MH Installers On-Line Continuing Education
Contents of this Course • Installation Standard applicable to Pre-April 1, 2007 homes • Requirements for steps • Ramps, Steps and Handrails • Refresher on Post-2007 Home Standards • SPS 320 Code Enforcement Refresher • Understanding Soils and Frost Heave
3 Primary Resources • Installation Codes • UDC Codes • Slides
Let’s Get Started • Act 45 laws of 2005 authorized the Department Commerce (now Department of Safety & Professional Standards) to adopt installation standards. • The UDC applies to both new and used (relocated) homes. However, the production date as shown on the data plate determines which code applies.
Pre-2007 Home • In this course Pre-2007 means a home build before April 1, 2007. • The applicable code is fairly short and is found in SPS 321.40. It is linked for you on the course page at www.housingalliance.us/InstalCE.htm
Pre-2007 Code • Anchoring is a preferred way to protect the home from the wind. However, if the home is not on a frost protected foundation, anchors can damage the home. • Since frost protected foundations are not required neither is anchoring.
Pre-2007 • Soil Requirements – SPS 321.40(2) • No footing may be placed on • Unprepared fill material • Top soil • Alluvial soil • Mud • All organic material must be removed
Soil bearing capacity must be determined so that the footing can be properly sized. • A pocket penetrometer is the least expensive method
Controlling water is primarily accomplished by grading the site. • Unlike the federal code, grading for Pre 2007 home is only required for 5 feet around the home. 10 feet however would be preferred but again not required.
Footings • Once the soil bearing capacity is determined the size of the footing can be determined. • The minimum footing size is 16 by 16 inches
Footings • If a ABS pad is used, its bearing capacity for a 16 by 16 pad must be 6,000 lbs
Footings • There are 4 acceptable types of footings • One nominal14 by 6 by 16 inch solid concrete block or two nominal 4 by 8 by 16 inch blocks • An 18 inch hole bored below the frost line or to unfractured soil and filled with concrete • A 16 by 16 inch ABS pad • Any other Department approved systems
Piers • In a pier where a single block is at the top of the pier with double blocks below, the double blocks must be positioned with their joint parallel to the main frame. • If a double block pier is used, the two footing blocks may be positioned with the joint parallel or perpendicular to the main frame.
Piers • A manufactured steel stand is accepted as a pier. Check it’s load bearing capacity however before use.
Pier Heights • Single stack piers are limited to 36 inches • Above 36 inches up to 80 inches double blocks with alternating orientations are required. • Above 80 inches mortar and ½ inch a steel reinforcing rod is additionally required • There is no limit on height
Pier Placement • The maximum pier separation is 7 feet • The piers must be plumb and centered under the contact area at the point of support • The outside piers cannot be more than 3 feet from the exterior of the home. • Additional piers are required in clear span openings in exterior walls or openings in mating walls of 4 or more feet
Blocks • Must be 2 core design. Cannot be 3 core or solid. • Cores are always placed vertically • No concrete block can contact the main frame
Caps • Since concrete piers cannot contact the frame, a cap is required. • Acceptable caps are • A solid concrete at least a nominal 2 inches • A solid wood block at least a nominal 2 inches • The cap must be the same width and length as the top of the pier • A two-piece cap shall be positioned with the joint perpendicular to the frame • The combined height of the cap material cannot exceed 3 ½ inches
Shims • Shims must have a dimension of at least 4 inches by 8 inches • They must all be from the same species of wood. (ABS shims are not allowed) • Shims and caps must be at least equal to No. 2 spruce pine and have a fiber bending stress rating of 1200 psi or better • Shims are to be driven in pairs from opposing sides of the pier
Wood • Trees are divided into two classes hardwoods and softwoods • Hardwoods have broad leaves and softwood have needles • Hardwood/Softwood does not describe the “hardness” of the wood • Drying wood from green to 5 percent moisture in some cases triples its strength
Wood • Force applied to one side of a beam creates compression on that side and is way to measure strength • The following woods have stress bending rates high enough to meet the 1200 psi rating • Douglas Fir • Hemlocks • Spruce Pine Fir but only select, no. 1 or no. 2 Spruce Pine Fir no 3 would not be acceptable
Clearance • A minimum clearance of 12” shall be maintained under at least 75% of the home. • (For homes built on or after 4/1/2007 the entire clearance area must be 12”) This is the end of the Pre-2007 Home Installation Code Section
Stairs, Steps, Railings – Consult SPS 321 • Stairway leading to non-habitable attics or crawl spaces are not covered by the UDC • Generally, stairways must measure at least 36” in width
Spiral Stairs • Often not just a decorative feature but a space necessity. • Spiral staircases shall be at least 26 inches wide measured from the outer edge of the supporting column to the inner edge of the handrail. • At the top and bottom of a flight, measurement shall be taken from the top of the nosing to the finished floor surface unless the finished surface is carpeting, in which case measurement shall be made to the hard surface below the carpeting.
Except for spiral staircases risers may not exceed 8 inches in height measured vertically from tread to tread. • Risers in spiral staircases may not exceed 9.5 inches in height measured vertically from tread to tread. • Rectangular treads shall have minimum tread depth of 9 inches measured horizontally from nosing to nosing.
