Modular homes are as safe as any traditional site-built house since every permanent structure is constructed under the same building regulations which are defined by the building codes. However, these regulations aren’t necessarily enough to certify the safety of every house and situation since they only establish the necessary rules to provide with the minimum safety standards.

Therefore, to assert the safety of a modular home we have to analyze its own circumstances and often build a structure that exceeds the building code’s requirements.

There are four things we should consider when building a safe modular home:

1. Building in an Earthquake prone area
2. Building in a hurricane prone area
3. Health hazards related to an excess of moisture
4. Material quality and degradation

In order to assure a safe house, it is key to take into consideration both its location and the different construction elements. Still, modular homes tend to offer a structure that in comparison, is safer than other house types due to their construction process. Therefore, building a house with modular construction is in general, a safety guarantee.

Are prefabricated homes safe?

Modular homes are prefabricated structures and as such there is a common concern regarding its safety. Prefabricated homes are often associated to mobile homes which carry a negative stigma in relation to safety. The safety issues associated to mobile homes have become the main headline in numerous times since after extreme storms such as hurricanes the severe damages caused in trailer parks are common [1].

However, mobile homes are only one type of prefabricated building and aren’t a good representation of prefabrication in general. The term prefabricated encompasses a wide number of construction types that having been built in a factory-like setting adhere to different building regulations and offer a variety of housing solutions.

There are two big different groups of prefabricated homes, those that are built as permanent structures such as stick built or modular homes and those conceived as non-permanent structures such as mobile or manufactured homes. The main distinction between these two relies on the of building regulations they are compelled to adhere to.

Nowadays the non-permanent building regulations: the HUD Codes; are endured and offer quite a safe environment to its occupants [2]. Notice though, that most of the mobile homes suffering from safety accidents such as the severe damages occurring during storms are usually build before 1976, when the HUD Code was first stablished [3].

Every permanent prefabricated structure is built according to either the HUD or the building codes, certifying the minimal safety standards to any prefabricated construction. Therefore, we could say that prefabricated constructions are safe, though the distinction between permanent and non-permanent structures is noticeable: permanent prefabricated homes are build sturdier and therefore safer than non-permanent ones.

 

Main things to consider to build a safe modular home

Every permanent construction both prefabricated and build on-site, is required to stick to the building codes. The building codes are based on the International Code Council® (ICC) though every state and location applies some modifications to fit their specific needs. Therefore, the building regulations required when building a modular home will highly depend on its location [4].

1.     Building in an Earthquake prone area

When building a modular home in an Earthquake prone area, we should check the strictness of the earthquake regulations set in the building codes for that specific location and if necessary exceed these recommendations to ensure the safety of the house.

For example, the building codes defined in California are quite strict regarding the Earthquake hazards. The intend of these codes, as it is said, is to protect life safety and prevent collapse which isn’t necessarily a guarantee that the building will be functional and habitable after a moderate earthquake [5]. Then, exceeding the requirements stablished by the building codes might offer a better outcome.

Modular homes often grant us some extra resistance in front of Earthquakes.  Since every module is manufactured in a factory and transported to the site where it is going to be assembled. During the shipping process, the module is exposed to a tremor similar to that one of an earthquake. Therefore, to ensure the structural integrity of each module during transportation each module is self-stabilized and build with a stronger resistance to the tremors. 

2.    Building in a Hurricane prone area

Those areas with a known recurrent impact of heavy storms such as hurricanes, are required to strengthen their building codes to avoid disastrous consequences according to the guidelines dictated by the Federal Emergency Management Agency (FEMA) [6]. Therefore, since all modular homes are built up to code they offer some sort of guarantee that the house will withstand the expected weather events of the area. 

However, as the Insurance Institute for Business & Home Safety (IBHS) states in their 2021 edition of Rating the States, not all states have codes up to date. In some states such as Massachusetts, Georgia or New York, the building codes aren’t yet strong enough to reduce the critical damages caused by hurricanes [7]. To ensure the safety of a modular home in front of hurricanes, it is key to identify any weakness in the local building codes and exceed the requirements if necessary.

Florida on the other side, since the devastating damages caused by hurricane Andrew in 1992 has strongly strengthened its building regulations and has now established the toughest building code standards of the nation [8]. Modular homes built in South Florida are considered safe in front of hurricanes just by having been build according to the building codes.

3.    Health hazards related to an excess of moisture

The presence of moisture indoors often leads to the growing of mold [9], which seriously affects the indoor air quality representing a health hazard for its occupants. Mold spores can cause allergic reactions, respiratory issues and other symptoms such as fatigue or headache when inhaled.

Some specific kinds of mold such as Stachybotrys and Aspergillus, represent even a more serious danger since they can produce mycotoxins which can lead to more serious illnesses [10]. Moisture control is key to avoid mold growth and ensure the safety of its occupants.

Being built according to the building codes or with modular technology isn’t a guarantee that the building construction will keep moisture under control. However, it is common for modular home manufacturers to offer energy efficient constructions which are highly insulated houses. A good insulation lowers the risk of condensations which are the common cause of mold [11]. Therefore, energy efficient modular homes are safe in front of mold.

