1. Problems caused by construction
Coordination between departments and majors (4 major problems)
Existing problem 1: Parapet wall, sunken toilet tube well Side walls, roof skylight walls, etc. are mostly made of bricks or block walls built on reinforced concrete slabs. Cracks can easily form at the interface between masonry and concrete, causing water leakage.
Solution: All buildings requiring flooding shall use cast-in-situ concrete for flooding. If there are no specific requirements for the building, the flooding height shall be 200.
Problem 2: The concrete strength levels of beams and slabs are different, making construction inconvenient.
Solution: The concrete strength levels of beams and slabs poured at the same time should be consistent.
Existing problem 3: The basement back-pouring strip must be poured at least 60 days later, but the waterproofing of the basement exterior wall and the backfilling of the foundation pit need to be constructed first. How to deal with it.
Solution: Set up a full-height prefabricated reinforced concrete slab on the outside of the basement exterior wall back-pouring zone. The slab is placed inside the waterproof layer of the basement exterior wall. The architectural design needs to consider the waterproofing practices and structure of this area. The design needs to consider that the slab is used to retain backfill soil before the post-pouring zone is poured.
Problem 4: The size of some wall stacks is too small, which is not convenient for masonry and the quality cannot be guaranteed.
Solution: When the size of the wall stacks connected to the concrete walls and columns is ≤120×120 or the length of one side is less than 120, cast-in-situ concrete wall stacks should be used.
Solving cracks in cast-in-place concrete floor slabs (6 major problems)
Existing problem 5: The strength level of the roof slab concrete is relatively high, which is prone to cracks and leakage.
Solution: The concrete strength grade of the roof structure should be ≤C25 as much as possible.
Problem 6: The concrete strength level of the basement floor is relatively high and is prone to cracks and water leakage.
Solution: For large-volume concrete with a long construction period (such as basement floors, exterior walls, etc.), the later strength of the concrete should be considered when designing, and the strength of concrete that is not less than 60 days old can be used.
Existing Problem 7: The interface between new and old concrete in the basement floor and side wall back-cast belt is prone to cracks and leakage often occurs.
Solution: The joints of the post-casting belt should be made into tongues and grooves; the main reinforcement should be disconnected at the post-casting belt; use expansion waterstops.
Existing Problem 8: When PVC electrical pipes are embedded in the cast-in-place concrete slab, cracks often appear in the concrete slab along the pipeline.
Solution: When PVC and other non-metallic pipes are pre-embedded in the reinforced concrete slab, place a 300-wide φ1.0×10×10 steel mesh along the bottom of the slab (outside the main ribs at the bottom of the slab) along the pipeline.
Existing Problem 9: There are a large number of equipment pipelines buried in the concrete slab in the front room of the elevator room, causing structural hazards and prone to cracks.
Solution: For boards with many embedded pipelines (such as elevator front rooms of high-rise buildings, etc.), the board thickness should be 30% according to the structural design requirements.
Existing question 10: Concrete slabs with waterproof requirements such as roofs have strict crack control requirements. How to control cracks.
Solution: Add crack-resistant fibers to the concrete of roof panel structures that require waterproofing. The amount of addition shall be provided by the bidding center or the general contractor for the parameters of the winning product, and shall be determined by the design unit.
Preventing subsidence of the first floor floor (3 major problems)
Existing problem 11: The first floor partition wall itself has settled, and settlement cracks have appeared in the wall.
Solution: Reinforced concrete foundation beams or foundations should be installed under the first-floor partition walls. Partition walls must not be placed directly on the building ground, and the concrete cushion in the original building ground must not be thickened (Yuanbao foundation) as the foundation for partition walls.
Problem 12: Outdoor steps, flower beds, etc. have sunk and deformed.
Solution: When designing outdoor accessories of a building, the design of its foundation and foundation should be considered.
Problem 13: The backfill soil on the first floor of the building is thick, and the quality of the backfill is difficult to guarantee.
Solution: When backfilling, supervision must be in place, and quality control and self-inspection measures must be strengthened. On the premise of backfilling in strict accordance with the specifications, the following reinforcement measures can be taken based on the actual project conditions:< /p>
(1) When backfilling sand, stone, sand and other low cohesion large particle size materials, no additional reinforcement is required.
(2) When the backfill soil thickness is less than 500m, no additional reinforcement is required.
(3) When the backfill thickness is 500 ≤ and ≤ 2000, and the ground span is less than 3000, place a φ6＠200 two-way steel mesh at the bottom of the concrete cushion on the building floor, and the mesh should be anchored into or placed on the surrounding structure; if the ground short span is ≥3000, in addition to adding steel mesh according to the above requirements, a ridge wall should be added at the bottom of the cushion. The side length of the grid formed by the ridge wall and the surrounding structure shall not exceed 3000. The ridge wall method is issued by the design unit. The ridge wall material should be masonry, and the supporting relationship with the upper concrete cushion should be guaranteed.
