The HUD-code for mobile homes is primarily a “performance" code, rather than a “prescriptive" code, meaning pretty much what it sounds like: instead of specifying what to install and how to install it, the code sets performance standards that give the manufacturer some leeway in how they choose to meet the standard. 

    The insulation performance standard is a U-value, also referred to as a Uo value, which is the overall coefficient of heat transfer through the envelope of the home. The map above shows the U-value requirements for the three thermal zones that HUD has mapped for their standards. A lower U-value number means better insulation. 

    But most people are more familiar with R-value, which is the opposite of U-value, and a measure of the resistance of a substance to thermal transmission. It is also the inverse of U-value, so 1 divided by the U-value equals the R-value, and a higher R-value means a better insulation rating. 

    Unfortunately, the conversion is not quite that simple since the U-value represents the transfer of energy through both conduction and radiation (which is why it often used for rating windows that have multiple different components with varying thermal transmission rates), while R-value represents only resistance to heat transfer. But the R-rating approximately correlates and is what most people understand, so here’s the conversion to R-value for the three zones:  Zone 1 = 8.62 R, Zone 2 = 10.41 R, Zone 3 = 12.65 R. 

    There are also several additional requirements:
  1) The installed heat equipment, combined with installed insulation, must be able to maintain minimum 70º F interior temperature (CFR 3280.5061).
  2) Cavities in exterior walls, floors, and ceilings must be provided with thermal insulation [CFR 3280.5061(b)].
  3) Homes manufactured for Zone 3 must have storm windows or insulated glass windows [CFR 3280.5061(c)].

       Also, go to our HUD-CODE FOR MOBILE HOMES page for a listing of our other HUD-code articles. And see our blog post How energy efficient is a mobile home?

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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?

• 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  and HEATING AND AIR CONDITIONING pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.