Do not drive the head of the fastener tightly against the siding nail hem. Allow approximately 1/32-inch gap (the thickness of a dime) between the fastener head and the vinyl.
With warmer weather, homeowners’ thoughts turn to exterior home improvements, such as vinyl siding. Because quality installation is the key for any home-improvement effort, exterior remodeling contractors who use proper techniques can improve their chances of getting referrals.
Following are some of the most important considerations to ensure the vinyl siding you install effectively replicates classic home exteriors and is aesthetically appealing, long lasting and low maintenance. Proper installation will not only help you avoid costly callbacks, but it will enhance your reputation for quality work.
Preparation Is Everything
Like any home-improvement project, vinyl-siding preparation can make or break the final job. Make sure you have all the necessary tools, fasteners and accessories. For vinyl siding, fasteners, such as nails or staples, should be able to penetrate 3/4 inch into the nailable surface.
A flat, level surface is necessary for proper installation of vinyl siding. In a re-siding job, be sure to nail down loose boards of existing siding and replace any rotten or damaged ones. Remove loose caulk and recaulk around windows, doors and other areas first to ensure a watertight seal. Check all walls for evenness and install furring strips where necessary, making sure to establish a smooth, continuous surface.
Waterproofing measures are important for siding’s longevity and performance. Vinyl siding is designed as an exterior cladding—not a water-resistive barrier. Because vinyl siding is designed to allow the material underneath it to breathe, it is not a watertight covering. Therefore, the first step to proper installation is to use a housewrap. High-quality housewraps keep water out while allowing moisture from the inside to escape. Not only do housewraps reduce or eliminate leaks, they limit air infiltration, helping to reduce heating costs. (To read about proper housewrap installation, see the March issue, page 62.)
Even where housewrap is applied, flashing is critical at all openings, such as windows. Use at least 10-inch flashing at inside and outside corners prior to installing the corner post. There should be at least 9-inch flashing on the bottom edge of the window and at least 8 1/2-inch flashing on all other sides if the windows are preinstalled nail fin windows.
Although nail fin windows on new construction jobs usually have flashing already applied, older remodeling jobs where previous vinyl or aluminum siding has been removed around the windows require flashing before re-siding. If a window with exterior casing has been previously installed without flashing, cover the exterior casing with aluminum or vinyl trim sheet. The trim sheet should be installed in weatherboard fashion with the bottom piece installed first, then overlapped by each side sheet and finished with the top sheet overlapping the side sheets. Install rigid head flashing on the top piece of exterior casing, covering the trim sheet. The rigid head flashing must be sealed to the exterior sheathing and to the top of the exterior casing.
Installers frequently think everything should be level or plumb when installing siding. However, in many jobs, siding is installed level on an unlevel structure. In these cases, the siding appears to be slanted, even if it was sided as “level.” Aesthetically, it is better to hang the siding straight with the structure. Although the level may tell you you’re off, it will look level to the eye.
Leave Some Wiggle Room
One of the most critical installation requirements for vinyl siding is allowing for expansion and contraction. All forms of vinyl siding expand and contract; a 12-foot piece of siding can “grow” 1/2 inch from the coldest temperature to the warmest.
Depending on the temperature at the time of installation, space allowances need to be given to accommodate movement. When installed at temperatures below 40 F, a 3/8-inch space is allotted between siding and accessories; 1/4 inch is allotted if installed above 40 F.
Vinyl siding and its accessories are designed with elongated slots to accommodate movement as the product expands and contracts. It also is important to leave a gap between the nail head or staple and the siding nail hem to account for movement on the nail shank. About 1/32 inch—the thickness of a dime—is the recommended gap. Position nails in the center of the slot to allow for expansion.
A good tip for assessing proper nailing is to make sure you can move the vinyl siding side to side or a corner post up or down slightly. Visually, you also should see a gap between the end of the siding and the back of the accessory. On the flip side, it is also possible to leave too large a gap. Overlapping siding and accessories is important; if pieces are cut too short in the heat of summer, they could possibly shrink out of the pocket of the accessory in the winter. Overlap one panel over the other by half of the factory notch, or approximately 1 inch. If the overlap is not enough, the panels could separate in colder weather; if it is too much, movement could be restricted.
When overlapping siding, face the overlap away from the driveway or front entryway to avoid showing seams. Overlaps or joints should be randomly placed, and if one joint needs to be directly placed above another, there should be a least three rows between them. To avoid waviness, look down the length of the panel when installing and adjust the nail in or out to keep the top lock straight. If the nail has to be adjusted out more than 1/4 inch, a shim should be placed between the wall and the back of the panel.
As you install panels, always check that the buttlock, or the lip at the bottom of the panel, is fully engaged with the panel below it for the entire length of the panel. When you get to openings or the top of a wall, there are techniques for installing partial profiles. Consult the Washington, D.C.-based Vinyl Siding Institute’s Vinyl Siding Installation Manual or your manufacturer’s instructions for details about these specific installation procedures, as well as proper techniques for installing fascia and soffit on a home.