Step 10 – Frame the Second Floor

You can see how I’ve been trying to keep the OSB flooring dry with a tarp but with the walls going up it is difficult.  Luckily, I spent some extra money on Weyerhauser EdgeGold OSB subfloor and according to their reps they are perfectly fine to get wet for a few weeks as long as they are given time to dry out.

Framing the second floor is not a whole lot different from framing the first.  Whereas on the first floor, the sill plate was pressure treated lumber, this isn’t necessary on the second.  Also, the bottom plate was bolted to the concrete foundation on the first floor, but on the second we simply nail it to the rim joists as you can see below.

Before raising the exterior walls, I toe-nailed the inside edge of the bottom plate to the floor boards.  These nails help enure the wall stays in position and doesn’t fall off the house before it gets nailed into place.

After going up and down the ladder many times cutting pieces for the walls I decided it was time to build something permanent.  The finished house will have a large spiral staircase but it would get messed up pretty quickly during building (as well as annoying) so instead I just threw together a makeshift ladder from some scrap wood.

Whereas the first floor walls were pretty simple, things got slightly more complicated on the second floor with the master bathroom as it has walled off areas for the shower, toilet, and two walk-in closets.  Several of these walls are angled, and one of the master bedroom walls is actually curved! 

Creating an angled wall is pretty simple.  You can see I have two walls meeting at a 45 degree angle on both the left and right side of the picture.  All you do is miter both top plates and bottom plates at 22.5 degrees so that when they fit together they create a 45 degree angle.  You can see how the studs meet on the inside wall and the small gap on the outer wall will be covered with a metal corner bead under the drywall.

At the center of the pic above I actually have three walls coming together in the shape of a ‘Y’.  For these I mitered the two arm walls with 45 degrees and joined them to a straight wall.  When it came time to add the top plate I had to do cut a special piece to fit with a jigsaw.

To build the circular wall, I had some 3/4 inch plywood ready.  I created a makeshift compass to get the right radius for the wall and transfer it to the plywood.  Then I drew out a second radius exactly 3.5 inches smaller than the first for the inside of the wall plate.  Sandwiching two of these pieces together, I ended up with an equivalent to a ‘curved’ 2×4.

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The one thing about a curved wall is that it uses a lot of studs!  The far side of the wall will curve right around the spiral staircase when it is installed. (I haven’t cut the opening completely yet for safety)

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Step 8c – Plumb and Line

With all of the 1st floor walls complete, it was neat to be able to navigate the rooms and get an idea of the feel of the dimensions of the house.   Before moving on to the 2nd floor I needed to take some time to ensure that all of my framing so far is straight, level, square, plumb, and true.  (For those who don’t know what the last two are, plumb means perpendicular to level and true means both level and plumb at the same time)  Once the subfloor is nailed to the floor joists it will tie everything together so this was my last chance to make sure it was just right.

I started by double checking the lengths of the top and bottom plates, and the lengths of the corner studs.  Next, I used a plumb bob to ensure each of the corners was plumb.  I used long 2×4’s nailed diagonally and nail stakes in the ground to push or pull the end of each wall as needed to plumb the ends of the wall.  I knew the foundation was level, so since the wall lengths were equal and plumb, I knew the walls were square and true as well.  I repeated the process for each wall, and then checked each wall for straightness.  Now I knew the corners were right, but in the middle of the wall there might be some waving.  I nailed a 2×4 block to the top corner on each end of the wall and stretched a string tightly between them.  Using a third 2×4 block, I checked all along the wall to ensure this block fit snugly between the wall and the string.  Where necessary I used additional bracing to make the wall straight.

With the exterior walls (hopefully) perfect, it was time for the interior walls.  I used a powder actuated hammer tool to nail the bottom plates of the interior walls into place.  This uses a .22 caliber explosive to drive the nail into the hard concrete.  You insert the nail into one end, put the .22 caliber load in the middle, and then strike the other end with a hammer.  The blow ignites the load, driving the nail in.  I double checked all of the measurements for the walls to ensure they were straight and then used the powder actuated hammer tool to attach them to the concrete.

