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Installation Codes. Manufactured Home Installer Course Part 2. Licensing for Installers. What’s been the Timeline? Jan 1, 2007 –licensing began April 1, 2007 – new installation code effective and inspections began. Licensing.

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installation codes

Installation Codes

Manufactured Home Installer CoursePart 2

licensing for installers
Licensing for Installers
  • What’s been the Timeline?
    • Jan 1, 2007 –licensing began
    • April 1, 2007 – new installation code effective and inspections began
  • You need a license to install a home on a foundation. If you ONLY do the following no license is required:
    • Anchoring – no
    • Grading – no
    • Excavation – no
    • Pouring basement – no
  • The person supervising the home going on the foundation - yes
  • Your license is subject to the requirements for General Supervision – the installer does not need to be on the job site but must be available to the building inspector
  • Homeowners are exempt from licensing but if people help and would otherwise need a license they must be licensed
licensing of installers
Licensing of Installers
  • Qualifications
  • 18 years old
  • Not been found responsible in any court or agency hearing of a violation of the installation law during prior 2 years
  • Not been found responsible in any court or agency hearing for failure to perform under installation contract or defrauding a person in the provision of installation services
application for installers license
Application for Installers License
  • A state license fee plus one time application fee for 4 year license
  • Take 12 hour qualifying class & pass exam
  • Renewal requires 12 hours of continuing education over the 4 year period
  • Also must not have been found responsible for breaking the rule or defrauding a customer
wisconsin installation standard
Wisconsin Installation Standard
  • Act 45 laws of 2005 authorized the Department Commerce to adopt standards
comm 21 40
Comm 21.40
  • Formerly Comm 27.18
  • Now a part of the UDC
  • Applies to homes built before April 1, 2007

April 1, 2007

Comm 21.40 applies Part 3285 applies

Home Built before April 1Home Built on or after April 1

  • Code starts on page 9 of your workbook
comm 21 401
Comm 21.40
  • Review pages 9 and 10 of your workbook for all of the details regarding the code for Pre-April 1, 2007 built homes.
comm 21 40 for homes before 4 1 2007
Comm 21.40 for homes before 4/1/2007
  • No footing on unprepared fill. All organic matter must be removed.
  • Soil bearing test using pocket penetrometer
  • Grade site to drain water away for minimum of 5 ft from home
  • A footing for every pier, nominal 16” by 16”
  • Consult others if soil is less than 2000 psi
comm 21 40 footings
Comm 21.40 Footings
  • one 4 by 16 by 16 solid blocks or two 4 by 8 by 16 solid blocks.
  • 16 by 16 ABS pad rated at not less than 6000 lbs
  • 18 inch diameter hole bored below the frost line or to unfractured bedrock and filled with poured concrete
  • Other materials or systems approved by Commerce
  • Note: frost protection not required
abs pads
ABS Pads
  • ABS pads are permitted for homes built prior to April 1, 2007.
  • The honeycomb always faces up
not all abs pads are the same
Not all ABS Pads are the Same!

4755 lbs/sq ft

4000 lbs/sq ft

5000 lbs/sq ft

In 2000 pfs soil, the capacity of each pad is as shown above, also the direction of a single stack of blocks is specified on the back with arrows.

