Greer Environmental Sciences Center: Educating from the Inside
Buildings that strive to meet LEED standards are increasingly used to teach students and visitors more about sustaining the world around them. When the Virginia Wesleyan University Greer Environmental Sciences Center was in early design, the phrases “science on display” and “identifiable sustainable features” were used in every meeting. Farther along in the project, it has become clear that unlike many other LEED buildings, this facility will stand out.
VMDO Architects designed the Center as a testament to both the environment and education. This facility will teach students and visitors the possibilities of working, learning, and living in harmony with the environment. Features of the building that engage natural systems, attract wildlife, and create compelling interior and exterior spaces will inspire a sense of place, connecting occupants in powerful ways to their local ecological community.
A facility created with the environment in mind
The building and its landscape will conserve resources and operate, in visible and measurable ways, in accord with its ecological environment. These strategies will teach important principles of environmental stewardship, including the interconnection of humans and natural systems, care for local watersheds, and strategies to understand and combat climate change.
For example, the polished concrete flooring throughout the open spaces of the building highlights the beauty of doing more with less. Instead of covering the structurally required concrete with other flooring types, the decision was made to leave the concrete exposed and polished to cut costs and conserve the resources that would have otherwise gone into making the material. Once forgotten at the bottom of the Mississippi River, “sinker cypress” is used throughout the interior and exterior of the building. The reclaimed wood has been clear-coated to allow the natural beauty of the material to show through, emphasizing the value of repurposing “wasted” material. The constructed stormwater wetland areas are designed to mimic natural hydrology with native wetland plant selections that are typical of wetland restoration projects. The native vegetation is excellent at soaking up floodwaters and stabilizing banks for protection against erosion. They also trap many pollutants absorbed from the water and prevent them from spreading or contaminating local waterways.
Educating from the inside
LEED Buildings like the Greer Environmental Sciences Center are now being used as a medium for environmental education, allowing users to get involved in the performance of the building. Because many people have never interacted with these strategies (such as a photovoltaic system or a green roof), it is difficult to portray how they are demonstrating environmental stewardship.
To help bridge the gap, the building dashboard (located in two common areas, one on each floor) will feature live data on the building’s performance, such as energy consumption, energy generation from solar panels, and resource usage. For students, staff, and visitors, the dashboard shows what impact the building and its occupants have on the production of greenhouse gas emissions and resource use. The dashboard will also feature a “Green Facts” section with tabs highlighting the identifiable sustainable features to be explored throughout the building and landscape. Additionally, extensive interior and exterior signage help guide and educate occupants on the building’s sustainable features and their impact on the environment.
Because the environmentally-sensitive features of the building are easily accessible, the building will engage students’ curiosity and create opportunities for research. Once completed, the building will have the capacity to attract students with a passion for the environment while stimulating grassroots involvement in conservation. The building can be considered a three-dimensional textbook for environmental stewardship, conservation efforts, and the functioning of a green facility in use each and every day.
Planning for and dealing with “blue marl” in earthen excavations
Site due diligence, including soil borings and soil testing, is a critical first step in the design and construction process. Across Virginia, and particularly throughout the Central Virginia and Hampton Roads regions, it is important to test for and, if found, properly dispose of an acidic soil referred to as “blue marl.”
“Blue marl” is a slang term for a type of bluish-green clay that is sometimes found in deep excavations. Technically, this clay is an acid sulfate soil, created when sulfide-bearing materials are exposed to air and oxidize. This oxidization results in a lowering of the pH of the soil, which can impair water quality and will not support plant or aquatic life. The primary elemental compound that creates the acid-forming conditions is pyrite, which is composed of sulfur and iron.
A primer on pH
A quick science recap: pH is the measure of a material’s acidity, alkalinity, or neutrality; a pH of 7 is neutral. From 0- 7 is acidic (hydrochloric acid is 0), from 7-14 is alkaline (liquid drain cleaner is 14).
So how acidic is blue marl? Neutral soil has a pH between 5.5 and 7.0. Most soils in the Commonwealth are naturally acidic with a pH between 4.5 and 5.5. Blue marl and similar acid sulfate soils have a pH of less than 4.0, and in extreme instances can reach as low as 1.8.
A single-unit of change in pH reflects a 10-fold change in acidity, meaning acid sulfate soils like blue marl can be anywhere from 1,000 to 10,000 times more acidic than balanced soil.
