Guide to Installing Vinyl Siding &Trim
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Vinyl siding on buildings: materials, installation, trim
Best construction practices for installing vinyl siding on buildings
Best construction practices for installing trim on vinyl-clad structures
How to install vinyl siding
How to avoid vinyl siding blow-offs
How to avoid vinyl siding buckling and other vinyl siding damage
Questions & answers about how to select, install, troubleshoot, & repair vinyl siding

This article discusses how to choose & install vinyl siding on buildings, including vinyl siding materials, installation, nailing, flashing, and trim.

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Vinyl Siding: Product Choices, Installation Details

Adapted/paraphrased with permission from Best Practices Guide to Residential Construction. Steven Bliss.

Vinyl siding blow off New Jersey (C) Daniel Friedman

This article series discusses best practices construction details for building exteriors, including water and air barriers, building flashing products & installation, wood siding material choices & installation, vinyl siding, stucco exteriors, building trim, exterior caulks and sealants, exterior building adhesives, and choices and application of exterior finishes on buildings: paints, stains. This article series includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Related articles about vinyl siding:
SIDING VINYL

Vinyl siding is the leading choice for residential siding in the United States, accounting for an estimated 36% of the siding market. It owes its popularity to its low cost and low maintenance needs.

When first introduced in the late 1950s, vinyl was criticized for fading rapidly, turning brittle in cold weather, and buckling (or “oil-canning”) in hot weather.

Vinyl siding, if not properly installed, is also vulnerable to siding or trim blow-offs in high winds [especially on the gable-ends of houses-DF] as our photo (left) demonstrates.

Through the use of additives to the resin and better installation techniques, however, manufacturers have addressed these concerns, and vinyl is finding its way onto more higher-end projects. Today’s premium products typically carry a 50-year, or “lifetime,” prorated warranty.

Vinyl Siding Materials

Vinyl siding remodeling (C) Daniel Friedman

Vinyl siding is composed of the plastic polyvinyl chloride (PVC) blended with a number of additives for specific properties: plasticizers for flexibility; stabilizers to prevent oxidation; UV radiation absorbers, such as titanium dioxide, to prevent fading and degradation; and pigments to add color.

Fillers are added to hold down costs, and the resin is extruded into a wide variety of the shapes that mimic natural siding materials. PVC is inherently fire resistant and carries a Class 1(A) fire-rating.

Our photo (left) shows a 1920's home that was re-sided with vinyl. Poughkeepsie, NY.

Composition of Vinyl Siding Materials Formulas, Oxidation

While enhanced formulas have improved vinyl’s performance over the years, it is not impervious to the elements. Oxidation still occurs and, over time, may cause a white dusting on the surface, particularly in wet, cloudy climates such as the Northeast or Northwest. In freezing weather, a stray baseball can still shatter a panel.

Also sunlight tends to fade dark colors, and excessive heat will soften and potentially distort the vinyl. To minimize the effects of heat and sunlight, most vinyl colors are muted, although some darker colors are available with special additives to stabilize the vinyl.

Heat-Damaged Vinyl Siding

Watch out: we sometimes find badly buckled or even burned vinyl building siding where someone placed a barbecue grill too close to the exterior wall (photo above left). And on rare occasions we've found siding that was buckled as if by this problem, but in a location where we couldn't imagine a barbecue taking place (photo above right). We think the product at right was defective, or it may have been damaged by a solvent. See Installation & Repair Procedures for Vinyl Siding for suggestions and tools that are used to remove and replace vinyl siding in the middle of a wall.

Watch out: Information about vinyl products (not just siding) that may produce odors or have other environmental concerns can be found at VINYL CHLORIDE HEALTH INFO and VINYL Siding or PLASTIC Window ODORS in buildings.

Vinyl Siding Thickness

Nowadays most vinyl siding is extruded in a two-layer process that puts the more expensive weather resistant resins only in the outer layer to save costs. While building codes allow vinyl siding as thin as .032 inch (32 mils), premium products range from about 40 to 50 mils, with the thicker products typically costing proportionately more.

Some contractors prefer a heavier material for residing jobs to better smooth over the irregular substrate.

Vinyl Siding Profiles

The rigidity of the siding, however, is more a function of its profile and particularly the thickness of the butt edge, which typically ranges from 1/2 to 3/4-inch (Figure 1-22)

Our photo of ship-lap profile vinyl siding (left) was provided courtesy of Carson Dunlop Associates.

