Very helpful thanks so much!!

You really ought to get the input of a local, see if the house could be hooked up to the sewer, etc. You didn't mention if the house is newer or on a slab or where the ADU comes into play. Some areas base septic requirements on bedrooms, not bathrooms.

Well there are limits to septic systems so some info for you as to what that might be. Any other items we nned picturees . Ranch style with or withut a basement or crawl space . IMO an ADU with no bathroom is just a shed for guests. I need a lot more info and so do you.

My area does not allow for a AUD with plumbing for we are single family home hood so detatched additions or basements cannot add kitchens or baths legally. Make sure you are zoned to allow for a bath pre purchase.

The zoning and septic will be your biggest problems. Have a chat with the building department and whatever entity controls septics. Additional problems could arise if you're in a watershed or near the property line. This would have to be a very expensive area to make the investment worth it.

Where in Austin are you? We're in the city of West Lake Hills and just went through the septic stuff -- I can't find the documents now but I'm almost positive our limit is based on number of bedrooms. I think messing with the septic would cause the most grief to you, so I'd check on that before buying if the extra bathroom is a deal breaker. And if you're on a slab, moving stuff around is expensive. It could be worth it though if it's in your ideal location!

@stiley This is the 78736 neighborhood... West Oak Hill off Thomas Springs Road. I contacted one of the septic servicing companies and they're pulling the info for me. Apparently it's based on sq footage + size of the tank. Will update the group. Stay tuned! :)

@5112bird love that area -- it's so pretty! I know COA rules are a lot different than WLH so I'm not any help. But good luck and I'll be following along.

Thanks Mark! Yes we are coming in way below value by about $100 K. I called the county and learned that the septic was installed in 1995, so it will be end of life. Although this is a major overhaul, the location, layout, land, size, neighborhood etc is what we have been wanting for years. So looking at this as long term goal to add in the next 5 years. But, if it is never possible that’s a deal breaker for me

On the market for 55 days in Austin sounds like a huge red flag, even if the listing is over priced. If the offer is accpeted contingent on inspection, I would make sure you get highly skilled trades people in to look at the property and give you their estimate for the work. Dont only go by what your home inspector says.

We paid a structural engineer to look at a home we put an offer on. It was some of the best money ever spent. Based on his report we backed out.

Go to city hall and get copies of all the permits on the property. It will be interesting to see what was done with and without a permit.

I always get the permits pulled for any house I work on. So much work is done with no permit it is scary. I have a piece of property my grandkids live in we lived there for 14 yrs we left in 1987 the septic tank is still just fine it gets pumped regualrily and inspected every 5 yrs no issues BTW the tank is concrete

Based on the location of the property my guess is the only permits needed may be a septic permit. Possibly an electrical permit, but maybe they have added additional permits since I lived in the area about 15 years ago. At least I hope they have, but depending on when things were done it is very likely it may not have needed a permit.

As for adding a bathroom - it may be cheaper to just add on to the structure to add a bathroom than trying to add one inside the existing structure as long as it is on the same side as the septic tank. Meaning it would be easier to tie it in to the septic tank if on the same side and adding on means not cutting into existing foundation besides tying into the foundation at the spot where you add on.

Although 1995 may seem like the septic is at the end of it's life it may not be if it has been carefully used (ie just normal use and adhering to septic use guideline) and pumped and no driving on the septic field. My old house was built in the 1970's and had the original septic still when I sold it in 2007 and it had no issues for the 8 years I lived there.

As noted above, the added building cannot be an Accessory Dwelling Unit (ADU) because it has no plumbing (requirement of any dwelling). So be sure that building was constructed to habitable standards.

A septic built in 1995 shouldn't be anywhere near the end of it's life if it was properly maintained and people didn't through stuff in toilets and sinks they shouldn't.

My house (4 BR, 2 1/2 BA) was built in 1979 and the septic system was still in great shape when I sold in 2020. The buyers did a thorough and very intrusive inspection!

Make sure there is not a sewer line nearby. The city may require you to abandon the septic system and hook on to the sewer line if one in near. This is a major expense, but still may be worth it. If a neighbor ran the line in for their home build, the city may reqire you to partially reimburse them for the cost of running the line and tapping into it. Or the city may say that your septic tank is not adequate to add a bathroom and will have to be replaced or a new one added. If this is the property for you, these things may not matter, but it’s good to know going into the purchase. My house had septic since 1958. No issues with it and it worked great. I added an addition to the house. Before starting, I abandoned the septic system as I knew the city would require me to and I tapped into the city sewer (different state than you). Septic system redo’s and abadonment require permits from both the county and city in my state.