I know of no such mandate in California but there could be peculiar things to your situation or there could be local code requirements. My best advice is to keep digging and pushing to get to the root of things. Also, there are metal system kits made specifically for re-roofing mobile homes. One of those might be more cost effective.
Help! Live in double wide and need new roof. Inspector told roofers they need to do metal roof. Roofer tells me its 40k and labor intensive opposed to shingle roof. Roof has slight pitch. Roofer wants to continue with shingle replacement but i dont want to have code violation and/penalties. Is it mandatory in california to put metal roof?
Yes metal roof is good for house
If it’s time to install a new roof, the variety of options available can floor you. Asphalt shingles have long been known for their reliability, cost-effectiveness, and ease of maintenance, making them the most popular roofing material on the market today. But now there’s a variety of options that deserve consideration especially metal, the second most popular roofing material thanks to its durability, longevity.
Shingle roofs are cheaper upfront,
generally are easier to install and repair.
Metal roofs tend to be more durable and eco-friendly.
If it’s time to install a new roof, the variety of options available can floor you. Asphalt shingles have long been known for their reliability, cost-effectiveness, and ease of maintenance, making them the most popular roofing material on the market today. But now there’s a variety of options that deserve consideration—especially metal, the second most popular roofing material thanks to its durability, longevity.
Shingle roofs are cheaper upfront,
generally are easier to install and repair.
Metal roofs tend to be more durable and eco-friendly.
Asphalt shingle is a popular choice indeed. In my humble opinion, they're easier to be fixed compared to metal roof. Metal roof usually come in a huge sheet. So you have to take the whole thing off to fix the leak if patching fails. On the other hand, shingles are in small pieces. So, it can be repaired easily by identifying the damaged piece.
However, this all goes down to the inspection. If the frame underneath the roof tiles has rotten and may not be able to sustain the weight of the roof some time soon, then roof replacement is probably another option to consider.
As for choosing metal roof, it does have good and bad side to it. It is light and durable. Some say it can last as long as the house.
Here's some metal roof disadvantages that you should know about as well:
Hope these opinions help!