Digging the Footers

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Our frost line in this part of Tennessee is 6". I've heard from a few local builders that the frost line is actually only 3" - it's doubled to be safe and prepare for an extreme scenario.

However, with piers, all the weight of the building is on these specific points, instead of distributed evenly throughout a perimeter foundation. So I'm more concerned with subsidence than heave. I want to make sure the ground where I put the pier can handle the weight. I guess even if a pier began to fail at some point, I could jack up the building there and put in new piers - but that would be a big undertaking. I might as well get it right the first time.

So I dug down to hardpan. Our soil is very clayey here, and hardpan is where the clay and sand is almost as hard as rock (about like shale). It's where, even if I come down with the full force of a mattock, I only penetrate the ground about an inch.

My footers are square, 16"x16", and I hit hardpan at about 28" in depth. 26" in some places, 30" in others. Regardless of frostline, I just don't see how you could ever set a foundation on anything other than hardpan or bedrock - the ground cannot give, it must be severely compressed.

Here's a hole:


I first cut out the sod with a shovel, then began digging with a pick/mattock. Once the hole got too deep to use a pick, I jumped on the shovel. After I could no longer get the shovel out, without disturbing the walls of the hole, I went to a posthole digger. It was only after I'd drive down hard with the posthole digger, get almost no dirt, and the digger made a clunk as it struck the hardpan, that I stopped digging. I then tamped the bottom of the hole with a tamper, and put in a bucket of gravel, which was also tamped. I put in gravel up to the right height for my pier, as my piers were in increments of 8". A solid footer was 16" in depth, and block above comes in heights of 8".

Here's one hole that had the edge of a boulder protruding into it, which I could not remove. So I'll pour the footer around it:


Here's a couple shots of the building site, as I dug the 12 footers, and mounded up the excavated soil beside them:



Here I'm measuring to get the correct height for my gravel base - the gravel gives additional support for the pier, and aids in drainage - it's 1/2" limestone:


Sometimes to get it just right I had to swish the gravel around and remove some, then tamp it again. I used a torpedo level to get the surface flat:


Remember the concrete parking slab and my ideas about breaking it up and using it as urbanite in the foundation? Right. This slab was 2" to 3" thick and sitting on a deep gravel base which it'd adhered to. It wasn't going anywhere without a jackhammer.

See, I was thinking of my patio I'd built last spring, and how easily I'd broken up the little slab outside the doorway - and it is easy, if you can lift and prop up one edge of the slab . . . then with one or two strokes it caves in and breaks like crackers. But if you can't lift it, then you're fighting against concrete's greatest strength - compression. I hit it with a sledgehammer hour after hour, dug pieces out, scored a grid of lines with the diamond blade on my circular saw - just one hole took half a day. A truly brutal workout, but eventually I hit dirt:


I guess I could have just built the pier up on top of the slab, but I was being cautious. From the surface, the slab didn't look very structurally sound. I thought it was important to cut through it.

Once I got through the slab, I then went on and dug down to hardpan and put in my layer of gravel:


Here's a shot of all 12 holes dug:


Another shot, from a different angle:


It's been a very wet spring, compared to the year before. Again and again we get torrential rain. All my footers on the east side get filled up with water:


The water sits in the hole for an entire day before it drains away. I'm concerned about this, but what do I expect, the bottom is hardpan, the walls hardened clay? The gravel will aid in drainage, and ultimately I think I'll put a trench drain around the uphill part of the site. Soon the hole of course will be filled with concrete.

Where our creek was basically dry with a few small pools and the spring last year, look at it this year:


It's a small river. And it's even running over grass and creating a marsh in our little valley with the giant maple:


And as far as our maple, look what the wind did:


I can't believe this tree toppled. It was a huge old-growth red maple. I took this photo last year with the kids in front of it:


My neighbors said we had a lot of fierce winds last winter, and many trees fell.

I found an old rusted oil drum while checking out the valley and all the downed trees:


I brought it up to the edge of our blueberry grove, and set it under an oak. I'll use it later for a rocket mass heater:


Here's our humanure compost bin. The compost from last year is on the left, and will not be added to so that it can cure for a year. We've started filling the chamber on the right. The center is for cover material - right now straw from Lowe's:

Here's a shot looking over the garden. The cabin is going in behind it, from this angle, to the left of the power pole - you can't really see the sitework from here:

Here's where we're living, as we build:

The gazebo with its tarp exterior is wonderfully comfortable - very close to indoors, but not too close. No wind, no rain, warm, few bugs. The tents are used for storage.

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With all the footer holes dug, I began mixing concrete in a wheelbarrow and pouring the footers. I've got both sand and gravel left over from last year. So all I need to purchase is Portland cement.

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In each hole I put a chair for suspending rebar [Hercules chair, $0.50 each], 1/2" rod in an X on the horizontal plane, suspended an inch or two from the bottom. Then 2 vertical rods buried in the gravel, tied to the horizontal ones with wire, and they will terminate an inch or two from the top of the piers. Another X of rebar laid horizontally will go near the top of the pier, and be tied with wire to the vertical rods, so it's all connected. I did a lot of research on the structure of concrete piers to arrive at this method.