Recognizing and testing for blue marl
Geotechnical borings may provide indications that suggest the presence of blue marl. Soils experts and those with experience with this material will likely be the first to recognize that the material may be present. Because blue marl and other acid sulfate soils have a neutral pH until they hit the atmosphere, the only true method of identifying fresh, unreacted sulfidic soil is to run lab tests on extracted soils. If handled dry, these soils may also have a strong odor of sulfur – similar to rotten eggs or burnt matches.
In testing for and removing blue marl from sites, Hourigan Construction has consulted with Virginia Tech’s Professor W. Lee Daniels, one of the nation’s leading experts in ground science. He notes that when testing for acid sulfate soils, it is important to collect multiple samples to identify potential acid-forming materials. Soil makeup can be highly variable due to construction, grading, mixing, and underground stratigraphy (the order and position of rock layers), so a single sample is never enough.
Handling and removal of blue marl
Blue marl left in the ground is not harmful if it is buried and no longer exposed to air, allowing it to oxidize. Blue marl that is excavated and exposed to air must be properly treated and disposed of, and not utilized for backfill, planting beds, or otherwise left on site.
If the presence of Blue Marl is confirmed to be in soils that need to be excavated, a plan should be developed on how to remove, transport and dispose of the soils. Due to their damaging nature, acid sulfate soils cannot be deposited in a typical landfill or used in offsite fill operations. The final disposal of the soil should be at a pre-approved location permitted to receive such materials. Permanent disposal plans can vary, but should include adding a laboratory-calculated amount of agricultural limestone to neutralize the soil.
Compared to removing non-acidic soils, the cost to remove blue marl is substantially more expensive. Factors include:
- haul charges, including travel distance to treatment and disposal facility and tipping fees per truck
- concentration of sulfates in the soil, which determines the amount of agricultural lime used to neutralize
- additional geographic and logistical factors
In conclusion, it pays to do your homework. If a planned project includes a deep excavation, it is advantageous to plan and prepare for potential soil conditions that could affect schedule and budget.
Building and designing college and university STEM facilities
To meet the workforce demands of the future, America needs well-trained college graduates majoring in science, technology, engineering, mathematics and health, a field commonly known as STEM education. As institutions of higher learning begin recruiting more students into coursework in these fields, outdated and inadequate facilities must be updated to meet this increased demand and create new spaces that cater to the future of STEM education.
Pointing to the research
EYP, a global consulting group with an eye on high-performance building design, has identified several strategies that colleges and universities can utilize to make STEM facilities a magnet for students and professors. The firm says such facilities should include:
1. Numerous strategically-placed “soft spaces,” such as lounges, alcoves and study areas, that spur informal learning and chance encounters for both students and faculty outside of class time
2. Flexible, innovative laboratory spaces that promote safe but efficient hands-on/active learning methods in which students can discover, digest and apply information while adjusting to the size and intention of the group;
3. Reconfigurable classroom spaces where professors can move furniture, create workgroups on the fly, and create active learning environments
4. Glass walls that put science and engineering on display and instill a heightened sense of community and collaboration
According to the EYP, an average of 15% of the square footage in interdisciplinary science buildings should be allocated for informal learning spaces. In the 1990s, this informal space accounted for only 5% of the floor plan.
Addressing the challenges
Construction of STEM facilities is not without challenges; existing facilities may require renovation or additions, and in some cases entirely new facilities must be constructed.
Many historic facilities, which are common in Virginia, must pay close attention to the preservation of existing elements. For example, many Virginia universities appear on historical registers and require collaboration with the Department of Historic Resources before performing any renovation. It’s also important to honor the character of the historic surroundings that these facilities often reside within. These older buildings often contain inadequate mechanical, electrical, and plumbing (MEP) systems, which could lead to costly and time-consuming updates.
Traditional academic buildings were often designed around lecture-oriented individual classrooms with little ability to promote collaborative group work. The current concept of “flipped classrooms” has been shown to be more effective, allowing students to spend class time focusing on exercises, projects, and discussions rather than traditional lectures. By keeping spaces as open and flexible as possible, classroom configurations can function as study area, research lab or discussion space with minimal effort.
Meeting the need
The development of a standalone environmental sciences building is a prime example of how STEM facilities must be built to meet the changing demands of academics. The Virginia Wesleyan University Greer Environmental Sciences Center in Virginia Beach is a modern, 40,000-square-foot facility that serves as a cornerstone to the university’s environmental sciences program.
