There's a debate to be had about whether giving the room dimensions (80x90 feet) at this point is justified. Cognitively, you'd think that (a) the PC's attention would be first attracted to the stuff in front of them (especially any hostile monsters!) before dimensional details, and also (b) to get exact footage you'd probably have to get in, explore, and pace it off. The counter-argument, I suppose, might be that letting the players draw the area on the party map allows them to mentally situate themselves there. Sometimes I go back-and-forth about whether the dimensions should be the first thing described, or the last.
Here's a synthesis: Give the players some notion of room size first, quickly, by just using the terms "small, medium, or large". Only give exact dimensions after a fight has been resolved, and exploration/ searching/ pacing/ mapping is possible. Of course, this requires some kind of consistency in your "size" descriptions, such that you're playing fair with the players. Here goes after a bit of research:
- Small -- Up to 200 square feet (10x10 or 10x20). Small living quarters or chapel.
- Medium -- Up to 2,000 square feet (from 20x20, 30' diameter around, to 30x60 or 40x50, etc.). Tower central room, guard hall, castle kitchen, big living quarters.
- Large -- Up to 20,000 square feet (from 50x50, up to 50x100, max 100x200). Keep great hall, largest DMG Appendix A room/ chamber/ cave size.
- Huge -- Up to 200,000 square feet (from 100x200, 150x350m, max 400x500). Major cathedral, largest DMG Appendix A cavern size.