External Wall Plastering Project of Residential Community
Project Overview:
1. External wall plastering decorative requirements (see Qingdao Tourism Planning and Architectural Design Research Institute drawing No. 2006-003), Construction Details -5 Energy Saving Insulation Detailed Drawing for External Walls (see standard drawing L96-J002) 40 (41, 42) external thermal insulation coating walls. The original 35mm polyurethane insulation board has been modified by the construction and design units to a 70-①C system external thermal insulation coating wall (see standard drawing L06-J113). In some areas with infill walls, the 66-①B system external thermal insulation is selected (see standard drawing L06-J113); Coating walls. A 40mm thick cast-in-place swallowtail groove polystyrene insulation board is selected, with a 45mm polystyrene particle mortar leveling layer.
Requirements for Polystyrene Particle Mortar Insulation Layer:
Pay attention to reserving the thickness of the polystyrene particle insulation slurry layer at special locations such as window and door side facades, top edges, and sills to ensure the insulation effect of these parts. At the corners of doors and windows, use a 20cm×30cm grid cloth for 45° diagonal reinforcement (the reinforcing grid cloth is located under the large surface grid cloth). Along the periphery of doors and windows, the corners of doors and windows should be wrapped with fiberglass grid cloth, and the single-side width of the wrapped grid cloth should not be less than 150mm.
Exterior Door and Window Openings (including enclosed balcony windows) are plastered according to the企method for inserting doors and windows afterward. The dimensions of the window openings are each 15mm～20mm on each side (i.e., after plastering, the size of a 1500*2000 window becomes 1470*1970). Doors are centrally placed (considering the frame as 100mm), and the企position is left at a distance from the outer wall surface (as shown in the attached drawing). For bay windows, the企is positioned 200mm away from the edge of the bay window slab, with a thickness of 15mm; all exterior window tops (including bay windows) have an eagle's beak, with a width as shown in the attached drawing, and for bay windows, it is 120mm. The height difference of the eagle's beak is no less than 10% or 10mm. All window sills (higher inside and lower outside), balconies (higher inside and lower outside), and parapet walls (higher outside and lower inside) have a water flow slope of 10% and no less than 10mm. Canopies and air conditioning panels have a water flow slope of 2%. Balconies, bay windows, and door and window openings (including enclosed balcony windows) must hang vertical lines.
Sample Diagrams for Exterior Bay Windows
Two, Requirements for Each Sub-item Construction Process
2.1 Cement Mortar Plastering
2.1.1 Construction Preparation
(1) Material Requirements
a. Cement: It is preferable to use 32.5 ordinary Portland cement or slag Portland cement or white cement. The same manufacturer and batch number should be used. There should be a factory certificate of conformity and a retest report for on-site sampling. If the date exceeds three months, re-sampling and testing should be carried out, and usage should follow the test results.
b. Sand: Coarse sand or medium sand, screened before use, with a clay content of no more than 3%.
c. Lime Putty: Should be made by hydrating quicklime blocks, filtered through a sieve with a mesh size no larger than 30×30mm, and stored in a settling tank. Hydration time, generally not less than 15 days at normal temperature. When using, lime putty should not contain unhydrated particles or other impurities.
d. Adhesive and Mineral Pigments: Materials such as cement, sand, and adhesives for bonding exterior wall tiles should be retested upon arrival, and must meet design and specification requirements before large-scale use.
2.1.2 Construction Process
(1) Process Flow
Base treatment, plugging bolt holes, hanging nets, spraying slurry → suspending vertically, squaring, finding rules → attaching plaster dots → applying base mortar → applying second layer mortar → snapping lines and dividing sections (inserting door and window frames afterward) → ZL particle insulation mortar.
(2) Key Points of Cement Mortar Plastering Construction
(a) Key Points of Construction
(1) Base Treatment: First, remove any protruding concrete from the wall surface cleanly. Use 1:2 cement mortar bricks with added water to moisten and plug scaffold eyes. Joints must be compact. Use 1:2 cement mortar with added expansive agent to plug bolt holes, penetrating no less than 50% into the wall. According to Qingdao Construction Bureau Document No. 95 of 2002, wherever masonry blocks meet concrete beams, columns, or shear walls, a 1.6mm steel wire mesh with a 20×20mm grid must be nailed. The width of the steel mesh must be greater than 300mm, and the overlap width with each substrate must be no less than 100mm. Spray 3mm thick 1:2:2 cement mortar with added M999 anti-crack latex mechanically, making it adhere firmly to the smooth base surface. Water curing until it cannot be peeled off easily is required.
