These questions are published by the Vinyl Siding Institute, Inc. (VSI) as a service to the industry. VSI members are manufacturers of vinyl and other polymeric siding and suppliers to the industry. The information provided in this document is offered in good faith and believed to be reliable, but is made without warranty, express or implied, as to merchantability, fitness for a particular purpose, or any other matter. VSI does not endorse the proprietary products or processes of any manufacturer. This document is not intended to provide specific advice, legal or otherwise, on particular products or processes. Readers should consult with their own legal and technical advisors, vinyl siding suppliers, and other appropriate sources (including but not limited to product or package labels, technical bulletins, or sales literature) that contain information about known and reasonably foreseeable health and safety risks of their proprietary products and processes. VSI, its members, and contributors do not assume any responsibility for the users’ compliance with applicable laws and regulations, nor for any persons relying on the information contained in this document.
Installers should review local building codes and manufacturers’ literature for variations that may apply to specific products and/or geographic areas.
Q: What are the keys to a good vinyl siding installation job?
A: Allowing for Expansion and Contraction
Vinyl siding contracts and expands as the outside temperature changes. To avoid structural or aesthetic problems associated with this characteristic, take the following steps:
- Apply nails or other fasteners in the center of the nailing slot and make sure the fastener penetrates a minimum of 3/4" (19mm) into a framing stud or furring. Make sure installed panels and accessories move freely from side to side.
- Do not drive the head of the nail tightly against the siding nailing hem. Allow approximately 1/32" (0.8mm) clearance (about the thickness of a dime) between the fastener head and the siding panel. Drive nails straight.
- Leave a minimum of ¼" (6.4mm) clearance at all openings and stops. When installing in temperatures below 40 degrees F, increase minimum clearance to 3/8" (9.5mm).
- Do not face nail or staple through siding except for one nail needed to finish at the top of a gable.
For more information, refer to page 15 of the VSI Vinyl Siding Installation Manual.
Keeping It Straight and Level
Keep in mind, siding is only as straight and stable as what lies under it. Below are some issues to address before you start installation:
- In residing, strapping or removal of uneven original siding may be necessary.
- In new construction, avoid the use of green lumber as the underlayment.
- When installing a siding panel, push up lightly along the bottom until the lock is fully engaged with the piece below it for the full length of the panel.
- Throughout installation, check the panels' horizontal alignment every few rows to make sure the siding is hanging straight and level on the wall. Also check for panel alignment around corner posts and above doors and windows.
Q: How do I prepare the structure's walls?
A: Your main goal in preparing the walls of the structure is to ensure a flat, even surface. On any project, remember to install code-compliant flashing before starting to apply siding.
As stated in the VSI Vinyl Siding Installation Manual, before you begin installing vinyl siding in a new construction project:
- Apply a water-resistive barrier, such as house wrap or felt paper.
- Check local building codes for additional requirements.
- Place drywall inside the house, on the floor of the room where it's going to be applied, to allow for floor-plate compression, which, if not addressed, can result in buckled siding where the floor meets the wall.
As stated in the VSI Vinyl Siding Installation Manual, before you begin construction on a residing project:
- Nail down loose boards on existing siding and replace rotten ones.
- Scrape off loose caulk and re-caulk around windows, doors, and other areas to prevent moisture penetration.
- Remove all protrusions such as gutters, downspouts, and light fixtures.
- Check all walls for evenness and install furring strips where necessary.
Q: How do I fasten vinyl siding to a wall?
A: Choose aluminum, galvanized steel, or other corrosion-resistant nails, staples, or screws. Aluminum trim pieces require aluminum or stainless steel fasteners. Remember, as temperatures change, vinyl siding can expand and contract ½" (12.7mm) or more over a 12'6" (3.81m) length.
- Heads should be 5/16" (7.9mm) minimum in diameter.
- Shank should be 1/8" (3.2mm) in diameter.
- 1 ½" (38.1mm) for general use.
- 2" (50.8mm) for residing.
- 2 ½" (63.5mm) minimum for going through siding with backerboard.
- 1" to 1 ½" (25.4mm to 38.1mm) for trim.
- Can be used if the screws do not restrict the normal expansion and contraction movement of the panel on the wall.
- Screws should be size #8, truss head or pan head, corrosion-resistant, self-tapping sheet metal screws.
- Not less than 16-guage semi-flattened to an elliptical cross-section.
- 1" (25.4mm) minimum in length and wide enough to allow free movement of the siding (approximately 1/32" [0.8mm] above and below the nailing hem).
No matter what fastener you choose, follow the basic fastening steps listed below:
- Make sure the fastener penetrates a minimum of 3/4" (19mm) into a framing stud or furring.
- Ensure panels are fully locked along the length of the bottom, but don't force them up tight or stretch the panels upward before nailing.
- Do not drive the head of the fastener tightly against the siding nail hem; instead leave a minimum of approximately 1/32" (0.8mm) clearance (the thickness of a dime) between the fastener head and the vinyl siding to prevent panel buckling as temperatures change.
