The Parts Of Your Replacement Siding System
Feb 17, 2025
A Home Exterior Glossary
Planning a siding replacement project? Learn the lingo of the pros with our handy glossary. Knowing these key words will help you choose a siding style you love and better understand the process when the installation crews arrive at your house.
Keep in mind that not all siding replacements will use all of these parts; it depends on the type of siding you’ve selected for your home.
Parts Of Your House
Backerboard or Sheathing
This is the structural layer that your siding panels attach to. Sheathing or backerboard is usually made of plywood or oriented strand board (OSB) that is attached to the framing of your house. It provides additional strength and rigidity for your home’s exterior walls. It also helps protect your home interior against the elements.
Eaves and Soffits
An eave is the edge of the roof that overhangs a wall. Soffits are the area of siding that protects your eaves. Soffit panels can be ventilated to allow air to enter or exit your attic, while keeping pests out.
Face
The face is the siding that is visible on your home after installation.
Fascia
The fascia is a trim piece along the edge of your roofline. It supports the roof’s sheathing and the front edge of the soffit. Your gutters are mounted onto the fascia board.
Gable
The gable is the triangular-shaped portion of the end wall of your home near the roof peak. Some people choose contrasting siding colors or styles for the gable to create visual interest in their home exterior design.
Replacement Siding Parts
Buttlock
A buttlock is a specific type of joint that connects two siding panels. It is usually an interlocking mechanism or an overlap, where the bottom edge of one siding panel connects with the top edge of the panel below it. The buttlock is responsible for creating a seamless joint that prevents water from getting behind your siding.
Center Butt Joint
The center butt is where a connection is made at the center of a siding panel. A center butt is where two panels meet in the middle of a wall section. However, with seamless polymer siding, there are no center butt joints.
Channel
When replacing vinyl siding, the channel is the area where siding and soffit panels attach to the trim or corner post. It can also refer to the trim itself, such as J-channel or F-channel. These are named for the letters of the alphabet they look like when you view them from the side.
Course
The course is a single row of siding. Depending on the type of siding, it can run horizontally from edge to edge or vertically from top to bottom.
Drip Cap
The drip cap directs water away from the top edge of vertical siding panels.
Flashing
Flashing is a layer used under your siding on windows and doors to keep water out. Flashing can be made of rubber, metal, or plastic.
Housewrap
Housewrap, sometimes called a vapor barrier or moisture barrier, is a synthetic material that goes over your house’s sheathing and under your house’s new siding. It prevents moisture from getting into the wall of your home.
Outside Corner Post
The outside corner post is where outside corners of the siding come together.
Perma-Strate Wall System®
This is the patented installation system that works with seamless polymer siding. It firmly holds the siding to the exterior of the home and creates a perfectly straight wall. It also allows your siding to naturally expand and contract as needed throughout the year.
Starter Strip
The starter strip is the first board attached to the bottom of an exterior wall of your home. It serves as the secure base for attaching more rows of siding and keeps each piece aligned.
Square
A square is a unit of measurement that determines the amount of siding material you need for your project. One square equals 100 square feet of surface area.
Trim
Trim refers to the pieces that create a finished edge to siding or soffit panels. Trim also goes around windows and doors or on corners and eaves.
Trim Coil
The trim coil is a steel or aluminum material that is used to case around your windows, so your house is totally enclosed and watertight.
Replacement Siding Styles
Board and Batten
Board and batten is a style of siding that consists of wide boards with narrow strips vertically applied over the joints to cover the gaps.
Lap
A lap is where two adjacent pieces of siding overlap one another, usually in lap-style siding, made up of horizontal planks. Styles may be called traditional lap, Dutch lap, or clapboard.
Shake
Shake is a shingle-type siding with a rustic look and uneven edges.
Vertical Siding Panels
In this siding style, panels are attached in a vertical orientation. Vertical siding panels are sometimes used on the sides of your home to accent the front.
Learn More About Siding Replacement
Check out these resources and information you may find helpful as you plan your home improvement journey.
