Old square nails can be 100 to over 200 years old, so they don't help with dating much. If they're tapered on all four sides they were probably forged by a blacksmith. If they're flat and only tapered on two opposite sides they were machine made. 'Machine-made' doesn't mean 'newer' though - Thomas Jefferson owned a factory for cutting nails.

Thick wood boards and beams with circular or up-and-down saw marks could date from +/- the Civil War out here, but could be much older in Maine, where they had water-powered mills as far back as the 1600s. According to what I've read in Old House Journal, asphalt shingles can date back to roughly 1900 and were popular by 1920. They can last 50 years and old ones are often found under newer ones. I found some circa 1930 still in fairly good shape here.

The house could be 100 - 150 years old? You can still find neglected old log cabins for sale for lumber salvage or restoration dating back to 1800 - 1830, but post and board construction would be newer. Even insect- and rot-resistant species of thick wood boards would rot after many decades of neglect if they were left exposed to the weather, so you're somewhat less likely to find intact boards than logs.

Checking into the local history of the area is often helpful. You can sometimes find old photos of structures that were considered 'old' when the photos were taken with a little descriptive information.