Choosing Siding and Cladding for a Renovation: What to Check First

Evaluating the Existing Wall Assembly

Before considering new siding, examine the current wall assembly. This includes not just the exterior finish, but also the sheathing, weather barrier, insulation, and framing behind it. Understanding these layers will inform decisions about material compatibility, attachment methods, and potential thermal or moisture improvements.

Look for any visible signs of damage, such as bowing, sagging, or significant cracks in the existing siding. These can indicate underlying structural issues or water penetration. Documenting these conditions with photographs can be helpful for discussions with contractors or material suppliers.

Assessing Structural Integrity and Substrate Condition

The substrate, typically the sheathing and framing, must be sound to support new siding or cladding. Rot, insect damage, or significant movement in the existing structure will compromise the new installation. A professional inspection may be necessary to determine the extent of any damage and the feasibility of repair.

For example, if you plan to replace lightweight vinyl siding with a heavier material like Brazilian hardwood or a composite cladding, the existing framing must be capable of bearing the increased load. Verify the condition of studs, headers, and any existing furring strips or rainscreen components. Any compromised sections will need repair or replacement before new materials are installed.

Moisture Management and Weather Barriers

Effective moisture management is critical for any exterior wall. Investigate the condition of the existing weather barrier (e.g., house wrap, building paper). If it's deteriorated, torn, or improperly installed, it should be repaired or replaced. Consider upgrading to a modern weather-resistive barrier, especially if you are changing the exterior material or if there have been past moisture issues.

A rainscreen assembly, which includes a ventilated air gap behind the cladding, is often recommended for enhanced moisture control and durability. If your existing wall does not have a rainscreen, a renovation is an opportune time to incorporate one. Materials like thermally modified wood or composite cladding can be part of a robust rainscreen system. (S1)

Pay close attention to flashing details around windows, doors, and other penetrations. Improper flashing is a common source of water intrusion. Ensure any new siding or cladding will integrate seamlessly with revised or new flashing components.

Material Compatibility and Appearance

When choosing new siding or cladding, consider how it will interact with existing building elements and the overall aesthetic. For example, if you are replacing a portion of a facade, ensure the new material complements any remaining finishes like stone, stucco, or brick. Consider color, texture, and profile. Thermally modified Ayous cladding offers a uniform appearance that can be stained or left to weather naturally, potentially blending with other natural materials. (S1)

Some materials, like Maximo Accoya, are acetylated wood products known for their stability and durability, making them suitable for various climates and exposures. (S1) Others, such as Norx composite cladding, offer consistent color and minimal maintenance. (S1) The choice should align with both the desired aesthetic and the practical demands of the site.

Consider the long-term appearance. Will the new material weather to a silver-gray patina, or will it retain its original color with maintenance? Understanding these characteristics helps set expectations for the renovated facade.

Renovation Suitability Checklist: A Worked Example

Consider a hypothetical renovation of a 20-foot wide by 10-foot high exterior wall section on a residential property. The existing siding is a worn cedar shingle, and the homeowner wants to upgrade to a more durable, low-maintenance material like Norx composite cladding, installed horizontally. The Norx composite cladding planks are 6 inches wide (nominal) and come in 16-foot lengths.

Initial Assessment Steps:

1. **Visual Inspection:** Observe peeling paint, loose shingles, and staining below windows. This suggests potential moisture intrusion and a compromised weather barrier.

2. **Substrate Check:** Remove a few shingles in a discreet area. The plywood sheathing appears intact but shows some discoloration. The studs behind are 16 inches on center.

3. **Moisture Barrier:** The existing building paper is brittle and has tears. This indicates a definite need for replacement.

4. **Flashing:** Window and door flashings are original and appear to be surface-mounted, not integrated properly. These will need to be replaced and detailed for a rainscreen.

5. **Desired Outcome:** A sleek, modern aesthetic with minimal maintenance. Norx composite cladding is selected for its consistent color and profile. (S1)

Based on this assessment, the renovation plan should include:

a. Complete removal of existing cedar shingles.

b. Inspection and repair/replacement of any damaged plywood sheathing.

c. Installation of a new, high-performance weather-resistive barrier.

d. Installation of vertical furring strips to create a rainscreen cavity.

e. Installation of new integrated flashing around windows and doors.

f. Installation of Norx composite cladding horizontally.

For the 20-foot by 10-foot section (200 square feet), using 6-inch wide (0.5-foot) Norx planks, each 16 feet long:

Each plank covers 0.5 ft * 16 ft = 8 square feet. Total planks needed for coverage: 200 sq ft / 8 sq ft/plank = 25 planks. However, considering cuts and waste, especially for a 20-foot wall with 16-foot planks, there will be a 4-foot offcut per full plank length. To minimize waste, planks can be cut to 16 feet and 4 feet for each row. You will need approximately 25 planks for direct coverage, plus an additional 10-15% for waste and cuts, bringing the purchase quantity to around 28-30 planks. This example highlights the need for precise measurements and a cut plan to optimize material use.

This level of detail ensures the new cladding performs as intended and addresses any underlying issues before they become larger problems.

Before you order

• Inspect existing siding for visible damage (cracks, rot, bowing, loose sections).
• Assess the condition of the substrate (sheathing, framing) for soundness and load-bearing capacity.
• Examine the existing weather barrier for tears, deterioration, or improper installation.
• Check flashing around windows, doors, and penetrations for proper integration and seal.
• Evaluate drainage at the base of the wall and ground clearance.
• Consider the desired aesthetic and long-term maintenance requirements for new materials.
• Determine if a rainscreen assembly is feasible or necessary for improved performance.
• Verify compatibility of new siding material with existing structural elements and adjacent finishes.
• Account for increased weight if switching to a heavier material.
• Plan for proper ventilation if incorporating a rainscreen system.

Confirm installation details, approved uses and warranty terms in the current instructions for the exact product and profile. Your installer should verify the substrate, structure and applicable project requirements.

Questions to help you decide

Keep planning your project