Fixing skirting boards to wall with significant gap in between

Question

We have had a wall re-plastered, due to a damp issue caused by rubble in an old fireplace and plaster bridging the concrete floor and the wall.

The plasterer has left a gap between the floor and the plaster to make sure it isn't bridging. This has lead to a number of places were there is nowhere for a normal skirting board adhesive to adhere the skirting to the wall, as the gap is to large. I will be happy filling any gap above the skirting boards, the issue it getting them attached to the wall.

I'm aware of two potential options I have to resolve this issue.

1. Attach small pieces of wood to the wall were the gaps are which is flush to the depth of the plastered wall and use these as the attachment points for the skirting. (I can see remains of these from previous skirting, but these are not viable to use in this situation), so I would need to create new ones.

2. Use a large amount of adhesive or use a expanding foam adhesive to fill the gap behind the skirting board and the wall.

I'm don't really want to do option 1 as the gaps range from a centimetre to around an inch, and I feel it would be to time consuming and difficult to make it consistent.

Option 2 feels better taking into account time and ability. My one issue with this is will I be able to undertake this, while still maintaining the integrity of the work carried out for the damp issue and to stop any reoccurrence of this.

Once attached the skirting will be painted and a new carpet fitted in the room.

Question : What is the best way to attach a skirting board to a wall were there is a gap between the two?

I am looking for confirmation of my above issues as well as any other viable options.

I am UK based so this also needs to be taken into consideration.

Answer 1

Option 1 is the only viable solution, to my mind. I've done that where drywall was above the subfloor. Anything less rigid will result in poor miters, movement, etc.