First structural inspection

  Between holidays, travel and weather delays this update has been delayed far longer than i would have anticipated .  However work has continued as well as can be achieved given the weather that we’ve had in north Georgia this winter.

   The next major milestone after beginning panel installation was the initial inspection by the structural engineers, Baku Patel and his assistant Srikanth Bajaj, of Palmer Engineering.  Since the construction method is new to the area the local planning department required us to contract with the structural engineering firm for onsite inspections of the panel installation.

   Before the discussion of the inspection a little background on the house is in order.  The basic plan of the house is a rectangle, with two bump-outs on the south side, a porch on the west, a mudroom on the east and a jog in the north wall.  The bump-outs on the south wall and the mudroom on the east lend strength to the walls; this meant that additional structure was needed on the west and north.  We ended up adding two shear walls, one on each side.  The north wall has eight feet of unbalanced backfill and the south is at grade.

   The first inspection was set for December 15.  By then the contractor had completed the following:

•  Dowels inserted and epoxied for all installed walls panels

•  Shear wall on west side - 11-foot panel

•  West wall from the shear wall to the north corner - 18-foot panels

•  North wall - 18-foot panels

•  East wall from the north corner to the intersection with the mudroom - 18-foot panels

•  Basement window  in the north bedroom - opening cut, mesh and rebar in place and ready for mortar

  The engineers were able to review the following structural elements:

•          FastFoot footing

•          Dowel spacing & length

•          Dowel to rebar connection in pilaster

•          Available depth for mortar behind rebar in pilasters

•          Application of RG1 mesh at interior and exterior corners

•          Application of RG2 mesh where necessary

•          RG3 mesh and rebar at top and bottom of window opening

•          RG2 mesh at corner of window columns

  

   There are a number of structural issues involved in building our plan using SCIPS.  The first issue was how to build the below-grade SCIPS walls.  To the best of my knowledge most houses built using GCT panels have not involved significant panel area below grade; most are cast concrete walls below grade with SCIPS panels above.  We wanted the added R-value of having the EPS below grade so additional strength was required.  The solution was to build pilasters - mortar and rebar columns - into the below-grade portions of the wall on the exterior surface.  These were at 16” OC. The rebar was placed inside the galvanized wire and the foam burned out to allow sufficient room for the structural mortar.  The wall rebar was tied to the dowels to meet code.

   The second issue was how to support the floors.  Both the main floor and the loft floor (approximately half of the area of the main floor) will be concrete, placed over steel floor joists.  That’s a lot of weight so we needed additional strength.  The solution was pilasters on the inside, also 16” OC, but offset 8” from the outside pilasters to preserve as much R-value as possible.

  The pilasters and rebar can be seen here:  note that the final burnout of foam and positioning of rebar had not been done when this was taken.

   The third structural issue was how design the window openings for maximum strength and minimum thermal bridging.  The solution, which was implemented and ready to inspect on the first window opening, involved burning out the foam to allow for the installation of horizontal rebar above and below the window, on the inside and outside wythes of mortar.

  The window opening, with rebar above and below, can be seen in the following picture:

   We had quite a crew assembled for the inspection.  In addition to the Baku and Sri from Palmer Engineering we were joined by Joe Martin of the architectural team, plus Victor Camacho and Scott Miller of Gulf Concrete.  Victor is VP of sales and operations as well as being an engineer, while Scott is the sales and technical advisor.

The video of the day of the inspection is here .

Results of the day’s review are below.

   The Fast-Foot footings met with general approval.  Placement of the dowels was quick.  Larry’s recommendation that we use epoxied dowels instead of rebar wired in place before the pour proved to be successful - it would have been quite difficult to keep the rebar in position during the pour.

   However, the dowel placement itself could have used a little more thought prior to installation.  Our original plan was to place the dowels so that they fit just inside the wire of the GCT panels.  However, after placing the panels and reviewing the situation prior to mortar application it was clear that the dowels should have been 1/2” inside the wire, in order to guarantee adequate mortar coverage. We ended up using spacers to move the rebar 1/2’ inside the wire.  Since the rebar was already placed and could not be bent where it came out of the concrete we ended up adding mortar for the bottom 18” in order to get the proper coverage.

