Raised access flooring

[tbedford]

I am conducting several tests for a 40,000 sq.ft medical facility with a raised floor.
While I was not on site every day, I did observe all trades take particular care with sealing all below floor cavities with sealant, including electrical conduit which passes through the floor.
I do expect some leakage.
I have measured approximately .005 thru .015 'wc in a numnber of areas. Does this suggest good sealing in some areas but not others.

I am measuring airflows this week so will be able to compare sum of diffusres to air measured at the air handler.

Is there a standard test for these floors?

thank you,

Tom

 

[KiwiMace]

I don't think you will ever expect the room/floor interface to be well sealed. It depends on whether it is designed as an access floor or a plenum for underfloor ac. An access floor will leak up to 25% but still hold a 0.3" differential. Carpeted, seam sealed UFAD raised flooring would be a different matter and I don't have numbers.

 

[GMcD]

I've dealt with a few 100,000 SF of raised floor UFAD systems - generally pressurized floors for both UFAD and Displacement Ventilation systems. Policing up all the floor plenum sealing is good, and make sure the exposed concrete is sealed with a low/no VOC sealer.

Most of the leakage I've encountered, after a sealed floor plenum is done, are the field-cut floor panels around columns and other places like full height acoustic walls and firewalls - those will be a hard thing to get done right.

Depending on the floor tile manufacturer, the panel to panel sealing can be an issue - I've seen some folks use duct tape to seal the panel to panel edges before the finished flooring material goes down. But then that sort of reduces the whole "accessible floor" service access doesn't it?

Locally, the feedback I've had from operators of general office buildings where the UFAD raised access floors have been used is that they are so tight and jammed with ducts, pipes, and cable trays, that the IT and Comms people hate them because the access and ease of dealing with services churn rate is worse than the usual dropped ceiling plenum. Trying to run new services in the raised floor while dealing with support posts every 24" on centre can be a pain.

 

[tbedford]

thanks for the input

I am finding the hard to fit interfaces is where UFAD leaks the most.
It was a bit of a chore policing the work, but it did get done reasonably well.
I was actually surprised when the engineer was very non-chalant about the sealing...maybe his fan is too large.

I will know by the end of the week and send more info..

Tom

 

[SAK9]

Air tightness between the conditioned space and the floor plenum is not very critical as the air is leaking into the space which it is supposed to serve.But they need to be reasonably tight as leaks may need to a "hissing" type noise generation.

However air tightness of the floor plenum on the remaining five sides which may border non conditioned spaces is very critical.Any penetrations,crevices etc on these sides would need rigourous treatment.