(2) Suspend Vertically, Square, Find Rules: Respectively suspend vertically and hang horizontal and vertical lines at door and window corners, pilasters, and wall surfaces. Since the external wall extends from the eaves to the ground, the plastered surface area is large, and the visible surfaces of doors, windows, balconies, exposed columns, and cornices need to be horizontally level and vertically straight. Therefore, the plastering operation must proceed step by step from one scaffold level to the next. Thus, finding the rules for external wall plastering involves first hanging vertical continuous lines from top to bottom at the four corners (for multi-story and high-rise buildings, steel wires can be used). Then, based on the roughly determined plastering thickness, control lines are preferably snapped on both sides of each scaffold level at major angles. Horizontal continuous lines are then pulled, and level lines marked as reference points. Vertical markers are made at each scaffold level, followed by making gauge sticks. Markers are set up, and gray cakes are applied, and lines are drawn on the wall surface to mark the control lines for the plastering layer.
(3) Apply the First Coat of Mortar: Apply a 3mm thick 1:1:6 cement lime putty mortar [with 1kg/m³ polypropylene anti-crack fibers added, water-cement ratio 0.4~0.5] as the base rough coat. Apply a second coat of 6mm thick 1:0.2:2.5 cement lime putty mortar (with polypropylene anti-crack fibers added, dosage 1.0kg/m³). This should be leveled in layers, aligned straight, and smoothed with a wooden trowel. Scrape and sweep to create patterns or grooves.
(4) Attach Division Strips: Attaching division strips should be done after the second coat is applied. Snap horizontal division lines every 600mm according to the previously marked level lines and division dimensions, ensuring they are level. Use ready-made plastic division strips with specifications of 20mm wide × 4mm high. Soak them in water before use to facilitate attachment and prevent deformation during use. Cut the strips to length based on the division line lengths, then apply plain cement slurry to the back of the strips using a steel trowel. Horizontal division lines should be attached below the level line for easier observation. After attaching one horizontal strip, check its flatness with a straightedge and apply the slurry around the edges of the strip to form an 8-shaped bevel (if it’s a horizontal line, start with the lower edge). For strips applied on the same day, the 8-shaped bevel can be 45°. For “overnight” strips not plastered on the same day, the bevel should be steeper, about 60°.
(5) Apply Third Coat of 1:0.2:2.5 Cement Lime Putty Mortar (with polypropylene anti-crack fibers added, dosage 1.0kg/m³). First, apply a thin layer of plain cement paste to ensure good adhesion with the base layer. Follow immediately with the topcoat, leveling it with the plaster dots and division strips. Use a straightedge to level horizontally and vertically, then smooth with a wooden trowel and press with an iron trowel for a glossy finish.
The construction sequence: From top to bottom for the base layer. After the base layer mortar is applied, raise the scaffolding and continue from top to bottom for the top layer mortar. Before applying the top layer, check if there are any voids or cracks in the base layer. If so, repair and then apply the top layer. Also, clean dirt and grime from the base layer, moisten with water, and then proceed with the top layer plastering.
(6) Drip Groove: The internal window sill is 20mm higher than the external window sill, forming a 6% drainage slope; drip grooves should be provided under exterior window sills, window lintels, canopies, balconies, caps, and prominent waistlines. The depth and width of the drip groove should be 10mm x 8mm, uniform and consistent.
(7) Quality Standards
Main Control Items
a. Dust, dirt, oil stains, etc., on the base surface before plastering should be cleaned thoroughly, and the surface should be moistened with water.
Inspection Method: Check construction records.
b. Types and properties of materials used in general plastering should comply with design requirements. The setting time and soundness of cement should pass reinspection. The mix ratio of mortar should comply with design requirements.
Inspection Method: Check product certificates, incoming inspection records, reinspection reports, and construction records.
c. Plastering work should be carried out in layers. When the total thickness of plastering is greater than or equal to 35mm, reinforcement measures should be taken. At the junctions of different material substrates, measures should be taken to prevent cracking.
Inspection Method: Check hidden project acceptance records and construction records.
d. The plastering layer must bond firmly with the base layer and between each plastering layer. There should be no delamination or hollow drums in the plastering layer, and no spalling or cracks on the surface layer.