   The application of the additional mesh is relatively straight-forward and no problems were identified.

   The plan for the windows underwent significant revision.  Instead of using rebar and burning out the foam the engineers agreed that an additional layer of mesh would be sufficient.  This would preserve the full foam for insulation and simplify installation.  

   All in all it was a successful day.  Now, on to mortar placement!

Placing the SCIPS panels – week one.

   Once the FastFoot foundation was completed it was time to move onto the task of erecting the SCIPS panels.  The foundations were either 30 or 36 inches wide, based on structural needs, and twelve inches high.  The structural engineer had specified two rows of rebar dowels, inside the wire of the SCIPS panels, on 16” centers.  The two rows would be staggered in order to maximize the EPS thickness.  Since there is up to eight feet of unbalanced backfill on the north side, tapering off on the east and west, and a lot of windows, the structural engineers have developed a series of pilasters – internal columns with rebar, carved out of the EPS, to transfer loads to the foundation.

Background on the panels:  

   This is a view of the panels as they are in the wire press at GCT.  The panel shown appears to be a PSG panel, which has channels for concrete and is used where additional strength is needed. 

A profile of the panels is here:

Note that the panels have corrugations which allow deeper mortar in portions of the finished wall.

We are using the PSM240 panels.  The dimensions are listed in the table below.

GCT SCIPs Dimensions Guide
PSM - Wall/Roof Single SCIP
Walls and Roofs
SCIP Model	Aprox. EPS Thick. (mm)	Aprox. EPS Thick. (in)	Aprox. Finish Section Thick. w/Conc. (in)
PSM40	39	1.54	4.24
PSP75 Partition	74	2.91	4.95
PSM80	79	3.11	5.81
PSM100	97	3.82	6.52
PSM120	117	4.61	7.31
PSM140	136	5.35	8.05
PSM160	155	6.10	8.80
PSM190	195	7.68	10.38
PSM240	242	9.53	12.23

   Although the EPS is 9.5 inches thick at any point the actual thickness, from the highest point on one side to the highest point on the other, is closer to 10.25 inches.

   Setting the panels involved multiple challenges:

1   1.       Stage all the bracing material and tools
2.       Move the panels
3.       Get the panel vertical and keep supported
4.       Lift it and slide down over dowels
5.       Make sure the panel(s) are level and plumb
6.       Brace
7.       Re-level and re-plumb
8.       Install second row of dowels

9    9.       Complete rebar and pilasters by burning out the foam and dropping rebar into the cavity.

   Moving the panels proved to be a manageable task.  Although bulky, the panels weigh approximately 100 pounds each, according to the workmen on the project.    The first panels, located near the home site, were carried by hand to the work area.  Later on we anticipate that a tractor with forklift blades will be used.  Larry had worked out a method to lift the panels which used short lengths of rebar, pushed through the EPS below a wire, as handles to allow the panels to be hoisted vertically.  The holes left after the rebar is removed can be foamed before the mortar is applied.

   The first panels to be installed were on the north side of the house.  All of the panels on the first course of the north and west sides, as well as most of the east, are 18’10” tall.  There are two shear walls inside the basement that are 11 feet tall.

   After researching the installation process Larry decided that the best way to approach the panel placement was to epoxy the outside row of dowels into place, then lean the panel against them from the inside while pushing it to vertical.  At this point the rebar ‘handles’ could be pushed through the panel and used to lift it and drop it over the dowels.  The panel could be brought close to plumb, then the FabForm brackets and walers could be used to bring it to plumb.  At a later date the dowels could be dropped down between the wire and the foam.  Epoxy would be placed in the holes and the dowels inserted then the rebar for the pilasters would be dropped into the panels.

