How To Ready A Hybrid Earthbag Wall Home For Roof Trusses

This project is beginning to be downright enjoyable. The earthbag walls that fell to high winds a few weeks ago have been rebuilt, the final foot of wall height has been fully framed and looks better than expected, and the foundation bricks have been laid for the construction of an interior bearing wall. What could go wrong?

Um...we'll get to that.

From the beginning, the incorporation of a centerline bearing wall had always been part of the plan. Premanufactured trusses are waiting onsite in a bundle, but these puppies are 36 feet long. Truss design has come a long way over the years, but that's a monster span for a little old low-pitch house roof. Holding everything up firmly in the middle makes sense.

Some of the lumber I had delivered from Home Depot a while back included a number of twenty foot two-by-fours. Counting foundation concrete blocks until you come to #26 is enough to locate dead center. To ensure straight-line construction down the full length of the floor plan, one of those boards was cut to a length that, when butted to a full length twenty-footer, produced a "house-long straight edge". Splicing those "sticks" with a four foot chunk of wood was enough to lock in a one piece "house divider". Let's call it an "HD" for the sake of brevity.

The HD super-board was situated on edge so that a four inch wide concrete row of bricks laid next to it would track dead-center through the floor plan. Checking things with the level showed that the ground at the front of the house sits about 1 1/2 inches higher in elevation than the rear of the building. I knew that already, but the confirmation made sense. To come up with an absolutely level floor, the foundation bricks (there only to keep framing wood from contact with the Earth) would need to be higher in relation to the rear wall and lower toward the front. Again, no surprises. Once some dirt had been squiggled around to level the HD board, each brick could track the board rather than the exterior wall heights...and all would be cool.

How to level the dirt? High tech: Brushing loose dirt here and there with bare fingers!

Hey, calculus and computers are both overrated, doncha know?

As you can see in the photos below, there are two gaps in the line of bricks. These will eventually accommodate doors which access the two bedrooms taking up the entire south half of the overall structure. We'll be utilizing 32 inch doors, so the openings are set at 32 3/8". Technically, allowing a quarter inch beyond nominal door width should be workable, but I don't trust myself that much...hence the extra 1/8" as a margin of error.

Note: Since a simple concrete strip would be easier to handle than all those loose bricks, the question will arise as to why I didn't simply build a form--the HD board would be good for one side of that anyway--and pour concrete footings. The answer is simple: It's too cold to pour concrete at this time of year unless you're highly experienced with handling freeze-thaw cycles, even here in southeastern Arizona. Not to mention, I've never done that well with concrete. A small mounting base for an air conditioner or some such, hey, no problem, but it's not my strong suit. So...loose premanufactured concrete bricks...okay?

Besides, the bricks were only fifty cents apiece. The entire wall foundation cost just a bit over twenty bucks.

There had to be one, right? At least this glitch was no big surprise. Simply put, a test brick split wide open rather than accept the business end of a three inch masonry nail. This means a "lost" day tomorrow, because every trip to Home Depot means running all the other errands that are put off between runs to Sierra Vista.

Anyway, several separate "goodies" will need to be purchased:

1. A masonry cutting blade for one of the Skilsaws. (One's actually a Black & Decker, but so?) The final brick needs to be cut to length and that, of course, requires a specialty blade.

2. Safety goggles. I'm mostly against "safety" in the official smother-me sense. The first thing to go on any chainsaw of mine is the so called safety tip, and don't even get me started on airbags and seatbelts. But I do know when discretion is the better part of valor, and power-cutting concrete is one of those times. Even a single chip lodged in your eyeball could ruin an otherwise perfectly fine day.

3. Shorter masonry nails. The nails on hand are 3 inches long. Home Depot has another version that's half an inch shorter, and for the interior walls, I'll go with those. For the much larger exterior wall concrete blocks, the three-inchers will work just fine.

4. One or more masonry drill bits. These little bricks are kind of wimpy. They'll do what I want them to do, but a bit of help is required...namely pilot holes to reduce the "bursting pressure" applied by nails. That's going to be a bit of a pain, since every single brick needs a hole drilled, but hey. Rome wasn't built in a day, and this house quite obviously wasn't, either.

The bricks didn't go down without a fight. Here's the contest, round by round:

Round 1: The new masonry saw blade fit the Skilsaw just fine but didn't "cut brick" worth beans. At full depth, things were pretty much a lost cause. It took many minutes, adjusting the depth of cut continually to take out about an eighth of an inch at a time, to get most of the way through the brick I wanted to shorten for the wall's east end. When the disgust level had risen too high for words, a quick slap against the saw bench was enough to break the remainder free. The judges scored that round even, a hard fought draw.

