Module 5 Repair and refurbishment

Transcription

1 Module 5 Repair and refurbishment

2 Module 5 Block 1 Refurbishment

3 3 Demolition Note: Before execution of demolition work advice on dismantling must be given by an expert. 1.) Examine existing structure, 2.) Check effects on adjacent buildings, 3.) Make safe or disconnect utilities (electric current, water, gas, sewage, telephone, remote heating). 4.) Consider influences of the weather 5.) Specify method of dismantling, 6.) Determine sequence of the individual dismantling stages, 7.) Keep traffic and escape routes free, 8.) Cordon off danger areas, 9.) Follow instructions for dismantling In the case of demolition by hand: Pull down the building in the reverse order with which it was erected Provide protection against falling debris Progressively dismantle scaffolding with the demolition work and reanchor Protect discharge openings

4 4 General Refurbishment and building protection comprises: Description Cause of defects Elimination of defects Fire prevention Noise abatement Thermal protection Damp protection Measure to Measure to decrease decrease fire risk and noise in the human increase stability of environment building Disregard of construction specifications and fire prevention regulations as well as material properties Improvement of structural engineering and encasing of structural components Un-moderated transmission of sound waves Reinforcement of acoustic insulation Measure to decrease heat transfer (thermal conduction, thermal convection, thermal radiation) from rooms to outside air and between rooms Lack of structural thermal protection (insulation) or damaged building fabric Repair of substrate damage and retrospective fitting of insulation Measure, which protects building from water ingress (groundwater, standing water, heavy rain etc.) and damp (fog, water vapour, air humidity, etc.) Destroyed or non existing damp courses, capillary moisture movement Repair of substrate damage and retrospective fitting of insulation Note: In the case of refurbishment and building protection regeneration of the existing fabric (structural components) is the crucial task to ensure a success result.

5 5 1. Building damage Causes of damage (selection) Measures for rectification (selection) Concrete spalling (Fig. 1) Frost damage, mechanical stress, shock and impact effects, salt damage Concrete repair including rust protection Broken or missing bricks (Fig. 2) Mechanical damage, impact and shock effects Replacement of bricks Flaking plaster (Fig. 3) Moisture ingress, frost damage, incorrect mixing of plaster Renovate plaster, put in place insulation barriers Moss, algae, fungus deposits (Fig. 4) Damp walls due to rising damp or condensation Dry out wall, renovate plaster, eliminate mould, re-paint or reclad

6 6 Causes of damage (selection) Measures for rectification (selection) Cracks in the brickwork (Fig. 5) Interaction of various structural components, high proportion of binder in plaster, uneven ground settlement, earth erosion, different building materials Compaction of ground, renovation of foundations, use of flexible sealant, application of bonding primer, repaint Cracks in beams (Fig. 6) Heavy structural stress, damp in the building Renewal of beams or filling of cavities Rust damage (Fig. 7) Lack of rust protection Rust removal and coating with rust protection Flaking paint (Fig. 8) Damp brickwork, salt-containing efflorescence, fungus Dry out, remove salt or fungus, renovate plaster, re-paint The following are described below by means of examples: 1. Concrete repair 2. Crack removal in screed or brickwork 3. Rectification of masonry damage caused by damp 4. Elimination of plaster damage 5. Beam renewal

7 7 2. Concrete repair Concrete spalling is understood to mean the destruction of concrete and steel reinforcement usually by forms of liquid, in which salts or gases are dissolved. Steps for repairing concrete surfaces: 1.) Loose concrete is removed, the concrete is cleaned and the steel reinforcement is de-rusted usually by sandblasting. 2.) Steel reinforcement is given two coats of rust protection coating. 3.) A coat of cement-based bonding primer is applied to the pre-wetted old concrete. 4.) The concrete cracks are filled with repair mortar. The mortar can contain plastic fibres for increased strength. 5.) A uniform and smooth surface is obtained with a covering of thin plaster (filling compound). 6.) Painting renews the appearance of the concrete.

8 8 3. Crack removal in screed or brickwork Steps for crack removal: 1.) Loose plaster or concrete is removed, cracked and porous screed and masonry are hacked off. The crack is widened with hammer and chisel. 2.) The crack is thoroughly cleaned with a wire brush and any dust removed by brush or vacuum cleaner. 3.) The surface concerned is well prewetted with clean water as far as the substrate.

9 9 4.) The crack is sealed with jointing compound, rubber mortar or filler. 5.) For better bonding the entire screed or wall is painted.

10 10 4. Rectification of wall damage caused by damp Steps for controlling the dampness of a wall: 1.) Remove old paint, loose plaster, dirt, dust etc. 2.) Drill first row of holes with masonry or concrete bit (diameter mm) approx. 10 cm above the floor. The holes should be spaced 10 cm apart. In the case of normal brickwork the hole is drilled diagonally at an angle of 35 downwards. 3.) Drill the second and then further row in each case offset by 5 cm laterally and upwards. In the case of natural stone masonry the holes must be drilled in the joints.

11 11 4.) Clean holes with vacuum cleaner nozzle. Insert funnels for filling the holes. 5.) Seal the holes with masonry filler or concrete. 6.) Apply new plaster.

12 12 5. Elimination of plaster damage Steps for renewing plaster: 1.) The old plaster is completely hacked off with hammer and chisel. 2.) Thoroughly clean the substrate, in particular steel and wood surfaces, with wire brush and apply rust protection or wood preservative. 3.) In the case of corners (example) attach the necessary formwork and any necessary reinforcement in the form of stainless wire mesh.

13 13 4.) Wet the brickwork and still firmly adhering plaster. 5.) Apply and smooth mortar (see module 4).

14 14 6. Regeneration of beams If beams are rotten or have cavities, they can be renovated or filled. Note: The refurbishment of wooden fabrications is only permitted in the case of non-load-bearing structural components (doors, windows, cladding, beams, which do not contribute to stability etc.). Steps for refurbishing beams: 1.) Hack out rotten material as far as the healthy wood. Remove wood chips with vacuum cleaner.

15 15 2.) Apply oil-based impregnating wood preservative (according to label or instructions) on dry wood and allow to dry. 3.) Seal side ends with plywood. 4.) Stir the filler mixture according to the manufacturer s instructions. The mixture consists of synthetic resin, hardener and filler (sawdust, quartz sand, etc.) To avoid rushing only mix small quantities! 5.) Fill mixture into the wood, spread and smooth. 6.) Filler made from sawdust can be worked on after hardening, but not fillers made with quartz sand. Therefore quartz sand fillers are more stable.