Once again, I used the plumb bob to square up the walls and attached them to the exterior walls with a splice plate.  I used additional bracing on the one long wall, but the others were so short that they should stay straight.

With this crucial step of straightening done, I was now confident enough to get going on the joists.

Step 8 – Frame the First Floor

After spending the weekend spraying the new slab down every hour or so, it was finally time to get the walls up!  This process of “wet curing” concrete can add up to 50 percent more strength when done for 3-7 days because it prevents the water inside the concrete from evaporating.  While many contractors immediately begin framing the house the day after the concrete is poured with no problems, I played it safe and waited until the 3rd day to get going.

The first step was to “snap lines” (see pic above) where the walls would go.  This will help me to ensure the bottoms of the walls stay straight and square to each other.  I took several measurements of the footings, including the diagonal measurements from corner to corner, to decide where to start.  The footings came out really good, but not perfect (this is my first solo build, after all!)  There will be a few small areas of concrete that stick out a bit or don’t come out far enough.  This is no problem at all structurally and visually it will be covered up by the siding, but in taking these measurements I was able to position the walls to minimize it as much as possible.

Here you can see where the concrete sticks out a half inch

The exterior walls will be framed on 2×6’s, so the first lines I snapped mark where the inside edge of the bottom plates will go, 5.5 inches in from my starting corner (for those not in the know, a 2×6 is actually only 5.5 inches wide on average)  Snapping lines is done using a chalk reel, which is basically a spool of string inside of a metal casing.  The casing has a sliding door so that you can fill it with chalk, that way when you pull out the string it gets covered in it.  I would put the end of the string on my mark on one end of the footing and weight it down with my sledge hammer, then allow the chalked string to unroll as I walked to the other side.  By pulling the string taut against the concrete and then lifting it just an inch, the line snapped back down leaving a neat line of chalk behind.

Once I had marked all the exterior walls, I grabbed the first sill plate from my pile of lumber and cut it down to 20′ (most lumber yards give you an extra 1/2 inch or so).  I lined it up on my line and marked out the anchor bolt locations, and then drilled them out.  (Remember that the bolts were embedded in the concrete footings so just the top part is sticking out)  Then I placed it over the bolts and made sure it lined up just right.  I repeated the procedure all the way around each wall until I had all 4 done.  With the placement of the exterior walls now set, I was able to measure out the locations of the interior walls and snap those lines as well.  It will be much easier to mark them now and serve as a sort of map to where my interior walls will be going.

I had to call a friend over to help me carry the 32′ long LVL top plate from the lumber pile over to the slab, and we set it on edge next to the bottom plate, which I had also turned on edge.  I used some clamps to hold them together perfectly lined up, and then used a tape measure to mark out the stud locations every 2 feet.  I had ordered the studs precut so that saved me a lot of time.  I just had to carry them over from the lumber pile and then inspect them and “crown” them.  Lumber being a product of nature is never perfect.  Sometimes they have significant bends or waves in them and I will save those for later.  The straighter ones I will use now, but even the straighter ones have a bit of a curve or “crown” in them.  I lined the crowns up all going the same direction which will make it easier to straighten them out later in the build.

 

 

 

Once all the studs were laid out on my marks it was just a matter of nailing them together.  Building codes offer several different ways to satisfy nailing requirements, and the one I chose will be 3 16D nails to connect each stud to the top and bottom plates.  I took my time and carefully aligned each stud to ensure that it didn’t stick out on either side of the top plate.  It is situations like these where even with my lack of experience I can guarantee I put together a better wall than 90% of the framing crews since they are focused on speed over quality.

For the window openings, a larger piece of lumber must be used to carry the load from the opening that is missing a stud to the studs on either side of it.  Again, building codes dictate several ways to satisfy these header requirements, and for mine I chose a single 2×10.  I will also be utilizing some metal hangers to carry the weight of the header instead of shorter studs called jack studs, although you can see that I did use jack studs for the entry door in the pic below.

