a strong key. When the chimney breast has been stabilised the mortar around the bricks forming the arch can be re-pointed in the same way but you may want to make a wooden form, shaped to the arch, to support the bricks while rooting out the old mortar and re-pointing.

You would probably be able to remove the blocks below the arch once the chimney breast has been stabilised but not until you're confident that none of the bricks forming the arch will fall out.

Hope this helps.
Cheers,
Cubist

 

[stuart45]

You might find a curved iron bar under the arch which adds stability.

 

[kevhill]

Thanks very much. Yes I've been thinking it's not a good idea to remove the block work until I've repointed the rest of the brick work.
Do you know if i should use a lime based or cement based mortar?

 

[Lacan07]

All mine have a curved bar supporting the arch, its sometimes set back so not particularly visible on inspection. If this room is on the ground floor you might want to use lime mortar to repoint.

Many people like to lime plaster their fireplaces but leave the arch exposed which I think looks rather smart.

 

[Kearn]

I wouldn’t be happy with just pointing, that’s an aesthetic not structural repair.
Lime, no place for cement here, although a very weak NHL would be probably ok given the setting.

I can’t work out the original form of your arch, as the bricks don’t appear to be cut/rubbed enough to form a solid curved shape with adequate contact, it almost looks like the centre needed a v shaped ‘keystone’ equivalent, which simply shouldn’t have been the case when built. Either way the arch looks like it has dropped a decent way. As you look at the photo, there appears to be missing brick on the pier, which should be taking the contact with the arch.

I would also be suspicious of the central header at the top of the load bearing triangle - looks like it has been meddled with from the differing coloured mortar. Presume the arch has dropped and repairs have been made without resetting the arch and this brick has dropped as the new mortar around is also wider than it should be.

Personally, I would be replastering in lime as these bricks were never to intended to be seen. An iron bar under arch packed up will give support from below. A lintel above a failed arch will help the stack, but the arch will probably still drop out further. And rake out the loose stuff only in the joints and if it’s in the range of 10-15 mm then just repoint in one go, almost flush finish but I prefer a little depression to help with the key for the scratch coat. If you choose to limewash instead, then point flush.

Assuming you’re pulling off a nasty rigid modern plaster, what happens at ceiling level where it meets the cornice, assuming it’s original? Care will be needed here too….

 

[paulc]

Had brickwork of a similar pattern and condition over my fireplace. Gave one of the bricks in the arch a prod, and it collapsed. Fortunately, just the bricks making up the arch came down. Ended up putting a concrete lintel in a tad higher where the gather started - Once plastered, no one is ever going to see it, so looks don't matter.

 

[stuart45]

What's your plan for the chimney?
Install a wood burner and expose and repoint the brickwork?

 

[CliffordPope]

A quality arch is made from special wedge shaped bricks. It would do its job without any mortar at all. But most domestic brick arches are formed from ordinary rectangular bricks that are dependent on the mortar to form the V-shapes, so obviously if the mortar crumbles than a rectangular brick can slip out, which seems to have happened with yours.
It depends really what you want to achieve - a secure arch as described by others, which will be plastered over anyway, or an elegant exposed arch rebuilt with re-positioned bricks.

 

[kevhill]

What's your plan for the chimney?
Install a wood burner and expose and repoint the brickwork?

The Plan is to expose and repoint and either use as a feature or put a bioethanol stove in the space.

 

[kevhill]

This is the look I am hoping to achieve

 

[kevhill]

You might find a curved iron bar under the arch

I wouldn’t be happy with just pointing, that’s an aesthetic not structural repair.
Lime, no place for cement here, although a very weak NHL would be probably ok given the setting.

I can’t work out the original form of your arch, as the bricks don’t appear to be cut/rubbed enough to form a solid curved shape with adequate contact, it almost looks like the centre needed a v shaped ‘keystone’ equivalent, which simply shouldn’t have been the case when built. Either way the arch looks like it has dropped a decent way. As you look at the photo, there appears to be missing brick on the pier, which should be taking the contact with the arch.

I would also be suspicious of the central header at the top of the load bearing triangle - looks like it has been meddled with from the differing coloured mortar. Presume the arch has dropped and repairs have been made without resetting the arch and this brick has dropped as the new mortar around is also wider than it should be.

Personally, I would be replastering in lime as these bricks were never to intended to be seen. An iron bar under arch packed up will give support from below. A lintel above a failed arch will help the stack, but the arch will probably still drop out further. And rake out the loose stuff only in the joints and if it’s in the range of 10-15 mm then just repoint in one go, almost flush finish but I prefer a little depression to help with the key for the scratch coat. If you choose to limewash instead, then point flush.

Assuming you’re pulling off a nasty rigid modern plaster, what happens at ceiling level where it meets the cornice, assuming it’s original? Care will be needed here too….

Thanks, the header brick at the top of the triangle does appear to have had work done to it. For some reason it has a piece of slate running across it and the rest if the mortar is slate coloured .

 

[stuart45]

The problem with segmental arches is that they put more pressure sideways than other types of arches. Therefore they generally need larger abutments. The jambs in the new photo are 13 inch, whereas yours are the minimum 9 inch. It looks like the jamb on the right might have moved out slightly just above the arch. This can cause the arch to move a bit. It's quite a common problem on older houses that have a segmental arch over the door next to the gable wall.
The one in the new photo looks like the arch was rebuilt a bit higher.

 

[Cubist]

You might find a curved iron bar under the arch which adds stability.

Stuarts right; iron or steel shaped to the required curve, with 'spurs' that would sit in the columns, would sometimes be used to provide support for the brickwork above. However, more often than not these were used instead of a wooden form and were regarded as a one time use tool for the purpose. These can be installed after the event but that may require the removal of the brickwork above to allow installation. Such irons/steels are relatively easy to make if a suitable fabricator or smith can be found.

Thanks very much. Yes I've been thinking it's not a good idea to remove the block work until I've repointed the rest of the brick work.
Do you know if i should use a lime based or cement based mortar?

Yes, a lime mortar is perfectly appropriate but I would check first that the original mortar is lime based first by testing a sample with some vinegar.

I'm aware that some believe that lime mortars are not strong enough for some purposes and are too weak to sustain an arched structure. Sadly, they are misinformed and I would refer them to the oldest lime built domed structure in the world, the Pantheon in Rome.

 

[Kearn]

Thanks, the header brick at the top of the triangle does appear to have had work done to it. For some reason it has a piece of slate running across it and the rest if the mortar is slate coloured .

Slate commonly used just to fill a gap too large for mortar alone, particuarly in the horizontal as it’s strong enough to pack out the gap crated by the dropping brick courses…