(4) When the backfill soil thickness is >2000, prefabricated reinforced concrete or cast-in-situ reinforced concrete ground shall be used.
2. Problems caused by design reasons
Coordination between departments and majors (2 major problems)
Existing problem 14: Sometimes the strength of partition walls and infill walls not good.
Solution: The strength grade of wall materials for non-load-bearing walls should be indicated in the drawings.
Existing question 15: Who is responsible for secondary design of steel structure, foundation treatment, etc.
Solution: The general contractor is responsible for completing the secondary in-depth design of the steel structure and foundation treatment. The design unit must fully cooperate to ensure the connection of the work.
Six major problems in fire protection design
Problems 16: The fire lane is not 4m wide, there is no return yard or return lane, and garden trees affect fire vehicles.
Solution: Implement in accordance with the specifications. The width of the fire lane shall be in accordance with the specifications. If the upper part of the fire truck return yard is a lawn, the lower structure design must meet the fire truck traffic requirements. The general garden plan shall be reviewed by the architectural designer. And report it to the fire department for approval.
Problem 17: The window area of ??the elevator front room is not enough 3m2.
Solution: Follow the specifications. If the area is less than 3m2, a pressurized air supply shaft can be added.
Problem 18: There is insufficient fire protection distance between buildings.
Solution: Follow the specifications.
Problem 19: There is no separation between the first floor of the stairwell and the basement.
Solution: Follow the specifications.
Problem 20: The generator and fire pump are not in the first phase, delaying the first phase acceptance time.
Solution: Consideration should be given to improving supporting facilities in the first phase. If the podium is not decorated or temporarily not in use, the fire protection system should be designed first, and acceptance can only be completed after the construction is completed.
Problem 21: There is no direct safety exit in the fire pump room.
Solution: Follow the specifications.
3. Common design problems and measures
Seven major problems with roof waterproofing
Existing problem 22: The quality of 911 waterproof materials in Guangzhou is unstable
Solutions:
1) Choose waterproof membrane and determine the thickness according to national regulations.
2) For villas in the northern region, two layers of membrane waterproofing are required according to the secondary waterproofing level.
Problem 23: The location of the thermal insulation layer is unclear.
Solutions:
1) Use extruded polystyrene board insulation material.
2) In northern areas, thermal insulation is done first and waterproofing is done later. In the south, waterproofing is done first and thermal insulation is done later.
Problem 24: Cracks and leaks at the bottom of the sky parapet wall.
Solution: Make concrete parapet below 300mm.
Problem 25: leakage around pipes, wells, and flues protruding from the roof.
Solution: A reinforced concrete waterproof reverse beam should be poured around the pipes, wells and flues protruding from the roof together with the roof structure. The elevation of the flat roof should be set at 250mm above the highest completed surface, and that of the sloped roof should be 250mm above the highest completed surface. Surface 250mm.
Existing Problem 26: Pipes are leaking through floors and roofs
Solution: Select and bury casings according to regulations; casings should be filled with asphalt fiber and waterproof ointment .
Existing Problem 27: There are two methods of construction methods for Spanish roof tiles, one is hanging and the other is lying. However, most of the villa roofs constructed according to the hanging stickers have water seepage.
Solution: Change to horizontal sticking process. If the roof slope is indeed too steep, strengthening measures such as hanging nets should be added during the horizontal lamination process, or the waterproof layer of the membrane should be thickened (more than 30mm) and then the hanging lamination process should be used for construction. The specific practices are based on the regional standards of each company. Tianjin area refers to nodes 2-5.
Existing Problem 28: Some units in the villa are designed with dark gutters, but because no strengthening measures were taken during the design, dark gutters leaked on many roofs.
Solution: uniformly change to open ditch, using 2-5 nodes.
Five Major Problems with Indoor Waterproofing
Existing Problem 29: Caisson-type bathrooms do not have side drains, making it easy for water to accumulate in the caisson, causing potential water seepage risks. When we were ready to add side drains, we couldn't add risers because the tube well area was not enough.
Solution: Add side drains. In northern areas, due to installation difficulties, the tube well can be appropriately enlarged.
Existing Problem 30: Installation of waterproof casing for caisson pipe wells. When installing pipe wells in bathrooms, the thickness of the pipe well walls (inside the caisson) is often only 8 to 10 cm. Concrete walls or brickwork are used, which cannot be properly installed. Install waterproof casing.
Solution: It is recommended that the wall thickness of the caisson pipe shaft should be 12cm, and it should be a steel Huning structure. The inside of the caisson should be elevated and not backfilled.
Problem 31: Bathroom wall leakage.
Solution: Flexibly waterproof the upper part to a height of 300mm, and make waterproof mortar on the upper part. In Beijing area, the concrete at the base of the wall is raised by 120mm.
Existing problem 32: When installing bathroom equipment, it cannot be fixed and is prone to leakage.
