Resilience Treatments & Strategies
Exterior Wall Finishes
Description
Lightweight materials applied on the outside of exterior walls’ structural elements. They protect the structure and also have an aesthetic purpose. Common historic finishes for exterior walls include renders (e.g., stucco), wood siding, and masonry as a veneer. In some historic masonry buildings, the exterior walls are load-bearing and not a veneer. Exterior materials are often coated for their own protection and aesthetics.
Typical risk factor of this component:
Moderate
Exterior wall finishes are exposed to elements such as wind and rain. Finishes, siding materials, and veneers have negligible importance to the structure’s stability and their failure generally has little to no impact on other assemblies. However, if the weather envelope is breached, further damage can follow quickly.
Typical Damages from Floods or Hurricanes
- Rising damp or salt crystallization within walls
- Moisture around downspouts
- Blistering, peeling, bubbling, scouring, or spalling stucco/render
- Spalling, pitting, or cracking masonry
- Wood siding has become waterlogged and is buckling, bowing, cupping, or swelling
- Eroded masonry pointing
- Lack of protective coatings
Other common conditions contributing to vulnerability towards floods or hurricanes
- Vegetation growing on exterior
- Metal components oxidizing, expanding, and causing structural and cosmetic damage to surrounding wall
- Uneven discoloration or wetting pattern on wall surface
- Heavy staining, scouring, dirt, efflorescence, or biological growth
Resilience Treatments and Strategies
In-house
Carefully remove light vegetation by hand and restore finishes. However, if vegetation is severe (e.g., penetrating through wall), consult an engineer to restore wall.
Monitor visible defects such as discoloration or wetting patterns (see also NPS Preservation Brief #47). If these patterns change or get worse, consult an architect or preservation specialist to investigate the cause.
Repair light damages such as isolated cracks in masonry or stucco/render (see also NPS Preservation Brief #22).
Gently clean affected masonry (e.g., stains, dirt, biological growth) with a diluted masonry cleaner (see also NPS Preservation Briefs #1, #6, and #47). If the condition still appears or quickly returns, talk to an architect or building conservation professional to determine cause of the problem and appropriate treatments.
Provide small expansion gaps between major exposed wood members and adjacent surfaces to account for expansion when saturated or shrinkage when drying.
Cover porous materials prior to storms to prevent them from intensive wetting or other extreme climatic conditions.
Repoint mortar joints (see also NPS Preservation Brief #2).
Professional needed [type]
Install damp-proofing to the foundation to combat rising damp [architect or engineer].
Repair, coat (e.g., paint, galvanize, wax), or replace damaged metal components with similar assemblies that will resist oxidation [architect].
Apply water-resistant coatings (e.g., silicone, acrylic resin, linseed oil, paraffin wax, fluopolymers) to exposed surfaces [architect or building conservation professional].
Apply water-resistant coatings to exposed surfaces [architect].
Restore or repair cracks, spalls, or other surface defects. Plastic substitute patches (e.g., epoxy resin) may be necessary where replicating the material is impossible. Consolidate or grout unstable masonry as needed after addressing underlying causes. Deformations and cracks beyond surface defects need assessment and possibly immediate stabilization [architect or engineer].
Provide protection to sensitive masonry or earthen walls (e.g., adobe) such as with canopies or extended roof eaves (may impact the integrity of design) [architect].
Remove excessive salts with poultices or leaching packs [building conservation professional].
Exterior Wall Finishes
Description
Lightweight materials applied on the outside of exterior walls’ structural elements. They protect the structure and also have an aesthetic purpose. Common historic finishes for exterior walls include renders (e.g., stucco), wood siding, and masonry as a veneer. In some historic masonry buildings, the exterior walls are load-bearing and not a veneer. Exterior materials are often coated for their own protection and aesthetics.
Typical risk factor of this component:
Moderate
Exterior wall finishes are exposed to elements such as wind and rain. Finishes, siding materials, and veneers have negligible importance to the structure’s stability and their failure generally has little to no impact on other assemblies. However, if the weather envelope is breached, further damage can follow quickly.
Typical Damages from Floods or Hurricanes
- Rising damp or salt crystallization within walls
- Moisture around downspouts
- Blistering, peeling, bubbling, scouring, or spalling stucco/render
- Spalling, pitting, or cracking masonry
- Wood siding has become waterlogged and is buckling, bowing, cupping, or swelling
- Eroded masonry pointing
- Lack of protective coatings
Other common conditions contributing to vulnerability towards floods or hurricanes
- Vegetation growing on exterior
- Metal components oxidizing, expanding, and causing structural and cosmetic damage to surrounding wall
- Uneven discoloration or wetting pattern on wall surface
- Heavy staining, scouring, dirt, efflorescence, or biological growth
Resilience Treatments and Strategies
In-house
Carefully remove light vegetation by hand and restore finishes. However, if vegetation is severe (e.g., penetrating through wall), consult an engineer to restore wall.
Monitor visible defects such as discoloration or wetting patterns (see also NPS Preservation Brief #47). If these patterns change or get worse, consult an architect or preservation specialist to investigate the cause.
Repair light damages such as isolated cracks in masonry or stucco/render (see also NPS Preservation Brief #22).
Gently clean affected masonry (e.g., stains, dirt, biological growth) with a diluted masonry cleaner (see also NPS Preservation Briefs #1, #6, and #47). If the condition still appears or quickly returns, talk to an architect or building conservation professional to determine cause of the problem and appropriate treatments.
Provide small expansion gaps between major exposed wood members and adjacent surfaces to account for expansion when saturated or shrinkage when drying.
Cover porous materials prior to storms to prevent them from intensive wetting or other extreme climatic conditions.
Repoint mortar joints (see also NPS Preservation Brief #2).
Professional needed [type]
Install damp-proofing to the foundation to combat rising damp [architect or engineer].
Repair, coat (e.g., paint, galvanize, wax), or replace damaged metal components with similar assemblies that will resist oxidation [architect].
Apply water-resistant coatings (e.g., silicone, acrylic resin, linseed oil, paraffin wax, fluopolymers) to exposed surfaces [architect or building conservation professional].
Apply water-resistant coatings to exposed surfaces [architect].
Restore or repair cracks, spalls, or other surface defects. Plastic substitute patches (e.g., epoxy resin) may be necessary where replicating the material is impossible. Consolidate or grout unstable masonry as needed after addressing underlying causes. Deformations and cracks beyond surface defects need assessment and possibly immediate stabilization [architect or engineer].
Provide protection to sensitive masonry or earthen walls (e.g., adobe) such as with canopies or extended roof eaves (may impact the integrity of design) [architect].
Remove excessive salts with poultices or leaching packs [building conservation professional].