Sagging roof 2

[JStructsteel]

So I looked a small house this am for a roof that is sagging. from the outside you can see the sheathing bowing between the rafters, and some noticeable bow in the rafters. This house is under contract for sale, and the inspector wrote it up. I checked it out, the rafters are 2x4 spanning about 12'-0" from ridge to eave. How do you justify that its been that way for 70 years, the wood is just creeping, and that its fine, when you know the design would never check.

The wood is in very good condition, i suspect the sheating is 3/8" or 1/2" max, and is just creeping over time.

Structurally Its in no worse shape than the 100 other houses built in the neighborhood. Just need to find a way to say in a report.

Suggestions?

 

[KootK]

The link I posted early to the Timber Frame Engineering Council...

And thanks for that. Killer info to have on hand for timber renovation and the consideration of the load duration factor.

...maybe I'll play with something in this vein as I do a good bit of historic work here in Virginia and this is a constant issue.

I feel that structural reliability in general would be a great choice. I'm in oil country and I know of a couple of guys that make a killing doing reliability work for industrial applications. They'll get paid more to figure out if a pipe will last 50 yr or 30 yr than I'll get for an entire building. It appears to be kind neat "sciency" work too for still being nominally within the realm of civil engineering. They don't have the supply and demand problem that we do (yet). I kinda feel like AI might be able to make hay in that space when the time comes.