Jack will keep an eye out for anyone following the group or paying undue attention. He is also very interested in the build of the houses, trying to discern if this is a rich, poor or average town by the cost of material used to build it.
Perception = 1d20 + 12 ⇒ (8) + 12 = 20
Know (engineering) = 1d20 + 12 ⇒ (4) + 12 = 16
Sense Motive = 1d20 + 3 ⇒ (1) + 3 = 4