May 14, 2009

Introduction

With the tightening credit market and corporations starving for cash, many construction projects are being considered for construction interruption and mothballing. When interrupting or mothballing a project, there is concern that the building structural elements will be subject to deterioration. This will ultimately reduce the building’s value to future buyers and could be the basis of a hidden defect claim for future owners.

Where options are available, immediately stopping construction is never desired as it exposes most or all of the construction and work already in place to hidden and consequential damage that could be significant. Leaving a building without protections also exposes it to risks of fire, vandalism, and weather.

Driving Principles

Mothballing a building requires consideration of architectural, structural, and MEP features already in place and the affects of weather, corrosion, and ventilation on these existing features. In approaching mothballing it is effective to first compare a variety of scenarios applicable to the building based upon already established guiding principles. It is extremely beneficial to examine historical case studies in the surrounding area and their results. As these individual scenarios are examined, recommendations can be arrived at for the protection of the work already in place. The driving principles for any project that is being considered for mothballing are as follows:

1. Leave nothing during pause where consequential damage could be hidden or significant. For example, cavities and chases where hidden damage can occur should be avoided.
   
2. Leave nothing uncovered or exposed that is not designed or intended to be exposed. Parts of buildings are intended to be covered during its life. Proper mothballing of a building should not leave buildings that are not designed to be exposed open to the elements.
   
3. Leave nothing that is not structurally stable. This is an obvious consideration, but during construction the areas of the buildings that fall under this category are not so obvious.
   
4. Do what has been done before, meet standard of care. There are published guidelines like those from the U.S. Army Corps of Engineers and the Heating Ventilating Contractor’s Association provide guidance on proper requirements for mothballing and layaway of buildings.
   
5. Assure protection for work in place due to basic casualty events (i.e. fire, security, mechanical/electrical operation, hurricanes/storms). This will include both a human presence on site but also automated monitoring sensors can also be used to satisfy this principle.
   
6. Monitor and document building during pause so that knowledge of conditions is maintained. Losing knowledge of a building prevents the owner from being able to provide documentation to the ultimate end user that the building was maintained to a standard that is acceptable.

Specific areas of concern are the architectural and weatherization; building envelope including glazing, exterior finish systems, and caulking; and concrete, elevated slabs and reinforced steel.

Architectural and Weatherization

Roofing

Will the roof be temporary or the final roof as-designed? If the roof is temporary, it must drain, tie-in with the edges, and be removable when construction begins again.

Temporary roofing should be installed on the uppermost (last) floors poured. The most likely method would be some sort of low-slope, one-ply membrane system fastened in such a way that future removal will create little damage to the concrete substrate. The temporary roofing will require detailing at the edges to protect vertical construction below as well as accommodate geometry (such as balconies) and protrusions (such as shafts, piping, etc.) not found on the finished roof levels. Tapered insulation will be required to provide slope to drain since the roof will be installed on a future floor that will need to be level. Drain systems will need to be installed to the roof level and tied in to the temporary roof. The temporary roof would have to meet wind load requirements for the particular location.

If the final roof is installed and lower floors have not fully received the vertical wall systems, there may be tie-in issues where vertical wall systems are not installed on the top floor. Installation of the final roof would thus require reworking of roof edge details that would allow for future installation of vertical wall systems.

Glazing

Fenestration must be considered to protect both completed and incomplete work. If windows and sliding glass doors are not installed, how will the work in place be protected? Also, storage of fenestration equipment on property must be considered.

Any glazing already installed needs to be protected. Depending on where these elements occur, there may be need for protection of top edges with temporary flashing and sealant. How perimeter sealant is to be applied will be dependent on level of completion of adjacent exterior wall finishes, such as stucco. If, for example, perimeter sealant is applied to raw concrete or CMU, then the concrete will need to be properly prepared and sealant installed in a manner that will allow it to be easily removed in the future for installation of other finishes.

Windows and doors purchased but not installed will need to be stored until construction resumes. There are several scenarios to consider:

Stop all fabrication of sliding glass doors not required at this time and only purchase what is needed to complete the mothballing. This may have contractual issues with the manufacturer/installer which will need to be addressed, such as terminating or putting current contract on hold. The benefit is avoiding having to store assembled doors.

