Boundary distance

[Phill Peck]

I'm planning on putting a side extension/porch on the side of my property (front door is actually on the side)

To the side of my property is a footpath separated by a picket fence.

How close to the boundary am I able to build?

I notice some of my neighbours have built right up to boundary even with eaves over hanging. I assume they were given planning permission for this.

I was hoping to build under permitted development.

 

[tony1851]

If it's a footpath to which the public have access, then for planning purposes it will be regarded as a highway, and generally you need planning permission for any extension forward of a wall facing a highway.
Porches are exempt, subject to being less than 3 sq m in floor area and no nearer than 2m to the highway (or picket fence in your case).