It’s called a belly wrap, belly board, or bottom board, depending on who you ask. We most often hear it called belly wrap, but HUD and manufactured home industry associations refer to it as a bottom board. It’s a moisture barrier and also helps to prevent the entry of insects and rodents into the home—as long as the belly wrap remains intact. But when plumbing repairs require cutting open the wrap, sometimes the area doesn’t get resealed afterwards; or it get taped-up with some hardware-store type duct tape that comes loose after a few days. 

    Once an opening in the wrap is combined with a section of missing skirting, mobile home owners in rural locations have found that local small wildlife likes to pull down the insulation for nesting material, or just for fun, and drag it around, loose under the home. So a small opening in the belly wrap can become a big mess of shredded insulation and torn plastic sheeting strips in the crawl space.

    Premium mobile homes have a netting stretched across underneath the belly wrap as a reinforcement, which prevents the gradual sagging between fastener rows that can occur over time. Large bulges in a belly wrap that is otherwise intact can indicate a plumbing leak under the floor. Cutting a pinhole in the bulge tells all.

    We recommend patching any access hole cut in the belly wrap to make a repair under the floor of the home immediately after completion of the repair. A neat trick to simplify closing up the opening after your repair is to begin by cutting an X-shape centered under where you want to work. You will have four flaps hanging down during your repair that can taped back up when work is completed. Both mechanical fastening and a flexible sealant or tape should be used to secure the repair area.

    The best repair technique is to install a sheet of lightweight sheathing within the belly opening above the hole, mechanically fasten (staple or nail) the torn area to the sheathing, apply a sealant to the edges (mastic, caulk or adhesive tape), then cover the whole area of the tear with a scrap piece of belly wrap that is also mechanically secured and sealed.

    Also, see our blog post When did a ground cover vapor barrier (plastic sheet) become required under a mobile/manufactured home? 

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manufactured/mobile homes? 
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Here’s links to a collection of our blog posts about MOBILE/MANUFACTURED HOMES:

• Where can I file a complaint if I have problems with my new or used manufactured/mobile home in Florida?

• What are the most common defects in mobile/manufactured home foundation piers?

• How do I determine the age of a very old mobile home?

• What is a "HUD label verification letter" for a mobile/manufactured home?  

• When did a ground cover vapor barrier (plastic sheet) become required under a mobile/manufactured home? 

• Is it safe to go under a mobile home? 

• Are older mobile homes unsafe? 

• What do I need to know about buying a foreclosed mobile home? 

• Does it make sense to buy an older mobile home and remodel it? 

• Where do I find the vehicle identification number (VIN) on a mobile home? 

• How do I find out how old a mobile home is and who manufactured it?

• What is the right price for a used mobile home?

• How energy efficient is a mobile home?

• When were the first double-wide mobile homes manufactured?

• How do I upgrade my old (pre-1976) mobile home to meet HUD standards?

• What size air conditioner is right for my mobile home? 

• Can you move an older mobile home in Florida? 

• What does the HUD tag look like and where do I find it on a mobile home? 

• Can you put a zone 1 mobile home in Florida?

• How can I remove water under my mobile home?

• What's the differences between a trailer, a mobile home, a manufactured home, and a modular home? 

• What is a D-sticker mobile home? 

• What are the tie-down requirements for a mobile home?

• How fireproof is a mobile home?  

• Can I install a mobile home myself?

• What is a Park Model mobile home?  

• Does an addition to a mobile home have to comply with the HUD Code? 

• What walls can I remove in a mobile home?

• What can I do to prevent dampness and mold in my mobile home? 

• How can I tell if a mobile home is well constructed?

• How can I tell the difference between a manufactured home and a modular home?

       Visit our MOBILE/MANUFACTURED HOMES  page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles. 

Illlustration above - from Moisture Problems in Mobile Homes, by the Manufactured Housing Research Alliance