Assessing the Existing Wall and Substrate
Before any new siding is installed, a thorough inspection of the existing wall is critical. Look for signs of water damage, rot, mildew, or structural issues. Any compromised areas must be repaired and dried completely to prevent future problems. This includes checking for proper flashing around windows and doors, and ensuring the existing weather barrier is intact and functional.
The condition of the substrate directly impacts the longevity and stability of your new hardwood siding. For example, if you are retrofitting over an existing stucco or masonry wall, you'll need to assess its flatness and integrity. Uneven surfaces will require leveling or furring strips to create a suitable plane for siding installation. For walls with existing siding, consider whether removal is necessary or if the new siding can be installed over it, provided the existing material is sound and provides a stable base.
Selecting Hardwood Siding Profiles for Retrofits
Hardwood siding comes in various profiles, each offering a distinct aesthetic and installation method. For retrofits, the choice of profile can influence the complexity of installation and the final appearance.
Shiplap profiles, such as those available in thermally modified wood or Brazilian hardwood, offer a clean, overlapping joint that helps shed water. This can be a practical choice for retrofits where a streamlined look is desired. Tongue and groove profiles provide a tight fit, often preferred for interior feature walls or sheltered exterior applications, though proper ventilation behind the siding is still essential.
Open-joint rainscreen systems, while more involved, provide excellent drainage and ventilation, which can be beneficial in retrofit situations where moisture management is a concern. Products like thermally modified Ayous or Maximo Accoya can be milled for these systems, offering enhanced stability.
Consider the existing architectural style of your home when selecting a profile. A bold grain Brazilian hardwood like Ipe or Cumaru might suit a modern aesthetic, while the clean grain of thermally modified Ash could complement a more minimalist design. Lumber Plus offers a range of hardwood siding options including thermally modified wood, Maximo Accoya, and various Brazilian hardwoods like Ipe, Cumaru, and Garapa.
You can explore our full range of siding and cladding options at our product page: [https://lumberplus.com/siding-and-cladding](https://lumberplus.com/siding-and-cladding)
Planning for Wall Thickness and Projections
Adding a layer of hardwood siding will increase the overall thickness of your wall. This is a critical consideration for elements like window and door frames, eaves, and corners. You may need to extend existing window and door jambs or add trim to accommodate the new siding thickness. Ensure that the new siding does not impede the operation of windows or doors.
For exterior retrofits, pay attention to the projection of the siding relative to any existing architectural features. Will the new siding align cleanly with existing soffits or corners, or will it create an awkward overhang or recess? Planning for these transitions early can prevent costly adjustments later in the project.
Ventilation and Moisture Management in Retrofits
Proper ventilation behind hardwood siding is crucial, especially in retrofit applications where existing wall components might trap moisture. A rainscreen assembly is often recommended, creating an air gap between the siding and the wall sheathing. This gap allows for drainage and airflow, helping to dry out any moisture that penetrates the siding.
Even if a full rainscreen system isn't implemented, ensure there is adequate space for air circulation. This might involve using furring strips or a drainage mat. Consider the climate; in humid or rainy environments, robust moisture management is even more critical. Thermally modified wood, known for its stability, can be a good choice for these applications.
More information on thermally modified wood can be found here: [https://lumberplus.com/thermally-modified-wood](https://lumberplus.com/thermally-modified-wood)
Worked Example: Retrofitting a 10-foot by 12-foot Wall
Let's consider retrofitting a flat, existing exterior wall measuring 10 feet high by 12 feet wide, currently finished with stucco. The goal is to install horizontal hardwood siding with a shiplap profile, featuring a 5-inch exposed face.
1. **Wall Assessment:** The stucco wall is sound, but slightly uneven. There are two 3-foot by 4-foot windows. The existing flashing appears adequate.
This provides a level plane and a drainage cavity. Additional furring will be placed around window openings.
