There are suppliers in China who can supply pre-cut SIPs and they say they can source other exterior and interior finishes (except electricals and plumbing) from other suppliers and ship it.

I was concerned because the tenant has roofing supplies all over the back yard in addition to a trailer and roofing machine in the street. 

You can ask the Sub's, or whoever you are going to do the work, which materials they need and price them out at other supply houses.

Plus the resources Africa supplies.  

I have done wholesaling in the past (not in RE, but in reverse supply chain liquidation), and had to deal with a lot of unethical and dishonest sellers.

At the time I didn't really understand why, since you had to pass the income and credit checks regardless and there were only 2 companies that owned all the upscale places so not a huge supply.       

But I don’t even play a lawyer on TV or the internet. 

Lot of new-co that gets grabbed by investors which adds supply.

In terms of new construction, a couple things to be aware of in San Luis Obispo County are water shortage issues and development fees/taxes which can significantly increase the building costs.SLO city and the neighboring cities are particularly diligent on their water usage, as most of the county's water supply comes from three surface water reservoirs and a groundwater basin.

It seems that good, decent, qualified tenants have the pick of the litter, often flaky and uncommitted when there is so much supply out there.