In general, more rigid products are easier to install, but they have more pronounced shadow lines at joints.

Siding panels come in several profiles, usually containing two to four courses of siding per panel. Panels range from 6 to 10 inches in width and are typically 12 feet long, although some manufacturers offer greater lengths.

Finishes found on vinyl wall siding range from completely smooth to heavily textured. A lightly textured finish most closely mimics painted wood siding.

Lock and Nailing Flanges on Vinyl Siding

Figure 1-22: Vinyl siding profiles (C) Wiley and Sons, S Bliss

All vinyl siding panels have a locking tab at the bottom of each panel that snaps over the top tab of the panel below.

Because of problems with blow-offs in high winds, some of the premium panels feature reinforced nailing flanges, either with a thickened extrusion or a hem as shown in Figure 1-22.

Tip: If you need to disassemble vinyl siding that has already been installed, especially if you don't want to have to take apart the whole wall, pick up a vinyl siding clinching tool at your building supply store.

This simple hooked blade looks a bit like the old frog knife used to clean horses hooves, but it serves a modern purpose of unhooking and re-hooking vinyl siding in the middle of a wall - DF.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Installation Procedures for Vinyl Siding

Waterproofing Vinyl Siding-Clad Walls

Vinyl siding is not waterproof. Since wind-driven rain will penetrate at lap joints, corner boards, and other penetrations, all new siding jobs should begin with the installation of a weather-resistant drainage plane consisting of building paper or plastic housewrap and integrated flashings. On residing jobs, any leaks should be repaired in the original flashing or cladding before installation begins.

See WATER BARRIERS, EXTERIOR for details, and also see our additional discussion about building codes and weather barriers behind vinyl siding found at SIDING VINYL.

Thermal Movement in Vinyl-Sided Walls

Vinyl siding nailing flange (C) Carson Dunlop Assoc

Because of its high coefficient of expansion, the key to successful installation of vinyl siding is to allow it to move freely as temperatures change.

A 12-foot length will vary in length up to 1/2 inch over a 100°F temperature change.

For that reason, manufacturers recommend leaving 1/4 inch clearance at receiving trim located at corners, windows, mounting blocks, or other places where the siding terminates or is notched.

Increase the clearance to 3/8 inch when installing in temperatures below 40°F.

Our photo (left, courtesy of Carson Dunlop Associates) shows the standard nailing flange used on most vinyl siding products - in this case with no nails installed. Just below we discuss how vinyl siding should be nailed.

Do not caulk the vinyl siding panels at overlap joints or at ends where they meet receiving trim.

Nailing Guidelines for Vinyl Siding - Mistakes mean Blow-Off or Buckling Siding

Nails in vinyl siding can also restrict movement and cause buckling problems. To prevent this, do not nail the siding tight. Instead, “hang” the siding by driving nails in the center of the nailing slots and leaving 1/32 to 1/16-inch (the thickness of a dime) between the fastener head and the siding.

Drive nails straight since the head of an angled nail can pinch and distort the siding. Use corrosion-resistant nails with heads at least 5/15-inch in diameter, such as roofing nails, driven at least 3/4-inch into solid wood (Figure 1-23).

Standard nailing spacing for vinyl siding is 16 inches on-center for horizontal panels, 12 inches for vertical panels. In high-wind areas, use extra nails and choose a product with a hemmed or reinforced nailing flange. Carson Dunlop's photo (below) demonstrates aluminum roofing nails used to hang vinyl siding on a building wall.

Vinyl siding nailing detail (C) Carson Dunlop Assoc

Experienced vinyl siding installers who want to avoid siding blow-off (see VINYL SIDING INSPECTION & REPAIR) refer to "hanging vinyl siding" on the building wall rather than "nailing vinyl siding to the building wall" precisely to remind workers not to nail siding so tightly that it buckles when heated.

On a wall section long enough to have spliced sections of vinyl wall siding in a given siding course, if we see vinyl wall siding that is buckled, we also check to see if the siding moves freely left and right on the wall. It's easy to either use the butt of your hand to try to slide a siding panel left or right - it should move about 1/2" or so. If the siding feels tight we may check further by grasping the end or edge of a siding section to see if we can pull or push it.

