Can commercial landlord raise rent based on new subtenant?

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Question: I have been leasing an office for the past year. Since I typically use my office only four days a week I informed the landlord that a professional counseling peer and friend of mine was interested in the possibility of sharing my office. We have worked out our schedules so that they would only be using my office the one day a week that I am out of the office. The landlord said that he would need to raise my rent since the office would be used more and there would be increased use of electricity. Is this legal? It seems to me that since I'm paying full rent, it shouldn't be any of his concern whether I'm using it one day a week or seven. Property manager Griswold replies: If you have a lease, then the terms cannot be changed unless the lease specifically limits the use or there is language indicating that the rent will be adjusted if an additional co-tenant is added. If the lease is silent on this situation then the owner must wait until the end of the lease to change the term...