3. **Siding Selection:** We choose thermally modified Ash shiplap siding with an actual face width of 5 inches and a nominal thickness of 3/4 inch. This wood offers good stability for exterior use.
4. **Quantity Calculation:**
* Total wall area: 10 ft * 12 ft = 120 sq ft.
* Window area: 2 windows * (3 ft * 4 ft) = 2 * 12 sq ft = 24 sq ft.
* Net siding area: 120 sq ft - 24 sq ft = 96 sq ft.
* With a 5-inch exposed face, each linear foot of siding covers 5/12 sq ft (0.4167 sq ft).
* Total linear feet needed: 96 sq ft / (5/12 sq ft/linear ft) = 96 * 12 / 5 = 230.4 linear feet.
* Assuming siding boards are typically supplied in various lengths, we would round up and account for waste (e.g., 10-15%). For this example, let's target 260 linear feet to account for cuts and potential future repairs. If available in 8-foot lengths, this would be 260 / 8 = 32.5 boards, so 33 boards would be purchased.
5. **Furring Strips:** For a 12-foot wide wall with strips 16 inches (1.33 ft) on center, you'd need 12 ft / 1.33 ft = 9 strips. Each strip is 10 feet tall, so 9 * 10 = 90 linear feet of furring strips. Add extra for windows and horizontal blocking.
6. **Details:** Plan for trim around the windows to accommodate the 3/4-inch siding and 3/4-inch furring, resulting in a 1.5-inch total projection from the original stucco surface. Corner details will require mitered cuts or corner trim pieces.
Fastening and Finishing Considerations
The choice of fasteners is crucial for a durable retrofit. Stainless steel fasteners are generally recommended to prevent corrosion and staining, especially with hardwoods. Hidden fastening systems can provide a clean, uninterrupted appearance, while face fastening offers a more traditional look.
Consider the finish for your hardwood siding. Leaving it unfinished will allow it to weather naturally, developing a silver-gray patina over time. Applying a UV-protective oil or stain can help maintain the original color and provide additional protection, though it will require periodic reapplication. Maximo Accoya, for example, is known for its dimensional stability and can be finished or left to weather.
Learn more about Maximo Accoya products here: [https://lumberplus.com/products/maximo-accoya](https://lumberplus.com/products/maximo-accoya)
Before you order
- Thoroughly inspect the existing wall for damage, moisture, and structural integrity.
- Determine if the existing substrate needs repair, leveling, or a new weather barrier.
- Choose a hardwood siding profile suitable for the retrofit, considering aesthetic and installation implications.
- Account for increased wall thickness at windows, doors, and corners.
- Plan for adequate ventilation and moisture management behind the new siding.
- Select appropriate fasteners for the chosen hardwood species and exposure.
- Decide on a finish (or no finish) and understand its long-term maintenance requirements.
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
Can I install hardwood siding directly over existing vinyl or aluminum siding?
It is generally not recommended to install hardwood siding directly over existing vinyl or aluminum siding. These materials are not designed to provide a structural or flat substrate for hardwood. It's best to remove the old siding, inspect the sheathing, address any issues, and then install furring strips or a rainscreen system before applying the hardwood siding to ensure proper support, ventilation, and drainage.
How do I ensure proper ventilation for hardwood siding in a retrofit?
For proper ventilation in a retrofit, create an air gap behind the hardwood siding. This is typically achieved by installing vertical furring strips over the existing wall sheathing or weather barrier. This gap allows air to circulate and moisture to drain, preventing rot and extending the life of the siding. Ensure that there are adequate insect screens at the top and bottom of the air gap.
What kind of maintenance does hardwood siding require after a retrofit?
Maintenance depends on whether the hardwood siding is finished or left to weather naturally. If left unfinished, it will gradually change color to a silver-gray patina and generally requires minimal upkeep beyond occasional cleaning. If a finish (like a UV-protective oil or stain) is applied, it will need reapplication periodically, typically every 1-3 years, depending on exposure to sun and weather, to maintain its appearance and protection.
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