The jack studs are the ones that are shorter than the regular studs on either side of the door opening

Once all the lumber was nailed together, I unrolled some “sill gasket” and placed it over the footing where the wall will be hoisted.  I also nailed some long 2×4’s to the top of the wall.  As we raise the wall, these boards will swing out and brace it.  The wall was very heavy but with a few friends we were able to get it airborne with ease.  Once it was vertical, I staked down the bracing boards and then screwed the nuts down over large square washers on the anchor bolts.

If you look closely you can see the white sill gasket underneath the bottom plate

Within a couple days I was able to finish the remaining 3 walls and raise them into place as well.  It’s so much fun to see my vision becoming reality!

The long 2x4s in front forming an ‘x’ are the bracing pieces I was talking about

Step 7c – Pour the Slab

One thing I realized I forgot to document was that I placed a cardboard box around the DWV pipe for the downstairs tub and filled it with gravel.  This will allow me to easily break the thin layer of concrete over the box and pull out all the gravel, leaving a nice area around the pipe giving me plenty of room to work when I hook it up to the tub.  With that final step complete I was ready to pour the slab.

A freshly poured slab is an incredibly beautiful thing.  When it first comes out of a truck it looks like a messy slop of oatmeal with blueberries in it (the blueberries being the gravel).  A long, straight 2×4 is used as a “screed” and run back and forth to level the slop.

After about 20-30 minutes, the slop has started to gel a bit, and the gravel sinks down just a little.  At this time, a long pole with a metal “float” attached is run across the concrete.  The float pushes the gravel further down and brings this very creamy part of the concrete up to the top.  It is this stage where the concrete really starts to take on a new personality, like an awkward teenager emerging from acne-filled puberty.

Another 30-45 minutes go by, and the concrete really starts to harden, but when you run a float over the top you can still get a tiny layer of cream to appear.  You continue working this cream back and forth over the top, smoothing and smoothing, until it too begins to harden.  At this time, a strong force over a small area of concrete will create an indentation, but by kneeling on pieces of plywood, the force is applied over a larger surface area and the concrete doesn’t move.  Using these “kneeboards”, you can get over to the center of the slab and work that as well.

Raphael working the bull float

I must admit that I had another learning experience during this pour as well.  Although I was certain I ordered the same amount of extra concrete as the last pour, in which we had quite a bit leftover at the end, we ended up running out of concrete with a tiny corner of the slab left.  I made a quick trip to the hardware store and we dropped 13 bags of concrete in, mixed it with water, and finished the job.  When it was all said and done, you can’t tell the difference, and hopefully there will be no negative side effects down the road.

After the concrete hardened, I went out and sprayed it down with a fine mist every 15 minutes or so.  While excess water added to the concrete before it has set will reduce the strength, when it is added after setting it slows the curing process and will prevent the cracking that can occur when the concrete sets too quickly.

Step 7b- Add Gravel, Vapor Barrier, and Rebar

Capillary forces are very powerful.  Have you ever been to a redwood forest and wondered how water gets from the roots to the leaves at the very top of the tree?  The answer is capillary force, and surprisingly, it works even more efficiently in concrete than it does in trees!  Scientists believe concrete has such powerful capillary force that it theoretically has the ability to drive water 6 miles upward against the force of gravity.  Wood maxes out at about 400 feet which is why you don’t see any trees get that high.  In an effort to curb these powerful forces, building codes require that a layer of gravel and a vapor barrier be placed underneath the concrete slab.  The gravel drains away any standing water, and the vapor barrier takes care of any water vapor. 

As you can see above, I have started adding the gravel layer inside my footing.  The long 2×12 boards act as barriers to prevent the gravel from occupying the “shovel footing” that is necessary to support the bearing wall that will soon be framed directly above it.  Once all the gravel has been added and compacted, the boards will be removed and a 12″ wide and 8″ deep ditch will be left behind.  It is much easier to create the ditch this way rather than shovel the gravel out.  When we pour the concrete for the slab, the concrete will flow into this ditch and the slab will be 8″ thicker along that line, giving added support to the bearing wall.  If you aren’t aware, a bearing wall means that it is supporting some of the weight of the house.  The entire roof of the house is supported on only two exterior walls, so none of the interior second story walls have any weight to carry. I could have supported the weight of the floor joists between the first and second stories in the same way, but I would have had to use special engineered I-Joists.  Instead, it was much easier to use two lengths of 2×12 joists and have them meet on top of one of the first story interior walls.  This wall is the bearing wall.