comm 21 40 piers
Comm 21.40 Piers
  • Concrete blocks, manufactured steel stands or manufactured concrete stands
  • Single stack piers limited to 36 inches
  • Single stack piers loads limited to 8,000 lbs
  • 36 to 80 inch piers – double blocked (layered in opposing layers)
  • 80 inch or more – double blocked laid in concrete mortar, cores filled with mortar and ½ inch steel reinforcing rod*
  • Note mortar and reinforcing rod is more stringent than Part 385
comm 21 40 concrete blocks
Comm 21.40 Concrete Blocks
  • 2 core design, construction grade 8x8x16
  • Cores placed with cores open vertically
  • Block nearest main frame shall be perpendicular to the linear direction of frame
  • No block may contact the frame
comm 21 40 pier spacing
Comm 21.40 – Pier Spacing
  • No more than 7 feet on center
  • No more than 3 feet from exterior side of each end wall
  • Can be varied to follow manufacturer tables
  • Piers under clear-span openings of 4 feet or more in mating walls
  • Piers must be plumb and centered under point of support
comm 21 40 caps
Comm 21.40 - Caps
  • Solid concrete block or solid wood block having nominal thickness of at least 2 inches
  • Cap must be same width and length as top of pier
  • No more than 2 pieces – 2 piece caps positioned with joint perpendicular to frame if used
comm 21 40 shims
Comm 21.40 - Shims
  • Where used, driven from opposing sides and be no less than 4” by 8”
  • Wood caps and shims at least equal to #2 spruce pine fir with min bending stress rating of 1200 psi. All wood caps must be of same species of wood. All shims must be of same species of wood.
  • Note - shims not required but concrete blocks cannot contact the frame.
comm 21 40 height limits
Comm 21.40 – Height limits
  • Combination of nominal 2 inch solid concrete block or wood cap plus shims must not exceed 3 ½ inches
  • Minimum clearance under home of 12 inches between lowest point of main frame in area of utility connections. Min clearance of 12 inches for 75% of home. Remainder may be less than 12 inches but cannot touch ground
recap on 21 40 on key items
Recap on 21.40 on key items
  • All organic matter removed
  • Proper drainage
  • 7 foot maximum spacing between piers
  • Construction grade blocks
  • Any hardwood used must be the same species
  • If ABS pads used, honeycomb is up
  • Double stacked blocks above 36”
federal installation standard
Federal Installation Standard
  • Known as Part 3285 this code applies to home built on or after April 1, 2007.
  • The Wisconsin changes are noted in the text in your binder – latest changes were 3/19/09
the standards
The Standards
  • 3280 – HUD Construction Standards for the home
  • 3285 – HUD Model Installation Standards
  • The following must be AT LEAST AS STRINGENT as the federal model
    • State Standards
    • Manufacturer Manuals
understanding part 3285
Understanding Part 3285
  • Use the Blue and Red Cheat Sheet
  • This Key to the Code will help you find applicable sections as you use the code quicker!
  • Words have meaning so read them carefully – see 3285.5
  • For example, an anchor is a part of an anchoring system.
  • DAPIA – means Design Approval Primary Inspection Agency
  • A manufacturer must provide with each new home a DAPIA approved designs and instructions that are consistent with the standards – 3285.2
application of the standard
Application of the Standard
  • These standards apply to HUD Code manufactured Homes not modulars.
fire separation
Fire Separation
  • Fire separation distances in accord with NFPA 501(a) must be maintained. Means 10 feet
  • Fire separation distance must also comply with Comm 26 in a mobile home park (10 feet between basic structures)
  • Local ordinances might have additional requirements
flood zones
Flood Zones
  • Installer is responsible to determine if home is being installed in flood zone. 3285.102(c) – Contact the zoning administrator for the county
  • If it is, special installation methods are required.
  • Note there are also Shoreland zoning implications
zone maps
Zone Maps
  • 3 maps in the HUD Code
    • Wind – Wisconsin in Zone 1
    • Roof Load – Wisconsin is South and Middle Zones
    • Thermal Zone – Wisconsin is Zone 3
      • U/O value must be less than 0.079
      • U/O is inverse of R value 0.079 = R 12.6
    • Homes may not be installed in a wind zone that exceeds the design load for the home.
  • See pages 11 & 12 in your workbook
site preparation
Site Preparation
  • Soil tests can be conducted with a pocket penetrometer
  • Footings must be sized and spaced according to soil bearing capacity
  • See the tables in 3285.202
  • Poor soils – peat, organic clays or uncompacted fill require a geologist, engineer or architect’s opinion
site drainage
Site Drainage
  • Drainage must be provided to direct surface water away from home and prevent build up under home.
  • Minimum slope of ½ inch per foot for the first 10 feet for homes built on or after April 1, 2007 and 5 feet for older homes.
  • Where site is sloped, home must be protected from surface runoff
gutters and downspouts
Gutters and Downspouts
  • Manufacturer must specify if the home is designed for gutters and downspouts
  • When installed, runoff must be directed away from the home
ground moisture control
Ground Moisture Control
  • Vapor barrier must be installed
  • Min. 6 mill poly or equivalent
  • Overlap 12 inches and seal
  • Barrier may be under, over or around footings
