A garage? A cabin? How 'bout 2 in 1?
Follow us as we build a garage/apartment at LNP
LET THE CONCRETE FLOW
Our newest catch phrase is "newfound respect for guys that work with concrete". We lined up our ducks, took all the necessary steps and made all the necessary preparations. We brought the will and knowledge. The only facet we might have miscalculated was the required physical strength and endurance. We have met the enemy....and it is us.
As we walk thru this week from hell, please remember that my original plan was for Donna and I to do ALL this ourselves. The only other help I planned on was our excavator, necessary to cut the hole and do all the other backhoe-type projects as we progressed. As it played out, we are certain that some level of divine intervention carried us along, without which it would have been a disaster.
A couple of days before ground breaking, I call our excavator to discuss the schedule and plans. Our focus is pouring the footing and and the walls. I have been watching the weather closely and it appears that a window of rain-free days will open up. The time is now. I tell Ben, our excavator, that I want to cut open the hole on Friday and do the footing pour on Monday. This will allow Donna and I ample time over the weekend to set the rebar and elevations for the top of footing. There is also a 4" PVC utility chase that must be set. It runs below the footing to keep the future water line below the frost line. I really liked my plan. Ben didn't. He just could not understand why we would need all that time. We talked some more. Within a couple of minutes, I knew we were being given a tough choice. You see, Ben also does concrete work. He is a real good guy, talented, and willing to help do just about any portion of the job that we want hire him for. It quickly becomes apparent that he will also get involved with the concrete pour....if we want him to. Yeah, "if we want him to"...? I would be nuts to turn down this opportunity. This is when the plan made a minor shift to the right and I knew we were in for a roller coaster ride.
Ben simply stated that we are going to cut the hole, place the iron, and pour the footing....all in one day. He cites other similar jobs, leading me to believe that this should be a piece of cake. I resist a bit, and try to bring him back to my original plan of using the weekend to prepare for the pour. No go. So, now I am faced with a decision and there really is only one answer. OK, we're on for the one-dayer.
At this point, let's hit the brakes for a moment and lay out some of the pre-dig preparations. Things like bringing down all the rebar for the concrete work and the PVC pipe and staging it nearby.
Donna and I made our final commitment on the location of the structure a couple of weeks prior. The week before the pour, we layed out the 4 corners, measuring the diagonals to verify square. We set stakes at these corners and pulled a string tightly between them. We set the stakes so that the string would be the exact centerline of the foundation walls. When the string was tight, I spray-painted directly over it into the grass and soil. This line will be where we want Ben to set the center of his bucket to dig.
We also marked the trench that must be dug to accommodate the garage floor drain that will be installed before pouring the interior slab.
OK, fast forward to crunch time....
We leave Thursday afternoon to stay overnight at LNP (this way, we can get up at the jobsite on Friday morning and kick it into gear). We did spend that Thursday afternoon making final preparations. I knew that we would want to set up batter boards to document the locations of the foundation that we had set the week before. Once Ben begins to dig, those paint lines are gone and we will need references for the original locations. Set up the batter boards.
The next morning, Ben arrives with his backhoe and we are off to the races. We walk and talk a bit. His first concern: the location of the batter boards. Huh? Yeah, they're way too close to the work. Uh oh. This is my first glimpse into the blessing of having experienced help; it's an omen. He says we can keep only one set and he will start at that corner. Past that, the other 3 sets have to be extended a LONG way back to get them outta the way. So, we pound 6 more stakes at a distance, set up longer lines, and relocate the strings to nails at the tops of the new stakes using the old locations as a guide.
Time to set our elevations and begin the dig. As planned, Ben has the fancy hi-tech rotational laser and measuring rod to simplify setting and verifying elevations. We pound in a rebar stake well off to the side of the work zone and set it's top as our reference of "zero height". It really has no use, unless there is some kinda screw-up....like knocking over the laser (fortunately, we never needed to use the "zero" stake).
The first job is to strip the top soil and grasses out of the interior where the slabs will be poured later.
Start cutting the hole.