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Here are some photos.

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A few of the piers top out so close to grade that there's no need to build up with block. So the footer itself is the pier, with the very top portion poured within a form of 2x4's, and two concrete anchor bolts put in. For these particular piers (4 of them), I only needed one vertical rod, as I'm not going up through the voids in concrete block.

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Here's a shot of the preliminary chair and rod setup:

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Next is setting up the wooden form, which I made from scrap roughsawn 2x4's and screws. It took some time to get it perfectly level - I had to gouge out a little on the high side of the hole, and build up a little with gravel and clay on the low side to seal the bottom of the form, so concrete wouldn't be oozing out:

I then braced it with concrete blocks, to hold it in position, before I filled with concrete:

Once I got a few inches within the top of the pier with concrete, I put in the upper X of 1/2" rebar, and tied it with wire to the vertical rod:

On top of this went the last of the concrete, which was smoothed across the form with a trowel. I put in the concrete anchor bolts in a diagonal position, to best hold my large 2x12 treated sill plate:

A closer shot, trowled smooth:

Where the piers need built up substantially above grade I went up with stacked concrete block, a minimum of four, stacked overlapping . . . and poured conventional below-grade footers for their foundations. In these footers I used two long vertical lengths of rebar so that I could penetrate and go up through the voids in the concrete block, which would later be filled with concrete.

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What was nice about these footers is that there was no need for formwork - the earth itself served as the form. Our clayey soil exposed to the sun for a few days basically turns to rock - so it made great walls for the holes, and I needed no tube formwork:

As far as getting the surface of the footer level, the concrete, as long as it's not too dry, basically self-levels (when too wet water will form on the surface). I used my torpedo level and smoothed around where I needed to, but all in all it was a breeze next to creating formwork. The surface of the footer can be a little rough and uneven as an inch of mortar goes on next and serves as the bed for the block.

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Here are shots of the footers:

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I laid cardboard over the footers the first few days to keep them moist so they would cure right and not crack in the sun. For the most part they stay well hydrated deep in the earth - so they don't need watering.

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In the lower of the two photos you can see one of the sill plates, drilled out and ready to go. This large 2x12 treated plate will give me plenty of room to position my girders exactly as I go up with the framing.

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Here's a last shot of the building site at evening:

Site Work

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The first step in any building project is of course the site work. I've picked the old parking slab beside the power pole as the site for our cabin for a number of reasons:

- It's centrally located and close to power.
- It's high and dry and gets blasted with sun throughout most of the day (no wood rot, good indoor air quality, passive solar orientation).
- It will be visible from the road and establish some presence here, at the same time shielding us from the road.
- There will be a wonderful view out the back of the cabin of the garden and barn and surrounding hillside.
- The parking slab is not usable structurally (it's thin and cracked and not level), but will shed water quickly and keep humidity down, thereby keeping the underneath of the cabin dry if we decide to go with a raised framed floor.
- But most of all it just feels like the right place to build.

But once the general location's decided, the real work begins. The exact position of the building needs laid out precisely. For this I use batterboards and line. I have a spool of masonry line, and for the boards, I'm going to use scraps from the wood pile. Here's a shot of them:

A book I have on building barns and outbuildings recommends using 2x4's for stakes to pound in to the ground to support the horizontal crossmember. I don't know what kind of soil they've got, but there was no way I was pounding an old 2x4 deep into the ground, even with cutting a point on the end and using my 2lb sledge. The boards split to pieces. I found a slim 1x2 stake works best. And if the stake isn't totally rigid once you've pounded it down, pound in another stake diagonally and screw it to it for a brace. It's important the batterboard never moves or it could throw off a line.

Here's a shot of Rachael and I methodically working away. She was critical for a lot of the measurements and checking level:

I positioned the cabin half in front of the garden, and half in front of the lawn. I put in batterboards at one corner, with the crossmembers level to each other. I then pounded in a stake at a distant corner, and ran a line to it so I could mark where the crossmember should go, level to the rest. I had to use a line level on the line to check level - not as accurate as I'd like, but my laser level was useless. Though the laser came on, it wasn't bright enough to put a red dot on where I pointed it - I tried changing the batteries, but it made no difference. Another high-tech piece of junk.

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Here's another shot of us measuring and working [Brooke's taking the photos], trying to get the layout perfectly square - something so incredibly frustrating I considered abandoning the whole project at one point and going back to work on the barn:

I felt like, with the barn, I already had a graded site, a stone foundation in, and the bulk of the structural framing done - why start over again from scratch? But I was nervous the barn was such a colossal project and would suck up so much time and money that I might not get it finished. I wanted something small to see through, from foundation to moving in, even if it's just a shell. So I kept plugging away at the cabin. I knew if I could get through the layout, the rest of the foundation would be mere gruntwork.

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Once I got the lines right and found square, I pounded a nail in to each crossmember where the line crossed it and wrapped the line around it. This would hold it in position.

