How to Build an Add-on for a Double-Wide

Charles Dodd White

A double-wide trailer can be greatly enhanced by building an add-on. This can seem like a tough task, but it is not necessarily beyond your ability. By proceeding carefully and with a solid plan in mind, you can add to the dimensions of your home, freeing up room for more activities.

Many additions end up only providing extra storage room. However, you can truly enhance your home by building a sound and intelligent area that takes advantage of the preexisting double-wide structure. The growth can be perfect to accommodate more family members, or simply to add a place for recreational uses.

  1. Build a foundation for the addition by sinking post holes with a post-hole digger. These holes should be approximately 18 inches deep. Make sure the sides of the holes are well excavated and you can place the posts firmly in the ground. Surround the post holes with quick-drying concrete and hold in place at a 90-degree angle to the ground until the concrete has completely set.

  2. Saw the posts off so that once a deck is built the floor will be level with the mobile home where the door enters into the addition. This is an important step, in that it determines how seamless the transition from the double-wide to the addition will be.

  3. Complete the flooring system for the addition by nailing studs in a rectangular framing pattern, placing each of the studs in the system approximately 36 inches apart. These underlying beams will provide the strength for the flooring.

  4. Nail plywood onto the floor system to provide a solid base. This flooring panel is the substratum for whatever finished flooring you intend to install—anything from tile to laminate.

  5. Raise vertical studs from the decking to provide a wall system for the addition. These studs should be no more than 48 inches apart.

  6. Nail down a horizontally laid crowning stud. This piece will close off the wall section and provide a base for the roofing system.

  7. Build a flat roof, using joists spaced every 48 inches, so that they match up with the studs in the wall system. Construct the roof itself by using plywood, roofing paper and shingles to complete the addition's weatherproofing.