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Hanging the Corners

Install vinyl corner posts at all inside and outside corners. To allow for expansion and contraction, the corner post is hung by placing a nail in the top of the uppermost nailing slot. The balance of the nailing should be in the center of the slots, 6 to 12 inches on center. This allows expansion and contraction to occur at the bottom of the corner post. Hanging the corner post also makes installation easier. I've watched more than one contractor fight with a flopping corner post as they struggled to nail it from the bottom up. Corner posts are available in 10- and 20-foot lengths. I always recommend using a one-piece corner post. Splices are unsightly and if designed incorrectly, may allow rain to enter. After the corner posts are installed, measure down from the chalk line snapped earlier, and snap another line that represents the top edge of the starter strip. The starter strip layout line is typically 2 inches above the bottom edge of the first siding course, but the distance will vary depending on the manufacturer. When installing the starter strip, leave 1/4-inch gaps between butting ends and at corner posts.

Running the Siding

Snap the first course of siding panels into the starter strip and fasten them along the top flange with nails driven through the center of the nailing slots. To allow for expansion and contraction, draw the nails up just short of snug (see ""). Use corrosion-resistant nails, with heads at least 5/16 inch in diameter (roofing nails, for example). Stagger the end laps and check alignment every five or six courses. Always overlap panels so the exposed ends face away from main entrances and high-traffic areas. The lap joints will be much less noticeable as people approach the building. Some installers will try to adjust the panel to an out-of-level condition by pulling one side of a panel up tighter than the other. Don't do this: Over-tensioned panels can tear when they contract. On the other hand, if the fit is too loose, the panel may work free from the locking hem as it expands. Consider this scenario: It's 10°F outside and you just finished installing a 10-foot length of fascia on the west end of a house. Next summer, when the temperatures hit the high 90s and the sun-baked surface of the fascia reaches 120°F, that 10-foot length will have grown over 1/2 inch. If it can't expand freely, buckling will result. If the scenario is reversed, and you've installed a 12-foot vinyl siding panel on the hottest day of the year, that panel can shrink a full 1/2 inch when temperatures drop to 10°F. The panel can tear apart if the shrinkage movement is restricted. If it were up to me, I would require every vinyl siding crew to spend five minutes at the beginning of each day chanting this mantra: "expansion and contraction, expansion and contraction, expansion and contraction...." This issue is responsible for over 80% of the complaints I investigate.

Door and Window Detailing

Use J-channel around windows and doors to receive the siding panels (Figures 4a & 4b).

Trimming a Window

Figure 4a. When trimming a window, first run J-channel around all four sides, detailing the head piece as shown.Figure 4b. Place a notched piece of coil stock at each corner of the sill to help direct water running down the J-channel over the top of the siding beneath.

Dual Utility Trim
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Figure 5. Dual utility trim is used to secure panels that have been notched around openings. Use the outer channel if the notch ends at the thicker portion of the panel profile; use the inner channel when the notch ends at the thinner panel profile. Use a snap-lock punch to punch barbs along the notched panel edge before inserting it into the utility trim. The barbs will hold the panel in place but allow the panel to expand and contract. Use this detail to secure the cut edge of panels at the soffit as well.