How important is it keeping a extension square

[helpneedhelp]

How critical is it that that a extension is perfectly square?

I am in the process of building my own kitchen extension i am about half way up, I started with the corners using a builders square and i am checking that is vertical as i go but thats proving quite hard because some blocks are kicking out slightly which effects the spirit level.

When i measure left to right at each end of the extension inner an out leaves thes there is a difference of about 10-15mm is that exceptable or will the roofer think im a cowboy.

Thx

 

[oilman]

Are you using a string?

 

[noseall]

when it comes time to bed the wall plates, these can be jiggled about until they are perfectly parallel regardless of a cm or so. one end can be moved in and his opposite number could be moved out.

you can gain or lose a fair bit across a 105mm wall!

it is very important (for a traditional cut roof) that the plates are parallel and reasonably level. any discrepancies within the masonry can be sorted by trimming off the rafter ends later on.