Timbers for lean-to roof

[jayc89]

I have a lean-to to roof at some point, it's approx 1m x 4.5m and runs along the side of the house, finished with some spare slates I have kicking around. The lean-to will likely get used for a couple of water accumulators at some point, so needs to be water-tight and insulated to some degree. 

I've just pulled out a load of 4x2 lengths from another room, that would otherwise be turned into firewood - Could I get away with roofing the lean-to using these? 

[Redbeard]

Has it got to comply with bldg Regs insofar as it may contain heating equipment? 4 x 2s are beefier than the 3 x 2 used in many Victorian roofs, so in terms of 'will they do the job?', probably yes (though we don't know the pitch, so don't know if it will need a purlin). 'Will it comply with Bldg Regs?': No idea!

[jayc89]

2 minutes ago, Redbeard said:

Has it got to comply with bldg Regs insofar as it may contain heating equipment? 4 x 2s are beefier than the 3 x 2 used in many Victorian roofs, so in terms of 'will they do the job?', probably yes (though we don't know the pitch, so don't know if it will need a purlin). 'Will it comply with Bldg Regs?': No idea!

 

Not being done under BR. In terms of pitch, no idea, a quick Google suggests 30 degrees? 

[markc]

Assuming it is 4.5m long with the room pitch being the 1+ metres then 4x2 is more than sufficient for rafters.

[George]

Agree. A span of 1m , even allowing for the pitch, is fine for a 4x2.