Let's take a moment to explain what's going on here. We are pouring what is called a "trench footing". Instead of opening up a wide area of the soil and then setting forms to create the wall of the concrete footing, we completely forego any forming and simply use the hole itself to be the concrete form. This is only suitable practice when the soils are stable and do not collapse or crumble easily. Our high clay content is perfect for a trench footing. I told Ben to bring a 2 ft wide bucket for the footing work. The 2 ft bucket will be used to cut open the trench footing, providing a 2 ft wide concrete footing when all is said and done. Of course, it is critical to set the bottom elevation of the trench accurately because it will dictate how thick the final footing will be...and how much concrete I have to pay for to fill it up to arrive at the the top of the footing. Our footing is planned to be 12" thick; that is where Ben sets the laser receiver on his backhoe. This will allow him to continue digging without any assistance. A portable laser beam receiver attaches magnetically to the arm of the backhoe and sounds a signal as the backhoe arm dives down to dig. Pretty cool.
Ben asks me if I want him to dig a secondary trench outside the footing trench. This evokes another "huh?". He says it will allow much easier access to the work. Of course, I'm all for that and let him rip it up. It turned out to be another excavation blessing.
I use a shovel to clean out what little crumbs remain in the hole. I know Ben is shaking his head, but it's my foundation and I want it perfectly clean for a firm footing. I also get to set the rebar. Normally, these guys like to just "float in the rebar". Before the pour, the rebar is dropped into the hole and manually raised to about center during the pour. This is acceptable practice, but does not guarantee that the iron will wind up exactly where I want it. Besides, I don't want the headache and having only 3 of us on the job for the pour will make this step a time consumer. So, I had rebar hairpins created to pound into the subsoil and pre-set the reinforcing at the optimal height and location. I start to set the steel.
You will note the rebar dowels set vertically into the center. These are key players. They are called grade stakes or grade pins. The tops of each of those grade pins are set exactly to the top of the footing height. Two people work together to set them. One person holds the measuring rod that plays off of the laser and the other person carefully pounds the pins into the soil until the very top is set at the correct elevation. Once again, the high-tech laser with the beeping receiver on the measuring rod is the only way to go and really makes this move along much faster that it would any other way. The top of each pin is painted orange and an orange stripe is painted along each side of the trench; all to allow locating them after the concrete has filled the hole.
It should be noted that Donna and I are already starting to feel the burn, and we haven't yet seen concrete. OY!
Speaking of which, bring on the mud. We used 13 yards of the standard 3000# mix; normal for a footing. Ben heads off the pour....I am very grateful (again). He works with the driver to carefully adjust the amount going into the hole. He is constantly using a concrete rake (aka; concrete placer). It allows him to not only push the mud a bit if too much goes in, but he uses it to lightly tap and float the surface until it is even with the tops of the grade pins. Those orange stripes on the dirt wall pay back big. As Ben moves along, he shows me how to work with a hand float to bring the surface of the footing right to the tops of the pins. The idea here is pretty simple. The concrete is poured fairly wet (the driver can control the amount of water in the mix by adding if necessary). This way, the slurry will seek it's own level....like water. If Ben does a good job of regulating the amount that goes in and I do a good job of floating the final surface, we should be able to keep the top of the footing within 1/4" all the way around. Of course, there are areas that I call out that are too thick. Ben would come over with the rake, push it in, scoop out a bit, and toss it off to the side of the hole. I would re-float it and look for the top of the pin. As the float moves over the wet slurry, I watch the painted stripe and can feel the trowel nick the tip of the pin. As I pass it, I can see if the mud floats back and covers it up...too deep and I call Ben to pull out a little more. I was very pleased and surprised at how little adjustment was necessary. As I noted above, it all starts with the guy regulating how much goes in. A tip of the hat also goes to the driver.
As a final step, before the concrete sets up, we re-attach the strings to the batter boards to determine the center of the wall, use a plumb bob to drop the measurement down to the top of the wet concrete, and insert rebar dowels about every 4 feet or so. This will help to tie the footing and the wall together. (this pic was actually shot the following morning)
DAY ONE IS IN THE CAN! Crack open the bottle of ibuprofen and start cleaning up. We're not quite done. You see, we have a schedule to keep. We are still going to go back home yet tonight, cuz we gotta get up tomorrow morning and head out to pick up the concrete forms tomorrow morning. Yeah, we are really learning the true meaning of bustin' hump.
Begin day 2
During my planning, I quickly discovered that there aren't very many places that rent concrete forms. Fortunately, I was able to find a place in collar suburbs of Chicago and was able to line up the required inventory for rental exactly when I wanted them. My only real concern was for their weight. This created two issues. One; would our truck and utility trailer be able to handle it? Two; would Donna and I be able to handle it? Well...let's find out.