Solution: It is recommended that all bathroom walls be made of solid bricks.
Existing problem 33: The indoor water pipe is punctured.
Solution: Try to avoid passing the door through the water and heating pipes, and pass through the wall from the side of the door, leaving casings in the shear wall.
Five major problems with exterior wall waterproofing
Problem 34: leakage from cracks in exterior walls.
Solution: The exterior wall is painted with anti-cracking fiber cement mortar.
Existing problem 35: wall material.
Solution: It is agreed that Guangzhou will trial autoclaved concrete blocks, but corresponding anti-cracking measures should be added (such as plastering and hanging nets on internal and external walls, and adding anti-cracking fibers to the plaster layer).
Existing Problem 36: Water leakage at window lintels and window sills
Solution: Window lintels should be built with drip lines; outer window sills should be lower than inner windowsills, and sufficient drainage slope should be made; aluminum alloy windows The lower frame must have a drainage structure; the outside of the aluminum alloy window must be sealed with waterproof glue. Strictly enforce construction regulations.
Existing Problem 37: There are many GRC exterior decorative components, and some exterior walls have no overhangs on the GRC skirtings, which can easily cause water leakage at the junction between the GRC components and the exterior wall, and there are also gaps between the GRC components. Connections are also prone to cracks.
Solutions:
1) Minimize the use of GRC and reduce the style of GRC lines.
2) After selecting the supplier, provide the installation nodes to the design unit in a timely manner. It can be installed only after the design is confirmed.
3) The design institute should indicate in the drawings the drainage slope of the decorative lines, the drip trough and the anti-cracking measures for the overlap of different materials.
4) The problem of line flooding and water seepage should be considered when designing the fixed plate.
5) The engineering department should carefully review the construction plan of the decorative lines.
Basement waterproofing
Problem 38: The quality of waterproofing materials is not up to standard.
Solution: Use membrane waterproofing, and the waterproof grade and design comply with national standards.
IV. Common problems and solutions at building nodes
Doors, windows and railings (11 major problems)
Existing problem 39: Use wooden doors for the sky-facing door, standard Not allowed.
Solution: Disable wooden doors at the entrance to the sky.
Existing Problem 40: Due to cost factors, Party A plans to cancel the steel frames of doors and windows in some properties. However, canceling the steel frames will cause the door and window openings to be unable to be closed in time after the structure is completed, which will affect the progress of the project. It is extremely large and can easily cause pollution and damage to the aluminum frame.
Solution: After calculating the cost of the general contract, submit it to the headquarters for approval.
Existing Problem 41: When the elevator is on the first floor and the wind is strong in autumn and winter, the elevator hall door cannot be closed in place and requires external force to close; when designing, the lobby elevator should be protected from wind and the elevator door can be opened and closed freely.
Solution: Agree and adopt its approach.
Problem 42: The railings, iron art, iron flowers, and protective railings are all uneven and cannot be used as construction basis.
Solutions:
1) Han Jianti’s wrought iron flower sample library information is provided and selected by the designer.
2) The design company designs large-scale drawings.
Existing problem 43: The height of the railing is less than 1100.
Solution: Follow the specifications.
Problem 44: The embedded parts of the balcony railing cannot be reserved during the main construction because there is no spacing between railing poles, and expansion screws are not allowed during installation, causing the structure to be destroyed.
Solution: Design to determine the spacing and large sample drawings.
Problem 45: The paint on the galvanized steel pipes on the balcony is peeling off and rusting.
Solution: The design must clearly match the paint (enamel).
Existing problem 46: The installation problem of the indoor window sill window guardrails.
Solution: The standardization design team will develop standard drawings.
Issue 47: According to residential design regulations: when the net height of the exterior window sill from the floor or ground is less than 0.8 meters, protective facilities should be installed. All open windows with a window sill height less than 0.8 meters should be Set up safety guardrails. In the current residential area under our jurisdiction, the height of the guardrails in the bay windows is low, and children can easily break the glass and fall. It is recommended to increase the height of the guardrails.
Solution: Follow the specifications.
Existing Problem 48: There are protective railings between each unit on the rooftop and platform to prevent outsiders from passing through to ensure safety; since the sliding doors of the windows cannot be closed and there are no anti-theft devices, this has appeared in many buildings. The owner entered the house through the sliding window on the platform, causing theft.
Solution: Agree, fully consider it in the design.
Existing Problem 49: Protective fences should be added to the landscape pools in the community to prevent children and the elderly from slipping and falling.
Solution: Do not adopt its approach.
Six major problems with decorative details
Existing problem 50: tiles on the facade of the aisle tube well.
Solution: Let the decoration professional produce a large sample to determine the color.
Problem 51: Improper connection between indoor wooden cabinets and walls.
Solution: handled by decoration.
I believe that after the above introduction, everyone has a certain understanding of it. Welcome to log in to Zhongda Consulting for more relevant information.
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