UFAD System Construction Best Practices Checklist
Introduction To UFAD System Construction Best Practices Checklist
Before Raised Floor Installation
1. Slab and Wall Sealing:
- All sheetrock walls and columns must be sealed to the slab using a durable, resilient, low-VOC caulk or fireproof sealing material suitable for the application. Use colored caulk instead of white or clear for easier inspection.
- Seal all vertical seams in drywall, including corners below the floor.
- Seal any through-slab, through-wall, or other penetrations in the slab or walls.
2. Conduit and Ductwork:
- Seal all conduits that terminate in the underfloor airway at the sheetrock and within the conduit itself. Use a removable sealing product for large conduits.
- Inspect ductwork to ensure air exits the end of the duct at 1500–2000 ft/min and throws no more than 50 ft to the furthest delivery point for cooling air.
- Seal around all four sides of duct penetrations, especially under the duct where it leaves the shaft.
3. Airway and Pressure Considerations:
- Check for major blockages in the underfloor supply airway, such as demising walls. Ensure they do not obstruct air travel to the perimeter.
- Use caution with air highways:
1. Verify air pressure drop calculations at full flow.
2. Consider temperature rise.
3. Check for leaks caused by wiring and conduit crossings. - Verify control wiring between floor boxes and thermostats.
- If two or more control dampers (or VFDs) control pressure in a large zone, ensure they use the same pressure reference or average the pressure references.
4. Material Suitability:
- Ensure all materials used underfloor are suitable for an environmental airway (e.g., plenum-rated Class A materials or as required by local codes).
After Raised Floor Installation
1. Floor Installation and Gaps:
- Install floors consistent with local seismic requirements.
- Minimize gaps between floor panels (approximately 3–4 business cards in width).
- Seal any gaps around the perimeter edge of the floor. Tight gaps can be addressed with carpet and cove molding; larger gaps may require caulking.
2. Air Sealing and Thermostats:
- Verify no air leaks into walls or thermostats. If air aspiration occurs at the thermostat, seal conduits at the floor and use an insulated thermostat sub-base.
- Ensure the floor pressure reference is the occupied space, not the external atmosphere.
- Ensure the underfloor high-pressure reference is not affected by velocity effects.
3. Static and Return Air Management:
- Locate static pressure references in areas free from localized static pressure changes.
- Ensure the return air bypass is used at the AHU or other methods are in place for humidity control.
- Ensure return air paths are clear and maintain a low static pressure loss (e.g., 0.02” wc or less if possible).
- Keep return air velocity at 100 ft/min through ceilings and 200 ft/min through walls.
4. Diffusers and Air valves:
- Leave protective plastic covers on diffusers during construction.
- Orient inlets to air valves away from supply air sources for better acoustic isolation.
- Avoid over-tightening diffuser screws.
5. Sealing and Penetrations:
- Seal holes through the floor for walls built on top of the floor before applying drywall. Perform these seals from the top and enforce quality control.
- Seal around floor boxes that do not self-seal on top of the carpet.
- Minimize penetrations in voice, data, and power boxes. Do not remove unnecessary knockout plates.
6. Electrical and Control Systems:
- Connect no more than 13 devices to one power supply.
- Run only control wires (no power wires) between power zones.
- Manage control cords during construction:
- Do not cut cords.
- Pull cords through conduits by the cable, not the Molex plug.
- Protect unconnected control cords from damage.
7. System Verification and Balancing:
- Balance return air to correct quantities per floor and verify return air static pressure loss during system balancing.
- Remove UFAD fan terminal filters after commissioning the system.
- Verify that the engineer’s operating sequence is followed for all installed equipment.
- Use a temperature reset strategy for core areas under low-load conditions.
8. Design and Construction Coordination:
- If a different design or construction team is responsible for the building shell versus tenant improvements (TI), ensure the mechanical engineer reviews TI plans to identify potential system problems.
9. Owner and Trade Compliance:
- Ensure all trades and the owner follow the established rules and best practices.