RSJ expansion?

[gasbusters]

Should there ve an expansion gap left when fitting an RSJ in a loft conversion?

The steel beam will be 5.88 meters long, but there was no mention of an expansion gap in the structural calc or plans.

Should i leave an expansion gap and if so how much at each end?

Thanks in advance

 

[johnny2007]

I don't think your house will have such extreme changes of temperature to affect a 6 metre rsj.
Unless you plan to keep the conversion without a roof for sky gazing...

 

[gasbusters]

Lol no we plan on keeping the roof in place!

Its going to be 2 rooms and a shower room, so only heat will becoming from radiators.

 

[tony1851]

A 6m steel beam will expand less than 1/10th of a millimeter for each deg. C increase in temperature.
So unless you install it on a freezing cold night, and then plan to operate a blast furnace in your loft, expansion will never be an issue.

 

[Leofric]

I obviously don't know your loft situation but is

it a problem leaving a 'bit of a gap' at each end anyway ​

 

[gasbusters]

I obviously don't know your loft situation but is

it a problem leaving a 'bit of a gap' at each end anyway ​

I only have 100mm space if i take out one brick depth. The neighbours half of the party wall is literally 10mm away, so most i could get is 10mm expansion gap with the steel sitting on 100mm of steal base plate

 

[tony1851]

It won't expand 10mm.

 

[garyo]

Like Tony says, the expansion ratio is vanishingly small. Over 6 metres it's 1.56mm per 20 degrees:

https://goodcalculators.com/thermal-expansion-calculator/

 

[Notch7]

Like Tony says, the expansion ratio is vanishingly small. Over 6 metres it's 1.56mm per 20 degrees:

https://goodcalculators.com/thermal-expansion-calculator/

Concorde could expand upto to 10" in flight.
More legroom

 

[johnny2007]

Never heard any structural engineer talk about rsj expansion/contraction.
Wood moves a lot more.

 

[Leofric]

Like Tony says it won't expand 10mm so if you have a 10mm gap each end anyway there won't be a problem .