Lintel/Beam size and joist hangers?

[thompo]

Hello

Looking for some advice on taking away or opening up a section of wall over hanging our hallway.

Here is the existing construction and what we would like to do.

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• thompo
• 16 Aug 2013
• 2

and the layout of where the section of wall is

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• thompo
• 20 Aug 2013
• 1

The whole thing is red brick but the bottom 150mm appears to be plasterboarded over so im guessing there is a lintel or beam in there already from a past doorway.

This section of wall is carrying 3 or 4 floor/roof joists above from an existing attic conversion (property is a bungalow, pitched roof with concrete tiles, only hallway/bedrooms above).

Any idea what size beam or lintel would be required? Span wall to wall is 1.1m so im wondering if a 100x65x1300 lintel would be enough or would i need be looking at steel?

Also is there a way to put joist hangers on a lintel so i could have the lintel in the celing void allowing a flat celing? Would i be best with a I beam for this purpose or would a timber beam be a possibility?

Cheers Neil

 

[tony1851]

Any idea what size beam or lintel would be required? Span wall to wall is 1.1m so im wondering if a 100x65x1300 lintel would be enough or would i need be looking at steel?

Don't use those thin concrete lintels - they're not reliable. What about a piece of 100x100 timber instead. That would be OK for that loading and span.

 

[^woody^]

Don't use those thin concrete lintels - they're not reliable.

They are more reliable than that advice.

 

[tony1851]

Don't use those thin concrete lintels - they're not reliable.

They are more reliable than that advice.

Rubbish.
Remember the old rule-of-thumb regarding timber lintels? - 'span in feet = depth in inches'.

Anyway, I've previously given reasons why the p/c lintels are no good for this type of job, so what specific gripe do you have about timber lintels?

 

[Pallatrax]

What size are you floor joists?

Say you have 8" x 2" you could make a tidy and sturdy job of cutting these and fitting a trimmer comprising of two of the same size timbers bolted together with m10 bolts and dog-tooth washers. You can then use jiffy hangers to connect the existing joists to this 8" x 4" beam.

Obviously you would need to make a suitable bearing either size, and prop and secure the timber/floor before doing anything, but the idea is no different to many openings for stairs.

Tom

 

[thompo]

Thanks for in the info, i would prefer the idea of a timber beam / Trimmer.

Unfortunately, its a very old conversion, previous owner comissioned it with out PP or building control over 30 years ago.
Joists are not up to current specs, 115x47mm or there abouts @ 300mm spacings, 3.5m clear spans.
Having said that, there is no bounce in floors and no sign of any failings over the years.

Would it be acceptable to use 2 off the same size joists as existing, bolted and supported? Given they are holding up over a 3.5m span, they should be fine over 1.1?

 

[Pallatrax]

I'm not qualified to say, but i'm sure two or three of them together would suffice over such a short span.

Tom

 

[tony1851]

Would it be acceptable to use 2 off the same size joists as existing, bolted and supported? Given they are holding up over a 3.5m span, they should be fine over 1.1?

Yes; in fact, two 4x2s bolted together (vertically) will be stronger than one 4x4 on its own.
Don't go overboard with the bolts, 2 or 3 will do.
The timber will also be easier to fix plasterboard to.

 

[^woody^]

I wonder why concrete lintels are approved by building control officers for situations like the OP's, when timber ones are not?

Surely building control would not allow use of unreliable lintels? Surely not

 

[tony1851]

I wonder why concrete lintels are approved by building control officers for situations like the OP's, when timber ones are not?

Surely building control would not allow use of unreliable lintels? Surely not

@ 'Woody'; stop stirring

@ OP; Use the timber lintel as you described - no problems - promise

 

[^woody^]

Oh sorry, I was just curious about the "unreliable" comment.

I just thought that concrete could be relied upon not to bow under load due to it being fast grown, and could also be relied upon to to move seasonally and crack plaster. Or burn in a fire

 

[tony1851]

Oh sorry, I was just curious about the "unreliable" comment.

I just thought that concrete could be relied upon not to bow under load due to it being fast grown, and could also be relied upon to to move seasonally and crack plaster. Or burn in a fire

In that case and as a matter of urgency, should the OP replace his timber floors with concrete-beam-and-block? And his roof structure?? And his staircase??

Once installed, the moisture content of a timber beam remains pretty much constant.

As for fire, elements of structure in a house only need 30 mins = 1 layer of Fireline? What's your problem?

 

[^woody^]

No, no and no. That's not how fire protection works, nor how timber behaves.

I'm still wondering why that's a different view to building control officers though

 

[tony1851]

I'm still wondering why that's a different view to building control officers though

That's probably because they were taught by the same narrow-minded, un-imaginative and inexperienced teachers as you obviously were.

Absolutely nothing wrong with timber beams - what on earth did we do before we had concrete, then?

 

[^woody^]

Yes, me and 15,000 BCO's in the same class, and you must have been out flying kites that day.

The issue is not adequacy of timber as a lintel (in some situations), but your assertion of the unreliability of concrete lintels.