VMDO Architects designed The Greer Environmental Sciences Center as a testament to both the environment and education. The center is constructed to spur collaboration across a mix of settings, featuring sophisticated indoor and outdoor learning spaces that embody “science on display” and promote hands-on experiences, interactive learning among teams, and interdisciplinary research in STEM fields.
The structure is organized thematically around the earth’s four spheres – atmosphere, hydrosphere, lithosphere, and biosphere, so those who flow throughout the building will do so in a manner consistent with the ways of nature. The facility contains seven customized laboratory spaces for various disciplines: chemistry, biology, oceanography, hydrology, marine and earth sciences as well as Geospatial Information Systems (GIS).
Classrooms and common spaces will also be accessible to non-science majors and provide opportunities for all students to develop a closer connection to the sciences. The greenhouse and research garden – an “outdoor classroom” – will include landscaping that emulates local ecosystems and creates a habitat for local wildlife.
Further embodying the ideal of “science on display,” the building itself will exemplify the STEM program in all aspects. The center’s sustainable design features a geothermal ground-source heat exchange, as well as photovoltaic solar panels and a small-scale wind turbine. Natural light will flow through the building’s large, eastern-facing side and capture the morning light.
The Greer Environmental Sciences Center aims to become a space conducive to the ever-changing needs of education and sustainability. In addition to including elements specific to STEM facilities, it will also be targeting LEED GOLD certification. For more information about the center, visit the Greer microsite.
Getting to the Right Idea First: 4 Tips to Help Compare Bids
When you go out to bid on a project, every contractor gets the same questions. But the answers you will receive – and the costs on each line item – may vary.
It’s important to understand how to properly compare bids between each contractor. “Bid scoping” helps you better evaluate the purchase, and when done properly, helps avoid future change orders, higher costs in the field, and potentially expensive fixes down the road.
While it may be tempting to select the lowest price, bid comparison can uncover reasons why the lowest bids are so low (perhaps the contractor overlooked a step, or didn’t have a full understanding of the project scope). Comparing bids could also help clarify why higher bids may justify the price tag.
Contractors often have different interpretations of the needs for a project, varying levels of service, or may combine line items. We find common scope gaps and exclusions in items that weren’t considered. These gaps typically include furniture, fixtures and equipment (FF&E), appliances (particularly in residences), cost ramifications of full height walls (potential need to relocate VAV boxes or redesign return air plenum space) (far more expensive than drywall), rough-ins of low voltage access control, mechanical and IT infrastructure (including server rooms/closets), fire alarms, and building automation systems (BAS).
To gain a clearer understanding of the project’s true costs, we recommend following four key steps to properly scope the bid.
1. Establish a required bid form, a uniform sheet that the general contractor/construction management company can fill out to help break down the scoped items and related costs.
2. Create an analysis sheet, that compares each bidder, side-by-side, and the cost of each line item. Down the left column, list all the materials and labor. Across the top, one column for each bid/contractor. Using a uniform format to plug in each data point can help gain a clear picture of the numbers for easier comparison.
3. Highlight consistencies and inconsistencies. All items, products, and services aren’t created equal. Identify major cost anomalies between bids. A significantly low number may not have accounted for all the work to be done – and the final true cost could vary greatly (and lead to headaches and change orders). A comparatively high bid may also signal an unnecessary level of work.
4. Develop questions. Comparing and contrasting will help inform your follow-up questions. Be sure to ask questions to ensure that the scope is fully addressed and that the assumed approach of each bid is understood.
Proper bid scoping not only removes uncertainties and manages expectations for both owners and contractors; it also helps avoid any cumbersome change orders – by getting to the right number from the start.
Remaining flexible as a construction management firm
As a construction management firm, we do our best to plan for sequencing and keep development on schedule, but some projects require additional flexibility. When Union Mission Ministries wanted to construct a 275-bed facility for homeless men in the Hampton Roads community, Hourigan Construction was happy to lend a hand and lead the development of this three-story men’s shelter.
While some funds had been raised for the shelter’s $13 million construction, pivotal to completing the project was the sale of Union’s old building in downtown Norfolk. Ministry leadership expected the sale of the location to be completed within a few months; ultimately, and unbeknownst to anyone at the time, that closing would take nearly two years.
