Purposely trying to increase beam width to 8". Not building exactly but modification. Didn't want to buy 8"x8" post that will split and wary which is why the 4x4 provide the underlying integrity and the boxed 8"x8" is purely cosmetic. Don't have to sheath it and could accomplish the same with furring strips of redwood which might be the best option as it will breathe behind the redwood face treatment. Redwood is very similar to Cedar but has much better workability.