Inspection Method: Observe; lightly tap with a small hammer; check construction records.
General Items
e. The surface quality of general plastering work should meet the following requirements:
Ordinary plastering surfaces should be smooth, clean, joints even, and partition seams clear.
High-grade plastering surfaces should be smooth, clean, color uniform, free of plastering marks, and partition seams and plaster lines should be clear and aesthetically pleasing.
Inspection Method: Observe; touch with hands.
f. The plastering surfaces around corners, holes, slots, and boxes should be neat and smooth; the plastering surfaces behind pipes should be flat.
Inspection Method: Observe.
g. The total thickness of the plastering layer should comply with design requirements; cement mortar should not be applied over lime mortar; gypsum plaster should not be applied over cement mortar.
Inspection Method: Check construction records.
h. The placement of plastering partition seams should comply with design requirements, and their width and depth should be uniform, with smooth surfaces and neatly arranged edges.
Inspection Method: Observe; measure with a ruler.
i. Parts requiring drainage should have drip lines (grooves). Drip lines (grooves) should be neat and straight, with the inner part higher than the outer part. The width and depth of the drip groove should not be less than 10mm.
Inspection Method: Observe; measure with a ruler.
m. The allowable deviations and inspection methods for the quality of general plastering work should comply with the provisions of the table below.
Allowable Deviations and Inspection Methods for General Plastering
Item Number Item Allowable Deviation (mm) Inspection Method Ordinary Plastering High-grade Plastering
1 Verticality of facade 4 3 Check with a 2m vertical detection ruler
2 Surface flatness 4 3 Check with a 2m straightedge and wedge gauge
3 Right angle squareness 4 3 Check with a right-angle detection ruler
4 Straightness of partition strips (seams) 4 3 Stretch a 5m line, if less than 5m stretch a full line, check with a steel straightedge
5 Straightness of wainscot and plinth upper edge 4 3 Stretch a 5m line, if less than 5m stretch a full line, check with a steel straightedge
2.2 Polyvinyl Acetate Powder Polystyrene Particle External Thermal Insulation Construction
2.2.1 Construction Process
Structural base treatment → suspend vertical lines, snap control lines → dot, dash, make openings → re-measure base flatness → apply polystyrene particle insulation slurry → accept insulation layer → apply cement crack-resistant mortar while pressing glass fiber mesh → accept crack-resistant protective layer → scrape flexible waterproof crack-resistant putty → finish and accept decorative layer
C System Structure (Cast-in-place)
B System Structure (Bonded)
2.2.2 Construction Preparation
(1) Set up a mixing shed, all materials must be mechanically mixed inside the mixing shed to prevent polystyrene particles from dispersing and affecting civilized construction;
(2) The location of the mixing shed should be sheltered from the wind, close to vertical transport machinery. The mixing shed should be enclosed on three sides, with one side as the entry-exit channel for materials, with a roof, and the ground should be flat and solid; away from sand and gravel yards, downwind of sand and gravel yards.
(3) Clean the building perimeter before thermal insulation construction to facilitate the recovery of fallen ash. Fallen ash should be re-mixed and used within 4 hours.
(4) Leave space for the thickness of the insulation layer at door and window frames, fill gaps in layers tightly, and protect the surface of the door and window frames. Windows should pass inspection before thermal insulation plastering begins, ensuring the distance from the insulation surface to the inside of the window frame is consistent.
(5) Strictly prohibit manual mixing of silicate polystyrene composite thermal insulation slurry on the ground and using expired slurry.
b Pre-requisites for Thermal Insulation Work:
(1) The verticality and flatness of the internal side of the external wall base should comply with current national construction and acceptance standards;
(2) External window frames should be installed and pass inspection;
(3) Scaffolding used for construction must be securely erected;
(4) All joints in the main structure should be handled in advance;
(5) Environmental temperature during operations should not be lower than 5°C;
(6) Construction holes and waste rebars left on the wall should be dealt with in advance;
(7) Concealed pipelines, boxes, and embedded components on the wall should be installed in advance, taking into account the impact of the insulation layer thickness.
2.2.3 Base Treatment
(1) The wall surface should be cleaned thoroughly, cleaning oil stains and sweeping away loose dust.
(2) Any protrusions on the wall surface exceeding 10mm should be removed.
