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The Lesser Known HUD Zones: Thermal and Roof Load Zones

HUD has zones for heat, humidity and snow. Find out how each zone ensures your mobile home is safe and durable and how to figure out which zone you're in.

If you’re interested in manufactured homes or own a manufactured home, you’ve probably heard about wind zones already, and may even know which wind zone you live in. However, you may not know that all manufactured homes are also built to thermal and roof load zone requirements.

Thermal Zones

There are three thermal zones in the U.S., and each HUD Code home is built to one of these zones based on where that home will be placed, not where the home building facility is located. These different thermal zones determine levels of heat leakage or heat transmission in the home.

Thermal Zone Map

Picture by Manufactured Housing Institute

One of the ways thermal zones help improve the safety and efficiency of manufactured homes is creating minimum insulation R-value requirements depending on different parts of the country. Many home builders offer energy efficient insulation upgrades that help further protect your home from weather conditions!

Humid and Fringe Climates

Another way manufactured homes meet standards for heat transmission is through their inherently tight construction. Since air infiltration, which is the air change rate of a home, is a key part of how homes leak heat in the winter or let hot summer air in, it’s important for a home to be built tightly!

A 2008 study by the University of Michigan found that a home built in a facility had an air change rate that meant the home was 7.6 times tighter than a typical site built home.¹

Another part of thermal protection in homes is whether a home is in a “humid climate” or a “fringe climate” which the HUD Code also determines.²


Photo by The US Department of Housing and Urban Development

If a home is placed in one of these climate zones, the home must conform to certain vapor retardant standards and other conditions to make sure moisture does not permeate the home.²

Roof Load Zones

There are also three different roof load zones in the U.S. These zones are again based on where the home is placed, not where the home is built.

Roof Load Zone map

Picture by Manufactured Housing Institute

Roof load zones vary depending on snow levels in different parts of the U.S. For example, states like Alaska and Maine have some of the highest snow load requirements. Other states like Colorado, parts of Michigan and parts of Wisconsin have a higher snow load than other parts of the U.S.

While modular homes are generally built to local codes and manufactured homes are built to HUD Code, roof load requirements are unique. The load levels created by HUD Code are based on how many pounds per square foot of snow the roof must resist, and HUD Code must be met by the builder.

In addition, certain states or counties can require higher snow loads than the HUD Code mandates.³ If a state or county requires a higher snow load, the manufactured home will be built to comply with the local standard!⁴

To account for different roof load requirements, the amount of trusses and the size of lumber used in the roof could change. The roof pitch and roof load are always taken into account when designing the roof of your home.

Where Can I Find My Home Roof Load Information?

HUD Code requires the data plate in a manufactured home to display the wind and roof load zones or whether the home has been designed to higher snow and wind loads than required. You can find your HUD data plate, which is different than your HUD Certification Label, on the back of one of your kitchen cabinets or hanging in your primary bedroom closet.

1. Doyoon Kim. Preliminary Life Cycle Analysis of Modular and Conventional Housing in Benton Harbor, Michigan. Report no. CSS08-05. Center for Sustainable Systems, University of Michigan. April 16, 2008.

2. Department of Housing and Urban Development, Manufactured Home Construction and Safety Standards; Final Rule, 24 CFR § 3280 (2005).

3. Department of Housing and Urban Development, Office of Asst. Sec. for Housing, Structural Design Requirements, 24 CFR § 3280.305 (2001).

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