Prefab vs Modular ADUs: Everything You Need To Know
Did you know that a modular ADU is often easier to get approved by your local governments than a prefab ADU? When it comes to needing more space for you or your family, we think understanding the differences between the two ADU types is essential. In this blog, we will share all the secrets of prefab vs. modular ADUs so you can make the best decision for your needs. So let’s get into it.
What Is The Difference Between Modular ADUs and Prefab ADUs?
The biggest difference between a modular ADU and a Prefab ADU is the way that they are constructed. A Modular ADU is built offsite in a controlled environment and shipped to your prepared site in sections. Upon the arrival of your modular ADU, the building will be finished with any remaining features. Once the ADU has been completed, connected to utilities, and has had its final on-site walk-through for occupancy approval, you can enjoy the space. Having an ADU installed can be a lengthy process. However, most municipal governments are more accepting of modular ADUs.
Prefab ADUs are created completely off-site and delivered to you. They are move-in ready once they have been connected to utilities. Often, prefab ADUs are like our Park Model homes or Tiny Homes. While these buildings provide great comfort and convenience, gaining clearance from your local government to place a prefab ADU on your property can be more challenging. Our prefab ADUs, as well as many other tiny homes, are built to RVIA standards. However, many governments still need to navigate how to incorporate prefab ADUS into their municipal zoning code. To learn more about zoning for your Prefab ADU, head over to our articles page; here, you can find a wealth of knowledge for these guidelines by state.
Are Prefab and Modular ADUS Built the Same Way?
No, Prefab and Modular ADUs are built the same way. Modular ADUS are built off-site and fully assembled on-site. Examples of certified Modular ADUs include our A-frame ADU, Rockwood ADU, and Sonoma ADU.
Prefab, or park model ADUs, are built offsite before arriving at your location. Here at Zook Cabins, we have park models in log cabin and modern styles. Check out the Alpine or Pinecrest Park models to see which you like best.
The only way that Prefab and modular ADUs are the same is that they can be used as Accessory Dwelling Units where zoning permits. Check out our blog titled “Top 7 ADU-friendly States” and see if your state has zoning that easily accommodates ADUs.
Can Prefab ADUs Be Built To Residential Codes?
Yes. However, this is relatively uncommon. Prefab ADUs are designed like tiny houses or park-model RVs, which do not meet residential codes. However, all of our park models meet the RVIA standards, allowing them to be classified as an RV.
Are Modular ADUs Built To Residential Code?
Yes. Whether you choose the A-frame, Rockwood, or Sonoma ADU, your modular ADU will be built to residential standards. A modular home is required to meet the same level of inspections as a traditional stick-built home. Ultimately, this means that a modular ADU is no different than a house built on-site.
Is a Prefab ADU More Affordable Than A Modular ADU?
Generally speaking, a prefab ADU will be more cost-effective than a modular ADU. This is because prefab ADUs are usually smaller in square footage than modular ADUs. With smaller square footage, overall construction costs will be lower, and the price will be lower.
Yet a modest modular ADU that does not have high-end finishes could be less expensive than a prefab ADU that capitalizes on luxury features.
Do Prefab ADUs and Modular ADUs Need The Same Kind Of Foundation?
No. Prefab ADUs and Modular ADUs need different kinds of foundations. Prefab ADUs should be placed on a cement pad or gravel foundation, similar to a shed foundation. On the other hand, Modular ADUS needs either a crawl space or a basement foundation to support the weight of the structure.
It is possible that a Prefab ADU could be placed on a foundation. However, all of this depends on what kind of trailer your prefab ADU has been built on.
Are Prefab ADUs or Modular ADUs Faster To Set Up?
Prefab ADUs are faster to set up as they can be “rolled in” and placed at your prepared location. Typically, all prefab ADUs need is a gravel or cement pad to park the unit. Upon its arrival, connect the water, sewer, and electrical system to the park model prefab ADU, and you will be ready to start enjoying your space.
Modular ADUs are built like homes, so they will need to pass final inspection once they have been delivered and finished. This process can take a few weeks. However, most municipalities are willing to accept modular ADUS faster than prefab homes.
Depending on your municipal guidelines, your prefab ADU may be subject to the same scrutiny as a modular ADU. As always, we recommend checking your local guidelines to see what you will be required before occupying the ADU.
Are Prefab ADUs and Modular ADUs Certified?
Yes, both prefab and modular ADUS are certified.
Prefab ADUs often fall under RVIA certifications, which qualify them to be registered as RVs. Modular ADUs are certified single-wide modular homes and thus submit to different requirements than an RV. Nonetheless, each model will leave Zook Cabins with appropriate certification, promising additional peace of mind.
Do Prefab Or Modular ADUs Last Longer?
Modular ADUs have a track record of lasting just as long as traditional stick-built houses. This is because modular ADUs are built to meet the same requirements, if not more, than stick-built homes.
Prefab ADUs do not yet have a predictable life span. This is for two reasons. First, prefab ADUs, like our park models, are new to the housing market. In the past, the only space that park models “fit into” were RVs. which have a life span of 10-30 years. Second, Park model homes tend to be built from better materials than RVs; as of now, tiny homes are estimated to last 30-50 years.
Overall, Modular ADUs have a longer track record than Prefab ADUs, so time will tell which one will outlast the other.
Conclusion:
Whether you choose a prefab or modular ADU, you can create a lifetime of memories. Right now, it seems like modular ADUs are easier to receive approval from your local government and will offer you the best value for your money. However, if you are looking for a more affordable option and your municipality is easy to work with, a prefab ADU may be the best solution for you. No matter what you decide, we are here to help you every step of the way.