SBS modified asphalt membrane waterproofing construction technology
This project is the first phase of the project, covering an area of ??13,650 square meters, including a factory building and a staff building. The factory building is a three-story frame structure, and the staff building is a five-story brick-concrete structure.
The waterproof material used for roof waterproofing in this project is polymer-modified asphalt waterproofing membrane.
According to the national technical regulations, the number of rolls used for defense varies depending on the waterproofing level of the building, as shown in Table 1.
Selection of membrane thickness (Table 1)
Roof waterproofing level Number of fortification lines Synthetic polymer waterproofing membrane Polymer modified asphalt waterproofing membrane
Level Ⅰ Three or more lines of defense should not be less than 1.5mm and should not be less than 3mm
Level Ⅱ Two lines of defense should not be less than 1.2mm Not less than 3mm
Level Ⅲ One line of defense It should not be less than 1.2mm and should not be less than 4mm
Level IV One-level fortification————
The waterproof level of this project is designed to be Level II. I participated in the roof waterproofing construction of this project during my graduation internship, and gained some understanding and experience of the construction technology of polymer-modified asphalt waterproofing membranes. The summary is as follows:
1. Preparations before construction
(1) Technical preparation work
Before the construction of the roof waterproofing project, the construction unit should organize technical management personnel to review the roof engineering drawings and master the detailed structure and relevant technical requirements in the construction drawings. And prepare the construction plan or technical measures for the roof project based on the actual situation of the project. Sufficient preparation work in the early stage of construction can avoid defects after construction and even quality accidents such as rework. At the same time, the project must be carried out in strict accordance with the construction organization plan, so as to prevent omissions, confusion, and inversion of work, which will affect the quality of the project.
According to the construction organization design, the construction leader should make a technical briefing to the team. The content of the technical explanation includes: construction parts, construction sequence, construction technology, structural levels, node fortification methods, reinforced parts and practices, project quality standards, technical measures to ensure quality, protective measures and safety precautions for finished products.
(2) Preparation of personnel and operation plan
The waterproofing of roofing projects must be carried out by professional waterproofing teams. Units without qualification certificates and non-waterproofing professional teams are strictly prohibited from waterproofing roofing projects. During construction, the construction unit or supervision company should carefully check the employment certificates of construction personnel. During construction, the construction unit should conduct quality self-inspection, self-inspection, and self-correction according to the construction process and level, and keep construction records. The supervision unit should do the acceptance work of each step. Only after the acceptance is passed, the next process or level can be carried out. Operation.
2. Key points of roof waterproofing construction
(1) Environmental requirements for construction
Polymer-modified asphalt waterproofing membranes are generally laid using the hot melt method Coiled materials should be constructed at temperatures between +50°C and +350°C. It is not suitable to operate in the open air in rain, snow, frost, fog, excessive atmospheric humidity, or windy weather, otherwise corresponding technical measures should be taken.
(2) Requirements for roof drainage slope
The drainage slope of flat roofs is 2% to 3%. When the slope is less than or equal to 2%, materials should be used to find the slope; When the slope is greater than 3%, structural slope finding should be used. The longitudinal slope of gutters and eaves shall not be less than 1%, and the drop at the bottom of the ditch shall not exceed 200mm. The slope within a diameter of 500mm around the water drop opening should not be less than 5%.
(3) Treatment of gaps and cracks in the roof base
The roof base of this project is cast-in-place reinforced concrete. When there are cracks in the slab, the cracks should be cut out with a chisel first. Make a 15-20mm wide and deep splay-shaped trench, then remove the gravel, blow the trench clean, and fill the cracks with caulking paste in two to three times. The interval between each time must be 15 minutes. Once the cracks are full, use a roller to flatten them.
(4) Construction of each structural layer of the roof
1. The construction process flow chart of membrane waterproofing is as follows
Clean the base layer → Paint the base layer Agent → Pave additional layer of membrane → Pave membrane → Hot-melt edge sealing → Water storage test → Protective layer
2. General waterproof construction practices
(1) Waterproof layer : It is made of waterproof membrane and corresponding membrane adhesive layered together. The number or thickness of layers is determined by the waterproof grade. A waterproof layer with independent waterproof capability is called a waterproof fortification.
Before laying the membrane, the base layer must be clean and dry, and the base treatment agent used with the membrane must be applied (this layer is called the binding layer) to ensure that the waterproof layer and the base layer are firmly bonded.
