Propping roof for below-wallplate work

[mfarrow]

Hi

In an extension, I have removed the outer leaf to gain extra room in the new upstairs bathroom. The existing internal lintel however is a ginormous concrete thing which has a slope at the front protruding into the cavity by 75mm (cavity's width). The length of the lintel is 2.5m. Think of a catnic extra heavy duty type but without the lower lip for the outer leaf.

I therefore wish to remove the lintel. Part of the opening will be bricked up and part will help form a doorway. Overall length for support under wall plate is 3m.

How am I best propping the cieling above the wall plate? Can i just prop between upstairs cieling and floor or do i need to transfer this downstairs as well? We have 3" joists 4" rafters, a rafter span of 2m to purlin and concrete double roman tiles.

All help much appreciated.

 

[tony1851]

Generally, roofs are not very heavy - just prop off the first-floor joists.

 

[mfarrow]

Thanks Tony.

 

[wessex101]

Don't just prop the ceiling unless you are sure the ceiling joists are well connected to the rafter feet. I would be inclined to put a bearer between the ceiling joists and rafter so you know you are propping the roof and not just the ceiling.

 

[mfarrow]

Thanks Wessex. I have a sloped edge (technical term?) with the joists connected to the rafters about 1' up from the wall plate, so I'm trusting they're securely fastened.

 

[tony1851]

That's a 'collar-braced' roof; as Wessex suggested, wedge a timber in the angle between the c/joists and rafters
incase the nailing is not too good.