  • Voids and tears must be repaired
  • 3285.204
ground moisture control1
Ground Moisture Control
  • 1 pint of water vapor is generated in 24 hours
  • @ 55 degrees under 10 sq. ft of floor area. 1500 sq ft home then equals 150 pints of water. That’s 16-19 gallons of water
foundations piers
Foundations - Piers
  • Concrete blocks – Must conform to ASTM standard C 90-02
  • Pressure treated wood – think pilings
  • Adjustable metal - Manufactured piers must be labeled or listed for loads and installed to the pier manufacturer’s instructions
pier loads
Pier loads
  • Must be designed with load taken into consideration
  • Spacing is dependant on factors such as soil bearing capacity and foot size
  • See tables at 3285.303
  • Pier spacing tables do not take into consideration flood or seismic loads
pier configuration
Pier Configuration
  • Load bearing blocks not decorative
  • Nominal 8 by 8 by 16 inches
  • Stacked with hollow cores aligned vertically
  • When stacked side by side, each layer at right angles to preceding one
  • Center beam/mating line supports are always required for multi-section homes
  • Primary failure regarding piers is insufficient sizing of mating line piers under ridge beam openings
  • Must evenly distribute loads across the capped hollow block piers
  • May be made of solid concrete or masonry at least 4 inches nominal thickness OR
  • hardwood lumber at least 2 inches thick
  • Must be same length and width as piers
  • Split caps on double stacked piers must be installed with long dimension across the joint in blocks below
  • Must be filled
  • Options
    • 2nd 4” concrete block but cannot contact frame
    • Nominal 4 by 6 by 1 inch shims
      • Must be used in pairs
      • Driven tightly
      • Must not occupy more than 1 inch of vertical space
manufactured piers
Manufactured Piers
  • Adjustable risers must not extend more than 2 inches when finally positioned
clearance under home
Clearance under Home
  • Minimum of 12 inches between lowest member of main frame and grade under all areas of the home
  • Comm 21.40 for older homes is A minimum clearance of 12 inches shall be maintained beneath the lowest point of the main frame in the area of any utility connection. A minimum clearance of 12 inches shall also be maintained under the home for at least 75% of the home. The remainder of the home may be less than 12 inches above the ground but may not touch the ground.
less than 36 piers
Less than 36” Piers
  • Permitted to be constructed of open or closed cell 8 by 8 by 16 when capacity of block is not exceeded
  • Long sides are at right angles to supported I-beam
  • Hollow cores stacked vertically
  • Horizontal offsets from top to bottom not to exceed ½ inch
  • No mortar unless instructions require it
piers 36 to 67 and corner piers
Piers 36 to 67” and Corner Piers
  • All frame piers 36 to 67” high and all corner piers over 3 block high must be double blocked
  • No mortar unless instructions require
  • Horizontal offsets not to exceed 1”
perimeter support piers
Perimeter support piers
  • Piers at mate-line supports, perimeter piers, and piers at exterior wall openings can be single open-cell or closed cell blocks to a maximum height of 54 inches
  • Must be installed with the long dimension parallel to perimeter rail
pier support locations
Pier Support Locations
  • No more than 24 inches from both ends of frame
  • No more than 120 inches center to center under the main I beam
  • Mating line, marriage wall line, ridge beam all mean the point where sections join and they require support – Be alert to extreme weight considerations in these locations!
perimeter support locations
Perimeter Support Locations
  • Both sides of any exterior door
  • Any side wall opening of 48 inches or more
  • Under any load-bearing porch posts, factory installed fireplaces and wood stoves 3285.311
alternative to perimeter supports
Alternative to Perimeter Supports
  • If additional floor joists or outriggers are providing perimeter support, the sizing of piers and footers under the main chassis beam must be adjusted.
  • Must be located on undisturbed soil or fill compacted to 90% of maximum relative density
  • A footing for every pier
  • Footing size depends on the load bearing capacity of soil, footings and piers
  • 3285.312
footing types
Footing Types
  • Concrete types
    • 4 inch nominal pre-cast pads meeting ASTM C 90-02 with 28 day compressive strength of 1,200 psi
    • 6-inch minimum poured in place concrete pads or slabs with at least 28 day compressive strength of 3,000 psi
  • Bad footing
footing types1
Footing Types
  • ABS footing pads – not really applicable for new homes since no frost protection
    • Installed according to pad manufacturer instructions and certified for use in soil classification at the site
    • Must be listed for required load capacity
  • Treated Wood – not really applicable since limited frost protection except for elevated type installations (pilings)
frost protection only 3 ways in wisconsin to install a post april 07 home
Frost ProtectionOnly 3 ways in Wisconsin to install a post April 07 home
  • Footings must be designed using methods and practices that prevent the effects of frost heave by:
    • Conventional below the frost line footing
    • Monolithic slab above frost line – Commerce has issued acceptable design
    • Insulated foundation system above frost line


