When council won't allow gallow brackets to remove chimney stack?

[fex10]

Epsom Ewell council state that they don't normally allow use of gallow brackets to support the chimney when the chimney stack (breast?) has been removed.

Are gallow brackets the L shaped brackets that in layman terms effectively create a shelf that the chimney then sits on?

So if gallow brackets are not allowed and the ceiling joists can't hold the chimney then whats the method? Are we talking a beam extending from external wall to external wall?

The council website says something about calculations to show that the chimney will be safely held. So when these local builders do the job do they really submit all their calculations? I know it's not exactly difficult to calculate a beam load, but am I to believe that Mr Local Bob Builder does it each time they remove a chimney stack?

 

[tony1851]

Councils vary as to how they view gallows brackets - some will allow them, others not.

Whether or not you can actually use them in practice depends on factors such as the proportion of chimney above the roof line, and the state of the brickwork.

If you have to use an alternative method, putting in a beam just below ceiling level is the usual way, though the council will usually ask for structural calculations to prove adequacy of the beam. Your builder does not supply these - you need to engage an engineer to do the necessary figures.
However, many builders tend to know by experience what type of beam is needed (even if they can't prove it), and if it is hefty enough, some building inspectors will sign it off without figures.

 

[fex10]

Thanks Tony. So beam below ceiling level, so it would be visible from the room? That doesn't bother me, just checking I understand. So this beam would go from one end of the house to the other or can it sit on an internal wall on one end?

Seeing as typical chimney is something like 50cm deep, would this normally need two beams rather than single beam supporting in the middle?

Thanks for clarifying the other bits as well. Last time we had work approved by the council we just did the calculations ourselves, the council engineer then went over them and approved them, meaning didn't need to pay a chartered engineer.

 

[tony1851]

Usually, just one beam is necessary, and it is put under the outer (loft) face of the chimney; if there are any loose bricks to the sides of the flue(s) which would be unsupported, jam a piece of thin steel plate under them, between the top of the beam, and the wall.

The beam is usually just below the ceiling, and spans from the outer wall to an inner wall - as long as the inner wall is itself load-bearing (does it go down to ground floor level?)

In some circumstances, you can put the beam above the ceiling, and sit it on top of the wall plate in the outer wall, though the top edge of the beam would need chamfering to clear the battens and tiles. Some will say you can't sit a steel beam on a timber wall plate, but in this instance you almost certainly can, as the load supported by the beam is in practice quite small, and the timber would not be over-stressed.

A good average section of beam is a 152x152x30, which would do on average spans (12ft?).

 

[fex10]

I just spoke to the council, they have said that the beam goes in the loft space, as you say, between the outer wall and inner wall. I'll check that the inner wall goes to the ground floor. I'm pretty sure it does.

Just need to find out what they expect to see in the calculations, whether it's a simple load calculation or if they want more.