After all of the gravel had been added, I leveled it out and then installed the horizontal layer of Roxul as you can see above.  Keep in mind that the more insulation added now, the lower the heating bill will be in the future.  Investing an extra $300 now will quickly pay off in a year or two, and then I will reap the benefits every year after that for the life of the house.  Once the insulation was added, I ran a plate compactor around everywhere to ensure the gravel was well compacted.  Then I pulled out the long 2x12s to create the shovel footing as you can see below.

The last steps were to add the vapor barrier and rebar.  The vapor barrier comes in a large roll so it was simply a matter of rolling it out and cutting it to fit.  Wherever a pipe penetrated I used vapor barrier tape to seal the hole.  I tucked all the edges of the barrier in between the two layers of insulation.  The rebar I lined up in a neat, four foot grid and set it on 2″ chairs so it would end up right in the middle of the 4″ slab.

 

Step 7a – Pull Stakes and Forms, Insulate, and Reinspect

After a couple weeks of frustration, I was rewarded with my second passing inspection today, giving me a green light to pour the concrete slab that will complete the foundation.  I do have a few more steps to take before then, which I will document in the next post, but the inspector is allowing me to just take a picture after the gravel is filled in so he doesn’t have to come back.  Weather is threatening not to cooperate but with a little luck I will have the slab poured before the end of the week.  It is hard to believe that when I get my next inspection, the house will be completely framed!  You can see to the left how the permit is kind of like a checklist that the inspector signs off as you move through the building process.  The two blank spots are not applicable to my build and I will actually be skipping over the rough plumbing, duct, and HVAC so the next inspection will be the ‘rough frame-roof’.  After that it will be nice and dry inside and I can work on finishing the plumbing & HVAC.

The frustrations I experienced over the last two weeks resulted from the same mistake that caused the two mishaps with the first concrete pour: underestimating the fantastic power of concrete.  I should have removed the stakes and forms as soon as 24 hours had passed from pouring the footings, but I was nervous and decided to wait an extra day.  When I finally got the nerve to pull the stakes they didn’t budge a millimeter.  I had purchased a fancy stake puller called a JackJaw that my mentor had used to remove his stakes,  but I had decided to go for the $225 unit instead of the $450 one.  The result was the rapid destruction of the tool as you can see below.

The bottom is NOT supposed to bend that way!

Thankfully, JackJaw has outstanding customer service and they offered to accept the unit back as a full price credit towards the more expensive one.  After a week of waiting, it finally arrived and though it was many times more powerful, it was still a battle to get the stakes out as they had now been setting in the concrete for over a week.  Using the customer service associate’s advice, I used a sledge to pound each stake in a few inches and then used the JackJaw to pull it up until it wouldn’t go out anymore, and then repeat the process.  It was an agonizingly slow process, and I still have 4 stakes in the ground as I’m typing this, but that’s about 92 stakes less than I had in the ground a week ago.

With the stakes out, you might think it would be quite easy to pull off the form boards.  The smooth plywood forms were still greasy from the last time they were used so they didn’t adhere to the concrete, and all the screws and stakes holding them together had been removed.  Unfortunately, because of the way the concrete had curled up and around the bottom of the form as I described in my previous post, removing them was just as excruciatingly time-consuming as pulling out the stakes.  Like running a marathon, it didn’t seem like a lot of fun while I was in the middle of it, but looking back on it the experience was much more rewarding this way and I surely have some additional muscle tone to show for it.