  • Frost line is 48 inches statewide as set by Commerce
acceptable slab design
Acceptable Slab Design
  • Seal is not required in Wisconsin version of installation standards per Comm 20.09(4)b
  • Larry Swaziek of the Department of Commerce issued an Acceptable Slab Design
  • (see page 94-95 in your workbook)
acceptable slab design1
Acceptable Slab Design
  • 6” thick
  • 10” thickened edge with rebar
  • Min 3000 psi concrete
  • Make sure you read the footnotes for design limitations very carefully
footing sizing table
Footing Sizing Table
  • How to use the tables
  • Use soil bearing capacity to determine size and thickness needed

This is a simplified pier plan for a home – 3 of the I-Beams are deleted for clarity

Calculate Bearing Points

Note that the marriage line piers are not equal distance apart


This is a simplified pier plan for a home – 3 of the I-Beams are deleted for clarity

Calculate Bearing Points

Write down all of the weights that exceed 5300 which is the capacity of a 6 inch thick slab

Look at the chart on the next page and note the following things:
  • Your soil bearing capacity – this section the table from pages 37-38 of your manual assumes 2000 psf soil.
  • What is your roof load zone? For our example we’ll use 30 psf.
  • What is the pier spacing you want to use?
table 1 frame only blocking1
Table 1 – Frame only blocking

All under 8000


2000 pfs soil



Pages 37 - 38


  • Don’t exceed 8,000 lb capacity of single stack of blocks or 16,000 lb capacity of double stack
  • If print shows required perimeter support make sure it is present
  • Concentrate on largest loads first usually the mating line
  • A + B dictates C
3 factors to consider
3 factors to consider
  • A. soil bearing capacity
  • B. pier spacing
  • C. footing size

A + B dictates C

footing tables
Footing tables
  • On pages 55-57
  • You can read these tables the same way.
A 6 inch slab cannot be used under portions of this home that exceed 5300 lbs
  • That means the marriage line area must be thickened
  • For below the frost line footings, pier loads above 3400 lbs require double blocking and larger footings that 16 x 16.

Calculate Bearing Points

Let’s Use the Tables to Design the Foundation

Note the load amounts

If this is a slab set note that mating line must be more than 6” thick per tables

biggest load table on pages 55 56
Biggest Load – Table on Pages 55 - 56

Footer 24 x 24 satisfies 7000 lb mating line load for below the frost line footings

biggest load table on pages 55 561
Biggest Load – Table on Pages 55 - 56

8” Slab thickness satisfies 7000 maximum load on mating line

biggest load table on pages 55 562
Biggest Load – Table on Pages 55 - 56

20 x 20 or 6” slab satisfies all other loads

tables assume square footings
Tables Assume Square Footings

It is a major mistake to read the footing tables in square dimensions and not properly translate those figures to a round bored hole.

translating to o
Translating □ to O

Area of a circle is:

PI x radius of circle

3.14 x (9 x 9) = 254

Quick Calc

18” circle = 254 inches

20” circle = 314 inches

24” circle = 452 inches

Diameter is 18 inches

Radius is 9 inches

Thus 20” diameter is not close to 20” square. 314” vs 400” – you need a 24 inch bored hole

