Checklist for Building a Modular Addition

Homebuyer Checklists

The Modular Homebook

“If you are thinking of ‘going modular,’ this could be your primer: it covers all the steps of the process and features a 16-page color insert that helps you visualize the possibilities.”

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Browse Floor Plans

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The Home Store offers over 450 standard floor plans for modular homes. Browse Floor Plans

11. Checklist for Building a Modular Addition

When planning for your modular addition your general contractor will have to examine several details about your current home and property.  The list is surprisingly long.  But if your GC ignores some of the details, you’ll be disappointed with the result and have to pay your GC to make the necessary corrections.

Below is a list of construction details your GC needs to consider when developing the scope of work, specifications, and pricing for your modular addition.  It’s best if your GC has experience with additions as well as renovation work, since almost all additions require some refurbishing of the existing structure.

Existing House

  • Style
  • Approximate age
  • Length and width
  • Height of first floor from ground
  • Height of eave from ground
  • Asbestos or lead paint – where

Property

  • Trees or brush need to be cut or moved – where
  • Landscaping will need to be redone – where
  • Driveway needs to be relocated or refinished – where
  • Sidewalk needs to be relocated or refinished – where
  • Crane can be located to set modules – where

Existing Foundation

  • Block, stone, or poured
  • Crawl or full
  • Wall height and thickness
  • Work required to shore up walls
  • Modular addition’s foundation can be connected to existing foundation – how connected
  • Modular addition’s foundation cannot be connected to existing foundation – how formed
  • Concrete for new foundation needs to be pumped – distance

Existing Siding

  • Material
  • Profile
  • Color
  • Siding needs to be removed and/or replaced – where and how matched

Existing Roofing

  • Truss or rafter framing
  • Pitch
  • Soffit width
  • Gable overhang size
  • Soffit width
  • Fascia height
  • Shingle type
  • Shingle color
  • Shingles need to be removed and/or replaced – where and how matched

Existing Electrical System

  • Service amperage
  • Overhead or underground
  • Meter location
  • Meter needs to be moved – where
  • Panel location
  • Panel needs to be moved – where
  • Panel disconnect needed
  • Smoke detectors in existing house – hardwired or battery
  • Existing smoke detectors connection to addition – how

Existing Heating System

  • System can produce enough BTUs to heat addition – type, fuel, location, vent method, and how connect
  • Modular addition needs new heating system – type, fuel, location, and vent method

Existing Domestic Hot Water System

  • System can produce enough hot water for addition – type, fuel, location, vent method, and how connect
  • Modular addition needs new hot water system – type, fuel, location, and vent method

Existing Water Supply

  • Well or town water
  • Sufficient water pressure
  • If well – size of pump and tank
  • If town water – size of service entering existing house
  • Entrance into existing house – where
  • Entrance needs to be moved – where
  • Connection to modular addition – how

Existing Waste System

  • Septic or town sewer
  • Height below top of foundation
  • If septic – system can meet demand from addition
  • If septic – system needs to be modified or replaced – where on property
  • Entrance into existing house – where
  • Entrance needs to be moved – where
  • Connection to modular addition – how

Connection from Modular Addition into Existing House

  • Location
  • Change existing windows to doors or existing doors to windows – where
  • Close-off existing windows/doors – where
  • Cut through existing wall – where and material
  • Move electric wires and/or meter – where
  • Move heating units – where
  • Move plumbing pipes – where
  • Install headers – where
  • Firestop required – specify

Draw a Site Plan Showing the Existing Roof

Include all information above plus existing locations and size of hose bibbs, GFIs, chimneys, roof vents, fireplaces, windows, doors, and any other relevant items.  Show where the crane will be located during set.

Draw the Basement Plan of the Existing Home

Include all information about water, sewer, heating system, hot water, basement stairs, windows, and any other relevant items.

Draw the 1st Floor Plan of the Existing Home

Include all information of first floor layout, locations of smoke detectors, location of entrance to modular addition, and any other relevant items.

Draw the 2nd Floor Plan of the Existing Home

Include all information of second floor layout, locations of smoke detectors, location of entrance to modular addition if it impacts on second floor, and any other relevant items.

For more information about building a modular addition, see Building a Modular Addition in my book The Modular Home.