Modular Homes Report

Build Informed

Modular Homes Buyers Guide

 

A big misconception is that modular homes are the same as mobile homes. and that is simply not the case. While we will not go into detail about manufactured homes or more commonly referred to as mobile homes, we will mention a couple of key differences.

Manufactured Homes
(these are usually referred to as “HUD-Code” or “mobile” homes but will be referred to in this book as manufactured homes) are built entirely in a factory in accordance with a federal building code adopted and administered by the U.S. Department of Housing and Urban Development (HUD) and known as the “HUD Code.” The HUD Code is a preemptive code, which means that it supercedes any state or local codes that apply in the area where the house will be sited. Homes arrive onsite complete with appliances, carpet, paint, lights, and with the util-
ities ready to be hooked up on site. They are typically 80 to 90 percent complete (those consisting of two or more sections or two stories, require extra on-site completion). The term “mobile home” does not apply today when most manufactured homes are not mobile at all. Many are placed on permanent foundations and are considered real property.
 
Modular Homes
Like manufactured homes, are also constructed in a factory. Modules are shipped to the site either ready to be finished inside and out or complete with interior amenities, appliances, paint, carpet, and more. They are typically 70 to 85 percent complete. These homes are built in accordance with the model building code adopted by the state. Local codes, if different than state codes, apply only to home installation as well as site-built elements, such as foundations, garages, decks, and porches. A modular home is built in sections, transported to the home site, and set on a foundation. Many are two or three stories high and can consist of two to six modules or sections.
Modular homes comprise a smaller part of the factory-built market than manufactured homes.

Price

The following chart provides a cost comparison of modular vs. site-built construction.

Modular-Homes vs. Site-Built-Homes Costs
Modular-Homes vs. Site-Built-Homes Costs
Modular and manufactured homes are constructed in a more efficient and cost-effective way because they’re built in a centralized, controlled environment and not subject to the many varying conditions of site construction. These can add significant cost overruns and extend even the most carefully devised production schedule. Such factors include inclement weather conditions, non availability of sophisticated production tools, working in awkward places, subcontractor delays, damage to building products and materials stored onsite, delivery problems, plus employee illness, injury, or unreliability.
• When the house is ordered, the price is set and is reliable. There won’t be unexpected price increases due to material price fluctuations or having to substitute another product when one specified is unavailable.
• Housing production factories are most often in rural areas where prevailing wage rates are lower than rates in areas where the house will be sited. Labor costs are also reduced because highly skilled laborers are not needed when jobs are organized into more simple, repetitive tasks, with sophisticated and automated tools, highly efficient working platforms, and immediately accessible materials.
Workers are generally employees of the housing production organization and can be more easily scheduled, managed, and trained in methods that yield greater productivity and efficiency. They go to work in the same place every day on a permanent basis, no matter the weather.
• Industry data shows that the labor cost component of a modular or manufactured home is typical
ly 8 to 12 percent of the total house construction cost, while the labor cost of a site-built home is upwards of 40 to 60 percent of the total cost. This savings on labor can be significant, particularly in an urban environment where labor is both expensive and scarce.
•  Factories purchase in bulk and generally receive deep discounts on building materials, which are passed on to the buyer. Manufactured home producers indicate they can save up to 30 per cent of cost on standard building materials through high-volume purchasing. Modular home producers enjoy similar benefits but not to the same extent, as their inventory usage is often lower.

Schedule

Building a modular home vs. traditional home can save you a lot of time, money and costly delays.  Although modular homes are built in a factory, there is still work to be done prior and post the home set.  Modular home construction requires much of the same upfront work as site built construction however offers a large benefit in efficiency of construction.   The two charts below outline the difference between modular construction and site built construction.  We will discuss each step further however notice how the charts differ.  Modular construction allows the simultaneous site development and home construction at the plant which reduces the schedule by 30% to as much as 50%.

