Slabtek Structural Slab - Part Two

Once inspections were completed, we were finally able to pour the concrete slab.  We used 4,000 PSI concrete which is more structurally stable and allowed us to pour a thinner slab.  In total we used 40% less concrete than a traditional structural slab.  The higher PSI also has a greater crack resistance and richer, darker gray color which is benefical to us since the slab will be exposed.

The slab was poured, hand trowelled and machine trowelled on the same day.  The entire process took approximately 10 hours.  Considering that this is the finished floor of the home, a super smooth finish was important.  Marshall Bailey and his crew did an impeccable job.  After approximately five days the slab was post tensioned by stretching the cables and bolting them to the slab.  The bolts were recessed in the side of the slab and the holes were filled with concrete grout.  One week after the slab was poured it was ready to be raised off the ground.

In the images you can see that there are 3" diameter discs approximately every 10 feet.  This is where the slab lifting mechanisms are located.  A pole is attached to the device and each turn raises the slab 1/4".  We had approximately 4 workers turning at once throughout this process to raise the slab 5" off the ground.  Once the slab was raised the discs were filled with concrete grout and leveled off.  We considered placing a round piece of stone in these holes as an accent and we may still do so in the future.

The slab being hand trowelled shortly after being poured

Our nice smooth machine trowelled slab

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The slab cantilever over the back edge of the hill

The Backyard

When we decided on this location and purchased the land, we still had no idea what our backyard would look like.  The trees and bushes were so dense and filled with vines that we could barely see the ground below.  Once winter began we finally got our first glance of what our future yard would look like.  Since then we've had the vines and underbrush removed for an even better view.

First View of the backyard

It's hard to see, but there is a fence that runs along the back of the property

Yes, that is a dart train.  We actually chose this lot because of it's wooded view with the Dart train behind.  "Urban" is the key word here.  The train really makes you feel like in you're in the middle of metropolitan area.

The backyard after the vines and undergrowth were cleared.  Our yard runs from the orange flagged stake on the left to the orange flagged stake on the right.  Our pets cannot wait to run up and down the hill chasing squirrels.

Slabtek Structural Slab - Part One

The Dallas Fort-Worth area is known to have very difficult soil conditions for building.  The majority of the soil is composed of clay and is highly expansive. Expansive soil, expands and contracts due to changes in the moisture content of the soil, causing structural problems through differential movement of the structure.  In many cases the soil type may vary underneath the structure, causing non-uniform movement.  When sections of the structure move separately, damage can occur to the foundation and framing.  This is most often seen as cracking in the slab or foundation, cracking in interior or exterior walls and misaligned doors and windows.  As with much of Dallas, the soil under our property is listed as expansive and a structural slab is required.

Structural slabs have long been referred to as the “Cadillac” of residential slabs.  There are two reasons for this:  1. The slab is structurally suspended above the ground to isolate the slab from soil movement.  2. They are the most expensive type of slab to construct.  They are often difficult to design and build, require additional excavation of the site and are very labor intensive.  Given these issues Diane Cheatham of Urban Edge Development pointed us towards the new Slabtek slab system.

Slabtek is a unique system that is more economical to build, requires less construction time, and allows for future adjustment of the slab.  The Slabtek system also uses 40% less piers and approximately 40% less concrete than a typical structured slab, therefore contributing to our green home.
A slabtek slab is a post-tensioned concrete slab that is poured on the ground and then raised to the desired height using lifting mechanisms that remain in place.  These lifting mechanisms also allow for future adjustment of the slab to counter shifts in the soil, preventing any future structural issues.

For additional information on this revolutionary product see: http://www.slabtek.com/SLABTEK.HTM

Leveling the site and putting the form boards in place

The measurements must be extremely precise on this project so we visit as often as possible.

Ross standing on the form boards for our bedroom cantilever.

Getting the slab ready for pouring

Adding the rebar and lifting mechanisms

Geothermal Heating and Cooling

A geothermal heat pump doesn’t use fossil fuel or refrigerant to heat and cool your home.  In the simplest terms, in the summer it extracts the heat and humidity from your home and in the winter it pumps the heat from the underground geothermal loop into your home.

According to US EPA, “geoexchange is the most energy-efficient, environmentally clean, and cost-effective space conditioning system available”. With operating efficiencies of 350% to 550%, geothermal will out perform any fossil fuel heating system.  With geothermal heating and cooling, you not only save money, but also protect our environment.  Each geothermal system installed is equal to planting one acre of trees or taking ten cars off the road.  The typical cost of installation 2000 sf home with dual control zones is approximately $20,000.  If you spend $2000 less on heating/cooling per year, this equals a 10 year 100% payback.  That doesn’t even take into account the 30% tax credit on the total cost of installation,
which makes the payback closer to 7 years.

For more on how geothermal works, the link below gives a detailed description.

http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html

The largest part of the cost for a geothermal system is the drilling of the wells.  The geothermal contractor will do a model to calculate how many wells your home will require.  Our house, which is less than 2000 sf, required (3) 300 foot deep wells or a one 3 ton unit with dual zones.  Our second floor will be controlled separately from the first floor using a programmable wifi enabled thermostat.  The benefit of using this type of thermostat is being able to log-on from anywhere and adjust the temperature of your home.

Geothermal Air Conditioning Service, LLC is the contractor we used for our system.  The photos below show the beginning of the geothermal process.

The drilling rig starting on the first well.  The orange flagged stake is marking the North side of our property.

The orange flagged stake in this picture is marking the South side our property, which is 40 feet wide and 125 feet deep.

We had some rain in the midst of the drilling which added to the mess.

Geothermal was the first part of construction, so the tubes were left out of the holes until they have something to connect too.  This process would be slightly different on an existing home.

The 300 foot deep wells were placed 20 feet apart along the length of our property.

Pre-Construction Party 11.11.11

Thank you to all our wonderful neighbors who attended our pre-construction party on 11.11.11.  It was Ross's birthday as well as the day we recieved our permit, so definitely a good day for us!

We had the idea to try and set up our 'dining room' on the lot and we served wine & cheese to our 25 guests.  This was a great way to meet our new neighbors before construction began and we are so excited to be part of such a great neighborhood. 

I tried to snap a picture in the dark during set up.  It didn't turn out, but you get the idea.  We did actually end up being able to plug in the lamp and that made a big difference!

Finally . . . . . it's official!

After spending another 4 hours at the city (on top of the 4 hours already spent) we finally recieved our construction permit today!  There were some hang ups due to the FEMA 100 year flood plain line moving, but it's all been worked out now.  We are thrilled that it is being issued on 11.11.11, which also happens to be Ross's birthday!  We haven't had much more time to work on the renderings, it's so hard to find time to do work for yourself, but updated drawings are below.  You should be able to click on the images for a larger view.

Floor plans and Elevations - Slight update

Just a small update with the final plans and exterior elevations . . . .

First Floor Plan

As you can see we've tried to make every bit of space functional by minimizing circulation spaces that aren't part of the room as a whole.

Second Floor Plan

Front Elevation (facing East)

Side Elevation (facing South)

Back Elevation (facing West)

Rear Elevation (facing North)