2.2.4 Interface Treatment
Interface roughening can be done using rollers, brooms, or wooden trowels, but adjustments to the mix ratio should be made; control the cement-to-sand ratio at 1:1, reasonably adjust the interface agent dosage. Roughening should not be too thick, but all concrete walls must undergo rough surface treatment. Red bricks do not require interface treatment but should be moistened once or twice 10-24 hours in advance.
2.2.5 Suspend Vertically, Snap Control Lines, Make Gray Cakes
(1) Snap thickness control lines and make thickness gray cakes, spacing greater than 2m between two gray cakes should be connected by a continuous line and additional gray cakes added to keep the distance between gray cakes (horizontal, vertical, diagonal) less than 2m; based on the vertical control continuous line, make vertical direction gray cakes, measure the thickness of the gray cakes, record, calculate the super-thick area project volume;
(2) Gray cakes are cut from waste polystyrene boards into 4x4cm pieces and bonded with cement or other low-drying shrinkage bonding materials.
2.2.6 Insulation Layer Construction
a Apply Base Insulation Slurry
During the preparation of the insulation slurry and crack-resistant mortar, dedicated personnel should be assigned to ensure the stirring time and water dosage standards; the quality of on-site stirring can be judged by observing its workability, anti-sliding property, paste condition, and wet apparent density. Control the plastering thickness around 10-15mm. Wait 24 hours before proceeding to the next process.
b Apply Surface Insulation Slurry
When applying the surface insulation layer, the flatness deviation should not exceed 4mm. When applying the insulation surface layer, the plastering thickness should be slightly higher than the gray cake thickness, then leveled with a straightedge to the design thickness, and locally repaired with a trowel for flatness. After 30 minutes of applying the insulation surface layer, use a trowel again to smooth the wall. Check with a plumb bob to reach the acceptance standard.
2.2.7 Partition Drip Grooves at Door and Window Openings (As Per Design Requirements)
After completing the insulation construction, snap the control lines for drip grooves according to the design requirements, use a wallpaper knife to cut along the line to form the preset recess, approximately 15mm deep, fill with crack-resistant mortar, ensure the crack-resistant mortar adheres firmly to the recess, remove floating slurry from both sides of the groove, and ensure the drip groove is securely embedded and level.
2.2.8 Crack-Resistant Layer Construction
After the insulation layer construction is completed for 3-7 days and passes quality inspection, the crack-resistant layer construction can begin.
(1) The length of alkali-resistant grid cloth should not exceed 3m, pre-cut to size, trim the edges of the grid cloth;
(2) When applying crack-resistant mortar, the thickness should be controlled at 3-5mm. After applying a certain width, immediately press the alkali-resistant grid cloth into place with an iron trowel. The lap width of the grid cloth should not be less than 50mm. Press one side first, then apply some crack-resistant mortar, and press the other side. Dry lapping is strictly prohibited. At corners, the alkali-resistant grid cloth should overlap, with a width ≥50mm. At external corners, it should also overlap, with a width ≥20mm. The grid cloth should be laid flat without wrinkles, with a mortar saturation rate of 100%, smoothed and stretched to maintain the squareness and verticality of corners.
(3) Lay double-layer alkali-resistant grid cloth on the first floor walls, using the same method as above. The grid cloth should be butt-jointed, and the crack-resistant mortar between the two layers of grid cloth should be fully filled, dry laying is strictly prohibited.
(4) Add an additional layer of reinforced grid cloth (200x300mm) at 45° angles around door and window openings.
(5) After applying the crack-resistant mortar, it is strictly prohibited to apply ordinary cement mortar for waistlines, corner trims, or rigid putty coatings such as cement or gypsum putty.
(6) Precautions for crack-resistant layer construction:
a Before constructing the crack-resistant layer, place a prefabricated long thin plate between the window frame and the insulation layer, with dimensions of 3mm thick and 5mm wide. Remove it after the crack-resistant layer is constructed for window sealant application.
b Control of crack-resistant layer flatness: First, ensure the flatness of the insulation layer meets the standard. If it does not, level it with insulation slurry beforehand. Reinforced grid cloth at window corners, internal and external corners should be pre-applied with crack-resistant mortar, followed by continuous large wall construction. Start with detailed areas and then overall construction, ensuring whole sheets of alkali-resistant grid cloth cover dispersed reinforcing alkali-resistant grid cloth. When overlapping alkali-resistant grid cloth, press the bottom layer into the crack-resistant mortar first,