   The crew consisted of Larry and three workers, with occasional (very occasional) help from the future homeowner. 

The process:

Footers, braces and dowels ready for placement of the first panel:

Moving a panel:

Placing the first panel:

Temporary bracing for the first panel:

   Perfecting the method.  Note that four people can set up the panel:  One to start lifting and then walk the panel up, one (out of the picture) with a 2x4 to push the panel to vertical, one to stabilize the base and one (on the bank) to control the top.

Close-up of dowels and panels:

Close-up of adjustment bracket

Bracing system in use

   The video of the first day of panel placement is here:  

Day 1 video

   Due to a heavy fog overnight the first few minutes are fuzzy but nothing of importance was missed.

   Placing the first panels was an adventure!  Bear in mind that to the best of my knowledge none of us had ever seen a SCIPS panel installed in real life.  Larry had visited job sites where GCT panels were used but they were all past the panel installation stage.  Our project is a bit more complicated than many due to the pilasters:  the dowels are taller than those on most GCT projects.  There were a several lessons learned during the first day:

1.      Eighteen foot panels are tall.  Very tall.  It was clear before the first panel was set that we needed a way to control the top of the panel.  Luckily the first panels were on the north side, which had been excavated, so the crew member with ‘the hook’ was closer to the top of the panel and could control it easier.  A fourteen-foot 2x4 with a hook on the end proved sufficient for the first few panels, until the gap between the foundation and embankment widened.
2.         The wire flanges on the panels provided major headaches.  There were several occasions when the crew would lift the panel high enough to clear the dowels but were unable to drop it because the wire on the panel being placed became tangled with the wire on the panel already in place.  (Note on the diagram above that the wire extends past the panel on the lower left and upper right.  This gives an overlap in the mesh in the back and front to use in tying the panels together with hog rings.)  The solution is to bend the wire before the panel is vertical so that the wire from the two panels doesn’t come into contact.  The crew member controlling the top of the panel also needs to make sure that he keeps it away from the other panel until it is set down over the dowels.
3.    .    Wire at the bottom of the panels, where it is set on the foundation, could also pose problems.  If it is a little longer than the panel then the foam of the panel can’t contact the footer and must be snipped off.  The crew also learned quickly to check this before lifting the panel.
4.        Make sure that you check all dimensions of the wall section after placing a panel.  In the first section the biggest problem was that the top of the wall was leaning away from the starting point in the same plane as the wall, not perpendicular to the wall as one might expect.
5.        Long panels are inherently more unstable than shorter ones.  It appears that panels longer than twelve feet are made of two pieces of EPS.  Although the mesh is welded there is still a small but noticeable hinging effect where the two pieces of foam meet.
6.        Using the Zont/Zuckle bracing system from FabForm was definitely the way to go.  Adjustments to get the panels plumb were easy to achieve with just a drill.  The system can be seen  here

   The installation process was significantly revised the morning of the second day.

   Justin, one of the crew members, spent some time looking at the work that would be required to drop the second row of dowels into place, epoxy them and then drop the long rebar into position.  His recommendation was that we do more work before placing the panels in order to save time later.  Holes for the dowels were widened slightly, to make sure that the dowels would drop into place easier.  The panel was burned out slightly and ten-foot lengths of rebar were wired into place inside the mesh before the panel was moved to the wall.  At first we were doing the rebar on the inside only, where the dowels were not in place.  Later the crew started adding rebar on both sides.  Once the rebar was being added on both sides it was  clear that a better work surface was needed so sawhorses were moved into position  to make it easier to flip the panels.  Finally, the heat gun that we started out using proved to be too slow so we moved to a small butane torch, then a larger torch.  We are still looking for the best way to burn out the foam in order to prep the panels.

