Bressummer Beam

[Ben]

Our ceiling dips (about 8mm) as it passes over our single storey bay (about 1.8m wide). Obviously the assumption is that the beam(s) that span the gap have deflected. Although that said, all the external brick work is level with no stepping cracks, the windows and lintels above and around are level, as are the floors directly above. Plus the dipped plaster sounds a little hollow when tapped, so I suppose it could be the plaster coming away from lath.

This leads me onto the beam replacement cost. I've seen people talk on various forums about £10k plus and I can't get my head around this figure. Obviously it'll need building regs approval, so that's £500 straight off, but beyond a little dismantling and rebuilding of the bay and bay roof and some internal plasterwork, surely it is no more difficult than taking down a supporting wall and inserting an RSJ, which for a 2m wall would be in the region of £1000 (exc vat, and without making good the cosmetics). Both will require some prep work, supporting of the brickwork/floors above and the insertion of the beam. Surely, all in should be more like £3k max for a small bay?

Could anyone enlighten me as to where these £10k figures are coming from, or is that for the really grand houses with 2 massive bays that need supporting?

Thanks

 

[Cubist]

From your description of the problem there seems to be little wrong other than an 8mm dip.

Bluntly, unless there are other issues you have not included above then you would be stark staring bonkers to consider spending a bean on such work.

 

[Stevers]

Unless there is a sign of impending failure (as in cracks) then for peace of mind you could just monitor the deflection over time. The beam(s) may be under sized in terms of deflection by modern standards, but how long has it been like that so far? It's perfectly possible for a beam particularly in timber to have excessive deflection by modern standards, but for it to be nowhere near failure in terms of shear or tensile strength (bending). Some timber comes out of the sawmill that bent too - although a good builder would have used that to his advantage.

This looks like an excellent opportunity to delay a large (and messy) expense forever!

 

[stuart45]

It's often only the bearing ends that go on them. If the masonry above looks OK, I wouldn't worry too much.
I've worked on knock throughs on spine walls, and bressummer replacement jobs, and generally there is a lot more work involved with bressummer replacement. They can also be taking the main floor joists.
The brickwork above will often need rebuilding.

 

[Ben]

Unless there is a sign of impending failure (as in cracks) then for peace of mind you could just monitor the deflection over time. The beam(s) may be under sized in terms of deflection by modern standards, but how long has it been like that so far? It's perfectly possible for a beam particularly in timber to have excessive deflection by modern standards, but for it to be nowhere near failure in terms of shear or tensile strength (bending). Some timber comes out of the sawmill that bent too - although a good builder would have used that to his advantage.

This looks like an excellent opportunity to delay a large (and messy) expense forever!

There are some hairline cracks dotted about the plaster, but nothing that would concern you in the absence of the dip.

 

[Cubist]

As I understand your initial post this bressummer is spanning a bay window with a 6 foot opening in a single floor structure so I am assuming that the most it can possibly be supporting would be some of the roofing timbers, perhaps some tiles and maybe a couple of courses of brickwork. As such there is unlikely to be a significant 'point load' near the middle of the timber that may cause an 8mm deflection; even if the builder used an 8x2 joist timber. However, it is feasible that an under-size timber, say 6x2, could produce that degree of deflection. Nevertheless, such a small degree of variation is precious little to worry about as it could easily be explained by other root causes such as sagging of the plaster. Personally, I would keep my wallet in my pocket and occasionally measure the deflection to see if it is worsening, while also being on the lookout for widening of existing cracks in the plaster or new ones appearing.

As to the £10k quote you were given - I suspect whoever came up with that price was already booking a holiday in the Maldives and looking for you to pay for it.

 

[CliffordPope]

Only the bay is single storey as I understand it. So the beam in question is level with the back of the bay, and supporting an unspecified number of floors above?

 

[Ben]

Yes, single story bay. Shallow slope on the bay roof. 2 storey house.

 

[malcolm]

Someone added a couple of bay windows to my place in 1920. The wood is undersized by modern standards and the ceilings have deformed in both by an inch or two. The slope of the bay was also very small and water on the bay roof ended up falling inwards rather than outwards. It's only the fall that caused me problems. One roof had rotted so I put some tapered wood on the joists before re-boarding to make it fall in the right direction.

Otherwise the deflection isn't a problem for me. It's had 100 years to get there and I can't see it getting much worse.

 

[Toby Newell]

£10,000 may or may not be ridiculous depending on the amount of work involved.

It's 2023, a single pink grapefruit is £2.30 from Ocado...

Last winter I worked on a house with a 300mm deflection.

Just finished a room last week on my current job with a 200mm deflection, former was a 1550 additional storey to a 1470 house, latter is a 1550 house.

Many of the Victorian properties I work on have 20 - 50mm deflections.

I get calls to ask me to level things all the time, if it's less than 100mm I tell them to forget it.

8mm??? Lol. The plaster on my current job was drooping more than 28mm.

I would say you have approximately nothing to worry about.

To be honest, if I bought a period property and insides were less than 8mm out of true I would ask for a refund... I mean, if you can find a new build these days which doesn't have an 8mm discrepency somewhere, you're flipping lucky

Have you seen the crooked house in Lavenham? I believe that dates from around 1390, I think the deflection there must be around half a metre, still standing...

Don't worry though, I'm sure you can find at least £10,000 worth of other work to do on your house if you poke around in the right places.

 

[paulc]

8mm dip ?
Are you sure it is the beam and not a variation in plaster thickness ?
I've got a bulge on one bedroom wall that protrudes a good 12mm. I reckon it was originally done by a drunkard trainee back in 1928. Many of the other walls and ceilings are far from being flat, although that is slowly being fixed as I insulate and replaster them.

 

[Toby Newell]

8mm dip ?
Are you sure it is the beam and not a variation in plaster thickness ?
I've got a bulge on one bedroom wall that protrudes a good 12mm. I reckon it was originally done by a drunkard trainee back in 1928. Many of the other walls and ceilings are far from being flat, although that is slowly being fixed as I insulate and replaster them.

That trainee must of got around a bit.

Pretty sure he worked on most of my jobs previously.

 

[philpjuk100]

DWB who used to post on here would not allow workmen to bring levels onto her property.