The laying methods of coiled materials include: cold bonding method, hot melt method, hot air welding method, self-adhesive method, etc. Coiled materials are generally laid in layers. When the roof slope is less than 3%, the coiled materials should be laid parallel to the ridge; when the slope is between 3% and 15%, the coiled materials can be laid parallel or perpendicular to the ridge. The overlap between the upper and lower layers and two adjacent rolls should be staggered. The overlapping joints of parallel roof ridges should follow the direction of water flow, and the overlapping joints of vertical roof ridges should follow the direction of the annual maximum frequency of wind.
When rolling materials are overlapped, the width of the overlap is determined according to the type of rolling materials and the paving method, as shown in Table 2. The overlapping joints of the rolling materials are bonded with a special adhesive matching the rolling materials. Seal everything tightly with sealing material.
When the membrane waterproof layer is covered with heavy objects or the base layer is greatly deformed, the air laying method, point gluing method and strip gluing method should be given priority.
Membrane overlap (Table 2)
Overlap direction Short side overlap width/mm Long side overlap width/mm
Paving method< /p>
Rolling material type: full gluing method, empty laying method
point gluing method
strip gluing method, full gluing method, empty laying method
point gluing method Method
Strip bonding method
Asphalt waterproofing membrane 100 150 70 100
Polymer modified asphalt waterproofing membrane 80 100 80 100
Polymer waterproof membrane pasting method 80 100 80 100
Welding method 50
(2) Leveling layer: It is the base layer for paving the membrane waterproof layer, providing waterproofing The membrane provides a flat, dense, strong and bondable structural foundation. Therefore, the leveling layer of the rolled material should be solid and should not have protruding sharp corners, pits or surface sand. When inspected with a 2-meter-long ruler, the gap between the ruler and the surface of the leveling layer should not exceed 5mm. , the gaps are only allowed to change gently, and there must be no more than one per meter length. The corners formed by the adjacent surfaces of the leveling layer should be made into arcs or obtuse angles.
When the base layer is solid concrete, use cement mortar leveling layer with a thickness of 20mm, a cement to mortar ratio of 1:2.5 to 1:3 (volume ratio), and a cement grade of no less than 425. The leveling layer must also be provided with grating joints and filled with sealing materials. This can avoid or reduce cracking of the leveling layer, so that when the structure deforms or the temperature difference deforms, the waterproof layer will not form cracks, leading to leakage. The seam width is 20mm, and the longitudinal and transverse spacing of the lattice seams is not greater than 6m. The lattice seams are located at the support ends of the roof panels, at the intersection of the waterproof layer and the protruding roof components at the corners of the roof, and at the intersection of the waterproof layer and the parapet. etc., and should be aligned with the end seam of the board, even and straight. When constructing the cement mortar leveling layer, first clean up the debris on the roof and floor and sprinkle water to moisten it. When laying mortar, follow the procedure from far to near and from high to low. Pave continuously in each grid once. Control the slope according to the design. Use a scraper with a length of more than 2m to scrape it flat. After the mortar has slightly absorbed water, Use a trowel to compact and smooth it. After 12 hours, cover it with a straw bag and water it for maintenance. Detailed nodes such as structures and pipe roots on the protruding roof should be made of arcs, truncated cones or square truncated cones, and should be made of fine stone concrete to avoid cracking of the roll material at the node locations and facilitate solid adhesion.
1． Water drop mouth: made within 500mm of the surrounding area, with a slope of ≥5% and smooth.
2. The roots of the parapet, the flue above the roof, and the stairs are made into arcs with a radius of 80mm, and are made of fine stone concrete.
3． Stretch out around the root of the roof pipe and use fine stone concrete to make a square frustum. The bottom surface of the frustum is 300mm wide and 60mm high, and is smooth and polished.
(3) Protective layer: Since the roof of this project is an upper roof, the method is: pour a 30~50mm thick fine stone concrete layer on the waterproof layer.
(5) Base treatment agent
In order to strengthen the bonding force between the waterproof membrane and the base layer and ensure the integrity, it is pre-painted on the base layer before the construction of the waterproof layer. of paint. Commonly used base treatment agents include cold base oil and primer (base treatment agent) matched with various polymer-modified asphalt membranes and synthetic polymer membranes. The selection should be compatible with the material of the membrane to avoid rolling. The material is corroded or incompatible with poor bonding.