  • After blocking and leveling, the manufactured home must be secured against the wind by an anchoring system
  • Anchoring equipment means ties, straps, cables, turnbuckles, chains and other approved components including tensioning devices that are used to secure a manufactured home to anchor assemblies.
  • Conventional anchors or alternative foundation system (Tie Down or Oliver Technologies type systems)
tie downs
Tie Downs
  • Maximum spacing – see the tables
  • See drawings for near beam and second beam methods
  • If sidewall or over the roof, mate-line or shear wall straps are installed, they must be connected
  • Must be augured at least 30 inches unless the foundation is a frost protected above frost line system
tie down straps
Tie Down Straps
  • 1 ¼ inch by 0.035 in or larger steel strapping conforming to ASTM D 3953-97 standard
  • Capable to resist a min ultimate load of 4750 lb and a working load of 3150 lbs (check listing labels) – Same capacity as the anchors
  • Coated with zinc to not less than 0.30 oz/ft2 of surface
tie down tips
Tie Down Tips
  • No long tails
  • Tension evenly or you might pull the home off the supports
  • Determine if stabilizer plate is needed – See anchor manufacturer instructions
  • Try locking clamp version
  • The anchors must be capable of meeting the loads the home was designed to withstand – see data plate
  • Follow the anchor company’s instructions for spacing, angles, connections and so forth
  • Install anchors to their FULL depth
  • A diagonal anchor tie is intended to resist horizontal or shear forces, but may also resist vertical, uplift and overturning forces
          • 3285.401
ground anchors
Ground Anchors
  • Must be listed (listed means approved)
  • Steel coated and weather protected. HUD now allows either zinc coated or painted anchors.
  • Capable to resist a min ultimate load of 4750 lb and a working load of 3150 lbs (check listing labels)
tie down engineering vector system
Tie Down Engineering Vector System

Several companies have alternative systems that work without anchors

vector system with longitudinal support
Vector System with Longitudinal Support

Note base plate and longitudinal support

tie down safety issues
Tie Down Safety Issues
  • Locate Utilities
    • abandoned electrical drops is a concern
    • utility lineman’s gloves are recommended
    • Test for power on anchor before connecting to home can be done using a simple voltage checker

$5.25 worth of safety

Image courtesy of Lab Safety, Janesville

on site structures
On-site structures
  • Each expansion room or other on-site structure must be able to support its own weight including any garage unless pre-designed by manufacturer, engineer or architect
  • Any addition must be designed by either the home manufacturer, a registered engineer or architect
optional equipment
Optional Equipment
  • Comfort systems (HVAC) must be installed by a licensed HVAC contractor if not factory installed
  • Air conditioning equipment must be properly sized
  • All heat producing equipment must be properly vented thru the skirting or exterior wall as appropriate
  • When not installed by home manufacturer, must be installed according to the appliance manufacturer’s instructions
  • Must be weather resistant
  • Attached so no water is trapped between siding and trim or forced up into the wall cavity trim
  • All wood skirting within 6 inches of the ground must be pressure treated or be naturally resistant to decay and termites – This would include lumber and sheathing extension if any of the wood is less than 6 inches above the ground
crawlspace venting
Crawlspace Venting
  • NEW - One square foot for every 1,500 sq ft of floor area – Important – Check with your manufacturer before proceeding with reduced venting
  • Vent openings as high as practicable
  • Vents must located on at least two opposite sides of home
  • Openings must be covered with a perforated corrosion and weather resistant covering to prevent rodent entry
the answer is a
The Answer is A
  • This panel has a large number of openings which although they are small allows more air to pass than the other panels which have much more hard surface area. Panels are rated, see the back of any panel you buy to know what you are getting.
access openings must
Access Openings MUST:
  • Not less than 18 wide by 24 high and not less than 3 sq ft
  • Must be located so that any utility connections under the home are accessible
  • 3285.505
dryer vents air conditioning combustion air vents
Dryer vents, air conditioning, & combustion air vents
  • Must pass through skirting to the outside
  • This includes fireplace air inlets
  • Air conditioner equipment not installed by the manufacturer must be done by a person holding an HVAC license!
ductwork plumbing fuel supplies
Ductwork, Plumbing & Fuel Supplies
  • Manufacturer must supply instructions for proper field assembly
  • When local water supply pressure exceeds 80 psi, a pressure reducing value must be installed
  • An identified and accessible shutoff value must be installed underneath or adjacent to the home
  • Crossovers and lines must be protected from freezing
  • Only listed MH heat tape is permitted
  • Water system must be inspected and tested for leaks after completion at the site.
    • Disconnect water heater if test is air only
piping support
Piping support
  • Water lines supported every 3 feet
  • Drain lines supported every 4 feet – See 48 inch on center max - 3280.608
gas supply
Gas Supply
  • Home design calls for system pressure of 10 to 14 inches of water column pressure (0.036 psi)
ductwork crossovers
Ductwork Crossovers
  • All ductwork connections must be sealed
  • Galvanized metal straps or tape and mastics listed to UL 181 A or B must be used around duct collar and secured tightly
  • Metal straps require metal sheet screws
    • Fasten with at least 3 galvanized sheet metal screws equally spaced around the collar
  • Max distance for duct supports is 4 feet
  • If straps are used they must be ½” wider than spacing of spirals in flex duct
    • Arrange so that straps cannot slip between spirals and to prevent kinking
  • Ducts cannot contact ground
    • Listed for exterior use only
  • Crossovers outside the envelop must be insulated with proper materials
  • In-floor or ceiling crossover connections must be sealed to prevent air leakage
subpart h electrical
Subpart H - Electrical
  • Snap connections may or must be fastened to adjacent stud – CHECK instructions
  • If a fixture is mounted on a combustible surface a limited combustible or non-combustible ring must be installed
  • Wires connected black to black, white to white and ground to ground
  • Test all connections
smoke alarms
Smoke Alarms
  • Additional shipped loose alarms for basement set models are typically provided by the manufacturer
  • They may be wired to communicate with factory installed units at main floor
  • A separate WI law also requires carbon monoxide detectors
exterior close up
Exterior close-up
  • Manufacturers provide instructions for joining sections. Pay particular attention to directions on fasteners
  • The mate-line gasket must be installed following manufacturer instructions
  • Exterior close up strips are trim that must be fastened securely and sealed with an exterior sealant
before sections are secured
Before Sections are Secured
  • The poly sheeting used for transport must be removed completely
hinged roofs and eaves
Hinged roofs and eaves
  • May be subject to alternative construction inspections if flue penetrations are above the hinge

