Ruins and cover saves clarification

It's come to my attention of a slight overlook with how we use ruins in our club.

As it stands at the moment we have been using 5th edition mentality with treating the whole piece as area terrain, and 4+ cover for being a ruin.

The rulebook states the following:

pg98.

All ruins are difficult terrain and provide a 4+ cover save.

A ruin might be mounted on a base, decorated with rubble, and
other debris. In this case, treat the base as area terrain.

If the ruin has not been mounted on a base, then the ground
floor is not counted as either difficult terrain or area
terrain.

pg91.

Area terrain is always difficult terrain. Models in area
terrain receive a 5+ cover save, regardless of whether or
not they are 25% obscured. Models that Go to Ground in
area terrain receive +2 to their cover save, rather than +1.

I've come to realise that only the base of a ruin is area terrain (5+), while the remainder uses true line of sight to determine if the model gains a 4+ cover from the ruin itself.

In my opinion we should start following this ruling properly from now on.

ive always done it that way! onlt models that are behidwe the wall get 4+ if i have direct line of sight it still is a 5+(all model seen) even if th model is in a ruin

If the model does not have at least 25% obscurity from any floor above the base, then it does not gain any cover (not even the 5+).

I know that not everyone at the club plays this way, but should be from now on

the above is for barrage correct? if it is its weird that it doesnt but does form a crater

The above is refering to all normal shooting. I wrote about the barrage on the barrage thread

ive gotta reread that myself, not convinced, pero i could be wrong.