145x100 Rafters ???

[jigabyte]

Hi All,

I am having a summer room built; 5.3 meters long by 3.6 meters out. My problem is I think my architec has gone way over the top on the room rafters. He has said I need 145x100mm rafters 400m center. A friend of mine around the corner is having a summer room built; 7.7 meters wide by 3.3 meter out and he has had passed 150x50 rafters with the same spacing. Is it necessary for me to have such large rafters; the reason I ask is because of the cost difference. Should I tell my building controller???

Not sure what I should do.

Thanks for any help,

Jiggy!!!

 

[noseall]

145mm x 100mm

Eh?

 

[jigabyte]

Yes that is what is on the drawings. The guy is ready for retirement and I think he has gone way over the top but I want some opinions.

 

[mikric]

Tell us how long your rafters will be and can give you the size you need, 145x100 does seem odd

 

[noseall]

Yes that is what is on the drawings. The guy is ready for retirement and I think he has gone way over the top but I want some opinions.

It is the section size that is weird and not necessarily ott.

Volume wise it may be right but not in that shape.

 

[jigabyte]

They will be around 4.2 meters in length. It is a slopping open planed roof running from the top out.

 

[Shytalkz]

Well they work for that span as C24 grade. He's mixed rough sawn and regularised sizes though.

 

[jigabyte]

Sorry to sound thick but what size would work. Most of the local builders merchants around here don't event do 100mm thick.

 

[^woody^]

If not an error, those are totally stupid section sizes and without any consideration of what timber is readily available or economics of getting them.

Phone the old boy up and get him to specify something more realistic

 

[jigabyte]

Thanks Woody; I'll do that and let you know where I get. Like I said building control has passed my friends at 150x50. I thought maybe 175x50 see as mine is 0.5 meters longs. Also bearing in mind I only have two velux windows and some tiles going on it. There is no top floor for cars; lol!

 

[Shytalkz]

Pitch?

 

[hotrod]

Pitch?

Cmon Shy, man of your talents. You've got all the figures you need from the OPs posts above. Chuck in a bit of Pythagoras and Bobs yer uncle .

 

[Shytalkz]

Oops, didn't read too closely and assumed rafter was plan span!

Ok, so it's 30°...

Regularised 50x175C24 or 75x150C24 for plan span 3600mm. With tiles on roof.

 

[jigabyte]

Thanks very much for all the advice; I was going to use 175x50. How have you worked out the pitch without knowing the highs at the house wall and the projected wall?

 

[CortinaV8]

http://en.wikipedia.org/wiki/Pythagorean_theorem