No Seal!

  • UPON COMPLETION – no gaps are permitted between structural elements
  • PRIOR TO COMPLETION – minor gaps not exceeding one inch are permitted PROVIDED they are filed upon completion
  • Fill gaps must be shimmed with dimensional lumber and fastener lengths used to make connections must be increased to provide adequate penetration into receiving lumber.
  • Pay particular attention to end wall and floor completion gaps – May have marriage wall sheathing in from end wall ends
close up
Close up
  • All shipping blocking, strapping or bracing must be removed from appliances, window and doors.
  • At a minimum, shipped loose wall panels must be installed using PVA adhesive on all framing members and fastened with 1 inch long staples or nails 6 inch on center panel edges and 12 inches on center in the field unless manufacturer directs other methods
bottom board
Bottom Board
  • Bottom Board is an industry term for barrier installed by the factory on the bottom of the floor system. It is for rodent control.
  • Inspect for loosing or areas damaged by transport or installation
  • Tears must be repaired
bottom board1
Bottom Board
  • Any missing insulation must be replaced
  • Splits or tears must be resealed with tape or patches
  • P traps must be checked to be sure they are well insulated and covered
  • All repaired edges must be taped or otherwise sealed
other udc issues to watch
Other UDC Issues to Watch
  • Site constructed elements subject to UDC
  • Basement stairs
  • Exterior decks, stairs and railings
  • Garage attachments
  • Habitable basements
    • Egress windows for bedrooms
    • Heating calculations for entire envelop
trouble spots basement stairs

Maintain 6'-4" Headroom In Required 3' Long Landing

Finished Stairwell Length (FSL)

Floor/Ceiling Depth


(Min. 6'-4")

Two Similar Right Triangles

Maintain 6'-4" Headroom In Required 3' Long Landing

Unit Rise

Max. 8"

Unit Run

Min. 9"

Headroom + Floor/Ceiling Depth (HFCD) Finished Stairwell Length(FSL)

Unit Rise Unit Run

So to solve for FSL, FSL = Unit Run x HFCD

Unit Rise

Trouble spots-Basement Stairs
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