Byggnadsfogar

Byggnadsfogar are joints in buildings designed to accommodate movement between construction elements, control the ingress of water and air, and support sealing and insulation. They appear in many locations, such as between walls and floors, at joints between prefabricated components, around window and door openings, at floor-to-wall transitions, and where different materials meet.

Their primary functions are to absorb differential movement from thermal expansion and contraction, settlement, and wind loads; to prevent crack propagation in structural and non-structural elements; and to maintain moisture control, airtightness, and acoustical performance. Some joints also serve fire safety purposes, requiring fire-rated sealants and assemblies to maintain compartmentalization.

Common types of byggnadsfogar include expansionsfogar (expansion joints) for large movements, rörelsefogar (movement joints) to accommodate differential movement between connected parts, and tätningsfogar (sealing joints) that are filled with fogmassa (sealants) to ensure watertight and airtight joints. In facades, joints are designed to allow movement and accommodate weatherproofing, often using a combination of elastomeric sealants and backing materials.

Materials and installation: Fogmassa can be silicone, polyurethane, or hybrid sealants, chosen for elasticity, weather resistance, and fire performance. Backing material and priming are important for bond quality. Proper surface preparation, correct joint dimensions, and skillful tool application are essential. For larger gaps or movements, fillers or backer rods are used to provide proper compression and adhesion.

Maintenance and standards: Joints should be inspected regularly for cracks, hardening, or loss of adhesion, with deteriorated sealants replaced to restore performance. Replacement intervals depend on climate, movement, and sealant type, but typical service lives range from about 10 to 25 years. Fire-rated joints require periodic verification to maintain safety requirements.