Round 2: After all that, the shortened brick was still a good quarter inch too long to fit into the required space. Three bricks placed on edge fit nicely, though it did require a bit of digging for deeper placement and left an odd "jog" in the corner that will make later flooring and wall paneling a bit trickier to apply. The brick won that one.

Round 3: Several boxes of shorter masonry nails in two inch lengths had been brought home with everything else. Unfortunately, even though that only required a brick to accept 1/2" of nail below the sill board, the test brick immediatly split right in two. The silver lining: See Round 4. Only because of that silver lining, Round 3 went to me.

Round 4: In a stroke of pure genius, I'd purchased a number of 3/8" rebar pieces in two foot lengths. The theory is that with these run down through the 2" x 4" sill board and a brick at four foot intervals, the wall should be well enough secured to keep it from ever "kicking" sideways. 3/8" holes were drilled through the sill board and then through the necessary bricks to accommodate the rebar...but since the drilling required different bits for board and brick, and since I was far too stupid to keep the board aboard the brick while drilling the masonry, the two holes (board and brick) ended up at different angles. This put rebar-stress on the brick during the pound-down-into-the-ground process, and seven of the nine bricks holding rebar did indeed split wide open. The heck with it. The masonry is there to hold the wood away from the dirt; it doesn't have to be pretty.

In the end, and only after long discussion among themselves, the judges awarded me this round and the overall win in what was obviously a (!) split decision.

After watching me run around on top of the walls for some minutes, Pam couldn't take any more. She simply had to throw on a jacket and toodle out to ask me what on Earth I thought I was doing. The answer was simple enough.

The interior bearing wall is there to prevent roof truss centers from sinking to eternity over tiime. That it also serves as half of the necessary partitioning to produce a number of rooms is beside the point. But since this is something of a do-it-yourself, cobbled together sort of project, just running the wall-top from one side of the building to the other might produce a problem. Namely, when the trusses were actually placed, the middle wall might be higher than the outside edge walls. That would not be good.

So I made a "string net". First, a cord was attached to nails and stretched directly above where the wall was to run (east-west). Then three more cords were stretched across that cord at right angles (north-south).

The visual effect was very, very cool. For the first time, standing inside the house gives you a definite feel of where the ceiling will be over your head.

By the time the sun had set (01/05/09), the top board had been solidly tacked at the ends and a few vertical studs installed. Weirdly enough, the center of the wall "sags" a good half inch below the string net. How come? Misperception. I'd cut the key stud that would define wall height at the point where the long 2" x 4" pieces meet. When I checked it after the cut, it seemed to be pushing the string up. Couldn't have that. So I cut the board precisely 1/2" shorter, nailed it in place...and then discovered it to be 1/2" shorter than necessary.

Go figure.

However, the decision was made to leave it like that. One half inch is a simple adjustment with wedges, and the gap guarantees the outside edges will not have a problem in seating firmly on the exterior wall planking. Our son, Zach, works on a crew that sets up mobile homes for long term occupancy, and they fine tune the leveling of each home with wedge adjustments every time. Additionally, the wedges will be invisible to the occupant after wall paneling is installed.

So: No harm, no foul.

After all the fussing and fuming surrounding the concrete bricks, it was nice to have something go smoothly. The only ho-hum in the entire line of vertical studs was the sudden realization that the door opening to what will become my wife's bedroom is slightly off kilter. That is, one side of the doorway is "kicked out" about 3/8" of an inch. The problem appears to have been caused by a not-quite-straight installation of a piece of rebar. In the end, I decided we were just going to have to live with that. It won't show much to the naked eye when completed, and it's definitely not a structural problem.

With the studs all in place, it was time to sheathe the first eight linear feet of one side of the wall to make sure the vertical studs won't be tempted to bend under load.

You've most likely seen plenty of home construction projects where all of the roof trusses are all standing proudly in the open air at one time. However, I'm way too cowardly to do it that way...for the following reasons:

1. There are currently two sets of braces holding the bearing wall in the correct position. They'd have to be removed to get out of the way of the sheathing. Sure, the braces could be reapplied by nailing into the open door frames, but....

2. As soon as eight feet of wall is "covered" with trusses, that small section of roof will immediately get its full complement of strand board sheathing before any more trusses are added. Finding out that one piece of strand board ended up without a truss underneath an edge is one thing. Finding out the entire roof skeleton had been incorrectly installed would be quite another.

The day went well enough. By sunset, the first two trusses were in place.

Now if I only didn't have to run to town tomorrow. Being this close to roofing the place...I want to get on with it!