But there was a demand for the new space, and the organization wanted to get rolling. So a plan was devised to get started under a reduced scope. At this point – November 2012 – approximately $2.5 million had been committed to the initial phase of construction out of the total project cost. This was also a time when development in Hampton Roads was still grappling with the economic fallout of the years prior.
Starts and stops
Hourigan agreed to work in starts and stops, picking the next logical step to keep the project on track. With the initial funds, the facility’s foundation was poured and structural steel was procured.
To keep the project moving, as funds were made available through thousands of donations to the ministry, Hourigan worked closely with the owner to modify design plans and develop alternative finishes that cost less, yet were still highly durable.
Financial constraints also affected sequencing; expensive mechanical systems, for example, arrived towards the end of the project, when they’d normally be installed midway through.
One of the biggest requirements for success was for those involved to remain flexible, and work together to find solutions to challenges. The project ultimately took three years, so contractors that bid early in the project were called on, and those that were able completed work far later than originally anticipated. Yet, many subs worked with the owner to keep costs contained at previously quoted levels.
John DeVan, First Vice-President of Union Mission, describes the pricing and labor flexibility as “a contribution from most of the contractors” that helped build the facility.
Closing on completion
The original men’s shelter sold in August 2014, green-lighting the final stretch of construction. The 75,000-square-foot facility, built on the mission’s campus as part of an $18 million capital campaign, was completed in May 2015.
The men’s shelter – along with a recently completed renovation to the adjacent women and children’s shelter – is a $30 million campus that was entirely paid for through donations and the previous building’s sale.
Union Mission is dedicated to serving the poor and homeless of the Hampton Roads community, many due to job loss, sudden family illness, or a battle with addiction. “The men’s facility also contains administrative office space, a commercial kitchen with cafeteria, conference space, an exercise facility, and large congregation areas.
Though one of Hourigan’s longest-running projects, it was very important work that needed to be done. To serve as a construction management firm in a community means to serve the community’s needs by remaining flexible and finding creative ways to make challenging projects work.
Funding, Donations and Zoning for Non-Profit Projects
Though standard commercial developments and private non-profit developments have many similarities, there are differences between the two that create unique challenges for non-profit projects. Although most design standards, construction procedures, permitting processes, and contractual requirements are similar for both, the following differences must be considered:
- Funding and Timing Considerations
- In-Kind Donations
- Community Engagement and Zoning
Funding and Timing Considerations
A typical commercial project must have a full commitment of funds (which can come from bank loans, cash, municipal participation, tax credits, etc.) before contracts are issued to design and construction professionals. However, a non-profit project is typically associated with additional challenges of timing for funding.
Before a non-profit projects begins its journey through design and construction, private donor funding sources may not have the urgency or ability to immediately fund the entire amount of their commitment. Larger funding sources normally come in the form of multiple lump sums over a period of time (say an average of 3 years) vs. the normal commercial funding source, which usually comes in the form of a lump sum bank loan funded upon finalization of the development deal. If the project is a Federal, State or municipal project, then funding is included in the yearly budgets and allocated to separate projects Both of these forms of funding are usually more definitive and timely than raising the funds from individual donors.
Because of this, private non-profit projects have a tendency to take longer to be fully funded due to timing and multiple sources of donor participation. Most non-profits will not proceed until all funds are “banked”, making the project start date push out until all funds are received, sometimes 3 years beyond the initialization of the Capital Campaign.
In-kind donations are offerings from donors that cannot contribute cash, mostly in the form of donations of goods or services. These donations are very generous in nature, but can also be time-consuming. The process involves relocating materials from the source of donation, storing for future use in the design, modifying the design specifications so that the in-kind materials can be incorporated correctly into the work, and accommodating the (usually small) quantities of in-kind material. Materials of this nature are very much welcomed, but are typically delivered later in the project than new materials after collection, processing, and installation. In the end, they can often cost just as much, if not more, than newer materials.
Community Engagement and Zoning
Most non-profit projects are involved in specific types of projects (such as education, environmental, arts, or specialized healthcare) that are developed on a donated site which may not be properly zoned. This requires engaging the surrounding community in an awareness campaign in order to gain support for the project. By engaging the community, the project team can potentially avoid protests that could stop or delay the local municipal permitting process. Typical Municipal, State, or Federal projects will not often have the same issues, since they are generally located on a properly zoned site.