 

 

Modular-Homes-Construction-Schedule
Modular-Homes-Construction-Schedule

Modular Home Construction Schedule

Step 1 (Design / Engineering)

  1. Design: The modular design phase starts with a existing home plan or plan concept.  With the experienced modular home designer, the home plans are created and finalized to include the important features that shall be part of the modular design.  Factors that need to be considered are but not limited to:
    1. Type of home (Two story, Ranch, Cape, Shore Style, etc..)
    2. Style of home (Traditional, Gable Facing, Modern, Log, etc..)
    3. Roof Style and Pitch
    4. Special Features like ADA compliance
    5. Square footage of home and modular count
    6. Modular home finish features (Hardwood, Granite, etc..)
    7. Foundation Type (Piles, Basement, Crawlspace)
    8. Home Direction
    9. Lot Features (Sloped lot may include a walkout basement)
    10. Budget
  2. Engineering:
    1. Home Direction
    2. Lot Features (Sloped lot may include a walkout basement)
    3. Site plan (Survey, plot plan)
    4. Grade plan
    5. Flat-work Plan
    6. Construction Code
    7. Building Plans
    8. Foundation Plans

Step 2 (Permits & Approvals)

  1. Permits: Most towns require the approval of a site plan (zoning) and blue prints (construction).  Most homeowners hire a GC (General Contractor) to pull the permits however some homeowners are able to save money by acting as their own GC.  Before deciding to act as your own GC, make sure to do plenty of research so that you are fully aware of the total scope of the project prior to taking on.

 

Step 3 (Site/Lot Development)

As outlined above, a big advantage of modular home construction is the site development and foundation are being worked on while the modular structures are being built in a climate controlled factory.  Once the modules are completed, they are transported to the site for installation on the foundation (home set).  Once the home is set, the home is typically weather tight and protected from the elements.

Additional site work to be considered is as follows:

  • Surveying
  • Demolation
  • Excavation
  • Grading
  • Site Drainage
  • Foundation Construction
  • Utility Install and Connection

Preparing the Foundation:

Developers of Modular Homes who have built on urban lots know how to ensure that the lot is ready for the foundation of any new house. Above-grade debris such as trees and rocks must be cleared, as well as any other site obstructions. Also of concern on lots that once contained houses are such buried items as septic tanks, foundation sections, fuel tanks, and abandoned supply lines, which can slow down site preparation. These and any other below-grade items must be unearthed and hauled away.
Access to the site is a major concern when working with factory-built homes. The location of the foundation will have an impact on access. The site must be able to accommodate the vehicles necessary to truck the home or modules and to set them on the foundation. A transport company representative can help plan for this. A representative of the crane company should also be sure to order a crane that is the proper size and radius for the home or modules.
 
 

Step 4 (Building / Construction)

During this phase the homeowner will start to see the fruits of their labor.  The foundation is started, the modular home is being constructed in the factory and all the pieces are going to align.
 
Installing the Foundation

It should be noted that although slab-on-grade foundations are the norm for much new site-built construction, they are not applicable to modular or manufactured homes, which have an integral floor already built it. Manufactured and modular homes must be placed on piers, crawlspaces, or full basements. The foundation should be constructed by the general contractor or by a subcontractor who specializes in foundations.  Just as a specification sheet drawn up with the manufacturer will list in detail everything involved in building the home, a specification sheet should also list in detail the design characteristics of the foundation. This is done through an architect or engineer. It is imperative that the foundation be precise in its layout, dimensions, and structural properties. With a site-built house it is relatively easy for builders to make slight adjustments for foundation errors or imprecise measurements. With factory-built homes, an entire home or module of an exact dimension is set on the foundation at once, leaving little room for error.  To ensure accurate dimensions, the foundation contractor who is not accustomed to building for modular homes should consider the following tips:

• Measure, re-measure, and then painstakingly stake out the foundation so that it will accommodate the factory-built home (the dimensions of which can be obtained from the manufacturer or retailer).
• Use a laser level to ensure that tops of forms or blocks are flat and level all around.
• If using a poured foundation, brace the forms extra firmly to avoid any shifting during the pour.  Another option is to use precast concrete foundation panels with steel-reinforced concrete studs, reinforced top and bottom beams, and concrete facings. These systems offer dimensional consistency and precise measurements. A typical panelized foundation can be erected in four to five hours with no on-site concrete work. Cost savings can be realized because precast systems, at about $45 a linear foot, are competitive with concrete block walls. They also go up much quicker, saving on labor costs. Cold-weather erection is common as no concrete pouring or curing is necessary. This enables work to be done during the colder winter months when many factory-built housing manufacturers offer discounts or at least are somewhat more flexible in pricing. The goal should be to have the foundation completed and inspected by the local building inspector a few days before the scheduled home arrival date. On the delivery day, everything should be in place so that the house can be completely installed on the foundation and buttoned
up tightly so that by the end of that day the house will be secured.
 
