The typical asking rate per listing is in the $20's per square foot per year. The Portsmouth region is going through a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 7% decline in rent.
Compared to the rest of the Greater Boston market, the Portsmouth region has more expensive rates, and you'll need to pay a premium to be in this hot submarket.
In the last 90 days, 20 listings have been made available, which means leases might be going fast. You'll want to be prepared to make an offer immediately. About 25% of the available space in the Portsmouth are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,450 sqft. Most properties in this market are approximately 2 floors. Most buildings in this area were built in 1918 and are Class A.