With the forms removed, I was able to apply the Roxul to the interior vertical face of the footing as you can see in the picture that started this post.  Many people find it puzzling that there is a layer of foam sandwiched inside two pours of concrete, but the layer of insulation will serve two important purposes.  It will protect the slab from frost heave during the winter, and work in unison with the walls and roof to reduce the heating and cooling load required to maintain a comfortable temperature in the house all year long.  Cold-weather climate builders have used foam called EPS (expanded polystyrene) that is commonly found in packaging for a new television or computer underneath or surrounding slabs for many years.  Not only is the manufacturing of the foam harmful to the environment, but the insulating power (r-value) slowly degrades over time.  With Roxul, a brand of rockwool, you don’t have either of these downsides.  It really is an incredible product as you can soak it down with a hose all you want, peel back the outer layer, and the inside will be bone dry.  As you can see to the left, I cut a 45 degree slope on the top of the Roxul.  This will allow for maximum insulation while also giving the slab a firm connection to the footing.

The last step was simple.  I just capped off the entire DWV system (Drain, Waste, Vent) and filled it with water.  As you can see, I added a 10′ section of ABS to one of the vents so I could show the required “10 foot head of pressure” for the inspector.  The force of gravity on the column of water held in that pipe applies a force to the entire system that the building code has approved to show that there are no leaks in the system.  It hasn’t happened a lot, but this was one of those rare times when I didn’t have to spend any extra time fixing a mistake I had made.  As you can see below, an empty and uncapped, upside down water bottle shows the water level holding steady, showing that there are no leaks.

 

 

Step 7 – Pour Concrete!

Today marked another milestone as the concrete was poured into place that will eventually support the load of 90% of the weight of the house.  As with almost every step in the build so far, there were definitely a few hiccups along the way, but at the end of the day I was pretty pleased with the results.

The major hiccup occurred when a couple of the pieces of wood I was using to hold the forms exactly 8″ apart from each other pulled away from the screws that were holding them in place.  This wasn’t catastrophic because the bottoms of the forms were held in place by the nail stakes, but it is the top of the forms that is the most crucial, so it was important to figure out how to push them back in place and hold them there.  The easiest fix was a little costly, but it worked and in the grand scheme of the build it will be a minor cost.  I had one of my friends (thank goodness I had some extra help!) run to the local building supply store and buy some steel spreaders and then we used some 2x4s to lever the tops of the forms back into place and lock them together with the spreaders.  I measured it out and the entire pour ended up being less than a 1/2 inch off all the way around the top.  Although the bottoms did bow out a little bit, they will be completely covered with dirt.  Crisis averted!

Here you can see the wooden spreader that ended up breaking next to my right hand

A little less than $100 worth of extra concrete. Better safe than sorry…

Another minor hiccup during the pour was that the weight of the concrete inside the forms was so great that it pushed the concrete underneath and up around the outside of the forms.  If you recall, the concrete was supposed to level out as it reached the bottom of the forms and press into the dirt, creating an upside down T.  Unfortunately the concrete started rising back up at the ends so in reality it was more like an upside down ‘T’.  Structurally, this was not an issue, and again, this part of the pour will eventually be completely covered by dirt.  The problem was that I hadn’t accounted for the additional concrete in my calculations.  I had ordered extra but started getting scared that the excess I had ordered wouldn’t be enough to cover it.  We solved this problem by pouring the bottom part of the T first and then pouring the top half after the bottom half had about a half hour to cure.  This incurred an additional hourly cost for the pump truck driver but running out of concrete would have been catastrophic.  As it turned out, we would have had enough but better safe than sorry.  We poured the excess concrete underneath the slab and it will result in needing less gravel in the next phase of the build.

Below you can see the finished result of the pour.  I removed all of the bracing but I’m having a little trouble removing a lot of the nail stakes.  I had purchased a powerful stake puller capable of exerting over 750 pounds of upward force on each stake but it wasn’t enough.  Thankfully, the company said they would send out the next model up and I would only have to pay the difference in price between the two.  Thanks JackJaw!!  It does set me back a week on getting the inspection for the second pour but it could have been worse.

A big shout out to my friends Michael and PJ for all their help  and also to Raphael and his crew who I hired to help with the pour!

