Passive systems help contain a fire to its room of origin, delaying its spread and providing time for firefighters to access the building and occupants to egress. As medical facilities commonly store oxygen and other highly flammable materials—and because occupants may be sedated, connected to equipment, or otherwise unable to vacate on their own—fire containment is especially critical in these environments.
Section 715.4, “Exterior Curtain Wall/Floor Intersection,” of IBC requires a barrier to prevent the spread of fire and hot gases from the interior joint, where a void exists between the fire-rated slab perimeter joint and the exterior nonrated curtain wall. Various local codes require the same. As tested and proven per ASTM E2307, Standard Test Method for Determining Fire Resistance of Perimeter Fire Barriers Using Intermediate-scale, Multistory Test Apparatus, noncombustible mineral wool could contain the interior spread of fire. Some varieties have been shown to withstand temperatures above 1093 C (2000 F), meaning they are a natural insulating material for the perimeter space.
Managing moisture from foundation to roof
Throughout the enclosure, moisture—whether vapor, liquid, or solid—is a pervasive threat, and insulation plays a key role in controlling it from the rooftop to the foundation. In both these locations, extruded polystyrene (XPS) rigid insulation supports moisture management, sustainability, and energy efficiency. Naturally resistant to water, XPS will not mold or support mildew growth, an important consideration in the healthcare environment.
The moisture performance of XPS is demonstrated in its industry-standard testing under ASTM C272, Standard Test Method for Water Absorption of Core Materials for Sandwich Constructions. The test requires insulation samples be submerged in water for 24 hours, then weighed for moisture absorption. In ASTM C272 laboratory tests, XPS has proven to be highly effective at resisting moisture absorption.
Due to its moisture resistance and ability to retain thermal performance, XPS can be used in harsh environments such as below grade and placed over the roof membrane in protected roof membrane assemblies. A range of densities/thicknesses and compressive strengths allow it to be tailored to individual applications.
In healthcare settings, the facility is often located in a densely populated area where stormwater management is required by stringent guidelines. Vegetated ‘green’ roofs and paver roofs are a type of protected membrane assembly (PRMA) with insulation installed over the waterproofing membrane as part of a configuration that can support plants and vegetation. When the insulation is placed above the membrane, water may be diverted from the storm sewer system, the waterproofing membrane is protected and therefore lasts longer, and the view of the roof from the patient area can be much more favorable.
The National Roofing Contractors Association (NRCA) recommends XPS products for rooftop vegetation installations because of their ability to resist absorption in a high-moisture location where water is being collected above the waterproofing membrane.
Additionally, tapered units can be used in roofing assemblies to create slope for positive drainage. While tapered units are common under the roof membrane in single-ply assemblies, tapered XPS may also be installed above the membrane due to its moisture resistance. This creates a range of design possibilities, including allowing for sloped drainage to manage stormwater on the deck while installing reverse tapered pieces to create a flat surface for vegetation or pavers.
Another trend in healthcare construction is sprawl. Helipads on roofs, parking structures, below-ground expansions, and underground tunnels to connect parts of a medical campus are a few construction examples vulnerable to moisture. Anything built below ground is more susceptible to this threat, as well as to hydrostatic pressure. Additionally, below-grade construction must be able to withstand traffic loads from above. Again, the natural properties of XPS support moisture control while also providing the necessary compressive strength for these critical areas.
Finally, the placement of insulation within the enclosure can support a healthcare facility’s efforts to address moisture/humidity issues. For example, in a magnetic resonance imaging (MRI) suite, the equipment operates utilizing strong electromagnetic forces. If the humidity in a given area falls too low, a machine may shut off—an incident that would directly affect patient care quality and negatively impact stress levels for both patients and staff. Careful placement of both the vapor barriers/retarders and the insulation in the wall support the HVAC system in controlling humidity within the building enclosure.
Acoustic privacy and performance
Privacy is another design factor that can have a direct impact on the patient experience and satisfaction. Insulating interior walls can improve overall noise reduction and increase patients’ privacy by decreasing the likelihood sensitive medical conversations will be overheard. The 1996 Health Insurance Portability and Accountability Act (HIPAA) sets guidelines for both visual and acoustic privacy. Although HIPAA does not regulate how a healthcare facility is designed specifically, its implications influence all aspects, such as the location of procedure areas and even the construction materials used. Insulation can support privacy initiatives by isolating sound.
When it comes to reducing sound transmission, wall design as well as the type of insulation used in the wall can affect noise levels. A lighter-gauge steel stud can provide better acoustical performance compared to a heavier one because the lower density reduces the transfer of acoustic energy. Depending on construction details and assemblies, the acoustic performance of mineral wool compared to fiberglass insulation in a wall construction can differ. Therefore, each wall design should be considered on a case-by-case basis when acoustic performance is required. It is recommended the actual insulation product be analyzed in the specific wall assembly to predict required performance.