I'm currently playing in a 5th edition game that's centered on investigation and social encounters rather than combat. My DM and I have both played 3.5 and were familiar with the Knowledge (Architecture and Engineering) check from that edition.
For some reason, our party keeps coming up with questions that would have required a Knowledge (Engineering) check in 3.5 but my DM and I are both at a loss for which skill to replicate this in 5e. So far we have been using either Intelligence (History) or Intelligence (Investigation) depending on whether or not a History check is reasonable.
Some examples:
- Find weak points in a bank wall to break in.
- Determine how sturdy a dam was/if it would burst.
- Looking at columns in an old building to see if we could knock the roof down.
- Identifying the style of architecture of a ruin to determine what we might expect.
Is this the correct course of action? Or is there a better skill that encompasses Knowledge (Engineering) per RAW?
Best Answer
Use an ordinary intelligence check.
PHB 178 states,
It seems to me that engineering knowledge would fall under this category. If you, as the DM, should decide that a character should be proficient in engineering, you can allow the player to add his/her proficiency bonus to the check as well.
Consider combined checks.
Some of the examples you gave could potentially fall under multiple skills--Johnathan Gross pointed out that one could use investigation or history instead. In cases like those, I like to use multiple, sequential checks.
For example, for finding weak points in a wall or a dam, one could roll Intelligence to know what kinds of weak points to look for, and then roll Investigation to actually find them. Of course, if the relevant feature is obvious, like in the columns example, a single Intelligence check would suffice.
If you choose to require multiple rolls, don't forget that it will significantly reduce the probability of success if the DCs are too high, so you should adjust your DCs appropriately.