Cold Bridging On RSJ

[SamCruise]

We are building a extension and have had to put in a rsj that sits across the back wall.

The wall is single storey at the moment and has no insulation in it at the present.

The RSJ was not insulated when installed just boarded and plastered over however when it got cold there where damp patches appearing so after hacking off the board and plaster we found that the rsj was very condensated.

Now we have filled the gaps with sections of insulated plasterboard polystyrene if i was to double board again with foil backed plasterboard would this be sufficent to stop the beam from condensating as only the side facing inwards is insulated?

The wall is dry now but you can still see where the damp came down to.

One of many problems posted!!

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• SamCruise
• 14 Mar 2013
• 1

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• SamCruise
• 14 Mar 2013
• 1

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• SamCruise
• 14 Mar 2013
• 1

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• SamCruise
• 14 Mar 2013
• 1

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• SamCruise
• 14 Mar 2013
• 1

 

[ivixor]

I am not an expert, but, you want to either stop the RSJ getting cold, or stop the warm moist air hitting the RSJ.

For the former, the insulation wants to go on the 'cold side' of the beam. For the latter, you want a moisture proof membrane such as polythene sheeting.