238T Metal-Over-Metal Recover

McElroy Metal has two patented 238T frameless Metal-Over-Metal recover options that provide low cost recover solutions over both existing exposed fastened and 3" tall trapezoidal standing seam systems. McElroy also has an accompanying patented day-lighting system that can be installed with both patented recover systems or on new construction. All three systems utilize McElroy's easily repairable symmetrical 238T standing seam panel while providing long-term solutions to existing metal roofs that have completed their service life at a cost that is competitive with single-ply recover and will last two (2) to four (4) times longer.  

Additional Details

The two frameless recover systems provide the following benefits:

  • Panels can be manufactured up to 24" wide, onsite, directly onto the roof to eliminate end laps and improve
    installation efficiency
  • Extremely high wind-uplift capacity when attached to purlins 5' o.c., which means no additional corner/edge framing
  • Individual panel removal and replacement capabilities which allows for easier repairs at a later date
  • Very little disruption to occupant
  • Increase wind uplift capacity of existing roof without added framing
  • Very little trash/landfill debris generated
  • Decades long service life
  • Direct attachment to the structure without expensive sub-framing
  • Extremely fast installation
  • Up to 100 psf snow load without added framing
  • Structural diaphragm is not altered
  • Patented transverse mounted skylight can be incorporated into the roofing system

Installation over Exposed Fastener Panels

The thru-fastened recover system is designed to be installed over existing panels up to 1.5" tall, such as R-Panel. The system utilizes tall clips that sit between the ribs of the existing panel and are attached directly to the purlin below. The air space between the two roofs is filled with insulation. The images below show the steps of a 238T Metal-Over-Metal recover. 

Utilizing McElroy's jobsite production vehicles, roof panels run from eave to ridge, eliminating the need for end laps.
Single length panels offer labor savings and improve weathertightness.

Once the panels are manufactured on the roof, then special die-cut insulation is placed over the existing roof panels.

  • Clips are attached to the structure
  • Insulation is installed between the clips
  • 238T panels are placed on top of the insulation
  • 238T panels are joined together using 238T seam caps
    and mechanical seamer

Seam caps are applied over adjoining 238T panels.

Note the two beads of butyl sealant in the seam cap that improves weathertightness.

For maximum strength and load handling capabilities, Multi-Span clips can run from eave to ridge as shown on the left. Multi-Span clips are often utilized in critical areas, such as corners, while standard clips are utilized for the majority of the roof. 

For high wind uplift or snow load area, McElroy's Multi-Span clip provides up to -93.5 psf allowable uplift or nearly 100 psf positive with a 24" wide panel installed over purlins 5' on center.

Installation Over Standing Seam Panels

The second recover system is designed to go over an existing 3" tall trapezoidal standing seam. The basic process is to set the 238T retrofit clips on the shoulder of the trapezoidal panel over the purlin, then fasten sideways through the seam. Once the clips are installed, the existing roof panels are fastened to the purlins, then insulation is added between the existing panel seams and the new panels are snapped into the clips.

  • No expensive sub-framing
  • Extremely fast installation
  • Wind load resistance can be increased up to 85.5 psf allowable over purlins 5' o.c.
  • Patented transverse mounted skylight can be incorporated into the roofing system
  • Purlin load carrying capacity increased 25 to 40%

 

On the Trapedzoidal Recover system, the clips are pre-installed to the side of the seam right over the purlins as shown. Later, the existing roof is screwed down into the purlins, 5" of insulation is added and the new 238T roof panels are snapped into the clips. Installation of this system is very efficient, resulting in low labor hours.

If the owner wants to keep or add skylights, it’s no problem. McElroy's patented 238T transverse mounted skylights can be installed over existing skylights or can be installed as a continuous light strip all the way to the ridge.