16" or 24" centres for 2x6 rafters?

[Rob Cheetham]

What would be the best centres to use for 2x6 rafters on a 10'x17' foot single sloped roof for a garden building. I'm wanting to do 24" centres. Will they be sufficient enough or should I do 16" centres. any reasoning for this would be appreciated too.

Thanks

 

[Jameshow]

Which way are they orientated?

You need more than 6" depth to span 17ft!

For 10ft 24" centres will be fine.

16" centres would be used on a floor to stop it bouncing.

Cheers James

 

[Rob Cheetham]

@jamess They would going front to back if that makes sense. So the rafters would be just over 10ft long each and going from left to right along the 17ft length.

Are you saying that 2x6 are not big enough. Theres me stepping them up from 2x4 lol. What about 2x8

Are you definetly sure 2x6 are not big enough?

But 24 centres will be ok?

 

[Inspector]

You could look up the span tables for 2x6 for flat roof and get something like this.
https://www.mycarpentry.com/rafter-span-tables.htmlYou'll have to find out what kind of loading the roof should take and then look up the minimum in the chart. Our loads here because of snow might be higher than the American chart shows and yours could be less. The 20lb loading chart linked shows 24" centres as acceptable and the 40lb loading as being closer to 16" spacing. You would only need 4 more 2x6s using 16" centres than if using 24". 25% more cost for the roof 2x6s in other words, the rest of the materials wouldn't change. Okay some more nails.

 

[Jameshow]

6" timbers on 24" centres are fine for 10ft span.

Cheers James

 

[dizjasta]

What would be the best centres to use for 2x6 rafters on a 10'x17' foot single sloped roof for a garden building. I'm wanting to do 24" centres. Will they be sufficient enough or should I do 16" centres. any reasoning for this would be appreciated too.

Thanks

Are you intending to use C16 or C24 grade timber?

 

[Rob Cheetham]

Are you intending to use C16 or C24 grade timber?

Ill be using c16 as my timber yeard does not stock c24 i dont think, but will check

You could look up the span tables for 2x6 for flat roof and get something like this.
https://www.mycarpentry.com/rafter-span-tables.htmlYou'll have to find out what kind of loading the roof should take and then look up the minimum in the chart. Our loads here because of snow might be higher than the American chart shows and yours could be less. The 20lb loading chart linked shows 24" centres as acceptable and the 40lb loading as being closer to 16" spacing. You would only need 4 more 2x6s using 16" centres than if using 24". 25% more cost for the roof 2x6s in other words, the rest of the materials wouldn't change. Okay some more nails.

i think i will be on the lower load limit im pretty sure as it hardly snows where I am in derby. Mayby one heavy snow a year if even that

. But I will definetly look up 16 inch centres to see if the pricing difference. May be worth it in the end.

Thanks

 

[clive griffiths]

Listen to the inspector, it is all in the tables.