If you are converting a loft in a terrace or a semi, the Act almost certainly applies, and it applies because of something structural rather than because of the size of the job. The new floor has to be carried, and in a house with a shared wall the cheapest way to carry it is to bear the steels into that wall. Cutting a pocket into a party structure is notifiable work. Here is what else in a typical conversion triggers it, and when the notices have to go out.
What in a loft conversion is notifiable
Cutting into the shared wall to take the bearing of a beam, which almost every conversion does. Raising the wall where a dormer or a new roof line needs it. Removing or altering a chimney breast that forms part of the party structure, which many conversions do to win headroom. Inserting a damp proof course or a tray into the shared wall. Weathering the junction where a new roof meets it. Any one of these is a party structure notice under section 3, and a conversion doing three of them still needs one notice per adjoining owner, describing them all.
When the notices go out
At least two months before the work begins, on every adjoining owner. In a mid terrace that is both neighbours; in a semi it is one; in a converted house it may be several owners at the same address. Count back from the day the builder wants to start rather than forward from today, because two months plus the fortnight for the reply plus the surveyors' time is longer than most people's build programme allows for once the scaffolding has been booked.
The loft conversion party wall agreement template question
There is no conversion specific award, and no template makes one. What varies between jobs is the special conditions: working hours in a terrace where somebody works nights, protection of the neighbour's loft insulation and stored belongings, dust control where the wall is opened, and access to the neighbour's side to weather the junction. Those are the clauses worth asking for by name, and the worksheet on this site sizes the document so you can see what you are commissioning before it is drafted.
Questions people ask about party wall agreement loft conversion
Does a Velux only conversion need a notice?
If nothing bears into the shared wall, nothing is cut into it and no chimney breast is touched, it may not. Get the structural drawings looked at rather than assuming, because the steels are the usual trigger and they are easy to miss on a plan.
What if the neighbour has already converted theirs?
It makes no difference to your obligation. Their conversion is not a consent to yours, and the wall is no less shared for having been cut into before.
Do I need a notice for scaffolding on the neighbour's side?
Scaffolding on their land is a matter of access rather than of the party structure. Where an award is made it can provide for access; without one, it needs their permission.