Being an engineer and a home inspector, here is where I draw the line and what I tell my client when I face a older home that is not constructed to today’s framing standards. As a home inspector, I can look at the home and determine whether or not the structure has performed ok for the last 174 years. If it is performing ok to date, my report will say so. But it will also say that if you want someone to tell you whether or not it will be ok in the future you’ll need to hire an engineer to evaluate the current framing and design any necessary repairs.
As a HI, I don’t want to take the liability for future performance on a home that is not framed to today’s code. I want to keep it on my client who may or may not follow my recommendation and hand it off to an engineer.
Regarding performance of this home for the last 174 years, as others have mentioned the gaps in those photos are indicating wall spread, which needs to be addressed, so as a HI I would already be calling for an engineer to come in and design necessary repairs on this home. BTW, I don’t call for the engineer to evaluate … he needs to do that in order to be able to “design necessary repairs”.