We arrived at the rental place. I had already done the research and knew that the form load would be a little over 5000#. My trailer is rated for 7000# gross weight, so we are near the edge. After adding the weight of the form ties, the waler brackets, the form oil, and other stuff to the truck bed, we are actually a few hundred pounds over the gross towing weight of our pick up truck. I knew that going in.
I was sweating bullets as I watched them load all that weight onto the trailer. Some creaks and pops, but we got it all on and adjusted the load a bit to try to keep the trailer balanced. At one point the truck squatted so low that I was sure the game was over, but after re-distributing, I got to the belief that we might actually make it. We did.
Early that afternoon, still on Day 2, we arrive at the job with the trailer.
Nope, not done yet today. We have to unload them and stage them around the hole. For the record, each of those forms is 2' wide x 4' tall. They weigh 40# apiece. Donna and I start slinging concrete forms and fill the foundation hole with more work.
OK, day 2 is complete. Yeah, the burn is definitely setting in....as is total exhaustion.
Ben gave me the number of a young guy that he often uses as support labor. He works for cash and is affordable. Fortunately, he was available and we hired him. It was that extra support that kept us forging forward. The 3 of us spent Day 3 (Sunday) setting up the forms to prepare for a pour the following day. I kept telling myself that this part of the job would be a breeze. Not so.
We used the batter board lines with the plumb bob to mark the top of the concrete footing with the exact location of the 4 corners at wall center. We moved that mark outward by 4" to get to the outside of the 8" thick concrete wall that would be poured there. A chalk line is snapped onto the top of the footing and now we have an outline of the outside of the wall. The forms are set using this chalk line as our guide. Yep; it took pretty much the rest of the day.
...end of day 3.
Good morning Day 4
I knew we were heading into a real tough project for this day 4. When we completed the work we did yesterday, I knew we still had a lot of preparation to execute, let alone try to pour the wall. The weather forecast really put pressure on us cuz it appeared that we didn't have enough time to waste another day preparing. Rain was coming in pretty soon. We needed to pour today.
So....last night, after setting up the forms, I blew a call into one of the local concrete guys that I had originally asked to quote the job. His name is Marvin. Marvin came recommended by Ben (our excavator) and also a neighbor or ours. My few discussions with Marvin proved him to be a good guy. Regretfully, his bid was high enough (along with the other bids that I gathered) to make it fiscally prudent that Donna and I do this job ourselves and pocket the remaining cash. So, here we are. We passed Marvin over, the pressure is on, and we really need his help.
I called Marvin and left him a voice mail. My message was simple. HELP! Well, not really that bad, but pretty much "hey, we're gonna finish forming the walls and pour concrete tomorrow....we could really use a set of skilled hands....can I convince you to join us for cash?"
Well, that next morning, the day of the pour, I had to run to the lumber yard early to pick up some more lumber for form supports. I check my voice mail and Marvin has responded. How cow....what a great guy! Yep, he is not doing anything really productive today and will come out to assist. What a relief!
Marvin arrives fairly early and put us back to work. He quickly senses my rookie concrete status and kinda took over. Works real well for me.
We finish bolstering the forms by pulling a tight string from each corner and then setting the tops of the forms directly below the string. This will yield a nice, straight wall. Then, we use my cheesy laser (Ben took the good one with him) to set marks inside the tops of the forms to designate the top of the wall. A chalk line is snapped and we now have a continuous line all the way around the inside of the forms. The plan is to pour up to the line and finish it there. Since we are at great risk of losing the line with concrete spatter and over-pour, we tap in finish nails about every 3 feet of so, right into the line. Like the grade pins in the footing, we will use these nails to float and trowel the top of the mud.
I have to set some blocks within the form to drop the top of the all where the future slab will run over the top of these walls we are going to pour. This drop occurs at both overhead doors and the service entrance door. I also have to set circular sleeves to allow 2 round holes thru the wall. One hole is for the floor drain that will be piped thru the wall and into a french drain at the exterior. The other hole is for the sewer main to exit to the septic tank. Then, lucky me, I get to spray the entire formwork with form oil. Jeesh, what a mess! And, talk about a long day and critical timing, the first concrete truck arrives while I'm still spraying the forms. Marvin and Donna take control of the pour.
