Metal Roof Panels

[PSUengineer1]

Please see attached pics. is the roof is clad with through-fastened metal R-panels? is the installation correct? The screws were installed in the flat sections, as opposed to the elevated edges of the metal panels. This installation provides greater exposure to water runoff and deterioration of the neoprene washers, allowing water to penetrate the screw hole. There is a large amount of rainwater entering the building every time it rains.

Please comment on following:
1. Installation
2. Code references regarding installation
3. agree or disagree with water intruding building becaused screws installed in flat sections
thank you for your time.

 

[Ron]

This installation is common for exposed fastener application. Obviously, concealed fasteners are preferred for the reasons you stated; however, for pre-engineered metal buildings (PEMB), exposed fasteners are more common. Concealed fastener roof systems are more expensive.

The fasteners used have a neoprene gasket or washer beneath the head for sealing. These last typically about 10 to 15 years and then the fasteners need to be replaced. This is also commonly done, using an oversized fastener with gaskets.

Do not step on a skylight panel...those will not support weight.

 

[XR250]

Sometime the PEMB folks are using the 26ga roof deck as a diaphragm. This would only work if they screwed the flats.

 

[TDIengineer]

Do not step on drywall when the roof sheathing has been removed and the layer of gyp board under the 2x rafter remains... bad things happen.

 

[XR250]

TDIengineer - have you been drinking again?

 

[banjowilly]

Most likely the fasteners are self drilling with a very shallow thread. Almost all screws can be tightened about half a turn & they will stop leaking. The shallow thread fasteners are prone to back off because of vibration & thermal movement, or strip out at installation. The old fashioned AB thread (larger diameter)screws should seal & stay tight. Butler Mfg. 5/16" "Scru-Bolt" is the only really failsafe fastener for an "R" panel roof. I did a research project on thru-fastened roof systems for a major manufacturer & built metal buildings for 27 years.
Whatever you do...don't ever put caulk over the fastener heads. It won't work & basically covers up the problems & makes it harder to fix the problem. FWIW, silicone caulking is not compatible with metal roof panels.
Also often times the sealant is uphill of the fasteners at the end laps. A serious installation error!

 

[msquared48]

TDI & Excel:

Worse things happen if you are straddling the joist.

Mike McCann
MMC Engineering