To avoid future problems with mold, ensure your modular home is properly insulated and offers moisture barriers integrated in the wall system. Moreover, to balance the moisture indoors ventilation is key since it reduces indoor moisture levels [12]. Incorporating mechanical ventilation will help prevent the emergence of mold.

4.    Material quality and degradation

The safety of a house should also consider any future risks the house could show when aging and degrading. Good quality materials as well as a high quality construction are key to avoid the house’s collapse and damaging particles getting into the air due to the degradation of materials.

In general, modular homes offer a higher quality construction with an exceptional attention to detail as well as an improved material condition. The industrialized construction process of the modules allows more efficient quality controls and a cleaner work with the usage of more sophisticated tools [13].

While the material selection of modular homes isn’t necessarily of higher quality than it would be in on-site construction, being built in a protected environment lowers the chances of material degradation during construction due to the exposure to changes in humidity or temperature [14].

The construction process of a modular home tends to grant the construction with an overall higher quality and attention to detail lowering the chances of early degradation of materials and offering a safer environment over time.

Modular homes are safer than most construction types

While it would be misleading to assure that all modular homes always offer a safe environment for its occupants, it is certain that modular construction provides the building with some advantages in regards to safety. The advantages of modular construction are directly related to their construction process:

• Module shipping: Since modules are transported to the building site, their structure is designed and built to be self-stabilized and resist the shipping tremors. The structure of a modular home is often sturdier than in other construction types.

• Predesigned construction: Given that most modular homes are predesigned and built to suit different clients, these designs often offer qualities such as energy efficiency and a mechanized ventilation system. Both these aspects ensure a proper indoor moisture control and reduce the likelihood of mold appearance.

• Controlled construction environment: Every module conforming the modular homes is built in a factory-like environment, providing the construction process with a sheltered environment. This setting is free from weather disruptions and enables a finer work quality as well as consistent quality controls.

• Centralized construction setting: The centralization of the building process in a protected environment provides the construction materials with the ideal storage space. Being preserved from the elements, materials maintain their initial qualities and offer a longer lasting construction.

References:

1. Funes, Y. (2021, May 23) Mobile Homes and Hurricanes: The True Cost of “Affordable” Housing Atmoshttps://atmos.earth/mobile-homes-south-vulnerable-hurricanes/
2. (2015, 9 July) What you need to know about the HUD Code Home First^TM https://homefirstcertified.com/what-you-need-to-know-about-the-hud-code/
3. Adkins C., (2018, July 4) Manufactured Home facts everyone should know Mobile Home Living For Mobile Homeowners By Mobile Homeowners https://www.triadfs.com/news/how-manufactured-homes-differ-from-mobile-and-modular-homes
4. I-Codes Code Adoption Map The Wagner Companies https://wagnercompanies.com/i-codes-code-adoption-map/
5. Expected Earthquake performance of building designed to the California building code State of California Seismic Safety Commission.  https://peer.berkeley.edu/sites/default/files/peer2019-05_ssc19-01.pdf
6. Ingargiola, J. & Sheldon, A.e & Ghorbi, L. (2015, November). Building Code Changes Resulting from FEMA’s Hurricane Sandy Mitigation Assessment Team Report. 380-386. 10.1061/9780784479711.037.
7. (2021, June 1) Inconsistent Building Codes leave some states vulnerable to hurricane damage Insurance Institute for Business & Home Safety (IBHS) https://ibhs.org/ibhs-news-releases/inconsistent-building-codes-leave-some-states-vulnerable/ 
8. Hurricane Resistant Requirement Graham Architectural Products https://www.grahamwindows.com/architectural-resources/hurricane-resistance/
9. Basic Facts about Mold and Dampness Centers for Disease Control and Prevention https://www.cdc.gov/mold/faqs.htm
10. Mold Health Risks State of Rhode Island Department of Health https://health.ri.gov/healthrisks/mold/
11. (2017, January 30) Energy efficient homes are becoming more important for tenants HomeLethttps://homelet.co.uk/landlord-insurance/landlord-lowdown-blog/article/energy-efficient-homes-are-becoming-more-important
12. Seppänen O., Kurnitski J. (2009 March)  Moisture control and ventilation – WHO Guidelines for Indoor Air Quality: Dampness and Mould. Geneva: World Health Organization. https://www.ncbi.nlm.nih.gov/books/NBK143947/
13. Martinez, S., Jardon, A., Navarro, J.M. and Gonzalez, M. (2008, April 18) Building industrialization: robotized assembly of modular products  Assembly Automation,  Vol. 28 No. 2, pp. 134-142. https://doi.org/10.1108/01445150810863716 
14. Misron, N. & Khoiry, M. A. & Hamzah, N. (2018). A Framework of Efficient Material Storage Management on Congested Construction Site. E3S Web of Conferences. 65. 03005. 10.1051/e3sconf/20186503005. https://www.researchgate.net/publication/329185666_A_Framework_of_Efficient_Material_Storage_Management_on_Congested_Construction_Site