All of a sudden, I hear this loud, raucous humming sound. I look up and Marvin has Donna running the concrete vibrator in and out of the concrete as they move along with the pour. Wow, what a test of strength....Donna kicks it butt. About 1/4 of the way into the pour, I finish oiling the forms and give Donna a well deserved break by taking over the concrete vibrator. Yeah right....a break for Donna....now it's time for her to help me float in the rebar into the top of the wall. This will include floating and troweling the finish and setting the anchor bolts. We are way, way beyond exhausted, and Marvin becomes our beacon of hope. He delivers and works like a well-oiled machine. This inspires both Donna and I to reach way down to find the strength to continue.
At the end of the day, there isn't enough cash in the world to pay Marvin what he really deserves. When I ask him how much cash would square him, he throws out some low ball figure. I trump it up, and give him more, knowing full well I still owe him. He offers to give us a hand when it comes time to pour the slabs. I can see the glimmer of hope in Donna's eyes as I gratefully accept his generous offer. Marvin loads his truck back up and drives away, leaving Donna and I to somehow catch our breath and realize what just happened.
Day 5....is it possible we might get a little break...???
After the wall pour, we collapse into our little 120 sq ft cabin and stay overnight at LNP. The next morning, we get up fairly early to clean up the area a bit and head back home. Yeah, this will be the day we need to catch our breath. It's Tueday now. We started all this last Friday. It's a blur. In fact, Donna gets 2 days to catch her breath cuz I gotta go into work tomorrow (Wednesday) and put in a day of catch-up at the office. This is all well and good, and provides the cushion we need, but it's never enough cuz Thursday morning, we are back on the road at 5:30 a.m. to head back and strip the forms.
So, I'm figgering that this should be the easy part....right? No real thinking, no calculations and measurements. Just tear it apart. Well, that is accurate, but don't forget to figure in the rain that we got overnight to create the jobsite mudpie, along with 5000# of forms that have to be re-loaded onto the trailer. I had called our young buck labor helper to see if we could woo him into some more cash work. No answer....wonder why? So, it's Donna and I against the concrete form world. Let's do it again.
So, how bad was it? Let's just say that we left our home at 5:30 a.m. We returned that evening, pulling into our driveway again at 10:30 p.m. Yeah; that bad. The payback is this:
After we got home at 10:30 that night, I left the trailer parked in our driveway and went back to work the following morning (Friday....it is now 1 week since we excavated the hole). I left work at noon so I could come back home and drive the entire form package back to the rental place and get rid of it....once and for all. Like all the other steps in this short journey, it worked like clockwork and by 4:00 that afternoon, I was driving an empty truck and trailer back home.....home-sweet-home. Deal done.
Now, we let it cure for a week or so to gain some of the strength in the walls so that it can be back-filled with soil from the outside, and the interior slab work can begin. We breath deeply and affirm our statement: new-found respect for the guys that do concrete work.
Well, time passes way too fast and planning cannot wait, so the next day I'm on the phone to Ben to make arrangements for the back-fill and slab preparation. It looks like this coming Tuesday will work into his schedule. That plan makes sense to us also; it gives the walls 8 days to cure....perfect.
I am used to seeing limestone aggregate being used to fill foundation interiors. A vibratory compactor is used during the installation to tamp it down as you move along. Ben tells us (once again) that this is not how things are done around here. Pea gravel is the player. It is small enough that it self-compacts; just dump it in and move it around to the desired grade. Makes sense to me, and who am I to argue...? Ben starts trucking in what turns into 60 tons of 1/4" washed pea gravel.
We spend a couple of days working in oppressive heat and humidity. While Ben is running his truck to the quarry, we continue to prepare for the slab pour. We are going to pour 2 separate slabs. The first is the larger. It is the garage floor. It comes in at 27' square, reinforced with wire mesh. The plan is a 5" thick slab. The second slab to be poured will contain reinforcement AND radiant heating tubing, hence the need to separate the pours. This means that we have to install the final garage floor drain pipe, the perimeter asphalt impregnated expansion joint, the forms at the garage doors and service door, and a form to separate the garage floor from the radiant tubing floor. This list keeps us busy.