 

 

Step 6c – Inner Forms, Plumbing and Bracing

I could save a lot of time and some money by pouring the concrete for the footings and slab at the same time, in which case I would be done with the formwork now.  For several reasons, I decided to pour them separately, so I needed to add an additional set of forms before I pour.  The double pour will allow for more control, hopefully resulting in a smoother, more level slab.  It also allows me to insulate the inside of the footing wall, instead of the outside.  You can always add insulation to the outside of the wall anytime you want if needed to reach the net-zero goal, but you can never add it to the inside once the concrete has been poured.

I set up the second set of forms exactly 8″ apart from the first set to create the 8″ stem wall required by the local building code.  The set up method was no different than that of the first set of forms: stakes in the ground, forms nailed to the stakes, scrap wood screwed to the forms to hold them tight to each other with no gap in between.  I attached the two forms together with the precise 8″ gap using some scrap wood.  I placed these scraps at the exact locations where my anchor bolts will go.  This way, I can use the scrap wood to hold the bolt while the concrete cures around it.  The conventional way is just to throw the bolts in wherever you “think” you might need them as the concrete is curing.  This often results in bolts ending up where studs or plumbing is supposed to go and needing to be cut and replaced, so the method I’m using is much more efficient.

 

Once the second set of forms were attached and level with the first set, I began straightening them out using the bracing shown here.  The boards may not look pretty, but they are free and I can’t see spending money on temporary bracing.  When it comes time to pour concrete, we will be banging the forms with hammers trying to work the air pockets out of the concrete so I need to ensure the forms won’t move around at all.

With the forms perfectly marking out the edges of the house, I now had a reference to place the plumbing.  Here you see the plumbing for the toilet which has to exit the concrete slab at the precise location where the toilet will go.  Notice that there is not a trap in the pipe because toilets have traps built into them.  When I connect the plumbing for the tub you will see that there is a u-shaped trap under the concrete that will hold a pocket of water and ensure that the gases from the septic tank don’t enter the house.  When bracing the main pipe here, I will need to maintain a downward slope of 1/4″ for every foot of pipe all the way through the line to the septic tank.  I used the builders level again to make sure that I was starting at the right spot.  Using the spec sheet that came with the septic tank, I know that he inlet is exactly 17″ below the top of the inspection ports that are visible from above.

The edge of the forms where the main sewer pipe will exit the concrete is a little less than 10′ from the inlet port, so the pipes must exit that spot 2.5″ above that height (10′ at 1/4″ per ft= 2.5″).  From there it gets much easier as I just had to slope the pipe at 1/4″ per foot until the end of the line.

The last step before the pour will be my electrical and utility sweeps, so be looking out for that in the next post!

Step 6b – Square and Level Forms

Work was slowed a little with selling a house, in-laws and fiancée visiting, and just enjoying fun summertime activities, but I’ve finally gotten enough done to get another post written up.  One of the more intimidating parts of the build has been putting up the form boards, and I’m confident it will hold up to be one of the more crucial aspects of the build.  It is one thing to make an incredibly detailed drawing on a CAD program in which everything is perfect and straight and level all the time.  It is quite another to take a crumbly and uneven medium like soil and place forms that will be just as straight and level as the CAD drawing.  I’ve thanked myself for sticking to a small footprint many times over the last few weeks as I trudge back and forth from my trusty builders level to the grade stake, fine tuning everything.  The dimensions I chose for the footprint have worked out nicely as well, since (24′)2 + (32′)2 = (40′) Thanks to Pythagoras I can very accurately check to ensure my corners form perfect 90 degree angles by measuring the distance between them to be 40′.

Before I explain what I did, it might help to visualize what the goal is.  Here’s what we want to accomplish…

It may not jump out at you at first, but there are two distinct sections of the foundation.  There is an 8″ stem wall at the top, and then a thicker 16″ footing below it.  The soil will act as a form for the 16″ footing and the form boards will create the stem wall.  Once the concrete has been poured and partially cured for the portion above, a second pour will create the flat slab inside.

