in Antics

Premature deck announcement (aka – SINKHOLIO)

So … we’re going to put a new deck on our house. I originally planned a big announcement (which really just means a long blog post with lots of capital letters), but I’ve come to realize if I try to plan something to completion, I will spend the rest of my life in the planning phase. It’s best to just start whatever needs starting and figure it out as I go. SO HERE WE ARE.

I mentioned the deck plan a couple months ago, and since then, I’ve done quite a bit of research and talked to a handful of professionals. My original plan was to have a contractor do the entire project. It’s going to be a very large job and as I tried to wrap my brain around it, I convinced myself that it would be worth a couple (THOUSAND) extra dollars to just have the pros come in and knock it out.

After having no less than three contractors take a look at the project and give me high level estimates, I realized that I had underestimated the market by about two-thirds. We could have purchased a nice automobile for the money this was going to cost. The options we were left with were A) pretend we live in a high-rise condo with no deck or yard, or B) build the damn thing ourselves. I found as I socialized the project that my friends and family tended to agree with whatever my plan was.

“We’re going to build a new deck.”

“Awesome! Deckbuilding is fun. I will help.”

“Actually, I think I’m going to have professionals do it. It’s a huge job.”

“You should totally have professionals do it! Your time is worth too much to spend all your weekends building a deck.”

“I talked to some professionals, and I think I’m going to do the whole job myself.”

“You should totally do it yourself. Deckbuilding is fun. I will help.”

I’ve been reading books (including this one put out by the Forest Products Society — highly recommended), talking to people, and creeping around friends’ houses looking at the underlying support structure(s) of their various outdoor leisure areas. Mostly, I’ve been preparing myself mentally for the project, which will doubtlessly gobble vastly more time and resources than I have ever invested in a home improvement project to date. It’s going to be a huge job. Like, retarded huge.

And we’ve already hit our first significant speed bump!

Two weekends ago, I was in the back yard outlining the proposed new deck with string to help visualize the project. As I was anchoring a pole where one of the new deck posts would be located, my foot sank into the ground. And it wasn’t like sinking into soft dirt or mud. It was like the top 2 inches of clay gave way and a hole about a foot deep opened up underneath me.

Oh. Great. A sinkhole. Right there. Where the deck … of course. Where else would a sinkhole … SENSATIONAL!!

I grabbed a shovel and quickly unearthed a problem area. A hole like this should take more than 10 minutes to dig:

After the existential freakout subsided, I contacted several of my landscape architect friends (Note to self: Why the hell do I know so many landscape architects?) Their initial diagnoses were identical: It’s an old construction bury pit and I would need to “over-excavate” the area and re-pack the dirt. So that’s what I did last Sunday. I wish there was a more entertaining story to tell, but I don’t know what to say about me digging a hole and then filling it right back up. Living the dream, indeed.

Photo set of me moving thousands of pounds of dirt with a spade shovel.

  1. We want to build a deck, too. Thanks for being our trial balloon. Would love to hear more about how it’s going!

  2. Heh. Yeah, old fill is a pretty common problem. In your photos it looks like you got most of the bad stuff out. You may want to get a mini-excavator to dig the rest out. Since you are going to want to get your pad footings down at least 18 inches (or whatever your local code defines as the frost level)you may be able to form up your footing in that area at the base of your excavation (provided that the native soil is firm enough). If your hole is deeper than 18 inches, instead of using extra concrete for your footing, backfill the hole with structural fill. That could either be the native soil or imported material (i.e. 3/4″ aggregate). You will want to compact that material with a “jumping jack” or similar mechanical equipment in lifts about six inches thick. A local geotechnical engineer could work with you to provide detailed construction recommendations. Building code may dictate that you need a structural engineer. Maybe your architect friends know someone. Otherwise, dig holes to hard ground, pour in lots of concrete, anchor posts to said concrete. Critical parts…firm soil below frost level. Give me a shout if you have more questions and I’ll try to point you in the right direction.

  3. Jesus- I was going to make a suggestion before I read mike D’s post. I’m going to go stare into a television and feel stupid for a bit. Except to say- “sucks for you”.

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