Remodelers Guide

Exterior Siding & Trim

TLDR

  • WRB & flashing inspected / approved
  • Layout established
  • Bottom course ≥ 8 in. above grade (IRC R703.7.1)
  • Blind-nail on studs, correct fasteners / length
  • Seal all field cuts & end-prime wood
  • Don't forget cap flashing

Overview

Siding and trim are the first line of defense against the weather. They are meant to keep most of the elements off of the weather resistive barrier below but should allow for some drying if water does get behind. There are lots of regional varieties of siding and we will go over processes to cover most of the common options like vinyl, lap siding (which can be Hardie fiber cement, LP Smartside, or traditional wood like cedar), and shakes. We'll also cover common trim types including wood, PVC, composite, and metal.

Types of Siding

Fiber Cement

Cement or fiber cement siding is made by a variety of manufacturers. The main product in our market is made by James Hardie. Fiber cement comes primed and must be painted. Some manufacturers sell pre-painted siding but it is difficult to install without damaging the finish.

Fiber cement comes in many profiles, including wood grain and smooth options. The panels are popular once installed because they look great and are durable, but the products are brittle, messy to cut, and difficult to install relative to other siding options.

Wood Siding

Wood siding was historically the most popular option and its what we find on the older houses in most of North America. On older homes it is usually a softwood and sometimes cedar, and it can last many decades if kept painted. Cedar is generally the only species we install now, although we do install pine on the underside of porch and sunroom ceilings because they are not exposed to weather.

WindsorOne has a 30 year exterior warranty if any cut edges are primed before install and the product is painted within the first year after installation, but the paint must be an exterior acrylic latex like Sherwin Williams Emerald.

Vinyl

Vinyl is one of the most common siding types on new homes. It comes in many colors and profiles from lap to shakes and some specialty options. It is inexpensive because it does not need to be painted, relatively easy to install, and can last 20 to 30 years.

Types of Trim

Wood Trim

Cedar or WindsorOne can be installed as trim on the exterior of a home. Wood siding and trim can attract insect pests and woodpeckers but are easy to install and repair.

Boral TruExterior

Boral TruExterior is made of poly-ash, some combinations of fly-ash and glue. It cuts and installs like wood but it is more like fiber cement in that it is brittle while handling and installing. It profiles very nicely and leaves crisp edges. The main selling point is that it does not move much on the wall, can be painted any color including dark colors, and it is completely waterproof.

PVC Trim

Azek is the primary option in PVC trim. It comes white and does not need to be painted, but like other pre-finished materials we need to be very careful while installing. The best way to install is with coretex screws which come with plugs to fill the holes left after screwing. Drawbacks are that Azek expands and contracts a lot and can become gappy on the wall. It is difficult to keep clean during and after installation, and the smooth side scratches easily. It can be painted in dark colors using special paints with high reflectivity.

Aluminum

Bent aluminum is often paired with vinyl siding. It comes in rolls 2’ wide x 50’ long and can be cut and shaped on site with a tool called a break. It comes in a a variety of standard colors and does not need to be painted after installation. We can install it hollow or over wood backing. Aluminum will become wavy if the flats are too large even if installed correctly. Once dented it cannot be repaired, only replaced.

Prerequisites

  • Windows and doors must be installed and flashed
  • Continuous WRB installed, taped, and inspected if applicable where local “WRB/Siding” inspection is required
  • Ledger boards installed and porches marked out
  • Lighting, outlet, spigot, mailbox, address locations marked or trim blocks pre-installed
  • Material should be on site, see order sheet

Materials / Tools Needed

  • Vinyl
    • 1.5" roofing nails, snips grinder, or saw
  • Fiber-Cement (Hardie)
    • Hardie saw blades, guillotine, siding nailer, spray primer, 15-ga trim gun
  • LP SmartSide
    • Wood tools, siding nailer, spray primer, 15-ga trim gun
  • PVC (Azek or Royal)
    • Cortex screws and plugs, PVC solvent weld, pocket hole jig and screws
  • Composite Trim (Boral TruExterior)
    • Siding nailer, 15-ga trim gun
  • Metal Trim
    • Metal blades, angle grinder, hand break, break, trim nails, pea shooter, narrow crown stapler

Process

  1. Determine Details or Mock-Up - Show client what the trim sizes and styles will look like, full scale examples help, but example photos, sketches, or renderings can work as well. Confirm corners trim, friezes, base, windows, bands, soffit, etc.
  2. Layout - Snap reference lines; bottom course and up. Possibly adjust reveals to hit windows, soffit/frieze cleanly.
  3. Trim First. Install corners, skirt, frieze. Keep manufacturer specified gaps and back-prime cut ends as needed. Screw & plug PVC, consider pocket hole screwing window trim from behind before installation. Install J-channel and starter strip for vinyl. Install drip cap and tape.
  4. Install Siding
    • Fiber-Cement Lap: blind-nail 1 in. down from top, 16 in. O.C., flash seams, prime cut edges
    • LP SmartSide Lap and Wood: blind-nail similar to fiber cement, prime cut edges
    • For cedar use stainless fasteners
  5. Caulk & Finish - Use a high quality sealant like Quad or similar. Typical to caulk body color against trim and not trim color. Painting PVC is not necessary, but it must be high reflective paint to avoid heating problems.

Inspections

  • WRB Inspection - Required only in some jurisdictions. They will be looking to see if weather resistive barrier is installed per manufacturer. Read and install per Tyvek instructions with cap staples, or taped Zip most commonly.

Client Interaction / Communication Notes

  • Confirm color and style in writing
  • Advise on maintenance schedule as part of your consultation
  • Talk about pests like insects and birds. I've seen woodpecker damage in Azek before
  • Plants will likely be damaged around the home
  • During repairs, new colors and old may not match or blend properly

Common Issues & How to Avoid Them

  • Make sure to leave required expansion joints where needed
  • Don't paint PVC trim dark colors

Resources