   Lessons from the remainder of week one:

1.    We had been warned ahead of time by Alton and Scott not to use too many hog rings until the wall was in the final prep stage for mortar, since one could lock the wall into a monolithic piece before the final adjustments were made.  The solution seems to be tying the panels together, high on the wall, with ½” temporary fencing tape.  It’s easy to cut, holds well when knotted and is easy to remove.  One source is  here

2.    Cutting the panels is more difficult than it might seem.  Cutting the wire is straightforward; it’s getting a good edge on the foam that’s difficult.  Most saws are too flexible and you end up with a wavy cut.  After a lot of trial and error the crew discovered the perfect solution:  a chain saw. Unfortunately it was deemed unacceptable for safety reasons so the latest plan, which is working well, uses chalk lines on both sides.  A Sawzall is now used to cut from each side and then the edge of a saw is used to shave the edges square.

3.    Corners are a pain in the anatomy.  See item #2 above for one reason, plus the bracing is more complicated.  In short sections it’s easy to move the plumb section of the wall to meet the out-of-plumb section rather than the reverse.  One of the tricks to keeping corners aligned is to tie the temporary fencing tape on the outside of the 90-degree angle.

4.    It’s far better to do as much as possible to the panels while they are on the ground.  Burning out the foam and inserting rebar are significantly easier when the top of the panel is not 18 feet up in the air.

5.    When unloading the tractor-trailer from GCT take the time to stack the panels so that the tractor can get close to them.  We had unloaded the truck as quickly as possible; unfortunately this created work later since the crew had to carry panels a longer way.  As mentioned in an earlier post we are very limited on space, however storing panels so they are accessible in the order needed may be possible with future deliveries.

   For those who want to see the full week's work it is here, all 22 minutes of it.

Logistics issues!

One thing I had failed to fully consider was exactly how much material goes into a SCIPS house.  EPS foam is wonderful insulation but when every panel has 9.5 inches of foam it really adds up.

Background:  the SCIPS materials from GCT will add up to five tractor-trailer loads.  This is broken down into two separate orders:  two loads to be followed by three loads.

   Challenge number one was getting the material to the property.  The home-site is on a small private road.  A very small private road.  Deliveries from GCT were originally scheduled to arrive on 52-foot flatbed trailers; however after the dispatcher visited the property he and Larry worked with GCT to fit everything on 48-foot trailers instead.  I was worried that the drivers would not be able to get the truck into the property so had made arrangements to use the parking lot of the community center to unload if it became necessary.  Luckily both truck drivers were skilled enough to back from a narrow two-lane road onto a narrow one-lane road so we didn’t have to go to the backup plan.  However it was quite a sight to see. 

    We had just enough room for one car to get by once the truck was positioned. 

Challenge number two was getting the material off the truck and stored on the property.  There were three types of materials: 

• ·         the panels (bulky but light),
• ·         pallets of wire mesh (small and not too heavy) and
•            pallets of mortar mix (small and very heavy).

 The first big limitation was that the forklift we had could only handle one ton loads and there were two tons of mortar on each pallet.  This meant that half the bags on each pallet had to be manually offloaded to a separate pallet before the remainder of the pallet could be unloaded.  It also doubled the amount of space we needed for storing the material. 

   The next problem was that the driveway was too narrow for the forklift to move the panels from the unloading area to the storage area.  Most of the panels in the first shipment are 18’10” tall.  This meant that the panels had to be taken from the truck, unstrapped and moved, four at a time, to a lowboy trailer.  Since I had decided to keep as many trees as possible around the home site there was not enough room to turn the truck around so the driver had to back all the way down the the 200 yard, winding driveway with a full load, unload, and then drive back to the entrance to pick up the next load.  The only real hold-up came when the driver of the lowboy trailer locked his keys in the truck, but even so the freight company driver said we were quicker unloading than the loading process at the factory.

   After the success of unloading the first load Larry scheduled the second load for the following day and the unloading process went even quicker.

Storing the materials was simple:  we had stocked up on pallets so the mortar storage was simply a question of finding space near the home site and the planned location for the mortar pump.

  We were able to store the panels off the ground on either dunnage from the truck or 4-foot lengths of railroad tie.  The final step was to double-tarp the mortar and spread wood chips around the panels which were not on pavement, to keep the rain from splashing the red Georgia clay on them.