Finally, all the necessary pea gravel has been dumped in. Ben uses the backhoe to push it around a bit to save us from having to move the bulk of it with shovels and rakes. We set up the laser and measuring rod and use it to carefully create a gentle slope from the exterior walls to the drain line pipe sticking up in the center. A drop of 1-1/2" is used as the grade. The top of the pea gravel is set 5" below the final height of the slab, graded with rakes and shovels to achieve the target slope.
We are dying from the heat and humidity, but the show must go on. This just becomes another subtle reminder of the hard work these guys do...day in, day out.
After scraping a little off here and pushing a little more there, we arrive at what appears to be the final grade for the pea gravel. We lay in a layer of 6 mil vapor barrier (plastic sheeting) and install the wire mesh. We are using 6 ga mesh with 6" x 6" spacing. We have elected to use the flat sheets; 8' x 15'. 8 sheets were trailered to the jobsite a couple of weeks ago. Ben, sensing our exhaustion and need for support, uses the front-end-loader with some chains on the backhoe to carry the sheets to thje edge of the foundation for us. Every little bit helps; we are appreciative. We place the sheets of mesh into the slab zone, trimming the edges to allow it to continue up onto the wall areas at the overhead door and service door cutouts. Since we are not going to pour for a few days and we don't want the wind to blow and mess up the plastic sheeting, we leave the mesh laying flat. The day we decide to pour, we will go around and insert 2" tall plastic support chairs to raise the mesh to it's final resting height within the concrete slab.
We did run into a little problem during all this hoopla. The masonry nails that I had hoped would sufficiently hold the asphalt expansion joint to the walls were not working. I tried cut nails and fluted/round nails....garbage! These expansion joint pieces are key players and must be firmly set against the wall. Not only will they provide the expansion cushion for later, they will be used during the pour to support the screed board as the concrete is struck for rough grade....very important that they don't move. I know the only sure cure is a ramset nailer, but it's not in our tool arsenal. This step will have to wait. We have already snapped the chalk lines around the wall perimeter, so we have all the necessary height markings. We elect to leave this step for another day....a day when we have purchased a ramset nailgun. It should go pretty quick, so the lost time is not severe.
We select this point to be done until pour-day. The area of unfinished pea gravel will be the second and final pour....soon come.
We returned 3 days later, on Sunday morning. We're packing a new ramset nailgun, along with an assortment of fasteners and charges. A little experimenting and we find a suitable system to attach the asphalt expansion joint to the concrete stem wall. The bar chairs are also installed to raise the wire mesh.
A small form is added to one corner to preclude the slab pour. It is the area where our main soil pipe will exit the foundation on it's way to the septic tank. The pipe is inordinately high in elevation and not ideal engineering by any stretch, but it is our only acceptable option. Referring to the Juice, Water, and Waste topic (see text entry further up this page), we are forced to begin the septic flow extremely high in order make the entire septic system work. We will have to "hide" the soil pipe with a relatively thin layer of soil near the foundation and be very careful in that area with any substantial weight. The pipe is actually running directly into an uphill grade, so it will reach decent depth fairly quickly.
The final step for this day, the day before the pour, is to mark the final grade at the drain pipe in the center of the slab. We have selected a 1-1/2" elevation drop from the slab perimeter to provide suitable slope to the drain. We shoot the elevation and mark the pipe with a piece of ductape. The bottom of the tape is the target.
Go to bed early cuz the hired guns will arrive early the following morning. We have already scheduled the concrete trucks to meet the same schedule; first delivery of the day.
More 'crete, if you please...
We calculated the slab pour to use about 11.25 yards. Since the available trucks will only carry about 10 yards, 2 are scheduled.
When we made the decision to handle as much of the foundation work as we felt we could, we knew that doing the flat work (slab pours) was beyond our DIY capabilities. Yeah, we have done some smaller slabs on our own, but this is a bit over the top for Donna and I. We knew right from the beginning that we would hire in help on this portion of the job. Ben and Marvin accept the job and are hired as helpers. Yeah...right...helpers, huh? Well, technically, they are hired help, but Donna and I gladly accept the fact that they will be running the show. Our job is support, labor, and go-fer....works for us.
The first thing we do is set a couple of grade stakes to determine the slab slope. A string is pulled from the top of the perimeter expansion joint to the bottom of the ductape on the drain. A pin is pounded in midway, setting the top of the pin even with the tight string. This is done on directly opposing sides of the drainpipe. The first part of the pour will be directly over this area. A continuous mound of concrete will be screeded flat, establishing the slope across the center of the slab.
