I have a 1930's DC brick rowhouse and will soon be adding onto it. It is necessary for me to ascertain the depth of my existing footer/foundation. Seems obvious to me that I should dig next to the foundation of the house until I reach the bottom.

Is this this right way to go? Are there any risks? I would assume I'd like to fill the hole ASAP, do I need to do anything special? Any suggestions, tips, warning would be much appreciated.

Also, any thoughts as to what I will find? What sort of footer/foundation was typically employed? Current min/req foundation depth is 30", is the current depth likely more or less than that? Thoughts? Wagers?

Contacting the code enforcement office would be most prudent.
You wouldn't like to dig up the job again if they haven't approved the work,would you?Yes,they can make you open it back up.

You'll have to contact 'Julie', or whatever the 'Call before you dig' outfit is in your area,get the proper permits and do this by the books.

1930's construction could have been a sandstone base 24 inches down and no further foundation below.. until exposed,you won't know.

KBC-

Thanks. I would just like to get a feel for the depth to help me getter better estimates from the foundation sub, so this will be before I get permits.

Knowing the building code for your area will assist you on talks with the subs too.

Actually, you might get a good lead from the code enforcer, if they visit in person, they know who they like to work with,who cut's corners,etc.

And remember,a permit is good for a long time,not just a few weeks.

Does your townhouse have a basement or a crawlspace?

If so, and if the floor of either is more than 30" below grade, you don't have to dig at all.

You already have your answer: The footings are below frost level for your area.

We have a basement, but it is a walkout at the back where the addition will be, so it doesn't help that much, but great idea!

You could drive an iron rod or pipe along side of the wall to feel the footer. Shouldn't be more than 24-30" down. That is if you don't have many rock in you soil. Have to do in in a couple of places to make sure you have not hit a rock. Surest way is to dig the hole. Best done with a set of post hole diggers. Should take about 30 minutes to dig and fill.

Excellent. That is really what I wanted to hear Harold. I don't mind a little digging, just didn't want to hurt anything.

Thanks!