When locking the vinyl siding panels into position, do not force them up or pull them down to adjust the alignment. Too tight panels can tear and too-loose panels can unlock and come loose. One exception is at the band joint between the first and second floor where panels may come unlocked due to shrinkage of the framing. To compensate for this, some contractors pull the panels a little tight over the band joist area.

Overlaps at Vinyl Siding Joints

Where more than one panel is needed along a run, overlap the two panels by about an inch, with the overlapped edge facing away from high traffic areas so they will be less visible.

Overlaps should be staggered at least 3 feet and in a random pattern to avoid creating a visual seam or step effect up the wall. Where possible, use a single piece of siding across the wall.

The fewer joints, the more attractive and water-resistant the job will be.

Our vinyl siding butt joint photo (left) shows how not to install this material.

Fixture Mounting Blocks on Vinyl Siding

Exterior fixtures—such as light fixtures, electrical panels, and hose bibs—can also cause problems if they are fastened through the siding, restricting its free movement.

Siding manufacturers sell mounting blocks with integral J-channel to hold panel ends and allow for movement.

Or the contractor can install wood mounting blocks before installing the siding and trim them with J-channel or utility trim.

Trim for Vinyl Siding

The appearance of a vinyl siding job often has more to do with the trim details than with the siding itself. By using wider trim pieces and avoiding the overuse of J-channel, the installer can produce a more attractive finished product. Manufacturers sell a wide range of accessories in PVC, aluminum, or vinyl-coated aluminum. Most contractors fabricate at least some of their trim pieces on site from either prefinished or vinyl-coated aluminum coil stock, using a sheet-metal break and other specialized tools.

Like vinyl siding, aluminum trim has a high coefficient of expansion so installation details need to accommodate movement. Avoid putting nails in the face of flat pieces of coil stock and allow 1/4 inch at edges for expansion and contraction. Where possible, use a vinyl receiving channel, roofing drip cap, or another piece of trim to support long runs of flat aluminum trim, minimizing the use of nails.

Where nails are required, use slotted nail holes, which can be made using a slot punch. Repainted aluminum or stainless-steel nails are available to match siding and trim colors. A one-inch hem placed along one edge of flat trim, such as fascia, will help minimize buckling or oil-canning.

Soffit and Fascia Products Used with Vinyl Siding

Figure 1-24: Vinyl and Aluminum Trim Construction Detail (C) Wiley and Sons, S Bliss

Most vinyl siding jobs include aluminum fascia trim and vinyl or aluminum soffit panels.

The fascia is typically secured at the top, either by the drip edge or a piece of vinyl utility trim, although it can also be fastened with a few face-nails (through slotted holes) if the nails will be hidden by a gutter.

The bottom lip of the fascia should be nailed sparingly in slotted holes to allow movement (Figure 1-24 at left).

The outside edge of the aluminum or vinyl soffit panels can be supported by the receiving channel (J-channel or F-channel) or by the L bend at the bottom of the fascia, as shown in Figure 1-24.

The back edge of the soffit is either supported by receiving channel or a wood or vinyl frieze board.

These details allow the fascia and soffit panels to move freely to accommodate thermal expansion and avoid buckling.

Windows and Door Trim with Vinyl Sided Walls - Using J-Channels

Figure 1-25: Window and door trim for vinyl siding (C) Wiley and Sons, S Bliss

Window and door trim is perhaps the most conspicuous part of a vinyl siding job. Good planning is important. If possible, plan the job so a full butt of the siding lands on top of the windows.

At window bottoms avoid the use of 3/4inch J-channel, which lets the unrestricted siding buckle. Instead use utility trim or under-sill trim to hold the siding tight here and at other horizontal projections. Where the vinyl has been notched below a window, use a snap-lock punch to create raised lugs along the top edge of the siding, locking it into the under-sill trim.

At window side and head jambs, J-channel is the most common treatment, with end tabs on the top J-channel bent over the side channels to deflect water (Figure 1-25).

While this detail helps shed water, it is important to note that J-channel does not serve as window head flashing. The window head should be properly flashed with the window’s top flange or drip cap lapped under the sheathing wrap and sealed to the sheathing with flashing tape.

Installing the Corner Post with Vinyl Siding

Figure 1-26: Vinyl Siding Corner Posts (C) J Wiley and Sons, S Bliss

To simplify installation and avoid the conspicuous look of J-channel around windows, one option is to use solid vinyl windows with an integral J-channel (Figure 1-26 far left).