Before spraying and applying cold base oil and base treatment agent, check the dryness of the leveling layer and clean it. Then use a brush to treat the nodes, periphery, corners and other parts of the roof first, and finally spray it on a large area. ,brush. The spray and brush should be thin and even, and should not leak white spots or be too thick or peeling. Apply cold base oil 1 to 2 days before paving, and apply the base treatment agent about 4 days after it dries before paving the membrane.
(6) Paving of roll materials
1. The laying direction of the membrane: The laying direction of the membrane should be determined according to the slope of the roof and whether there is vibration on the roof. When the roof slope is less than 3%, the membrane should be laid parallel to the roof ridge; when the roof slope is 3% to 15%, the membrane can be laid parallel or perpendicular to the roof ridge; when the roof slope is greater than 15% or subject to vibration, the asphalt roll The materials should be laid perpendicular to the roof ridge, and other materials can be laid parallel or perpendicular to the roof ridge according to the actual situation. Laying is carried out layer by layer from the eaves to the ridge. All types of membranes should be overlapped at the top and bottom. The overlapping positions of multi-layer membranes should be staggered. The upper and lower membranes should not be laid vertically.
2. The order of applying membranes: When constructing the waterproof layer, you should first prepare the nodes, additional layers and areas where roof drainage is concentrated (such as the connection between the roof and the water outlet, cornices, gutters, gutters, roof corners, board end seams, etc. ), and then construct upward from the lowest elevation of the roof. When paving gutter and eaves rolled materials, it is advisable to follow the direction of the gutter and eaves to reduce overlap.
When paving multi-span roofs and roofs with high and low spans, they should be carried out in the order of high first, then low, first far, then near.
3． Rolling material overlapping method and width: The overlapping method is used for paving rolling materials, and the overlap joints of the upper and lower layers and two adjacent rolling materials should be staggered. The lap joints parallel to the roof ridge should overlap in the direction of water flow; the lap joints perpendicular to the roof ridge should smoothly overlap with the prevailing wind direction.
Each layer of rolled materials laid in stacks should be overlapped at the junction between the gutter and the roof, and the overlapping joints should be staggered; the joints should be left on the side of the roof or gutter, not at the bottom of the ditch.
On arched roofs with a slope exceeding 25% and on slopes under skylights, short-side overlaps should be avoided as much as possible. When short-side overlaps are necessary, measures should be taken at the overlap to prevent the roll from sliding down. .
The overlapping widths of various coiled materials are shown in Table (3):
Overlap width of rolled materials (mm) (Table 3)
Paving method
Rolling material type Short edge overlapping Long edge overlapping
Full gluing method Empty laying, dot gluing, strip gluing method Full gluing method Empty laying, dot gluing, strip gluing< /p>
Asphalt waterproofing membrane 100 150 70 100
Polymer modified asphalt waterproofing membrane 80 100 80 100
Synthetic polymer waterproofing membrane Adhesive 80 100 80 100
Adhesive tape 50 60 50 60
Single seam welding 60, effective welding width is not less than 25
Double seam welding 80, effective welding width 10 ×2＋Cavity width
(7) Details of waterproofing membrane
1. Deformation joints: Since this project is a roof of constant height, the roof deformation joints are processed with flat joints. That is, the seams are filled with foam, the upper part is filled with cushioning material, the seams are covered with galvanized steel sheets, and then a waterproof layer is made. As shown below.
2. Flashing: Flashing refers to the waterproofing treatment at the intersection of the roof waterproof layer and the vertical wall or vertical components of the roof. The focus of waterproofing membrane roofing should be on turning the waterproof layer, fixing and closing on the vertical wall. The turning point should be made into an arc to prevent the coil from being broken. The membrane at the flooded area should be fully pasted. The height of the membrane should be determined by the design, but the minimum should not be less than 250mm. The closing and sealing forms should be determined according to the wall material. When the wall is made of brick and is not too high, the rolled material should be closed directly under the top of the parapet wall, and the top should be waterproofed, as shown in the figure below. This project adopts the roofing treatment.
3． Cornice: Waterproof cornice is divided into several forms: free fall, external eaves, and gutter inside the parapet. The schematic diagram of its structure is shown in the figure below.
