This is another in a series of guest posts by industry members who are innovating in ambulatory healthcare design. This post is by Ben Davenny, principal of ACENTECH, a leader in acoustics, technology, and vibration consulting for healthcare facilities.
A recent trend in healthcare spaces is emerging where exam room walls are stopping at or just above the ceiling. There are a number of reasons for doing this, including:
This arrangement is allowed by the 2022 FGI Guidelines for Design and Construction of Outpatient Facilities. FGI allows for a composite Sound Transmission Class (STC) rating of 40 between exam rooms that have electronic sound masking. I’ll explain why that requirement allows for walls that stop short of the deck.
When you stop the wall construction short of the deck, the ceiling construction comes into play. The ASTM has a test for the room to room sound isolation provided by a ceiling, which is the Ceiling Attenuation Class (CAC). The CAC is effectively the STC between rooms that is provided by the ceiling. You should select a ceiling system with CAC 40. To preserve the sound isolation effectiveness of the ceiling with a plenum return system, you should make the return openings as small as mechanically possible and have acoustically lined elbows, canopies, or silencers above the return openings. When grilles are less than the size of the ceiling tile, they should be set in sheet metal panels that rest within the ceiling grid. The light fixtures should be sealed as well and should not ventilate into the ceiling plenum. The best arrangement would be pendant lighting, but they are not typical in exam rooms. There should be no holes in the back housing behind the light fixture.
The FGI requirement for exam room to exam room isolation with no masking is STC 50. This requirement is not achievable for the non-full-height wall case, because the ceiling influences the effective STC between rooms. You don’t want to build an STC 50 wall if the ceiling-path STC is 40. The appropriate wall construction is STC 45 for the wall, which could be achieved with a GWB stud wall, or with a modular prefabricated system.
When the exam room walls don’t go to the deck, sound masking is critical. The sound masking in the exam rooms can be provided by direct field systems that penetrate the ceiling or by plenum systems above the ceiling. The masking sound levels in exam rooms should be between 42 and 44 dBA to be loud enough to cover up intruding speech but quiet enough to enable conversations within the exam room. For the plenum systems, you will need to be careful if you have a fully open plenum and you are using two different sound levels, one for exam rooms, and one for open areas and corridors.
The doors should be fully sealed, including the door bottom. Use gaskets on the door frame and either an automatic door bottom or a raised threshold and passive bulb seal on the door bottom. The benefit of the threshold and passive seal option for the door bottom is reduced maintenance and problems with misalignment. However, it does introduce a height discontinuity into the floor. The thresholds could be as low as 1/4 inch.
Be careful with sliding doors, because these can be difficult to seal. The hardest parts to seal are the vertical trailing edge and the head of the door. Make sure the door includes an automatic door bottom! I recommend doing a mockup with various manufacturers to determine the quality of construction and of sound isolation, to see if the door meets your needs.
If there’s a noisy space next to an exam room, like a mechanical room, you’ll need to use a more substantial full-height wall to reduce noise transmission.
If you are renovating a high-ceiling space, such as a former big box store and you don’t want to run walls to the deck, you should construct gypsum board “caps” above conference and meeting rooms, spaces for which we do not recommend sound masking.
Stopping walls short of the deck can work for exam rooms, if you pay attention to the details. Give us a call if you are thinking of doing this on your next project.
Contact Ben Davenny at ACENTECH: https://www.acentech.com/contact/contact-us/
Hardaway|Sziabowski Architects is a leader in Ambulatory Healthcare design. Contact us using the form below or at https://www.hsarchitecture.com/contact-us if we can help you with your facility.