The next step is to run another mound along the slab perimeter walls that parallel this center mound. The concrete puddle is struck to elevation with hand floats, using the expansion joint as the gauge.
With these screeded mounds established, the space in between is quickly poured and screeded. Ben and Marvin use the mound heights at each end to guide the height of the screed as they "saw" back and forth to establish the rough slab elevation.
The second truck arrives like clockwork and the slab pour is completed. As Ben and Marvin's helper, I fared pretty well. They only yelled at me about a dozen times for screwing up. I also believe that this could have easily been 3 dozen times if it weren't for the fact that I was the guy with the checkbook at the end of the day.
The bull float makes the next appearance. It is tools like this that become part of the good decision to hire in the help. There is no way that I wanted to rent something like this, let alone use it for the first time on MY project. They float the entire slab, then attach a skate-like blade to the bottom to cut in control joints.
By this time, the sun has come over the trees. The temperature is elevating, but it shouldn't get over about 85 degrees today. The big variable is the wind. We are getting gusts that feel to be in the 25 - 30 mph range. The show must go on.
We wait for about 30 minutes after floating. The slab has hardened enough for Ben and Marvin to really earn their keep for the day. They have brought the power trowler, but the surface is too soft to walk on and it's drying pretty quickly due to the sun/wind combination, so the only option left is to begin hand troweling. I am given the difficult job (Ha!) of working the slope for the rain ledge at the overhead door openings.
At the end of some total 6 hours, Ben and Marvin pack it in and collect their pay. We are pleased with the results.
Dski and I keep the slab wet by occasionally sprinkling the surface with filtered pond water that is pumped up through a hose. We want to attempt slowing the surface from drying too quickly. The wind is really tootin'.
The next step to complete this foundation work is pouring the second and final slab. We separated it out as a different pour for a few reasons. The first slab has a pitch to a french drain line. This second slab pour will be flat. Moreover, it will be cast with a bit more than reinforcing embedded. It will also contain a radiant heat tubing matrix and the related insulation. It is planned to be living space in the form of a shop (sometimes referred to as a man-cave). At 15' x 28', it should fit the bill. To allow some flexibility in design, we are going to lay out the windows to allow for the possibility of inserting a wall at the center, creating 2 roooms of 15' x 14'.....ie; bedroom size. Quite frankly, development of this area is so far down the road in the construction schedule that the only concern we have right now is getting the Pex tubing into the slab and keep on moving along with construction of the structure.
The forms from the first slab (along the edge that separates the 2 slabs) are removed and we begin preparing slab #2. We had to truck in a couple more yards of pea gravel, then rake it out level. 1-1/2" rigid styrofoam insulation is attached to the entire slab perimeter. We use the ramset with small squares of plywood as a washer of sorts to keep the nail from completely blowing thru the foam.
We used the hammer drill to tap holes into the first slab, then epoxied 3/8" smooth steel dowels into the holes. This will tie both slabs together, helping to stabilize any potential movement.
A layer of plastic vapor barrier is laid over the graded pea gravel and the entire area is filled in with 2" high density foam insulation.
All the blowout holes from the ramset/plywood block holes and the cutouts from the dowels are filled with expanding foam. Any cracks around the perimeter (where the floor meets the wall) are also foamed in. Bring on da Pex.
Before this project, I didn't know squat about Pex. Quite frankly, I still don't...but....there is plenty of schooling available online and we managed to stumble thru our first Pex experience.
I wound up purchasing a roll of 1/2" x 1000' oxygen-barrier Pex from an Ebay store. They also supplied the necessary manifold and the plastic staples to hold the tubing down to the insulation. I wound up on my hands and knees, wrestling the Pex snake while Donna woman-handled the entire roll by rolling it ahead of me as we meticulously and laboriously stapled it down.
There are 3 separate tubing circuits. The idea is to run the outbound side of a circuit toward the perimeter walls, where the floor is likely to be the coldest. After it catches a portion of this colder outside wall, the circuit is guided back into the the interior, weaving back and forth and eventually winding up back where it started. This is where the manifold is located and controls all the circuits. Of course, we have selected a manifold that is designed to handle 3 circuits.