Here's a shot of the southeast corner:

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Here's a shot of the site from further back:

With all the lines in, we dropped plumb bobs at the intersections to mark where the corner piers should go. We then measured down the lines and marked where additional piers would go - every 6 feet along the long axis of the building, every 8 feet at the short, with 12 in all. We dropped plumb bobs from these marks for the rest of the pier locations.

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Here's a pic of the finished site work, the lines level and square, the center points of the piers marked with tent stakes:

With the site work over, and stress, Rachael moved on to building a doll village for all her Barbies:

She's on the fort her and Brooke had started building last year. While Rachael hammers away at doll building (she's using lumber cutoffs I'd stored in the shed for firewood), Brooke takes clay from the barn and sculpts furniture.

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The girls have planted seeds in our pots and we put them in the sun for germination:

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They're going to be the chief gardeners this year, while I work on building.

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Return to Tennessee

. We packed up and left Atlanta for Tennessee on April 8th. We weren't bringing seedlings this time so we had a little more room in the car. Gardening is not going to be as much of a focus as getting a cabin built. We put our furniture in storage.

Here's the property as soon as we pulled up and parked in front of the pumphouse:

The barn is still in good shape, even after a long wet winter. Sealing the boards must have helped. Their color has faded, but there's no sign of rot.

Our old block fireplace made from debris from the fire hasn't changed. I need to take down the ramshackle board wall I put up to keep the wind from destroying our screened-in tent:

Remember the flycatcher that nested in our pumphouse . . . where I got totally fed up with her eggs' inability to hatch and her constant in and out so we had no place to rest, and when I went to move her eggs I found 5 little chicks? Well, she's nested in the pumphouse again (she gets in through the eaves - the door was shut and locked). But this time she's built a new nest at the back of one of the shelves. And she's already got one egg:

She's not going anywhere.

Here's a shot of the garden, with our old tomato stakes:

Our creek is full of more water than we've ever seen it before, which is exciting. So we will have a guaranteed water source at least half the year, besides our well:

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Here's a shot looking down from the gazebo over the property . . . no leaves on the trees, the sight rather empty:

The roof of the gazebo is basically destroyed. It looks like the weight of snow has ripped the canvas. We'll have to rebuild the roof with metal conduit and create some sort of custom-yurt covering that will shed water better:

But the pad we'd built for the gazebo is still in perfect condition. This is where I'd stayed all last year while the kids slept in the truck. It was comfortable except for the giant hornets.

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Since the gazebo's out, we first move into the pumphouse:

It's pretty cramped for the three of us, but we've got a space heater, and at night we stuff all the cracks in the door with sheets, so we stay quite warm.

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Our first project is to move the gazebo down to the barn to create some sort of livable dwelling while we build the cabin. I place a board between two corner sections and carry that, while the girls each carry one corner. We walk it this way down the hill to the barn.

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But unfortunately it won't fit through the big barn opening because it's too tall. I foolishly try to turn it on its side to bring it in, but it's too heavy and one of the metal crossbars bends. It doesn't break though, so it's not the end of the world. The only thing to do is to remove the roof to get it in, which takes a while.

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We put the gazebo in the center of the barn to use the posts to tie tarps to. And the floor is graded level with no vegetation, so there will be far less bugs. And it's much closer to the toilet and building site and our source of power, so it will be a far more convenient place to be.

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Once the gazebo's in, we lay old boards down across the dirt for a floor:

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I put a large blue tarp up for the roof, folded in half and doubled over to give it extra strength. We then put up our gazebo mesh and bamboo blinds. Once the futon's in, and a rug, it's like a little apartment:

The earth behind the barn where I'd cut out for the dwelling has caved in a little and washed over the corner and sill plates. At some point I'm going to have to cut the land back, and create a 10' wide aisle like I did on the side, so that the land slopes down and away from the building at all points. Hopefully I won't be doing that by hand. For now I just shovel out the dirt that's spilled over the foundation:

The borate-treated sill plates show no sign of rot, which is good. This building gets a tremendous amount of sun and that helps keep everything dry.

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We move more tents into the barn area to use for storage. The barn becomes 'tent city'. If you look closely you can see I've put a little cook-slab out in front of the refurbished gazebo:

We use this slab not only to cook, but a place to continue our daily practice of making green smoothies. The dandelions are in flower everywhere:

Here's a shot of my collecting bag full of flowers, and the creek-water and bananas for our smoothie:

Here's another shot of the property. It's quite cold for April, and Rachael's got her sweater and hat on:

The first rainstorm that hits pretty much soaks everything in the gazebo, and I'm depressed. Rain just blows horizontally through the mesh and makes sleep impossible. I think about it for a while, then decide to run to the store for tarps to use for makeshift walls. The tarps can hang from the frame and be lowered or raised depending on the weather.

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We put the tarps in, and it works! With the mesh, and blinds, and tarps, and board floor, the place, though only 12x12, really feels like a home. Not only does no rain blow through, but wind doesn't either, so it's much warmer and feels more secure. We even bring the space heater in during extreme cold, and it warms up fast.

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This is where we'll live while we build the cabin:

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