Hi. Anything related to the bricks and mortar itself.......
Although, if I had to get technical, the trigger is not the claiming of the expenditure, but it's the use thereof for trade purposes. I.e. If you utilized that room for your business, and didn't claim anything for income tax purposes, that room would still be excluded from your primary residence exclusion on the basis that it was was used for trade purposes. Practically however, I wouldn't be concerned unless you acclaimed expenditure related to it.