Past Performance is No Guarantee of Future Results: Resort Revamp Causes New Mold Issues

Expert Contributors:

During the process of converting a traditional luxury Caribbean resort to a vacation ownership club, mold and moisture issues were unexpectedly discovered. The owner of the resort was left surprised as he had owned and operated similar properties for many years without experiencing mold and moisture related problems. The causes of these problems were found to be the design and construction of the new HVAC and building envelope systems needed for the conversion. To avoid the discovered mold and moisture issues, these systems needed to align with the original building design intent. However, this combination of new systems represented a fundamental change from how the building was originally designed, constructed, and successfully operated as it was before.

From Conventional Rooms to Vacation Club

One major factor in this renovated resort's mold and moisture issues was the configuration of new walls and the interior build-out during the conversion process. Many older resorts in coastal tropical conditions do not use wall systems with framed cavities. Instead, these resorts typically use walls made of plaster or stucco over masonry or concrete. This wall system is forgiving and protects against common mold and moisture problems in tropical climates.

tropical hotel mold problems in conventional drywall framed walls
Many island hotel rooms have CMU block and plaster walls that are more forgiving to mold problems as compared to conventional drywall framed walls.

One reason why this wall system is forgiving is because these walls eliminate air flow passages, reducing the potential for condensation-related moisture and mold problems inside the wall cavity. Additionally, with wall systems that are not frame construction, building compartmentalization improves. This is because individual guest rooms generally do not communicate air from one guest room to another, even if there are pressures across the walls. If negative pressure differences are causing outdoor air infiltration, those pressures do not easily allow for the outdoor air to flow through the building, therefore impacting fewer rooms at any given time.

new framed wall for mep services for kitchenette
New framed wall to provide MEP services for a new kitchenette inadvertently connected the interior of the rooms with the crawl space and the attic.

Converting a traditional hotel room into a vacation ownership unit can require the addition of a kitchenette, which drives the need for additional plumbing and electrical services. In this resort, only limited services could be provided through the masonry block wall, so adding a framed wall for the MEP services was necessary. This new framed wall not only resulted in new air pathways, but it also now connected the crawl space to the attic and the air conditioned space.

Difficulty Improving the HVAC System

Another area of concern during the conversion process is the modification of the HVAC system. Installing new HVAC systems into an existing building can be difficult, as existing hotels may have constraints such as limited above-ceiling space for new ductwork, walls in place that will require penetrating with new ductwork, and restrictions on the types of new MEP services required to support new guest room cooling units. These constructability issues can significantly influence the designer as the owner pressures the project to remain within budget. Additionally, these constructability issues can influence the contractor's ability to provide a clean installation.

One of the greatest difficulties to overcome during the conversion process is the owner's perception that the same HVAC systems used in the original resort will suffice to convert to a vacation ownership resort. Owners may need to understand the need for new HVAC systems required to achieve the building pressurization to address the new wall system and interior build-out that comes with a vacation ownership conversion. In the past, as a traditional resort, the owner may have only experienced mostly interior surface mold and moisture problems managed by housekeeping. With no wall cavities or interior buildout for air to flow and cause condensation problems, the air would enter the rooms causing mostly visible mold and moisture problems that housekeeping (or engineering) could identify and then clean and manage. This results in significant inertia from ownership against the design and construction team when recommendations are made for more expensive HVAC systems than in the original resort.

drywall mold growth in hot humid climates
As outdoor air travels through a wall system, it washes surfaces causing conditions for mold growth on material like drywall.

For this vacation club resort, the HVAC system that resulted in negative pressure, in combination with the direct openings into the framed walls from both the attic and the crawl space, resulted in outdoor air washing interior surfaces. Naturally, this resulted in a condition that was conducive to mold and moisture problems.

Understanding Potential Problems

In conclusion, despite the industry knowing for years that certain combinations of mechanical and building envelope systems do not work in areas where the climate is a historical issue when it comes to preventing building moisture failures, these designs continue to be implemented in renovation projects. As a result, properties that have performed very well in the past are now unable to prevent mold and moisture problems from occurring, puzzling owners, designers, and contractors. It is important for all parties involved in the conversion process to understand the potential issues that can arise and to design and construct systems that align with the original building design intent to prevent mold and moisture problems in the future.