Larry Asks: "I want to build a 9′x12′ pergola (2×6 joists and perimeter, 2×3′s on top fairly closely spaced to create shade) over a deck on the end of a 1996 Fuqua 24×60 mobile home. The 12′ dimension is parallel to the home. The home is structurally in excellent condition. My intention was to attach a 2x6x12 ledger board to the end of the house then use standard joist hangers to support that side of the pergola and support the opposite side with 4×6 pressure treated posts. The outside construction of the home is verticle lath. My question and perhaps problem is that what I hoped were 2×4 studs
beneath the lath don’t seem to be that beefy. As I pre drill, the drill bit goes thru the lath it then encounters what seems to be wood that is only about 3/4 of an inch thick. Is it possible that the the lath is attached to something that small. What ever it is , it is spaced every 16″ . "
Welcome to the wonderful world of mobile home construction. You are thinking manufactured homes are over-built like site built homes.
HUD (The Federal Government) sets standards which mobile homes must meet. This includes things like wind resistence, snow loads, etc. The manufacturers have full time engineers on staff to make sure their product MEETS but DOES NOT EXCEED the requirements. An example of this is shingles. On a site built home I believe you can add two layers of new shingles before you reach the point where you have to remove the old ones before you add another layer. On mobile homes you should always remove the shingles (even one layer) before adding new ones.
In the case of your pergola, you do not want to add ANY weight to the house. Make your new structure entirely self-supporting.