So here’s the rundown of what I did.  I cut a couple small 9″ blocks to hold the form in place while I screwed it to the nail stakes.  I chose 9″ because the footing needs to be a minimum of 7″ deep and I wanted just a small buffer in case any dirt caved in between the time I level the forms and the time the inspector comes to check the depth of the footing.  With the unfortunately sky high concrete prices in the area I will pay about 200 dollars for this buffer but I’ve decided it is worth it.  I set each form on the blocks and then lifted it up just slightly before screwing it to the stakes I had pounded in.  The extra lift at the end is something I learned from my mentor.  It is quite simple to nail in a stake just a bit more to lower the form, yet even with incredible strength it is virtually impossible to pull one out of the ground and expect it to stay there.  By nailing the form to the stakes just a bit higher than they needed to be I was able to easily fine tune the forms by pounding a stake down just a bit here or there.

I used the builders level to decide how much extra to pound each stake in.  I used a couple clamps and a small 2×4 as a jig to hold the grade stake straight on top of the form and then checked the height with the level.  Using this point as a reference, I worked my way around the perimeter, clamping the grade stake on top of the form, checking the height against the reference height, pounding the nail stake holding the form down a bit if needed, and then rechecking the height with the level.  Once all the forms were level, I measured the lengths of each side and then measured the diagonals to ensure the sides were squared to each other (as I explained above).

You can just barely see the grade stake clamped to the top of the boards to the upper right of the pic

Although they are called nail stakes, I decided to use screws to attach the forms.  The screws are more expensive, but are easier both to install and to remove once the concrete has been poured.  With any luck I will be able to remove them in good condition and reuse them later on in the build.

 

Step 6a – Stakes and Steel

Concrete can withstand an incredible amount of force when it is compressed, but doesn’t do as well when it experiences tension forces.  Steel reinforcement (rebar) embedded in the concrete helps give it more tensile strength.  County building codes require two runs of horizontal rebar at the bottom of the footings and one horizontal run within the top 12″ of the stem wall.  These requirements are very clearly spelled out with some pictures on the county website.  The three horizontal runs must be connected by L-shaped vertical rebar every 4 feet, alternating direction between the two bottom rows of horizontal rebar.

An excerpt from the County Construction Guide

One of the more difficult aspects of installing rebar is ensuring that it is embedded inside the concrete (most codes require 3″) as opposed to just lying on top of it or underneath it.  I will be using small blocks called dobies to hold the rebar up so that when the concrete is poured over it they will stay the required 3″ off the ground.  The vertical rebar is held upright by tying it to the bottom runs using rebar tie wire.  To make things easier, I bought a neat little tool for $15 that quickly and neatly twists the tie wires together for you as you pull on the handle.

Using the rebar tie tool to attach two pieces together

Rebar comes in lengths up to 20′ so when you need a longer run than that you need to splice two or more pieces together.  These splices must not occur in exactly the same spots on each run and must be 50 bar diameters in length.  Since I am using #4 rebar, the diameter is 4/8 or 1/2″ (#5 rebar would be 5/8″ in diameter, etc.)  If we multiply that by 50 we get 25″ so the spliced rebar must overlap by at least that length.  I had already used Rhino to figure out exactly where I wanted these splices so it was simply a matter of cutting them, bending them, and using the rebar tie tool to attach them together.

I noticed that one of my Point Roberts neighbors had an old rusty rebar bender/cutter in his yard and asked him if I could borrow it for a week.  It was barely holding itself together and at least twice as hard to operate as a newer one, but it did the job and saved me the money it would have cost to rent one.  The two notches on the front work together to shear the bar in two, and the knobs on the side work together to form a 90 degree bend in the rebar.   I put the stakes to hold the form work in first to ensure that the rebar wouldn’t be blocking me from putting them in just the right place.  Then I installed the rebar before hanging the form boards up so I wouldn’t have to work around them.

 

 

You can see above how the alternating vertical rebar join together the two bottom horizontal runs and the top horizontal run.  Once the forms are hung on the stakes, I will use some more rebar tie wire to straighten out the runs a bit so they don’t sag and wave so much.