roof vents

[scrumpyjack]

I have just had a loft extension done and noticed that there are no roof vents fitted-they are still in their box where the builder left them.
Are these a requirement or will my existing ventilation be enough
The room is boarded out now and ready to plaster so they would have to be done from outside. Is this usual

 

[datarebal]

They are done from outside anyway

 

[scrumpyjack]

They are done from outside anyway

What off the ladder? The scaffold is only on one side of the house and doesn't go that high anyway....Interesting..skyhooks maybe