We have temporarily mounted the manifold on a make-shift 2 x 4 frame, constructed in the area where it will eventually wind up permanently. A pressure gauge and schrader valve are installed. The entire system is pumped up to about 45 lbs and monitored for leaks. Yep, we found leaks, but fortunately they are all located at the connections between the Pex and the manifold. We move forward preparing for the concrete pour, but occassionally check the pressure to make sure all is air tight.
The reinforcing for this slab will be #4 rebar (1/2" dia) set at 18" on center. 24" on center is acceptable practice, but I am the King of Overkill and have the necessary steel available. Since the only other consideration is allowing enough room for the guys doing the concrete to step between the reinforcing, I make sure my hired guns don't have feet over 18" long and finish laying in the steel. The rebar matt is laid up on plastic bar chairs, elevated 2" above the foam base. The slab will pour at 5" thick.
I should back up a little to explain the area where the Pex tubing enters and exits the slab. A buffer must be provided so that the Pex is not transitioning without protection. We have chosen 3/4" PVC electrical conduit elbows. They work great.
We also added a 7th tube to the mess. It is connected to nothing, but will allow another option (learned during research on the www). If and when we actually fire this system up, we will need to adjust the flow of heated liquid by use of a thermostat. The simplest way is a wall thermostat. The downside to that system, though, is that the wall thermostat will react to the ambiant air in the room, while the real player (the heated slab) is changing temps at a different rate. The best way, then, to monitor the slab heat would be to have a thermostat built right into the slab itself. With an empty tube running into the slab (and somewhat separated from adjacent heating tubing), a thermistor can be inserted; a temperature probe of sorts. This will be used to adjust the flow of heated liquid thru the slab. The probe tubing can be seen in the above pic. It is the 3rd tube run from the left/top of the pic, runs out about 5 feet, and terminates at a brass fitting to cap it off.
OK....bring on the 'crete....again.
The Ben and Marvin Show is scheduled for their final tour. I, once again, accept the role as their go-fer and the final pour is on. Everything I have read assures me that the Pex tubing is plenty resilient and will take the abuse of being walked all over during the concrete pour. Hard to believe, but there's no other way. We watch the fresh concrete for bubbles that would indicate a leak. Should this occur, we would have to scoop the 'crete from the area of the breach and allow it to cure before we could return to fix the compromised Pex area and repair the slab crater. We found no areas of bubbles and the pressure maintained on the gauge. Whew!
Since we got some surface/finish cracking on the first slab, I am very concerned for the finish quality on this slab. I have fibreglas reinforcing added to the mix at the plant and they send along 5 gallons of Kure & Seal. The fibreglas strands surely cannot hurt the project and might aid in keeping the finish tight. The Kure & Seal will be applied as soon as I can walk on the curing slab, some hour or two after the pour is complete. It turns out to be a very good decision and the final slab looks great.
WARNING NOTE FOR THOSE THAT MAY FOLLOW THIS PATH.... Kure & Seal is solvent based and will eat thru foam insulation like a hot knife in butter. We nix'd spraying it on with a tank sprayer and used the more controlled method of rolling it on with paint roller. We kept it about 2" away from the foam perimeter. Good decision...very good.
The next facet of progress was creating an area for storage outside the foundation. We can't use the concrete slab areas because we need that space for framing the walls. This would be a good time to create some sort of driveway apron outside the garage door openings. This project would be part and parcel to completing our french drain. Our excavation contractor, Ben, is a very busy guy and timing is everything when we need his help. It was our turn this weekend and Ben brought the dump truck and backhoe.
We designed the foundation with a french drain for the garage area. The slab pours were sloped to a 4" PVC drain that we ran to the stem wall of the foundation and stopped. It's time to pick up where we ended and finish the drain line.
We lay out the drain field and mark it with spray paint to, marking off the end of the trench 35 feet away from the foundation.
Ben digs the hole. Donna and I lay in some cheapo landscape fabric in a (feable) effort to keep the gravel drain field separated from soil infiltration. Ben fills about half the trench with gravel. We glue up and install the perforated pipe sections, verifying a negative slope away from the foundation.
The rest of the trench is filled and one more truckload of gravel is added to the leftover trench gravel to complete an area of about 30' x 35' as a gravel driveway apron in front of the garage door openings. Drain complete.
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