You could use a door snake to seal up the crack, or if you have a surface spray barrier, if they crawl across it they will die anyway.

TBH we've had a very badly infested house sprayed (by an exterminator) and the spidies didn't travel much, just curled up and died. The ****roaches (speaking from my tropical ****roach-infested Darwin days) are the ones that travel, but even so they don't get very far before they cark it. Just be ready to vaccuum up some corpses afterwards

ETA - if we're using pest sprays anywhere on the property we vacate the whole place for as many hours as possible afterwards, to allow the fumes to subside.