Home Construction
The modular home construction is typically started concurrently with the foundation.  At this time the boxes or modular home components are being assembled in the factory.  The savings of both time and money are realized during this phase due to the home construction is not dependent on foundation completion.  With modular construction, we now have two consecutive phases working with both the foundation and home construction working independently and concurrently.
 
A large part of the home inspections may occur in the factory while the home is being finished.  Modular homes can take anywhere from three to ten days while being constructed in the factory.
 
A typical modular home spec sheet may look similar to below:

Start of sample spec sheet

CONSTRUCTION

  • 2×10 floor joists @ 16″ O.C. (2×10 floor joist @ 12″ O.C. on 31 ‘6″ wide models are optional and is recommended)
  • Southern yellow pine (SYP) double perimeter band joists
  • 3/4″ tongue and groove O.S. B. floor sheathing, glued and nailed.
  • 7/12 non-storage rafters @ 12″ O.C.
  • 7/16″ O.S.B. roof sheathing
  • Shingle-over ridge vent
  • 10″ eave and gable end overhangs
  • 8’0″ ceiling height 5/8″ type “X” ceiling gypsum board
  • 2×6 exterior wall studs @ 16″ O.C.
  • 7/16″ O.S.B. exterior wall sheathing
  • 2×4 interior wall studs @ 16″ O.C.. (2×6 plumbing walls)
  • 2×4 mating wall studs @ 16″ O.C. with non-structural sheathing
  • 1/2″ wall gypsum board applied with foam adhesive on bearing walls or glued and screwed on interior partitions

 

INSULATION

  • R-38 fiberglass ceiling insulation with vapor barrier
  • R-21 fiberglass exterior wall insulation with vapor barrier
  • Tyvek Wind barrier housewrap
  • Wrap Flex Floor Wrap

 

PLUMBING AND HEATING

  • Hot water Baseboard
  • PEX water supply and PVC DWV lines stubbed through floor
  • Shut-off valves on all fixtures
  • Anti-scald valves on tubs and showers
  • Future Vent 2″ PVC

 

ELECTRICAL

  • 200-amp panel board with 40 breaker spaces
  • Decora style silent rocker switches
  • AC/DC smoke detectors and carbon monoxide detectors, per code
  • Receptacles with ground fault circuit interrupter (GFCI) protection, per code
  • Switched receptacle in Living Room and Bedrooms Ceiling lights in Foyer, Kitchen, Hall, Utility, Walk-in Closets, Basement Stairwell, and Attic
  • Chandelier in Dining area
  • LED (5″)-fire rated/water proof surface mount down light over kitchen sink
  • One exterior light at each exterior door
  • Satin nickel lighting fixtures
  • Door chimes – buttons at front and rear or side door
  • Two RG6 television jacks and two CAT-5 telephone jacks

EXTERIOR

  • Certainteed Mainstreet vinyl siding in double 4″ Clapboard or Dutchlap
  • Certainteed Landmark Limited Lifetime architectural shingles
  • 15# shingle underlayment and ice shield installed per code
  • Aluminum drip edge and 6″ fascia
  • Vented vinyl soffit
  • Therma-Tru fiberglass 6-panel front door with vinyl jambs and brickmould
  • Therma-Tru fiberglass half-lite rear door with vinyl jambs and brickmould
  • 6′ vinyl sliding patio door w/low-e glass (floor plan dictates) with screen
  • Ply Gem MW Classic Series double hung vinyl windows – tilt sash, DP50, Warm Edge, low-e glass, Argon gas filled with full screens
  • Vinyl Raised Panel or Louvered shutters on front elevation
  • Satin nickel locksets and hinges (Locksets keyed alike)

 

INTERIOR

  • Smooth ceiling finish
  • Two coats minimum interior wall primer
  • 6-panel colonial white, hollow core doors with 3 mortised hinges
  • Wood colonial trim, painted white, 2-1/4″ casing and 3-1/4″ base molding
  • Window stools with return mitered ends
  • Satin nickel locksets and hinges, and matching door stops
  • Privacy locksets on bathrooms and master bedroom
  • Vinyl-coated metal closet, pantry and linen closet shelving