- Start fastening in the center of the panel and work toward the ends.
- Center the fasteners in the slots to allow for expansion and contraction. (Start fastening vertical siding and corner posts in the top of the uppermost slots to hold them in position. Place all other fasteners in the center of the slots.)
- Drive fasteners straight and level to prevent panel distortion and buckling.
- Space fasteners a maximum of 16" (406.6mm) apart for the horizontal siding panels, every 12" (305mm) for vertical siding panels, and every 8" to 12" (203mm to 305mm) for accessories unless otherwise specified by the manufacturer.
- If a nail slot does not allow centering/securing into a nailable surface, use a nail hole slot punch to extend the slot and allow centering of the fastener.
For more information, refer to pages 14 and 15 of the VSI Vinyl Siding Installation Manual.
Q: How do I cut vinyl siding safely and accurately?
A: You can use a circular saw, tin snips, utility knife, or a scoring tool to cut vinyl siding. Depending on the tools you use, for a safe, clean, and straight cut:
- Wear safety goggles for all cutting and nailing operations and follow safe construction practices.
- With a circular saw, install the fine-toothed (plywood) blade backwards on the saw and cut slowly, especially in cold weather. SAFETY WARNING: DO NOT TRY TO CUT MATERIALS OTHER THAN VINYL SIDING WITH A REVERSED DIRECTION SAW BLADE.
- When using tin snips to cut siding, avoid closing the blades completely at the end of a stroke.
- With a utility knife or scoring tool, score the vinyl face up with medium pressure and snap it in half. It's not necessary to cut all the way through the vinyl.
For more information, refer to page 16 of the VSI Vinyl Siding Installation Manual.
Q: What do I need to know about wall and window flashing?
A: As stated in the VSI Vinyl Siding Installation Manual, always install flashing that meets the requirements of ICC AC148, such as aluminum coil stock, around windows, doors, other openings, inside and outside corners, and the intersection of walls and roofing. The most important tip to remember when applying window flashing is that flashing should extend past the nail flanges of the window (or any accessory) to prevent water infiltration. The flashing must be long enough to direct water over the nail flange of the last full course of siding.
With this in mind, you should first apply the flashing on the underside of the window, then to the sides of the window (make sure to overlap the bottom flashing), and finally, to the top of the window.
For more information, refer to page 20 of the VSI Vinyl Siding Installation Manual.
Q: What are some tips for fitting siding under windows and around fixtures?
A: Since vinyl siding can expand and contract depending on the outdoor temperature, fitting siding under windows requires careful measuring and planning. To mark the vinyl panel to be cut, follow the steps below:
- Hold the panel under the window and mark the width of the window opening on the panel. Add approximately ¼" (6.4mm) to both sides-these marks represent the vertical cuts.
- Lock a small piece of scrap siding into the lower panel next to the window. Mark it ¼" (6.4mm) below the sill height. This will serve as a template for the horizontal cuts.
- Transfer the horizontal measurement to the panel that will be installed under the window. Measurement may not be the same on both sides of the window.
After you have cut the panel with tin snips or a utility knife, you're ready to install it under the window. The VSI Vinyl Siding Installation Manual outlines the following installation procedure:
- Use a snap lock punch to place lugs in the cut edge of the panel every 6" (152.4mm) so that the raised lug is on the outside face.
- Install undersill trim under/over the window as a receiver for the cut siding. Undersill trim is used anytime the top lock or bottom lock has been removed from the siding. Furring may be needed to maintain the face of the panel at the desired angle.
- Install the siding panel, making sure the lugs (from the snap lock punch) lock into the utility trim.
For more information, refer to page 24 of the VSI Vinyl Siding Installation Manual.
Q: How do I install vertical siding and how does it differ from horizontal panel installation?
A: For the most part, follow the same procedures for installing vertical vinyl siding as horizontal siding, with a few noted differences. Below, you'll find a summary of important steps that apply only to vertical panel installation:
Getting Started with Vertical Siding
- Snap a level chalkline around the base of the sidewalls. Usually, the chalkline is positioned so the bottom of the J-channel that will be installed like a starter strip is ¼" (6.4mm) below the lowest point on the wall that will be sided. Install a J-channel along the chalkline as a receiver for the vertical siding.
- Find the center of each sidewall and use a level or plumbline to install two back-to-back J-channels. Leave ¼" (6.4mm) gap at the top and bottom. These will serve as starter strips in which to lock the vertical siding.
Installing Vertical Siding
Working from the starter strip to the corners, lock each panel and fasten every 12" (305mm). Vertical panels are terminated into the J-channel installed at top and the vertical base or J-channel installed at bottom.
Windows and Doors:
- Cut the panels (if necessary) to fit the openings, allowing ¼" (6.4mm) for expansion.