These considerations often affect non-profit projects and can serve as possible delays during projects. However, with proper planning and special procedures, Hourigan has been able to minimize the impact on schedule and cost associated with non-profit projects.
Preserving History and Maintaining Schedule: Working with DHR
As cities expand and neighborhoods thrive, it’s critical to keep the integrity of historic buildings while also modernizing them to the times and preserving them for the future.
When owners of historic structures make upgrades to these buildings, significant state and federal tax credits (25% of eligible rehabilitation expenses for state credit and 20% of eligible rehabilitation expenses for federal credit) are available for eligible expenses. However, earning them requires working hand-in-hand with the Virginia Department of Historic Resources (DHR).
Hourigan Construction has served as construction manager on numerous DHR projects, most recently a seminary in Richmond’s Northside. The project at Union Theological Seminary began as a 33,000-square-foot interior renovation to be completed over the course of 11 months. The project included a complete life safety replacement, with added security, fire alarms and sprinklers; a full-service commercial kitchen; elevator upgrades; and an ornamental stair glass railing between its café and basement. Additional funds were available for exterior improvements to the facility – a new slate roof and windows, which added to the original scope of work.
DHR is committed to preserving the architectural and historical integrity of buildings, both inside and out, while updating structures to the times (such as compliance with ADA). The role of DHR is an important one to preserve the character of our state’s history. The agency’s involvement is important for the greater good, but will nonetheless require additional time and approvals to otherwise standard construction processes and sequencing. In order to ensure success in your historic preservation process, you should consider the following:
Talk early with approving bodies
Once the owner’s requirements are known, it’s important to sit down with DHR and the city – the two approving bodies – and understand those organizations’ expectations and suggestions to ensure the project moves as quickly as possible. Materials that will pass one agency may not with the other. Establishing a relationship up front keeps things progressing down the road.
Hire a historic preservation consultant
Bringing in a historic preservation consultant will provide both owner and contractors with a trusted resource for research and guidance. The consultant can identify significant features that require preservation along with strategies for development.
Watch the clock
Before work begins, owners must submit a phasing plan to show all work that will be completed during the project. It’s important to account time for material and process approvals, which typically take a minimum of 30 days (but can last months). If possible, try to involve the construction management company in the process early. Owners and architects often work hand-in-hand to choose and match materials, and many of these finishes are chosen before the contractor is involved. With DHR projects, the earlier the contractor can play a role, the quicker the project will move.
Virtual construction modeling can help owners, architects and builders identify and rework issues before the build – and keep on schedule to a speedy approval.
Understand that matching finishes pose challenges
Much of a DHR approval comes down to matching older, outdated materials to modern finishes that offer additional protection and material life.
Windows are character-defining features that must be properly rehabilitated to give them long and sustainable service lives. Many DHR projects run into bottlenecks when windows need replacing, as they did at Union. Divided light windows at the seminary required matching the mullions and muntins that make up the window grids (Mullions are the horizontal or vertical beams between adjoining windows; muntins are the smaller strips of wood that divide the panes). All told, it took three months for Union’s roof and windows to be approved – a quick turnaround, thanks to the collaboration with the preservation consultant and communications with DHR and the city.
The seminary also needed a new slate roof, which required inspecting the materials to ensure a match to its historic look, feel, and color. New copper flashing was also added to provide greater protection.
Interiors aren’t overlooked, either. Walls, faucets, transoms (beams separating the door from windows above), ceiling heights, archways, ductwork, sprinklers and mechanical systems were all inspected and approved to ensure consistency with the historic preservation.
Historic preservation enriches our lives in both tangible and intangible ways, and keeps us connected to our heritage. Rehabilitation is good for the economy, too, creating jobs, new commercial and residential spaces, and additional tax revenues. So while preservation may take time, the long-term impact is worthwhile for everyone involved.
Downloads and Additional Resources:
- Preservation Briefs on a variety of materials, from the National Park Service
- Technical Reports from DHR
- Rehabilitation Tax Credits homepage (includes Frequently Asked Questions)
Location matters – a universal truth in almost all types of development projects. With the recent push towards sustainable living comes a demand for housing in easily accessed locations. Many people want an ability to either walk or bike to where they live, work and play. For this reason, land is frequently the largest determining factor in new development and construction. Properties on open land (also known as “green field”) are in high demand, but are also high-dollar and hard to come by. Green field properties in popular locations are frequently priced out of an owner’s budget, and lots that are available may already be occupied with an existing structure. With a little creativity and planning, repurposing an existing structure may turn an imposing project into a realistic one. By considering renovation or restoration, an owner can build in a prime location while still saving time and money.
