Attached Garage ADU vs Deattatched ADU (Both 1bd1br)

[Gabriel Garcia]

I have a 1,360 sqft home in Hayward, CA on a 6,100 sqft lot. The 2 garage  measures 17'x20'. The garage shares a wall with the second living room.

Here is a picture so you can get an idea of the lot + house sizes: https://imgur.com/a/chPO0k5

Initially, I had decided to convert the garage and second livingroom into a small (530sqft ish) 1br1bd to rent out. I am doing everything myself with the help of family that work in constructions. Estimated costs are about 20-30k (if anyone knows someone that can help me out with title 24, please let me know!)

However, someone on this forum recommended to look into making it a dettatched ADU, as I would not lose square footage in the main house (with conversion, main home would be 870 sqft) and would bring up the value of the property if I ever look to sell the house or get a HELOC for future. For this, I would not be able to do the work myself so I asked my brother-in-law (who builds homes under a contractor) and he said he can probably do it for 120k-140k. WIll look around for quotes on this as well to confirm prices.

What do you guys think? Is the added cost of doing a detattched ADU in the backyard worth it? Or should I continue with the original plan to convert the garage?

Thank you!