What is the bottom piece of vinyl siding called?

The bottom piece of vinyl siding is called the starter strip. The starter strip serves an important function when installing vinyl siding – it provides a solid, level base for the first course of siding to be attached to. Without a starter strip, it would be difficult to get the first row of vinyl siding properly aligned and secured.

What Does the Starter Strip Do?

There are a few key jobs the vinyl siding starter strip performs:

• Creates a straight, even base – The starter strip levels out any uneven spots or imperfections on the exterior wall surface. This allows the first course of siding to start off straight and remain straight.
• Secures the first siding panel – The starter strip contains a locking channel that the bottom edge of the vinyl siding panels slide into and lock into place.
• Offsets the slope of the ground – Installation typically starts at the lowest point of the wall. The starter strip compensates for any slope in the ground so siding remains horizontal.
• Provides proper spacing from the ground – Building code requires a minimum gap between the bottom edge of the siding and the ground. The starter strip positions the siding the correct distance above the ground.
• Protects from moisture – The starter strip creates a moisture barrier between the bottom of the siding and the foundation or splash back area.

Without the starter strip properly leveled and secured, the vinyl siding installation is off to a bad start and problems will cascade from there. Taking the time to install the starter strip correctly pays off in the long run.

What is a Starter Strip Made Of?

Vinyl starter strips are predominantly made from PVC (polyvinyl chloride). This is the same material that vinyl siding is produced from. PVC is a durable, weather-resistant plastic commonly used for home exteriors.

Here are some of the advantages of PVC starter strips:

• Durable – Withstands weather, impacts, and bending without cracking or breaking
• Flexible – Can adapt to contours of wall surface while remaining rigid
• Long-lasting – Does not rot or deteriorate; retains original shape and color
• Low-maintenance – Requires no painting, sealing, staining, etc.
• Moisture-resistant – Repels water and resists swelling, warping and discoloration
• Affordable – PVC is an inexpensive material to manufacture
• Lightweight – Easy to transport and work with

Vinyl starter strips typically have a thickness of about 0.035 inches. Heavy duty starter strips are available at around 0.050 inches thick for added durability and rigidity on larger projects.

Where Are Starter Strips Located?

Starter strips are installed along the bottom edges of walls where vinyl siding will be applied. They encircle the entire perimeter of the building:

• Bottom edges of all exterior walls
• Under soffits and eaves if siding will be installed in those areas
• Above windows and doors if siding will extend over them

Having starter strips around all lower edges ensures the first course of siding has a continuous base to interlock with. Without enclosing the entire area, there would be gaps between the starter strips and siding.

How Are Starter Strips Installed?

Proper starter strip installation involves several steps:

1. Measure area to be sided and cut starter strips to required lengths.
2. Starting at the lowest point, attach strips snug to the wall surface allowing minimum 1/4 inch spacing at the bottom edge.
3. Use galvanized nails, screws, or adhesive to secure the strip every 8 to 12 inches.
4. Overlap strip ends by at least 1 inch and make sure they are perfectly aligned.
5. Install strips around entire perimeter, including over windows, doors and corners.
6. Make sure strips remain completely level with each other.
7. Seal any gaps with vinyl trim or caulk.

Taking precise measurements and keeping the starter strips as level as possible are the most critical factors for proper installation. Rushing this step can undermine the results of the entire siding job.

How is the First Course of Siding Attached?

With the starter strips creating an even base, the bottom edge of the first siding panel can be fitted into the strip’s receiving channel and locked into place. The siding will overlap the top of the starter strip to conceal it.

The siding piece is slid down into the channel at an angle, then rotated forward until it clicks and locks. Additional panels are secured side-by-side, overlapping the previous panel by about 1 inch until the first course is completed.

The starter strip supports the weight of the bottom course while the interlocking panels hold each other in place. Additional courses are stacked upward from there, each one installing easier thanks to the starter strip beginning the siding on a perfectly straight and level line.

What if Sections are Misaligned?

With the precision required, there are times when a section of starter strip may wind up slightly misaligned. This can throw off the entire first course of siding above it. There are a couple ways to remedy this:

• Remove any fasteners from the high side of the misaligned strip and tap it down into proper position with a rubber mallet. Re-fasten it.
• Leave the original strip intact and install a new starter strip right on top of it, positioned correctly. The slight difference in thickness is not significant.

With the new starter strip in the proper position, the first siding course can lock into it correctly. An irregular starter strip should be rectified rather than trying to install siding over it while it’s misaligned.

Matching Starter Strips to Siding

For the best visual results, the starter strip should closely match the style and color of the siding. If noticeably different, it can create an unsightly gap at the bottom of the siding.

There are a few ways to achieve a matching look:

• Use starter strip provided by the siding manufacturer. It’s made specifically for that siding style and color.
• Use a piece of actual siding material. Cut the bottom locking tab off and use it as starter strip.
• Buy a white starter strip and paint it to match the siding. Use a high quality exterior grade latex paint.

Take care with darker starter strips to prevent obvious soil or staining at the bottom edge after installation. Even with matched colors, the transition point may still be visible on close inspection, but overall appearance will be clean.

Can Starter Strips be Reused?

In some cases when siding is being replaced, existing starter strips are left in place to attach the new siding. This saves effort and expenses. However, there are some drawbacks to reusing old starter strips:

• Fading or brittleness may make reused strips more noticeable.
• Damage or warping may prevent proper installation.
• Moisture or insect damage weakens the integrity.
• Difficulty achieving full interlock with new siding.
• Can negate warranty of new siding product.

Unless the existing starter strips are in perfect condition, new ones should be installed. The small initial cost is worth achieving the best possible end results.

Starter Strip vs. Utility Trim

Another product sometimes used along the bottom of vinyl siding is utility trim. While it may seem similar, there are differences between starter strips and utility trim:

Starter Strip	Utility Trim
Installed first before any siding	Installed afterward to conceal exposed edges
Levels wall and establishes course lines	Follows existing siding lines
Interlocks with siding	Attaches independently from siding
Often matches siding color	Usually white or cream

While utility trim serves an aesthetic purpose, the starter strip performs important functional roles in the siding installation.

Conclusion

In summary, the starter strip is the crucial bottom component of vinyl siding. It provides an even, level base to begin the siding installation and establishes the critical first course alignment. Taking care to properly measure and attach the starter strip saves much aggravation down the road. Matching the strip with the siding’s style and color results in a clean finish. While starter strips play a relatively minor role, they have an outsized impact on the success of any siding project.