Adaptive Reuse and Brownfield Development
Adaptive reuse refers to the process of utilizing an older structure for a different purpose than its original intent. On the other hand, brownfield development is the preservation and reuse of existing structures for the same purpose. Both processes can be cost-effective and reduce the overall duration of construction if owners are smart in their approach. Many projects of this nature are completed without major impact to existing structural components, which also allows for historic preservation of existing facades and key landmarks. In addition, both adaptive reuse and brownfield development can be key factors in land conservation and the reduction of urban sprawl.
Lifecycle Analysis: Refresh or Renovate?
When considering the purchase of an existing facility, there are a myriad of topics and issues that need to be considered prior to deciding on a large-scale renovation. If none of the primary functions of an existing facility will be changed, the task could be as simple as refreshing paint and interior finishes. As long as the existing infrastructure and technology are up-to-date, the duration and cost of a simple refresh are drastically lower than a full-blown renovation.
Most often, an existing facility may be appropriate from an overall size and structural standpoint; but the infrastructure, technology, and layout need to be updated. In this instance, lifecycle analysis and building assessments are crucial first steps when evaluating an existing facility. Construction managers and discipline-specific engineers need to carefully analyze the existing building’s structure, plumbing, HVAC, electrical and communications systems to determine what can be salvaged from the existing infrastructure. This evaluation needs to analyze not only immediate needs, but long-term maintenance costs and future expansion as well. When it comes to major facility infrastructure, existing components can sometimes be an excellent resource and are often better than their newer counterparts.
Hazardous materials are often one of the major concerns for developers and owners when approaching large scale renovations of older buildings. Some potentially hazardous materials include asbestos, lead paint, polychlorinated biphenyls (PCBs), mold and mercury – all of which can seem daunting in a project of this nature. If identified early and proper techniques are used, the hazardious materials issue does not need to be a major deterrent to rebuilding an existing facility. In addition, many older occupied facilities have already undergone large-scale abatement programs to remove these materials due to government regulations.
Plumbing is often another concern. However, since most multi-story office buildings have plumbingin the core of the building, early analysis often leads to the reuse of the core infrastructure for wastewater and domestic supply. While today’s modern codes require more efficient plumbing fixtures, the infrastructure systems to support these fixtures can often be updated and reused.
Two Commercial Place
The Two Commercial Place project is an excellent example of a reuse success story. Located in the heart of downtown Norfolk, VA, the 40-year-old structure was categorized as “Class C” (functional space with basic finishes) at the beginning of the project. Luckily, during early building analysis, it was discovered that all hazardous materials had been removed and the plumbing backbone was well-structured. Only minor updates were necessary for lateral layouts and fixtures, making this project an excellent example of successful reuse. When the Two Commercial Place project is complete, the office building will be a “Class A” space, one of the most prestigious distinctions in office space categorization. “Class A” facilities have high-quality finishes, state-of-the-art technology, excellent accessibility and are often one of the most desired spaces in the market.
While there can be setbacks to a renovation project, it is often the best solution when an owner wants land in a prime location. To view other renovation projects, visit our project portfolio and filter by “renovations.” If you are considering an adaptive reuse or brownfield development project, you may also want to take into account the delivery method. Here are a few blog posts about several possible delivery methods:
- Selecting the Right Delivery Method — An Overview of Design-Assist
- Design Build: A Model of Collaboration and Empowerment
- CM at Risk: A Delivery Method Focused on Collaboration
Considerations of Concrete: From Pour to Polish
Polished concrete has become a popular flooring option due to its modern, attractive design aesthetic and durable, low maintenance finish. It requires no waxing or special sealers, and is simple to clean. Like anything in the construction industry, special care must be paid in order to utilize this finish in an effective manner. When considering polished concrete, several things should be discussed with the project team before construction begins.
1. A level surface is key.
The levelness of a pour is key to a uniformly polished floor. To maintain a consistent aggregate exposure and sheen, the slab shouldn’t vary more than one-sixteenth of an inch across the surface. Flatness is measured in levels (referred to as the FF rating). An FF rating of 50 is advised, since the finish-grinder is relying on a flat surface to achieve a uniform grind that will expose the aggregates (salt & pepper sprinkled effect). If the areas are not precisely leveled, differences will be evident in the appearance of the aggregate.
