Breeze block outer wall - render alternatives?

Afternoon all,

Looking to save a bit of money on an extension and researching alternatives to rendering - are there any, or is render the only option to keep it water tight? Have seen there are some heavy duty sealants available, but do these last?

Builder doing the job says there's £6,000 of rendering (it's a significant double storey extension) and said you might be able to use a sealer - he's not used one before though. Of course the breeze blocks are ugly but it's virtually out of sight (mid-terrace house).

On the other side it's cavity insulation with another course of breeze block, which will then be battoned, boarded and skimmed.

I obviously don't want damp problems further down the line, so if it's a bad idea just say!

Thanks in advance

You paid a huge amount for a big extension but you are considering leaving as blockwork????? Get it rendered properly, man!

How many m2? 6k seems like a lot for concrete render if you already have the scaff in place.

Tile hanging - fibre/cement boards ?

Thanks for your comments all. If it was on view, it wouldn't be a question and would just render. But - as the majority of the wall is not on show - I thought I'd see if there were other viable options. Seems silly to pay for render if it's for cosmetic purposes and there's a cheaper way to waterproof the breeze block.

I don't know m2 off the top of my head, must be around 150m2 though. Scaffolding not in place, no.

Any further thoughts around the sealer?

Thanks