  Now on to placing the panels!

Additional thoughts on FastFoot footings

   Since FastFoot footers rest on the ground, instead of in the ground there are two situations which users may need to consider.

• Three sides of the footings are exposed to the air, instead of just the top.  This means that the risk of freezing would be significantly higher than with traditional footings.  I ended up covering the footings with wheat straw and tarps when it went down to 18 degrees F shortly after they were poured.  We had no damage from the cold temperatures.
• The footings make an excellent dam:  you need to plan ahead to make sure they can drain.  We had three inches of rain one night and if we had not planned ahead we would have had a lake on our hands.  Larry had a sump pump available as a back-up if needed but the homesite drained quickly.

Excavation and Footings

              On October 30 the heavy equipment arrived to begin the excavation.  It was finished on November 5.

Notes regarding the construction camera: I changed the exposure rate several times in an attempt to find the best way to document the process.  I ended up with more exposures per minute, a five-second interval. I deleted early morning and late afternoon times when nothing significant was happening in order to shorten the film. I also had to move the camera as excavation continued.

A link to the construction camera footage of the excavation is here:

Excavation

The footing subcontractor pronounced the excavation a success.  The maximum deviation from the desired elevation was less than 1.5 inches.

               Once the excavation was finished it was time for the installation of the FastFoot forms.  The final design of the foundation included 36” wide footings, 12” deep, on the west side and 30” wide footings, 12” deep, for the remainder of the foundation.   The thicker west footing was required because there is a stud wall inside the SCIPS wall on that side.  We decided to add 6” in width on portions of the south in order to support the deck; our goal is to support the deck as an independent structure rather than using the SCIPS wall as a structural member.

                Basic information on the FastFoot system can be found here:

http://www.fab-form.com/fastfoot/fastfootOverview.php

http://www.fab-form.com/fastfoot/fastfootInstallation.php

               This video gives an overview of the setup and concrete placement*:

FastFoot Footings

                The finished FastFoot fabric, bracing and penetrations before placement of the concrete: 

Warning:  Wide angle lenses make straight lines look curved!!

East side from the north

 West side from the north

Transition from 36" to 30" footing

Footing penetration detail:  radon mitigation

Close-up of Radon mitigation pipe

                The pour in process:

Beginning of the pour

Screeding

Final level check

              

  Completed footings:

 From the northwest

North side from the west with shear wall

Mudroom from the north

Center of the south wall

Sanitary line on south side

                The verdict from the subcontractor:  once they have worked their way through the learning curve it will be quicker than the standard dug footings.  Setup takes some time but it's easier dealing with the rebar when everything is above ground. 

Three notes for future reference if anyone is interested in using FastFoot: 

1.       Stanley, the subcontractor, said that he originally underestimated the amount of concrete necessary.  It bulges out below the bracing (FastFoot's technical term is apparently "pooching out") so he said that you need to calculate the concrete needed based on the outside of the 2 x 4 bracing, not the inside dimensions.

2.       They ran into one problem close to the end, when the final 2 x 4 (you might know it!) twisted off the bracing.  They were able to get everything back level by using leverage to move it back into place and then adding additional bracing.  The FastFoot installation instructions tell you to use two nails, at different angles, to hold the bracing.  He used three:  one double-headed scaffold nail and two ring-shank nails.  After talking to Alton it looks like one nail at the center of the bracing and a hex-head screw at the top might be a better solution:  the screw would be stronger than the nail at preventing twisting and would be easier to remove.

3.       Alton noted that contractors who are interested in using the FastFoot system on an ongoing basis might want to investigate metal stakes such as these:  http://www.marshallstamping.com/nail_stakes.html  They are reusable and penetrate the ground much easier than wooden stakes.

*             In most cases I have deleted long stretches of inactivity.  However, in this case I preserved the two-hour wait for the concrete truck in order to give a true sense of the day’s flow.