Demolition
At the start of this project, we decided that instead of making small repairs piecemeal, we would focus on addressing the root problems associated with each element of the building's infrastructure.
In most cases, this involved complete dissassembly of each building component. We started with the floor, then the 2nd story apartment, interior partition walls, a mezzanine, and the storefront. Once most of the problematic elements were eliminated, we began stabilizing the foundation and eventually the floor.
Many of the building materials were saved and have been or will be reused elsewhere in the project. The floor joists, for example, looked dirty and uninteresting when first removed. These 2" thick, 16" deep pieces of cypress are very beautiful when planed down.
Most of the storefront components were taken apart and carefully catalogued so that they can be re-installed nearly to their orginal configuration and appearance.
Foundation
The orginal foundation consisted of a series of brick masonry piers spaced evenly down the middle of the building in the crawlspace. They were in excellent condition and hadn't showed any signs of major settling over the 80+ years they had been in service. We decided to reuse these elements to support a new set of columns to cary the loads of the 2nd level.
Before we could work on the old masonry foundation, we had to remove the exiting beam which rested on these piers. This beam was (barely) supporting wooden columns that carried the 2nd floor and roof. In order to do this, we first had to support the building on temporary jacks and posts - which was a major challenge in itself due to the uneven and weak soil under the building and the 18' between the ground (bottom of the crawlspace) and the ceiling joists.
Once the old posts were removed, we rebuilt the masonry piers and installed new, bigger columns on the new foundations. The new columns are 8" x 8" solid-sawn cypress. This material was chosen because it was locally avaialable and almost all of the original wooden building components were cypress. Click here to see why they are 8" x 8"
Floor
One of the most badly damaged building components was the floor. Moisture under the building had wicked up the masonry walls causing many of the joist ends to deteriorate to the point where the floor was about to completely collapse. Like most of the buildings in the area, the floor system was a series spanning from one masonry wall to a central beam leaving a crawl space of 3-5 feet. For three months out of the year, there was 6-12 inches of standing water in the crawl space and for the rest of the year, dampness pervaded causing an unpleasant interior envioronment.
In order to solve the problem of the collapsing floor and the pervalence of moisture, we decided to fill the crawl space, add a water proofing membrane, and a concrete slab.
Because we had limited time and hands, we broke the floor up into 7 sections each about 7 feet wide runing the full 32-foot width of the building and placed concrete one section at a time.
Roof
There are two sections of roof: the upper roof (over the 2nd story apartment) and the lower roof covering the remainder of the building. The second story apartment is approximately 800 square feet (about 1/4 of the total building area). Prior to undertaking the complete tear-off and rebuild of the entire roof, volunteers Eckerson and Austin experimented with the smaller upper roof which required a total of 96 man-hours.
The old roof consisted of 3 layers, all of which were removed to expose the original roof decking and framing. This resulted in the decision to replace a significant portion of the roof decking and one of the roof trusses, which were badly deteriorated. This process, which included hauling tons of waste material down to the dumpster, was the most exhausting and time consuming portion of the job.
The new roof is composed of a 3-inch layer of "polyisosanurate" insulation (which has an R-value of 18.5) and an acrylic-polyester membrane fully adhered to the insulation. This roofing solution was chosen for its simplicity of installation, weight, life-cycle-cost, and (because the insulation is on the outside) it allows for an exposed structure in the apartment. The final coat of white acrylic has a reflectance of 98.9% which means an equivalent R-value of 28. The temperature inside the apartment now (currently un-airconditioned) is comfortable, even on the hottest and most humid summer days in Helena, Arkansas.
The lower roof was quite different from the upper. A previous owner had built a shed-type roof over the existing using corrugated galvanized metal panels. On top of this was a hot-mopped built up roof. There were two major problems with this roof: 1) The metal panels didn't provide a solid substrate for foot trafic (or a 20 pounds per square foot live load) and the built up roofing material was not sufficiently adhered to the corrugated metal.
All of this material was removed. A new framework was constructed to support new decking and then the same arcylic-polyester membrane used on the upper roof was applied.
For more information on the acrylic-polyester roof product, see www.metacrylics.com
Skylights
Many of the downtown buildings (420CS included) have traditionally had skylights. While re-building the lower roof, we decided to add 4 skylights. These were built using the scrap pieces of decking material and some aluminum frames that were found in the building during demolition. The only new material used in these skylights was the safety glass. The glass is 1/4" thick, made of two sheets of 1/8" tempered glass with a plastic reinforcement material sandwiched between the individual sheets. The glass was adhered to the aluminum frame forming a rigid assembly. This assembly hinges on the wooden box enclosure and can be opened to provide natural ventilation.
Images of the skylights are included in the "Roof" slideshow. The video here is a time lapse movie made from over 500 still photographs taken using a digital camera being controlled with a laptop computer. A program called CPix was used to control the camera. It was set up to take a photograph every 15 seconds. The digital camera used was a Nikon Coolpix 990.
Movie available for download here. Right click and choose "Save As".
Beam Replacement
The ceiling construction is very similar to that of the floor described above: there are joists spanning from the masonry walls to a beam in the center which is supported by the columns. The original beam was made of five boards nailed together. There were two 2" x 10" boards on each side and the middle board was a 2" x 3" spacer. This "gang-nailed" beam was coming apart and twisting.
In order to replace this beam, we had to again support the building on temporary jacks, posts, and beams so that we could remove the load from the old beam, disassemble it, and install a new beam. The new beam is solid cypress, 8" x 12".
Lifting 300+ pounds of wood 14 feet in the air was an interesting challenge. We invented a way to build a temporary structure (which came to be known as "the treehouse") composed of support towers and lateral bracing. A 2.5-ton car jack was used to lift each end in succession about 12" at a time until it was high enough to be slid into place on to of the posts.
Many structural improvements were made to the ceiling joists and joist-beam connection during this project. Metal brackets were fabricated to secure the beam-beam and beam-post connections.
For more information on how the size of this beam was determined, click here
Another time lapse movie showing the process was created in the same method described in the "Skylight" section. However, this beam hoisting process spanned 4 days and the time between photos was 1 minute. Click on the image above to play.
Download here. Right click and choose "Save As".
