Putting a beam in an extension

[brianj42]

Ok dok, here we go.

I currently have a flat roof, nothing above, non load bearing, kitchen 5mtrs deep and 6 metres wide.

The back wall is blockwork and the roof joists sit happily on this.

I now want to extend out another 4 metres and knock this wall out having one large kitchen.

To do this I will have an open span of exactly 5 metres. So, woth a pier each end I am looking at a 5.6M spanning requirement.

I would love more than anything to span this in wood as the new extension will be post and beam, so a large wood beam across the centre would be better.

The beam would be holding the roof joists from the house to the middle and from the middle to the back of the new extension.

Try as I may I can't find any info about using wood beams over such a (5.6M ) span.

As I say, its a flat roof, none load bearing, nowt above.

Wood or Steel ?

Cheers

Brian

 

[noseall]

I am looking at a 5.6M spanning requirement.......Try as I may I can't find any info about using wood beams over such a (5.6M ) span.

Hardly surprising. They don't make trees that big.

 

[Nozzle]

I am looking at a 5.6M spanning requirement.......Try as I may I can't find any info about using wood beams over such a (5.6M ) span.

Hardly surprising. They don't make trees that big.

Cocky bugger.

Check out glulam, a fine alternative to steel.

Nozzle

 

[brianj42]

Someone should tell that to the 60 metre run of 50 ft high bloody fir trees in my back garden. Turn your back for one minute and they have reached for the sky.

glulam looks the part, any idea on pricing for a 5.6M one. I could wait until Monday but any indicative price would be appreciated.

Cheers chaps

 

[stuart45]

http://www.timberlink.co.uk/sawn-timber/building-and-carcassing/purlins/
You can get long timbers.

 

[noseall]

The point I was making is you are better off going for steel for practical reasons.

I'm sure there is a beam made from popcorn somewhere but why bother.

Steel is compact, inexpensive and strong and not that difficult to fit that is why designers specify it.

Forget glulam a total faff and not particularly practical either.

 

[tony1851]

The problem in having a timber beam over that span is one of deflection. To avoid excessive deflection, a timber beam would be fairly deep and probably visually obtrusive.

A 152 x 152 x 30 steel beam would do fine in that location.

 

[geraldthehamster]

What about a steel, with a timber casing to match the post-and-beam of the extension?

Cheers
Richard

 

[brianj42]

Cheers chaps. I'll price up a steel and a glulam on Monday and go from there. I do know however that wood casings for steels are more expensive than the steel itself so may have to go with a plasterboard covering.....

 

[Nozzle]

I think steel needs fireproofing too? Maybe this is just in large buildings.

Nozzle

 

[tony1851]

I think steel needs fireproofing too? Maybe this is just in large buildings.

Nozzle

If the beam is only supporting a roof, it does not have to have any fire resistance, so in that situation the steel could be left exposed!
Strange but true!

 

[RonnyRaygun]

Cheers chaps. I'll price up a steel and a glulam on Monday and go from there. I do know however that wood casings for steels are more expensive than the steel itself so may have to go with a plasterboard covering.....

How much head room have you got. You might find your glulam ends up too deep to be practical.

 

[geraldthehamster]

Cheers chaps. I'll price up a steel and a glulam on Monday and go from there. I do know however that wood casings for steels are more expensive than the steel itself so may have to go with a plasterboard covering.....

I made my own. It wouldn't fool anyone for very long but has the right feel to it. 5.2 metres in softwood, about 12" by 8", timber cost £109 if I remember rightly. Noggins in web of the steel, fireline board screwed to them to cover the steel, timber fixed over that with no more nails and many 50mm pins from a gun, minor fettling with belt sander ...

Cheers
Richard

 

[brianj42]

Steel is a third the price of the Glulam so steel it is. Thanks to all who commented

 

[ban-all-sheds]

What about a steel, with a timber casing to match the post-and-beam of the extension?