Green Roofs

After looking over the conceptual site plan drawing for the Academic and Student Affairs Building, I realized it was going to have a green roof.  Some of the benefits of green roofs include:

• Reduce cooling loads on building by fifty to ninety percent.  With Blacksburg climate this won't play as much as a factor as it would in a hot/dry climate such as Arizona, but is still cost efficient.  Evaporative cooling is the cooling of air through the evaporation of water.  Both simple and cost effective.
• Reduces storm water run off, using this water to irrigate the vegetation on the roof.
•  LEED points and filtering of pollutants out of the rainwater.

Below is a picture of a building in Japan with a green roofs:

A terraced roof top overlooking Fukuoka's Tenjin Central Park in Japan.

Detailed look at the green terraces. 

"Effluent follows the drainage system of a natural mountain. The system used as a base entails rainwater from the top floor (13th floor) permeating into the soil and following water paths, before permeating through to the step gardens on lower floors, before reaching the ground level."http://www.treehugger.com/files/2008/07/green-roofs-fukuoka-japan.php

Raise the Roof

 On my way home from eating lunch in Downtown Blacksburg not long ago I glanced over in passing to see a house floating in the air, so I decided to turn around and check it out.  It was an older house, possibly built in the 1920-1940 time period (guess).  The foundation was made up of of approximately 12 concrete piers with dimensions that appeared to be 12"(l) x 12" (w) x 24" (h) which the house rested on (see picture below).

Located on Progress Street, downtown, behind the new Chipolte Restaurant

After being jacked up by locally owned Virginia House Movers, Inc. with hydraulic jacks placed under the floor joists and girders, large timbers were placed under for support (approximately 15).  This raised structure to an elevation to about 6-8 feet above ground.  The ground elevation in the rear of the house was lower than the front, so more timbers may have been used.  Placed on top of the timbers and under the floor joists are steel girders for carry the load to the structure from the floor joists to the timbers to the ground.  

This process has to be managed slowly and carefuly as to not damage the structural integrity of the existing structure.  Many hydraulic jacks have to be used, professionally, placed in strategic locations on load bearing points, and then lifted in sequence, slowly.  I did not see any damage or rotting occurring under the house, so I don't believe it was jacked up to do repairs.  There are many possibilities the homeowner has intended for this:  Repairs on joists/girders, adding a basement below grade (see code in Blacksburg), or even moving the house to a different location.  Judging by the sign, it appears that the latter will be occurring with this structure.  This is a common practice in Blacksburg.  I have personally seen 3 structures in the Downtown area that have been jacked up, one being the Alexander Black House, a Queen Anne Victorian architecture style located on Draper Road <http://www.blacksburg.va.us/Index.aspx?page=65>.  This site will give you a historic overview of the house and a time lapse video of the move.  The Alexander Black House was originally located where the Kent Square Parking Garage is now.

                                               

Wood Forming System for Retaining Wall

A wood forming system is being erected here by workers.  It is a labor intensive process and this wall took close to a week to erect.  Each tie has to be individually placed along with the vertical and horizontal forming lumber.  The vertical studs and sheathing are placed first.  Then the horizontal wales that will hold the snap ties are placed.  You can see the individual tie holders (wedges) being nailed to the wales by the workers.  This is explained in detail in the bottom picture.  Also, support members have been placed at an angle to keep the formwork structurally sound and the workers safe.  These ties maintain a predetermined space in relation to opposing forms. 

Finished wall and "catwalk" for workers to pour the concrete down into the formwork, via boom or bucket.  I believe a concrete bucked hoisted by crane was used on this wall to place the concrete.  The conceptual drawings of the front of the building show this area being back-filled and the entrance being at the same elevation as that of McBryde and Holden Hall.  However, the backside of the the Academic and Student Affairs building will be at a lower elevation, similar to that of the ICTAS I building seen in this picture. 

Snap Tie detail drawing.  Note that the formwork is made from plywood and dimension lumber.  The entire assembly is fastened together with removable clamps.  Form ties between opposite plywood panels separate them and hold them against the pressure of wet concrete.

Academic and Student Affairs Building

After excavation of the southern side of the site, the hill was covered with tyvek or similar material to combat erosion and keep the hill intact while the retaining wall is formed at placed.  Below are pictures of the southern side.   

Workers placing formwork.  Most, if not all the caisson holes have been drilled and prepped.  Notice the hill covered with tyvek as discussed earlier.  Column rebar is being spliced into the caisson piers (top of picture).

Workers splicing column rebar into the piers/caissons that have been drilled. 

Caisson/Pier formwork

Rain, mud, and other debris will get into the drilled hole for the piers.  Pictured above are workers mucking out the hole with a shovel and air hose.  Notice the safety caps so the workers won't get impaled. 

Slab has been poured for the southernmost retaining wall.  Columns have been spliced/tied into the caissons and safety caps have been placed on all rebar.

Continued forming of slab formwork and working mucking out the caisson hole with shovel and airhose.