[Empact]

Definitely appreciate that many will benefit from farming it out, so I think this company substantially expands the addressable market, but in support of DIY (as someone who was raised in the house my father built), building your own such modest project is very achievable, particularly if you farm out electrical and plumbing concerns. With respect to managing contractors, my understanding is that roughly daily supervision will do, which can be manageable even with full-time employment. You may have better ways of spending your time, but let's not use that as a basis for overly-narrowing our own concerns and capabilities.

[quickthrower2]

Why do you have to supervise the work of the trades but not this startup? Why are they more trustworthy? If they are ... then you can probably get someone else who is trustworthy to do the job for straight money rather than owning part of your house.

If this startup did what they did but just arranged finance as a broker and acted as a letting agent I think it’d be a better deal. The issue I have is the splitting ownership and income. I don’t think that’s in anyone’s interest.

[Empact]

In one case you’re hiring the work yourself, in the other case you’re bringing on a partner who is sharing in the rewards. In the latter case the incentives are better aligned.

“Not to oversee workmen is to leave them your purse open.” — Poor Richard’s Almanac

[Balgair]

I've personally built a few of these granny units in the East Bay over a few summers. It is very DIY-able, but it is faaaaar from simple to do yourself. If you go the contrator route, you had better know the crew personally as supervision is not turn-key.

One example: The concrete pad.

You must know the size of the pad. Then, you have to take soil mesurements for moisture and compaction. If you do not do this, your pad WILL crack as the center's moisture and it's volume changes relative to the soil outside the garder. This is especially a concern in South Bay clay and loam soils. There are many many Levitt-town style houses that are experiencing pad issues. These issues cause the building to shift. Doors will not close, gaps appear in walls, etc. This can happen within 5 years of the pour. Rebar must be tied off at each interesction, otherwise the pad will shift even more so. The garder on the pad must be 24 inches deep. Depending on the size of the building and the load on the pad (which is estimated beforehand) you have to tie the building into the garder with steel hooks (min 0.5' diameter, at least 12' into the pad) due to earthquakes. Concrete's drying period is dependant on a lot of factors, but weather is a big one. Before further construction occurs, the drying must be completed correctly. Actually getting the equipment, tools, and personel to the site is another headache too.

Ok, got that very slimmed down list off the top of my head? Those are just some of the issues with the pad. Multiply that throughout the entire build and there are a lot of little problems to solve and they have very big effects in 5 years time.

So, if you decide to trust your contractor, you had better really trust your contractor. These issues are not simple and there are a LOT of corners that can be skimped on without you knowing.