Thread: Mobile home vinyl siding

I do not do to many mobile homes. Had one today and the vinyl siding has no moisture barrier like tyvek behind it. Just vinyl and OSB. Everything I have read from vinyl siding suppliers says it has to have a moisture barrier behind it. Is there some code that allows manufactured housing to not adhere to the siding manufacturers requirements.?

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Originally Posted by ren ramsey

I do not do to many mobile homes. Had one today and the vinyl siding has no moisture barrier like tyvek behind it. Just vinyl and OSB. Everything I have read from vinyl siding suppliers says it has to have a moisture barrier behind it. Is there some code that allows manufactured housing to not adhere to the siding manufacturers requirements.?

The requirement for a weather barrier behind vinyl is a relatively recent addition to the IRC. Of course, manufactured houses are built under a HUD code. It would not surprise me if that code still does not require it.

Originally Posted by Mark Reinmiller

The requirement for a weather barrier behind vinyl is a relatively recent addition to the IRC. Of course, manufactured houses are built under a HUD code. It would not surprise me if that code still does not require it.

.........you're right, the HUD construction standard does not specify the use of a weather barrier behind siding. Many HUD mfd. home builders use a proprietary vinyl siding which also did not include specs for a weather barrier behind their product. As more manufacturers now use standard builder's grade products, the install directives must be adhered to - so many of today's mainstream HUD codes will have weather barriers behind the vinyl rain-screen.......Greg

Originally Posted by Gregory Booth

.........you're right, the HUD construction standard does not specify the use of a weather barrier behind siding. Many HUD mfd. home builders use a proprietary vinyl siding which also did not include specs for a weather barrier behind their product. As more manufacturers now use standard builder's grade products, the install directives must be adhered to - so many of today's mainstream HUD codes will have weather barriers behind the vinyl rain-screen.......Greg

I'm pretty sure 2006 was the year the IRC required a WRB behind vinyl on stick built homes.

As for manufactured homes, all since that point and time that I have seen, have had a WRB from what I can tell. Don't forget that HUD also defers/defaults to current codes if an item or system is not addressed by HUD.

Originally Posted by Scott Patterson

I'm pretty sure 2006 was the year the IRC required a WRB behind vinyl on stick built homes.

As for manufactured homes, all since that point and time that I have seen, have had a WRB from what I can tell. Don't forget that HUD also defers/defaults to current codes if an item or system is not addressed by HUD.

........there are many sections within the HUD codes. That which governs manufactured housing does not defer to any other "current codes" so be careful of what you might cite as a deficiency. In this instance regarding wrb's, or lack thereof - if the manufacturer is installing a product that does not specify(address) a wrb it is compliant without. There are still factory homes being built utilizing various sidings without weather barriers - and they are code compliant. We know it's not sound building practice but it still meets code. Yet another reason to be careful when citing "code" in our inspections.......Greg

This is what the IRC says about manufactured homes: (underlining is mine)

- Appendix E - Manufactured Housing Used as Dwellings
- - SECTION AE101 SCOPE
- - - AE101.1 General.
- - - - These provisions shall be applicable only to a manufactured home used as a single dwelling unit installed on privately owned (nonrental) lots and shall apply to the following:
- - - - - 1. Construction, alteration and repair of any foundation system which is necessary to provide for the installation of a manufactured home unit.
- - - - - 2. Construction, installation, addition, alteration, repair or maintenance of the building service equipment which is necessary for connecting manufactured homes to water, fuel, or power supplies and sewage systems.
- - - - - 3. Alterations, additions or repairs to existing manufactured homes. The construction, alteration, moving, demolition, repair and use of accessory buildings and structures, and their building service equipment, shall comply with the requirements of the codes adopted by this jurisdiction.
- - - - These provisions shall not be applicable to the design and construction of manufactured homes and shall not be deemed to authorize either modifications or additions to manufactured homes where otherwise prohibited.
- - - - - Exception: In addition to these provisions, new and replacement manufactured homes to be located in flood hazard areas as established in Table R301.2(1) of the International Residential Code shall meet the applicable requirements of Section R322 of the International Residential Code.


- SECTION AE102 APPLICATION TO EXISTING MANUFACTURED HOMES AND BUILDING SERVICE EQUIPMENT
- - AE102.1 General.
- - - Manufactured homes and their building service equipment to which additions, alterations or repairs are made shall comply with all the requirements of these provisions for new facilities, except as specifically provided in this section.
- - AE102.2 Additions, alterations or repairs.
- - - Additions made to a manufactured home shall conform to one of the following:
- - - - 1. Be certified under the National Manufactured Housing Construction and Safety Standards Act of 1974 (42 U.S.C. Section 5401, et seq.).
- - - - 2. Be designed and constructed to comply with the applicable provisions of the National Manufactured Housing Construction and Safety Standards Act of 1974 (42 U.S.C. Section 5401, et seq.).
- - - - 3. Be designed and constructed in compliance with the code adopted by this jurisdiction.
Additions shall be structurally separated from the manufactured home.
- - - - - Exception: A structural separation need not be provided when structural calculations are provided to justify the omission of such separation.
- - - Alterations or repairs may be made to any manufactured home or to its building service equipment without requiring the existing manufactured home or its building service equipment to comply with all the requirements of these provisions, provided the alteration or repair conforms to that required for new construction, and provided further that no hazard to life, health or safety will be created by such additions, alterations or repairs.
- - - Alterations or repairs to an existing manufactured home, which are nonstructural and do not adversely affect any structural member or any part of the building or structure having required fire protection, may be made with materials equivalent to those of which the manufactured home structure is constructed, subject to approval by the building official.
- - - - Exception: The installation or replacement of glass shall be required for new installations.
- - - Minor additions, alterations and repairs to existing building service equipment installations may be made in accordance with the codes in effect at the time the original installation was made, subject to the approval of the building official, and provided such additions, alterations and repairs will not cause the existing building service equipment to become unsafe, insanitary or overloaded.

To complicate matters even more: (underlining is mine)
- SECTION R102 APPLICABILITY
- - R102.5 Appendices.
- - - Provisions in the appendices shall not apply unless specifically referenced in the adopting ordinance.

So, even if the above appendix does apply to some parts, or all, of a manufactured home, the appendix only apply is specifically referenced and adopted by local ordinance.

Be very careful about applying a "building" code for homes which are "built" to a home which is "manufactured".