reposted-rendering advice of a poorly built outhouse

[suzybare]

ive recently bought an old terrace and it has a poorly built outhouse on the back to use for the washing machine/cold storage-its freezing-poorly insulated too.

it has a lean too roof felted, which im sure is leaking-this is another problems i need to recitify.

it is one brick thick and this has cracks in between the cement. it seems that when it rains hard it comes through onto the walls. it did have plasterboard on the walls but i ripped this off as the damp was coming right through.
without tearing the whole the thing down and starting again is there anything i can do to prevent the rain coming through these cracks and the brickwork. so i maybe able to plasterboard the walls again

such as waterproof glazings? is it PVA
or render plaster on the outside that i can paint over with some outdoor waterproof paint?
i know the roof needs doing and this is a seperate issue but what can be
done to the walls?

any advice is welcome
please reply in laymens terms-im a girl teaching myself DIY so i dont get ripped off and know what the builders will be talking about!!

 

[JohnD]

you can spend the next ten years patching it before you give up, knock it down and build a new one

Or you could save yourself ten years and a lot of effort and cost.