RSJ v Wooden beam

[another_richard]

Hello,

(first of all great site with lots of very helpful people that has an uncanny knack of having topics on for discussion just as I am thinking about asking them. However, this one has not come up so I feel I must pose this question any help would be wonderful).

bit new to the site so I hope this works.

House is Victorian 1900 in the Hastings area (still buy a 4 bed house for under 160k).

It has three floors two rooms over two over two, with a cast iron fireplace in each except this one (pictured or linked to picture below) which is the kitchen, (ground floor back).

It was bricked up and as you can see I have opened it and under orders have extended up the size of the fireplace to accomodate the gas cooker as the kitchen is such a small space.

In a fit of pique I added a wooden beam and afterwards fell asleep regretting it. I think it should be metal RSJs in order to pass Building Regs, is this true?

If so, I will take it out put the RSJs in and box the beam around it.

http://host.photogalaxy.net/viewer.php?id=90854_DSCF11101.JPG

I know it is not a country cottage and a wooden beam is un-Victorian but...

Will this pass building regs or do they indeed even apply?

I plan to put two rsjs in to take the weight, one behind the other, or leave it as is?

Many thanks for any help

Rich

 

[Penners]

I can't answer your question about building regs, but as a matter of general interest, the weight that your lintel is carrying is actually a fair bit less than you might think.

It's tempting to think that the lintel carries the entire front face of the chimney. In actual fact, if you were to pull the lintel out, the brickwork would collapse in a pyramid shape, starting full width just above the lintel, and then tapering up to just one brick wide.

Now that I've got that off my chest, perhaps someone who really knows what they're talking about will answer your question.

 

[MdB]

Again, I am somebody that doesn't know what he is talking about but is going to give advice anyway....

Basic rules of (most) building regs are that is has to be sensible. You won't find a reg that says you have to fit an RSJ. You will find a reg that says the lintel has to take the weight of what it is supporting and that you have done the calculations to prove this.

As Penners says, your lintel does not look like it is carrying very much weight at all and that beam looks like it is easily big enough to my untutored eye.

Building control regs are here if you want to have a look through them.

 

[Lime]

The best advice I can give (now that you have done it without prior contact with building control) is tidy it up and, when you sell the property, say it was like that when you bought it.

 

[Penners]

say it was like that when you bought it.

Ah - the DIYers mantra!

 

[NT]

The beam will only support the triangle of brickwork above it. All the rest of the brickwork will be supported by other interlocking brickwork. Your beam looks very large for such a small support job.

It wont pass BR if its a bare wood beam in a fireplace. Everything you do must comply with BR, that's the law. You might wonder why when nothing else in the house does, but them have decided so.


NT

 

[Gervase]

Building Regs are merely approved documents, and if you have a sane BCO you should be able to persuade him/her that a wooden beam is more than adequate for the job. Building Regs do not state that such a lintel has to be centric, cat, rolled steel, concrete, wood or whatever - merely that it must be up to the job. As you won't have an open fire, merely a hob, the issue is up for debate IMO.
Talk to your BCO and get him/her onside.

 

[Flyfisher]

Talk to your BCO and get him/her onside.

But how will you get the BCO on-side without being able to show the loading calculations that prove the wooden beam is up to the job?
I seriously doubt the BCO will take the personal risk of approving the work without such supporting evidence; why should they? Besides, that would be rather unprofessional wouldn't it?

Now that it's done, I tend to agree with Lime's pragmatic suggestion.

 

[Gervase]

Any decent structural engineer should be able to provide loadings for pitch pine, oak, iroko or any common timber. It's not as if wood is some strange new material that no-one's yet investigated!

 

[Jon Maine]

If you put steel in or wood in a structural position if its holding up a major portion of the house it should have calculations provided for by an engineer.
However, I must say simple door window and fireplace lintels perhaps are not perhaps in the same situation. As stated previously the load on this lintel is merely the triangle of masonry 45 degrees from each of the bearings up. probably not much more than 100kgs if that.
Structurally you are competent without a doubt, perhaps the fact its a fireplace and wooden and potentially exposed closely to excessive heat may be more of an issue.
BCOs are varied in pragmatism in my experience. I think perhaps you should call for advice first asking if you were to replace the lintel with the one you have put in if they would require anything. I suspect not.
Do consider the exposure to heat though I have had to replace wooden lintels with concrete above stone fireplaces as they have burnt right through.

 

[Flyfisher]

Any decent structural engineer should be able to provide loadings for pitch pine, oak, iroko or any common timber. It's not as if wood is some strange new material that no-one's yet investigated!

I don't doubt they could, but since the job has already been done it's all a bit like bolting horses and stable doors. Is it really worth it? In absolute, proper-way-to-do-it, professional terms - of course.
In practice, I doubt it.

 

[Flyfisher]

Do consider the exposure to heat though I have had to replace wooden lintels with concrete above stone fireplaces as they have burnt right through.

We had a chimney fire once that resulted in a large oak lintel being smoldered away over a couple of days, but the chimney didn't collapse (thank goodness!).

I offer this purely as an anecdote, not as any reassurance for anyone else's fireplace!

 

[biffvernon]

Period property should be maintained with period methods. No steel, concrete or structural engineers allowed.

(Or BCOs)

 

[biffvernon]

a large oak lintel being smoldered away over a couple of days,

In a major fire a steel joist deforms to the point of failure rather quickly while an oak beam charrs on the outside but maintains it's strength for a long time, allowing folk to escape.

 

[Penners]

But how will you get the BCO on-side without being able to show the loading calculations

In a case like this lintel, I reckon that - during a routine BCO inspection - I would nod towards the lintel and casually say something like, "that'll do the job, won't it?"

Unless the BCO is a real jobsworth, he/she will see that it's obviously well specified for the application and think no more about it.

That's a suggestion, not a promise!

 

[another_richard]

Thanks to everyone for your advice.

I am afraind I do not have any calculations. The pine beam (came form a reclamation yard - church converted into flats) is around 6 inches square.

We have been given a contact number of the BCO and plan to suggest what we 'plan to do'.

Just to confirm, the house is not listed, (shame as we are one of the last ouses in the road with sash windows) and we plan to put the cooker into the space, no open fire.

Many thanks again and please keep up the good work.

Rich

 

[plumbers mate]

The fireplace in my dining room has a thin iron rod - perhaps I section, but about an inch maximum in depth, holding up the brickwork.

 

[Penners]

Hmmm - you don't sneeze too often in that room, do you?

 

[plumbers mate]

Frequently - it's the dust from the chimney ...
I discovered this rod when trying to wedge a bit of board into place to stop the detritus showers - the fire place isn't used but is usable.
The board wedged nicely in the bar which s why I think it's an "I" section one. There may be something else hidden in the stygian gloom of the fireplace of course.

 

[NT]

The requirement not to use wooden structural elements within a foot or 2 of the fire dates back to at least 1924 Build Regs. And no, thats not from memory


NT