I’ve come across this one other time and generally recommend a structural engineer evaluate. I can’t seem to find much info on this though. Is this installation ever acceptable? My wording is such:
One or more rafters were observed to be discontinuous from the ridge to the top plate, which is generally an improper connection and interrupts the load path. The load transfer needs to be continuous from roof through walls and headers, as well as floors, beams, and columns, to the foundation. Spliced rafters, if acceptable, generally need additional support in the form of beams or girders beneath them, and must be designed by a structural engineer.
To answer your question (bold above) yes this can be an acceptable building practice. We will look at it from the perspective of more modern builds which this appears to be older.
Splicing rafters, without perlin or other supports, is considered acceptable even in the newer building codes as long as the spliced rafters have not exceeded the acceptable span limits for the species of wood used. You can read about the span limits in the IRC Section R802. However at the splice point there are fastener numbers/patterns required to be used.
In newer construction I rarely see spliced rafters that have not been provided with purlins at the splice joints even if the wood species span limits have not been exceeded. It is the prudent thing to do to prevent issues in the future and the amount of additional lumber for purlins is negligible compared to the issues that might result even if the span limits were not violated and the right conditions occur to cause issues.
In an older home such as this one unless you are a wood expert you may never know the species. Newer wood obviously will have grade stamps on it to tell this. If there was no movement of the splice joint in those “X” years then most likely it may never happen. However there is never anything wrong with adding a note in the report about this condition when no issues are noted with the splice point and I could not determine the maximum span length for the wood species. If it were mine I would probably write something such as the following. Of course I would add a picture marked up to display the conditions I describe.
Rafters for roof construction were noted as having been spliced. This is typically an allowed condition if certain parameters have not been violated. Due to the age of this construction not enough information can be obtained to determine if this is an unacceptable condition. However at this time no issues are apparent with this condition. “Additional wording added here”.
The additional wording would vary due to the home’s age and situation. If it is a new build I cite Codes and would add the parameters I could not determine and put it back on the Builder to provide this information and display what Code or standard allows this. On an existing home I might consider recommending a review by a framer or if enough other issues were there in framing or other areas of the home that suggested structural concerns then I might well recommend an engineer to review it. In a much older home if there appeared to be no issues present I would note no issues have occurred and leave it to the client if they want to pursue it further.
BTW the Codes also defer some specifications of framing to The American Wood Council Wood Frame Construction Manual and other AWC pubs. If you read those AWC pubs and look back at the Codes you would not be surprised then where some of the Code requirements come from.
In the picture you display here though there is another potential issue. Unless my eyes are deceiving me those two members spliced together are not the same size lumber. So what was the original intended size? Which of the two sizes were considered the proper size for roof rafters on that home. It would not hurt to call that out for further review.
Fairly common repair in older homes. Could last forever could fail tomorrow. Should be reported (bear in mind the additional weight of the plank sheathing). Good narrative above.
Great answer, thanks for taking the time to write that up. My research is pretty consistent with what you noted. In this particular case the house was over 100 years old and had other issues such as sagging deck, broken & separated rafters and tension ties, and structural sagging, WDI damage, etc, so I mentioned this as well. You are right, the main rafters are closer to 3" wide and the spliced secion is closer to 1" thick. They had a structural inspection today and he basically confirmed what I wrote up.
