ADU vs room addition for SFH in the CA Bay Area

[Nhi Nguyen]

I have a couple of SFHs in Hayward, right around 1200-1500 sqft (3/2), single story, dated.

Options are:

1) convert the existing room addition (and add some more) to turn it into an ADU in the back (~550 sqft for 1/1)

2) keep the existing room addition but convert the garage into ADU (350 sqft of 1/1)

3) remodel the existing addition as a forth bed room & 3rd bathroom

Rent for a 3/2 of ~1200 sqft around this neighborhood is ranging from $2800-$3200 depending on quality and layout, with the garage. I think 4/3 is about $3500-$3600.

Rent for 1/1 is about $1500-$1800.

I know the ADU will bring in more $ in total.

Concerns I have are regarding to the complexity of multiple tenants within the SFH zone: will there be problems with parking, disputes, noise (because of shared wall), sharing yard, etc.

Other concern is about the resale value. I’ve built multiple ADUs for my clients. But I’ve never sold one for myself. Would the $/sqft be the same as if it’s just part of the house?

Any other insights about this are appreciated.