The modern, high tech engineered replacement for old-fashioned gutters
- How to Estimate Materials -
Measure the horizontal length of all the roof drip edge where you want the louvers - the same places that gutters would have been. Just get someone to hold the other end of a tape measure, and each of you "eyeball" at what's "about even" with the end of the roof drip edge ( unless you want to crawl up ladders to get it exact ). Divide the total footage by 5 because the louver sections are each 5 ft long. Then multiply the whole thing by 1.07, to allow for waste. This is the APPROXIMATE number of sections you need. To get a more accurate count, read the installation details, and figure each run separately. In your measuring, do not include any edges that are not horizontal, because no appreciable rain drips off these places - such as along the angular edges of gables.
If your fascia board is not plumb, check the "Special Adjustments for some Roof Types" below.
Finally, figure one diverter in every valley that comes within two feet of a drip edge (most valleys come all the way to the drip edges). This is your materials list, that you will order.
- Basic Installation Instructions -
The main thing to watch for when installing the louver sections, is to get them positioned properly in relation to the "drip edge" of the roof. The support brackets fasten to the fascia. There are three brackets for each 5 ft section, but even the smallest partial section needs at least two brackets.
If there is no fascia, use Mansard Brackets.
VERTICALLY, the louvers must be at least 3 inches below the drip edge, which works out as 3" to the bottom of the bracket. If you can go more than 3", it's better. Mount the brackets as far down on the fascia as possible - flush with the bottom of the fascia board, unless it's cement board. For cement board, every hole has to be predrilled, and the bottom screw needs to be at least 1/2 an inch from the bottom of the board to keep the board from breaking out. If you cannot get at least 3" because the fascia is too small, you will need to add vertical spacers on each bracket.
HORIZONTALLY, the upright flange part of the bracket ( that screws to the fascia ) must be between 1.5 inches and 2.5 inches behind the drip edge. So, if the drip edge hangs out 3 inches past the fascia, you will need a 1 inch horizontal spacer on each bracket to get it out farther.
Obviously, most roof edges will not be multiples of 5 ft long, so you will almost always have to cut a section to complete each run. We use the most "pointy nose" tin snips we can find, to cut each louver vane from the top, then again from the bottom, so that it breaks easily and cleanly. Cutting with tin snips always twists the metal some, so we straighten each vane back out with pliers, to keep it pretty. The cleats that hold the louver sections together are 11" apart, and any partial section piece must have at least two cleats to be usable, therefore the minimum usable piece will be at least 11.5" long. Also, the first cleat is 2.5" from each end, so when cutting one section to finish two runs, the smallest usable piece is 11+2.5 = 13.5" or 0.225 sections. This means that if you wind up with less than 12" remaining at the end of a run, you need to cut the next to last section back, so that the last section can be at least 12".
The mounting brackets need to be as far as practical from the cleats, so the louvers can bend to snap into the brackets. The exception to this is when you have a lot of unsupported louver beyond the last cleat. In that case, put the bracket about 5" to 6" from the cleat, else the louvers a long way from the last cleat will not stay in the bracket. On a very short piece, you can make it work with brackets up to about 2" from each cleat. Typical bracket spacing for a whole section will be 8", 30", and 52 " from one end. After mounting the brackets for a section, hook the end of each bracket into the second louver, and snap the back of the louver section down, into place. To make the sections line up with each other visually, allow the ends to overlap 1/8" to 1/4", in such a way that the lower section end rides on top of the higher end, pulling them into alignment with one another.
CAUTION: Please note that Rain Louvers will not work on tile or metal roofs. The decreased friction of the roof, combined with the way these roofs focus the water in streams, will cause the rain to completely overshoot the louvers in a hard rain.
- Special Adjustments for some Roof Types -
In addition to the vertical and horizontal spacing, some fascia is not plumb, but is built at right angles to the roof rafters, which means the louvers would be useless if you mounted the brackets directly on the fascia at that angle. The louver cluster needs to be horizontal, not tilted. So, if your fascia is not straight up and down (vertically plumb), you will also need "pitch correction" adapters. If you need help figuring the pitch of your roof for "pitch correction" adapters, let us know.
If the shingles hang over beyond the fascia more than 2 1/2 inches, you will need to figure on adding horizontal spacers, to get the louvers in the right position. These are frequently needed when the fascia is not plumb, to get the louvers into position. We even had a roof that each bracket needed an angular adapter and TWO horizontal spacers!