Headroom • Stairways shall be provided with a minimum headroom clearance of 76 inches measured vertically from a line parallel to the nosing of the treads to the ceiling, soffit or any overhead obstruction directly above that line. • The headroom clearance shall be maintained over a landing that is at the top or bottom of a stairway for a minimum distance of 36 inches in the direction of travel of the stairway.
Variance in Height Within a stairway flight, the greatest tread depth may not exceed the smallest tread depth by more than 3/8 inch and the greatest riser height may not exceed the smallest riser height by more than 3/8 inch. WOW!
The walking surface of stair treads and landings shall be a planar surface that is free of lips or protrusions that could present a tripping hazard. • Stairways leading to non-habitable attics or crawl spaces are not covered by the UDC. • Generally, stairways shall be at least 36 inches wide.
Common Defects • Openings in handrails/guardrails • Gripping surfaces on handrails • Headroom • Uniformity • Landings
Cable or Ropes • If cables or ropes are used in a handrail or guardrail shall be strung with maximum openings of 3 ½ inches with vertical supports 4 feet Incorrect – opening exceeds 3 ½ inches
Stairways with open risers shall be constructed to prevent the through-passage of a sphere with a diameter of 4 inches or larger between any 2 adjacent treads.
Design Standards • Handrails and guardrails must be designed to withstand a 200 lb load applied in any direction. • Any glazing used must be safety glazing • Exterior handrails and guardrails must be made of metal, decay resistant or pressure treated wood, or shall be protected from the weather.
Handrails Forms • A common violation regarding decks and stairs involves handrail shapes. • Must be symmetrical at the vertical centerline to allow for equal wraparound of the fingers and thumb. • Where the handrail is round or truncated round cross sectional gripping surface must have a whole diameter of 2 inches. 2 inches
Continuity • Handrails must be continuous for the entire length of the stairs except: • At an intermediate landing • A handrail may have newel posts • At an intermediate wall provided • the upper rail is returned to the wall or provided with a flared end, • The horizontal offset between the 2 rails is no more than 12” measured from the center of the rails, and • Both upper and lower rails can be reached from the same tread without taking a step.
Landings • An intermediate landing is required in any stairs that has a height of 12 feet or more. • Intermediate landings connecting straight stairs or stairs at a right angle must be as wide as the stairs and measure at least 36 inches in the direction of travel. • Curved or irregular landings shall have a radius of at least 36 inches.
Landings • The level landing at the top and base of every stairs shall be as wide as the stairs and shall be at least 3 feet in the direction of travel • A landing is not required • between the door and top of the interior stairs if the door does not swing over the stairs • Between a sliding glass door and the top of an exterior stairs of 3 or fewer risers
Landings • The exterior landing, platform or sidewalk at an exterior doorway shall not exceed 8 inches below the interior floor elevation and shall have at least 36 inches of surface in the direction of travel
Ramp Landings • A level landing shall be provided at the top, at the foot and at any change of direction of the ramp. • The landing must be at least as wide as the ramp and shall measure at least 3 feet in the direction of travel.
Ramps • Ramps shall not have a slop greater than 1 in 8. (One foot of rise for each 8 feet of run.) • Walkways with a slope of less than 1 in 20 are not considered ramps. • Ramps must have a slip resistant surface.
Clearance • The clearance between the handrail and a wall shall be at least 1 ½ inches. • Handrails and their trim can project a maximum of 4 ½ inches into the required width of the stairs or landing.
Required Handrails • When the ramp has a gradient greater than 1 in 12 AND which overcomes a change in elevation of 24 inches or more, shall have a handrail on both sides. • Every ramp that overcomes a change of elevation of 8 inches or more shall have at least one handrail. • Handrails shall be located to the top of the handrail is at least 30 inches but not more than 38 inches above the ramp surface.
The opening in a handrail shall prevent the passage of a sphere with a diameter of 4 inches or larger. The triangular area formed by the tread, riser or guardrail shall have an opening that prevents the passage of sphere of 6 inches or more This design is decorative but openings exceed 4 inches. Openings in Handrails This completes the section on stair, ramps and handrails
Federal Installation Standard • Each state must adopt a version that is at least as stringent as the federal model code. • Each manufacture must provide 2 sets of instructions • At least 1 method for temporary support when sited at the plant, retailer’s lot or home site • Instructions for the installation of the home
Federal Installation Standard • An installer must follow the temporary set instruction until the home is placed on its foundation • Failure to support the home while stored could result in structural damage
Federal Installation Standard • Variation to the installation instructions by an installer is not permitted unless permitted by the manufacturer, a professional engineer or architect. • Any alteration to the instructions must not impose additional loads to the home or its foundation
Federal Installation Standard • The installation standard applies to manufactured homes only not • Modular homes • RV’s • A manufactured home is defined in federal law as 8 body feet or more in width or 40 body feet in length or when erected is 320 or more square feet (additional requirements can be found in the definitions section of the code)
Federal Installation Standard • Before placing the home on the site consider the impact of: • Fire separation distances as may be required by NFPA 501A and any local requirements • The existence of flood plains • Wind zone • Roof load zone • And the Thermal zone
Caps – this section is unique to WI* • Acceptable caps are* • A combination of up to two-4” thick concrete blocks and not more than one-2” hardwood lumber. • Lumber must be at the top of the pier. • A 4” block cannot be the bottom block in the pier but by be mixed with other blocks
Caps • The cap must be the same width and length as the top of the pier • A two-piece cap shall be positioned with the joint perpendicular to the frame