For the more traditional look of flat trim around the window, you can use vinyl widow casing, which is typically 2 1/2 inches wide with an integral J-channel. Corners.

Set the inside and outside vinyl corner posts about 1/4 inch below the soffit or frieze above, and lock them in place with nails at the top of the uppermost nailing slots.

Then nail in the center of the slots every 6 to 12 inches so that any movement is downward, not upward. Vinyl corner trim tends to be wavy, so following a snapped line is helpful (Figure 1-27 above right).

Vinyl-Siding J-Channel Errors Over Windows: Leaks

Damaged vinyl siding (C) Daniel Friedman

In our photo at above left it looks like really sloppy J-channel work during siding installation, leaving a leak at the window sill.

Our photo of improperly-cut J-channel trim around a window (above right) shows a more serious problem than may be immediately apparent.

In Spackenkill, Poughkeepsie, NY we found an entire neighborhood of homes in which nearly all of the windows were rotted beyond repair due to this error. The same installer had done all the J-channel vinyl siding work on all the homes.

Watch out: J-Channel errors can rot windows and doors: Wind-blown rain sent inside the J-channel trim and into the window structure was the problem caused because the installer didn't follow the manufacturer's instructions. Properly the top J-channel is trimmed to include a tab bent over the vertical J-channel to route water outside, not inside the trim. The little flap and proper J-channel installation details are shown in Figure 1-25.

Wood Trim Installation with Vinyl Siding

Figure 1-28: Traditional Trim (C) Wiley and Sons, S Bliss

For those attracted to the low-maintenance appeal of vinyl siding but who want the look of traditional trim, builders can use wood or composite trim rabbeted or built out to create a receiving channel for the siding. For example, 5/4--inch corner boards can be rabbeted to receive the siding, or standard 3/4-inch stock can be furred out the thickness of the vinyl siding to create a similar effect (see Figure 1-28).

Window and door casings in a vinyl-sided wall can be fashioned the same way. Either use a furring strip to raise the casing above the vinyl siding or use a thicker profile with a rabbet. At the bottom of the window, you can partially conceal the undersill trim in the rabbet. To shed water, the head casing will still need conventional head flashing and J-channel, but these will be relatively inconspicuous.

-- Adapted with permission from Best Practices Guide to Residential Construction.

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InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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SIDING VINYL

Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Paul Galow - technical consultant on networking, LAN design, applications support. Galow Consulting Services, 914-204-1749, email: paulgalow@galowconsulting.com
John Rudy, Advantage Home Inspections, Flemington N.J. 08822 home inspector, 908-806- 6364, Home, Radon & Termite Inspections, Central & Parts of North New Jersey, email: jonadvantage1@yahoo.com
Malco® Products siding tools are available from that company, including the SideSwiper II SRT2 discussed at Malco's website. Websearch 09/07/2010 http://malcoproducts.com/product/roofing-siding-gutter/siding-vinyl/siding-tools-vinyl/sideswiper-ii. Malco also produces other vinyl siding repair tools such as aprons, awls, hole punches, saw blades, and tools for for fiber cement products including power-assisted cutters
Parmetol, a wood preservativerecommended by the manufacturer was used as a fungicidal additive to paint on the Blue Poplar wood sculpture in Amsterdam, by artist Mari Shields [ - art conservation consult DJF-artist MS 2010]

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Vinyl Siding: Product Choices, Installation Details

Vinyl Siding Materials

Composition of Vinyl Siding Materials Formulas, Oxidation

Heat-Damaged Vinyl Siding

Vinyl Siding Thickness

Vinyl Siding Profiles

Lock and Nailing Flanges on Vinyl Siding

Installation Procedures for Vinyl Siding

Waterproofing Vinyl Siding-Clad Walls

Thermal Movement in Vinyl-Sided Walls

Nailing Guidelines for Vinyl Siding - Mistakes mean Blow-Off or Buckling Siding

Overlaps at Vinyl Siding Joints

Fixture Mounting Blocks on Vinyl Siding

Trim for Vinyl Siding

Soffit and Fascia Products Used with Vinyl Siding

Windows and Door Trim with Vinyl Sided Walls - Using J-Channels

Installing the Corner Post with Vinyl Siding

Vinyl-Siding J-Channel Errors Over Windows: Leaks

Wood Trim Installation with Vinyl Siding

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair