Brick house

What does "built like a brick ****house" mean

It's slang from 40 or 50 years ago, describing a voluptuous woman.
An outhouse is normally constructed out of cheap wood planks and discarded materials ... so, to build one out of bricks is absurdly, extravagantly, conspicuously overbuilt.

More discussion at www.phrases.org.uk bulletin_board 8 messages 451.html