We have a few from overseas that have a tax requirement of showing material costs on larger items (furnace, hot water tank, windows, roof etc) so we send them material receipts.  

If you are considering an prefab ADU, take a look at the prefab options with Back Porch Homes, they are prefab stick built homes and all materials used can be replaced/repaired with products you can find at your favorite hardware store instead of specialty stores like more manufactured homes.

You arent taking into consideration rising lumber and materials costs , contractors are busy and wont get to your job for a month or two .

I can come back in person for only a few weeks out of the year (gotta stay tax exempt), so basically one big trip home each year or so.I've got some good reading material for tonight, and hopefully I can find a few hours of stable connection tomorrow as well. 

I do not possess the creativity when it comes to home design to decide how I want the kitchen or bathroom to look and what materials I want to use.

And on top of it, it isn't easily scalable I wouldn't think.Glad it works for you and that you have been able to promote your business with this post.Ultimately, the killer (pun intended) for this type of structure is landlord liability.

This is such a great resource for assisting each other and to promote growth and learning (especially for the new folks like myself!)

The doors are about $1,500 and $125 labor and materials per door.

@Nancy Roth,with granite you care about this:-material cost-installer cost-solid cabinets under (also leveled!!!)

Luckily, we operate our own management company and have been compiling an extensive packet of materials to share with investors.