To board up is to cover windows and doors with planks. Board up before the storm.
It is done against weather, against vandals and against nothing at all when a shop closes for good. A boarded up street is the clearest sign of a town in trouble.
1phraseboard upTo cover windows and doors with planks.
“They had to board up the whole front before the wind arrived.”
board up is a phrase.
Practised in Phrasal Verbs