- If panel is uncut or cut down in the "V"-shaped groove of a piece of vertical siding, simply insert it into a 3/8" (9.5mm) J-channel, locking the other side on to the previously applied panel. A furring strip should be installed to prevent panel detachment.
- If the panel is cut on the flat surface, install undersill trim, backed by furring, into the J-channel. The flat surface of the vertical siding should be snaplock-punched and fitted into the undersill trim. The panel is further secured above and below the windows and above the door when the panel is fastened in place.
- Install the undersill trim or 3/8" (9.5mm) J-channel into the receiver of the corner post.
- If the panel is cut in the bottom of the V-groove, insert it into the J-channel. A furring strip should be provided prior to panel insertion to prevent detachment.
- If the panel is cut on the flat surface, install undersill trim, backed by furring, into the J-channel. Punch snap locks along the cut edge of the panel at 6" (152.4mm) intervals and snap it into the undersill trim.
- To create a balanced appearance, divide the length of the wall by the exposure of the vertical panel to be used. For example, if the wall requires 20 full panels plus an additional 8" (203mm), then the first and last pieces installed would be cut to a new width of 4" (102mm). Make sure to allow for proper depth in the receiving channels of the accessories at both ends when measuring.
- To install the siding, if partial panels are required, mark the line to cut by measuring from the edge of the lock of the panel and cut the panel to the proper width. This will leave a panel with an intact nail hem and proper exposure.
For more information, refer to pages 27 - 31 of the VSI Vinyl Siding Installation Manual.
Q: What should I know about installing soffit?
A: Ventilation is an important aspect of soffit installation that should be considered before you begin work. Consult a local building official for the appropriate requirements for your area and use vented soffit or other vented products as necessary.
Inspect and plan your job in advance. Surfaces should be uniform and straight from any viewing angle. For residing applications, nail down any loose panels, boards, or shingles and fur when necessary.
Installing Soffit Over Open Eaves
- Step 1: Install receiving channels (soffit receiver or J-channel). Nailing strips must be installed if the eave span is greater than 16" (406mm), unless otherwise specified in the soffit manufacturer's instructions. In areas with high wind restrictions, nailing should not exceed 12" (305mm) on center, unless otherwise specified by the manufacturer.
- Step 2: Measure from the wall to the fascia board and subtract ½" (12.7mm) to allow for expansion; mark and cut the soffit.
- Step 3: Insert the panel into the channel on the wall, then into the channel at the fascia board. Make certain the panel is perpendicular to the wall, then nail with trim nails. Drive the nail through the nail flange and "V"-shaped groove within the soffit panel, leaving space for the full expansion allowance in the receiving channel.
- Step 4: To turn a corner, measure from the channel at the wall corner to the channel at the corner of the fascia board and subtract ¼" (6.4mm) for expansion. Cut and install soffit double channel lineal or back-to-back J-channel. If necessary, install nailing strips to provide backing for the lineal. Miter cut the corner soffit panels and install as in Step 3.
- Step 5: To complete the installation, apply utility trim and fasten the aluminum fascia cap or formed aluminum coil stock with painted trim nails. If necessary to face nail fascia, drill holes for the trim nails to allow for expansion and to reduce denting of the aluminum.
Installing Soffit Over Enclosed Eaves
- Step 1: Determine preferred method of installing soffit at fascia board. When installing J-channel at either wall of fascia board, nail every 8" to 12" (203mm to 305mm).
- Step 2: If soffit is to turn a corner, cut and install J-channel to allow ¼" (6.4mm) for expansion at each of the adjoining walls and fascia boards. When installing vented soffit panels, if the existing soffit doesn't have openings for ventilation, cut an adequate number of openings before installing soffit panels.
- To complete the installation, follow steps 3 through 5 from the open eaves installation instructions listed above.
For more information, refer to pages 32 - 35 of the VSI Vinyl Siding Installation Manual.
Q: How do I replace a damaged panel?
A: To remove a panel for any reason, follow the steps below:
- Slip a zip lock or unlocking tool behind the bottom lock of the panel above the one to be replaced and unzip it from the lock on the damaged panel.
- Gently bend out upper panel. Take the nails out of the damaged panel and remove it.
- Lock on the new panel and nail it up.
- Use the unlocking tool again to zip the upper panel over the lock on the new panel.
For more information, refer to page 37 of the VSI Vinyl Siding Installation Manual.
Important note: VSI staff cannot provide information beyond what is posted on our website. For additional information regarding vinyl siding installation, please contact the manufacturer of your vinyl siding.
- What are the keys to a good vinyl siding installation job?
- How do I prepare the structure's walls?
- How do I fasten vinyl siding to a wall?
- How do I cut vinyl siding safely and accurately?
- What do I need to know about wall and window flashing?
- What are some tips for fitting siding under windows and around fixtures?
- How do I install vertical siding and how does it differ from horizontal panel installation?
- What should I know about installing soffit?
- How do I replace a damaged panel?