 

FLOOR COVERING

  • Vinyl sheet flooring in Foyer, Kitchen, Bathrooms and Utility over 1/4″ luan underlayment
  • Shaw 25 oz. carpet (stain safety treated and FHA certified) over an 8 lb. 7/16″ pad

 

KITCHEN SPECIFICATIONS

  • Merillat Spring Valley Square oak cabinets – traditional overlay, recessed panel w/ single roll-out trays in base cabinets, (where applicable), soft close action dovetail drawers and soft close action doors
  • Crown molding on wall cabinets
  • Square edge laminate countertop and backsplash 8″ deep double bowl stainless steel sink
  • Moen SRS kitchen faucet with side spray
  • 30″ range hood – vented to exterior 110V receptacle for gas range
  •  

BATHROOMS

  • Merillat Spring Valley Square oak vanity base cabinets – traditional overlay, recessed panel, soft close action dovetail drawers and soft close action doors (applicable per cabinet design)
  • One-piece cultured marble vanity top and bowl
  • 18″ x 24″ recessed medicine cabinet with mirrored door and decorative light
  • 60″ one-piece fiberglass tub/shower combination (also 36″, 48″, 60″ shower or 60″ tub – floor plan dictates)
  • Elongated low consumption 1.6 gpf toilet
  • Moen lavatory faucet in brushed nickel
  • Ceiling fan/light combination – vented to exterior

 

ADDITIONAL RAISED-RANCH SPECIFICATIONS

  • Recessed entry (floor plan dictates)
  • Foyer light
  • Hot water baseboard heating element for landing, shipped loose
  • Landing with vinyl sheet flooring and 1/4″ luan, shipped loose
  • Stairs up to living area with carpet and pad, shipped loose

 

ADDITIONAL CAPE SPECIFICATIONS

  • 12/12 rafters @ 16″ O.C.
  • Tongue and groove O.S.B. floor sheathing between knee walls, tacked in place
  • 3″ PVC waste line and two 3/4″ supply lines stubbed to second story
  • 3 Electrical circuits run to second story
  • Two #3 (3046) PlyGem MW Classic Series double hung vinyl windows – tilt sash, DP50, Warm Edge, low-e glass, Argon gas filled with full screensand trim, shipped loose for second story gable ends
  • 36″ stairs installed to second story (carpet and pad shipped loose)
  • Cape attic unfinished

 

ADDITIONAL TWO STORY SPECIFICATIONS

 

  • 2×6 ceiling joists @ 16″ O.C.. with double 2×10 perimeter band joists
  • 2×4 mating wall studs @ 16″ O.C. with non-structural sheathing
  • 2×4 mating wall studs @ 16″ O.C. with non-structural sheathing
  • Fiberglass insulation along exterior perimeter between floor and ceiling
  • Second story horizontal plumbing lines run
  • All second story siding shipped loose Stairs to second story installed (carpet and pad shipped loose) – floor plan dictates

End of sample spec sheet

Once the home is completed in the factory and passed quality control inspections as well as required inspections, it is wrapped and ready for shipment to the construction site.

At this point, delivery is scheduled around foundation completion and the home is transported to the site and set on the foundation.

Step 5 (Site Completion)

This phase begins with the home tie-ins and finish work.  During this phase, the drywall is finished at the marriage walls, plumbing and electrical are connected, flooring installed, finish counter tops and tile are installed.

The following list is a sample of the common work for site completion with modular homes.

  1. Finish Electric install
  2. Finish Plumbing install
  3. Install and finish HVAC (furnace, compressor, etc..)
  4. Siding and Roof shingle button up
  5. Sheetrock, trim and paint
  6. Appliance installation
  7. Final Grade and Flatwork
  8. Gutters and Downspouts
  9. Floor Coverings
  10. Countertops

(Please contact your modular homes dealer for a complete and accurate list, the list above is in no way provided to be a complete and accurate list for all modular homes and is just used as a general informational guide).

At the end of this phase you should be able to apply for the CO (Certificate of Occupancy).

 

Check out this helpful article from freshhome.

Check out this article from Bob Vila

Modular Home Faqs