Purchase material only (extrusions) for all doors but do not fabricate. This would make it easier to store until construction resumes. Risks will include 1) problems of where material will be stored and 2) possibility that the sub-contractor doing work when construction resumes will not be the same potentially leaving the developer with unusable proprietary material.

Complete fabrication of all sliding glass doors and store those doors not installed. Storage scenarios include on-site in the buildings or off-site in a warehouse. Since the building will be temporarily dried-in for at least some floors, storage on-site on protected floors would make the most sense. However, such on-site storage areas would need to be selected with consideration to staging issues to avoid as much double moving as possible once construction restarts. Additionally, any storage scenarios need to consider the risks of the extra handling of the doors and potential problems with racking and other damage.

For all scenarios, consideration should be given to protection of sliding glass doors in place, such as installation of a film membrane or shrink wrap over the exposed surfaces to minimize staining and corrosion and reduce maintenance costs.

Exterior Finish Systems and Caulking

Lack of stucco or paint or some sealant on work already in place, exposes that work to risk. Temporary sealant application may be required at certain locations. Where stucco is scheduled to be installed, evaluation must be made of any sealers used to prevent corrosion since these sealers may prevent bonding of the stucco when the work is restarted. Temporary sealant application may be required at certain locations.
 
Elevated Slabs

Exposed balconies that are not protected will be at risk. Exposed balcony slabs can be protected with penetrating sealer. Railing pockets can be protected with a temporary membrane and possibly drilled weeps. If temporary guard rails are in place, they will need to be assessed for long-term efficacy and maintenance.

For various conditions, balcony slabs should be protected with the penetrating sealer specified. Additionally, a temporary UV resistant waterproofing membrane will be needed over the foam railing pocket block-outs to prevent water from pooling in the pockets. As an additional precaution, it may make sense to drill temporary weep holes through the bottom of the pockets to ensure drainage in case the temporary membrane fails.

Waterproofing details at interface between the balcony slabs and vertical construction (walls and sliding glass doors) will need to be installed.

Temporary guardrails will be removed when sliders are installed. Temporary guardrails will need to remain for fall protection for maintenance personnel. The condition, anchoring, and fastening of the guardrails will need to be assessed to determine the long-term efficacy to act as protection and remain in place during high wind events, as well as ongoing maintenance requirements (such as replacement of wood components that deteriorate over time).

Curtain Wall Systems
Temporary infill may be required at floors that are scheduled to eventually have curtain wall systems. Temporary infill could consist of painted plywood and metal stud construction with temporary sealant applied where infill interfaces with the surrounding structure. Because of the height spans at lower floors, the temporary infill will need to be engineered to withstand high wind events.

Structural Systems

Concrete Floor Slabs and Other Exposed Concrete and Masonry Structure

Consideration of these elements would be based upon whether or not a permanent roof was in place and what had been decided upon in regards to fenestration and exterior wall assemblies. Any exposed area will be at risk. Lower level structural elements (including decks, water features, etc.) will need waterproofing. Open floors above would require protection for interior concrete and masonry elements.

Any temporary protective coatings would need to be analyzed for their affect on finish coatings that would be applied after construction restarts (such as bonding issues with direct-applied stucco).

Incomplete ground level, low level decks, and hard-scaping elements may be only partially complete and temporary protection would be required.

If waterproofing has been specified, that would need to be installed. Some waterproofing systems may require temporary or permanent protection if they cannot be exposed to elements (including UV) for extended periods.

Reinforcing Steel

Any exposed areas of reinforcing steel will be at risk. If there is some exposed reinforcing steel at the last floor poured to allow for connection to structure when construction resumes, it will need to be temporarily protected from corrosion and other damage. Post-tension pockets will have to be grouted.

Site Grading and Drainage

The site should be graded and storm drainage in place, either permanent or temporary, to prevent water from pooling against the building.

Maintenance

On-going inspections and maintenance will be required, especially for materials that can degrade quickly.

