b'Architectural Sheet Metalwatertight at the lap because you just lay one trim on top of the other instead of notching them and trying to slide them together. Photo 3 Photo 3There are two ways to install a cleated valley. One is to do a double cleat with no fasteners penetrating the valley trim that allows the valley to float. Besides no penetrations, this also provides a wider area for the water to flow because the cleat us up high on the valley trim. A valley trim made from 24 stock will provide between 7 and 8 between the end of the panel and the diverter. Photo 4The last method for fabricating and installing an architectural valley over a solid deck is to use an offset cleat set in tape sealant on top of the valley trim 4 to 6 up from the diverter. The offset cleat is fastened through to the plywood or if installing over iso, it is fastened though into a 16 gauge back up plate under the valley. In order for this type of system to remain watertight, there has to bePhoto 4significant pressure holding the offset cleat down over the tape sealant. This is why you should use a backup plate when installing this detail over iso. This method also fixes the valley where it will not move. When installing a new roof in a structural application over open framing, you should switch to a fixed eave, fixed valley, and floating ridge. You do this because on open framing you do not want to use water shedding details. You want watertight details since there is no secondary waterproofing. In all cases you will install a 16-gauge offset back up plate under the valley trim. The back up plate can be offset up or down because a structural standing seam roof is installed using clips that hold the panels anywhere from 3/8 to 1above the purlins. A plate that is offset UP will keep the valley trim in the same plane as the roof. Photo 5A valley plate that is offset DOWN will drop the valley below the plane of thePhoto 5roof. This is helpful on long valley runs on lower slopes or when retrofitting a leaking valley.TIPSCurved Roof Applications: Ifyouareinasituation whereyouhavetoputa valleyintoacurvedroof then the best approach is drop the valley down below the plane of the roof. This is easy to do on jobs where youareinstallingovera steel deck with iso. On this job there was 4inches of ISO in two layers so it was easy to leave a trench that was about a foot wide and have a welded stainless teel valley installed. A prefinished sheet matching the roof was cut to the curve andPhoto 6then glued down to the bottom of the valley. Photo 6Long Runs: One area where valleys can be very problematic is where there are long runs with a lot of drainage area on lower slopes where the water will overtake the valley trim. In this case, it is a good idea to think about making the valley extra wide and dropping it down. On this job, we had a about 140-foot valley on a 2/12 slope and it was obvious that the existing valley was getting overwhelmed with the water flow and was a major source of leaks. The existing roof was a 2 double lock installed over 3 iso over a metal deck.We cut back the ribs of the existing roof to create a 4 wide trough. Then we infilled between the ribs with 2 iso/cover board/peel and stick. We installed 2 special symmetrical standing seam panels 24 wide so there was a 2 3/8 seam with continuous clips down the middle. Here we ended up with a 140 long, free floating valley with no www.mrca.orgMidwest Roofer 13'