But I've heard something like "it's better to get it knocked down and take it to the roof through the stairs". Do British use knock down to mean "disassemble"?We wouldn't say "knock it down"in AE. ...
I believe you. I've heard "knock something down"* with this meaning in the language of construction workers and repairmen. I agree with Florentia, however, that "break it down", or "take it apart" are more likely expressions in the U.S.But I've heard something like "it's better to get it knocked down and take it to the roof through the stairs".
Not in BE. I would use "take apart" in 1. and "folded up" or "took apart" in 3.knock down
1. Take apart for storage or shipping, as in We need to knock down this chest to ship it safely overseas. 3. To disassemble something into parts, as for storage or shipping: I knocked down the tables and put them back in the closet. The vendors knock their stalls down at the end of the day.[Mid-1900s]