Harsh environmental conditions can cause premature degradation of many building envelope materials; especially sealants; therefore, an ongoing inspection and maintenance program will be required under any scenario to ensure that the envelope functions as a weather barrier and/or coatings and membranes function to protect structural and other elements.

Surfaces should be maintained to be free of all debris and loose material that could damage the exterior envelope elements during possible wind events.

Mechanical and Ventilation

The mechanical systems that will be installed at the time of construction pause will be minimal. The systems are primarily designed as a support of construction, and only a small portion of the building out for the lower levels has been installed. To diminish the risk of hidden damage during the construction pause, it is recommended that the duct board ductwork installed on the lower levels be removed, as well as any other areas of installed materials that are porous in nature.

Environmental Control during Construction Pause

One of the greatest risks for avoiding damage during the construction pause is the accumulation of moisture in the enclosed areas. If the building is dried in – which includes installation of roof and glazing so the building will be at what is considered a core and shell condition there will be no mechanical system in place or operating that will be able to control the indoor environment. Core and shell construction with no cooling activated will not have a risk of cold surface condensation; however, there is a risk of increased indoor accumulation and increased relative humidity that must be controlled. Best practices dictate that the most effective way to control indoor moisture levels in an un-air conditioned building is to ventilate the building, even in a hot, humid climate where the ventilation air source will be the outdoors.

Monitoring During Construction Pause

A well-purposed plan for monitoring during the construction pause will help to create a proactive environment that will help to find potential problems that can arise during a construction pause. This plan should include both visual inspection and observations, and the deployment of a remote alarm and sensing system like OmniSense in various locations, so that remote sensing of moisture levels can be monitored. This specifically will include the following:

• Sensors that measure temperature, RH, DP and moisture monitoring
  
• Protocols and responsive action to areas reporting elevated relative humidity
  
• Protocols and responsive action to water intrusion events

Fire Sprinkler and Life Safety

All life-safety systems must meet minimum building code requirements including active fire sprinkler stand pipe.

• Ventilation
  
• Provide ventilation to the glazed portions of the building.
  
• Plumbing and Electrical
  
• Minimally installed systems must be deactivated if not in use.
  
• Monitoring
  
• Provide monitoring of space using remote sensing and regular on-site visits by a third party.

Case Studies

Case Study 1: Hotel, Mid-Rise

This was a case where the project had been mothballed for six years after having been fully dried-in including the roof, glazing, stucco, and paint. The buildings were in shell and core condition with no interior construction completed. The owner and maintenance were of a sophisticated nature and the end result was that there was only nominal damage to the work in place after the pause in construction.

Case Study 2: Hotel, Open-Slab, No Shell

In this case the project had also been mothballed for several years. The project was constructed on grade slab with exposed steel before the pause in construction. Again, the project had a sophisticated owner and maintenance scenario, but, due to insufficient planning in the scope of the termination of construction, the project required full demolition of all exposed concrete and steel and the result was a complete loss of work in place.

Case Study 3: Mid-Rise Buildings

This project was mothballed for three years and, when construction was paused, the shell and core had been given a full build-out and the interior had been completed. What makes this case unique is that the lending institution had enacted a poor maintenance plan with no ventilation control provided for the paused construction site so that the end result was a complete loss of work in place and required full demolition.

Case Study 4: ACOE Guidelines for Mothballing Projects

The U.S. Army Corps of Engineers (ACOE) has compiled a list of best practices when it comes to the mothballing and pausing of construction. Their findings are based on various styles of construction in various geographical locations. The ACOE has made the following guidelines:

• Buildings need to be dried-in.
  
• A sufficient ventilation system needs to be provided and maintained.
  
• Security, maintenance, and monitoring are imperative implementations to provide an environment to proactively treat/avoid possible problems.
  
• A prescriptive response for repairs and causal events needs to be implemented.
  
• All non-essential building service systems need to be deactivated.

Other Considerations

There are other considerations when mothballing a project that have legal and impacts to the community. These include but may not be limited to:

• Land use and permitting issues.
  
• Insurance and contractual issues with contractors, subcontractors, and suppliers.
  
• Community “eye-sore” issues and impacts to the adjacent aesthetics.