Son is nearly at high back booster weight limit.

[Starlet9729]

DS is nearly 36kg which is the specified weight limit on his high back booster. He is 9 years and old still looks comfortable in it. He is not quite tall enough to not use a seat at all - I’d rather he use one anyway.

But what do I do when he exceeds the weight limit?

Booster seats both high back and cushions specify a 36kg weight limit which is 5.6 stones hey are advertised to be used up until 12 (I don’t know what a normal weight for a 12 year old is but sure it’s more than that).

Advice?

You can use the booster seats anyway, they're just listed as such to comply with legislation. What height is your 9 year old?

Keep him in a booster until he fits the seat see here for an example of what that that means. Go by height, not weight.
My very slim 11 yr old is under 36kg. We moved him into a booster cushion last autumn, as his shoulders were getting too wide for the hbb, but he doesnt fit the adult seat in my car.

He is about 132cm I think! He does still fit into it comfortably!

I know he isn’t tall enough not to use one - today I let him sit in the front without a car seat whilst I moved our car from our space to outside our house to clean (literally 30 seconds). You can not use a booster when they reach 135cm is the correct? Because I can’t imagine having sitting comfortably in one even after growing 3cm! Maybe he’s got a shorter body and longer legs or something.. he doesn’t look anywhere beer tall enough!

Near

You MUST use a car seat if they are under 135cm. I dont think there is an upper limit. That said, I'm sure if I sat on a booster cushion, my head would be against the roof!! Much of Europe use car seats until 150cm, and that is about the height adult seats are designed for as a minimium.
As I said above, my 11 yr old doesnt fit comfortably in my car (he just fits in DHs car). He is still using a cushion. He is very slight, but not particularly short - about 145cm, I think.

You can use them up to 150cm if they still fit :)

Weight limit doesn't matter with HBBs. It's just the end of the legislation. In 1982 when they made that law they didn't imagine that anybody would be using booster seats past about 5 or so!