2. Big spaces are easier to level.
Buildings with smaller rooms (e.g., residential spaces) require pours to be broken up by room and must be leveled by hand. In larger spaces (e.g., breweries or stadiums) the pour will be smoother since a laser screed can be used to help level the floor. In this case, the cost of the laser screed technology will need to be built into the budget. If the space is too small to utilize a laser screed, research can be done to find a local concrete contractor that can deliver FF 50 ratings via hand finishing. While an option, hand finishing isn’t always recommended. To ensure maximum finish consistency, employing laser screed technology is suggested.
3. Protection should be high-priority.
During construction, slab protection becomes critical to preserve the integrity of the concrete until finishing can begin. Since the concrete slab is typically poured at the beginning of a project, the slab is exposed throughout the duration of construction. From the moment the concrete is poured until the moment it gets polished, it must be protected from damage. Depending on the desired class of aggregate exposure, some topical damage (spilled paint, for example) may not be ground away. To protect the slab, plywood mats below man-lifts, temperature control measures, and plastic boards with sealed joints can all be used. Since the concrete will cure and evaporate moisture once it has been poured, ‘breathable tape’ (not duct tape) is recommended for joints. Using tape that doesn’t breathe could result in trapped moisture that would leave lines on the slab after temporary protection is removed. Moisture lines could catch finishing stain and sealer and potentially ruin the slab.
4. Cracking can be expected.
Due to the nature of the product, concrete slabs can crack as the building settles into place; but with proper care, cracking can be controlled. Adding fibers to concrete pre-pour can help reinforce the material, and strategically placing control joints to isolate slabs can account for the shifting of the building’s steel support columns. Additionally, while the industry standard for concrete depth is four inches, it can be increased in order to gain stability.
In the right setting, a polished concrete finish can offer long-term durability and sophisticated beauty. By taking special notice of space, protection and attention to detail, even the most intricate polished concrete project can go a little smoother.
This blog post was a collaboration between Gibson Luck and Ryan Byrd, both of which were involved in polished concrete application during the Hope Church project.
Dream realized: CBF earns the Living Building Challenge certification
This May, the Brock Environmental Center was awarded the coveted Living Building Challenge designation from the International Living Future Institute, the world’s most rigorous and ambitious performance standard for buildings. The designation was a humble recognition of the Chesapeake Bay Foundation’s realized dream: to create a facility that positively impacts its surroundings, creates its own energy and water requirements, and stands as a model for the future of sustainable construction and engineering.
The Center is, indeed, a living building. Today, in addition to producing more power than it consumes and producing its own drinking water from rainwater, residents of Virginia Beach and surrounding communities are invited to enjoy the building and its grounds. It drew approximately 35,000 visitors last year—while staff anticipated about 1/7th of that.
Among the Brock Environmental Center’s components of sustainable construction and engineering to meet the Living Building Challenge’s seven petals are:
- Net Zero Energy: Energy use is reduced by 80% when compared to a typical office building, and the facility produced 83% more power than it consumed in 2015. This excess power is sent directly back into the grid to help power adjacent homes and businesses.
- Rainwater collection and treatment systems, for collecting rainwater to create drinking water and for use in sinks and showers (greywater); 100% of the water is collected and treated on site.
- Composting toilets (blackwater), to transform human waste into usable compost.
- Stormwater management systems, which help water to recharge into the ground through permeable surfaces.
- Renewable energy technologies, including photovoltaic solar cells, two wind turbines, geothermal wells, heating and cooling retention, rainwater usage, that each contribute to the facility being a net-zero energy building.
- Reclaimed and salvaged exterior and interior materials, such as sinker cypress wood siding, gym flooring re-purposed and re-finished for flooring, and old school gym bleachers for interior trim, salvaged ceramic, and champagne corks are repurposed as knobs
- Triple-glazed windows with a high insulating capacity, created with 100% FSC certified wood frames.
- A preserved waterfront site that allows visitors to connect to nature.
- Architecture that limits straight lines, which do not exist in nature.
- Access to the building that limits vehicular traffic and encourages walking and biking.
For those involved in the creation of the Brock Environmental Center, this was more than a construction project. The challenge of building the Center became a passion, forming a bond that transcended a working relationship among all of the individuals and companies involved.