4. Rainwater outlet: Rainwater outlet is a key part where roof rainwater is collected and discharged to water pipes. It requires smooth drainage to prevent leakage and blockage. The material of the rainwater outlet is UPVC plastic, which is divided into horizontal and straight types. The straight rainwater outlet is used for the hole at the bottom of the gutter, and the horizontal rainwater outlet is used for drainage outside the parapet. The factory building and staff building of this project adopt straight and horizontal rainwater outlets respectively, as shown in the figure below. The location of the rainwater bucket should pay attention to its elevation to ensure that it is the lowest point for drainage. The slope within a diameter of 500mm around the rainwater outlet should not be less than 5%.
5． Access to the upper level roof: The steps for the roof stairwell and the access to the upper level roof are shown in the figure below: the leveling layer on the outer side of the steps and the level, the additional waterproof layer, and the end of the waterproof layer are equivalent to the roof parapet. The width of the step is 250mm. The ends of all waterproof membranes are fixed with cement nails with gaskets. The maximum nail distance is less than 900mm. The ends of all waterproof membranes are filled and sealed with sealing materials.
3. Protection of roof waterproofing membrane
After the waterproofing membrane is laid, it must be well protected to avoid affecting the waterproofing effect. Spread 300mm × 300mm expanded perlite insulation blocks on the waterproof layer, and then add a 3cm thick cement mortar protective layer on top of it. Steel wire mesh is laid inside this layer. The protective layer is set with grid joints and the joints are filled with sealing materials. , better protect the waterproof layer.
IV. Precautions
In order to block the influence of water vapor from indoors and cause the roof waterproofing layer to bulge, in general structure, exhaust pipes are often installed in the insulation layer of the roof. Make a vapor barrier layer on the air channel and above it (for example: one layer of oil paper, one layer of felt and two oils, or one layer of cloth and two glue, etc.) to block the upward penetration of water vapor. The spacing between exhaust ducts should be 6 meters, arranged vertically and horizontally, not blocked, and connected to exhaust holes connected to the atmosphere. Before constructing the drainage roof waterproofing layer, check whether the exhaust duct is blocked and clean and clear it.
It is not very difficult to make a good waterproof layer of roofing membranes. As long as we follow the construction process of roofing membrane waterproofing, implement it layer by layer, strictly control it, and do every step of the work carefully according to the specifications, we will be able to It can prevent roof leakage caused by construction.
V. Acceptance of roof waterproofing
1. Quality standards and acceptance
1.1. Insulation layer
Insulation material (50mm thick poly The moisture content of the stupid board must meet the design requirements, the quality of the material must meet the specification requirements, and the factory certificate and retest report must be checked.
The plate insulation material should be close to the base layer, laid flat and firmly, and the joints should be tight. When installing exhaust grooves, the spacing and width of the exhaust grooves should be correct.
The allowable deviation of the thickness of the insulation layer: ±5% of the plate insulation material, and shall not be greater than 4mm.
1.2. Slope layer
The overall cast-in-situ slope layer should be mixed evenly, laid in layers, properly compacted, the surface should be flat, and the slope should be correct.
The allowable deviation of the thickness of the slope layer: the overall cast-in-place slope layer is +10% and -5%. The spacing and width of the lattice seams are correct.
1.3. Leveling layer
The drainage slope of the leveling layer must meet the design requirements. The cement mortar leveling layer should be smooth and calendered, and there should be no looseness or peeling.
The location and spacing of the leveling layer gratings should meet the design requirements. The allowable deviation of the surface flatness of the leveling layer is 5mm.
1.4. Waterproof layer
The membrane waterproof layer must not have leakage or water accumulation, and the detailed waterproof structure must meet the design requirements.
The overlapping seams of the membrane waterproof layer are firmly bonded and tightly sealed, and there must be no wrinkles, warping, bubbling and other defects. The end of the waterproof membrane should be bonded to the base layer and fixed firmly, the seams should be sealed tightly, and the membrane should be paved in the correct direction.
The ends of gutters, gutters, cornices, flashings and facade membranes should be cut neatly, inserted into the reserved grooves, and fixed with metal battens and nails. The maximum nail spacing should not be greater than 900mm. , and fill it tightly with sealing material.
The allowable deviation of the roll overlap is -10mm.
1.5. Protective layer
The protective layer of silver paint should be firmly adhered to the coil, the thickness should be uniform, and no coating should be missed.
The colored cement bricks are protected and pasted firmly, with uniform color and clean surface. The area of ??the dividing joints is not more than 100m2, and the width of the dividing joints meets the requirements.
1.6. Project acceptance
The acceptance of roof sub-projects shall be carried out according to the insulation layer, leveling layer, waterproof layer and detailed structure. One spot will be inspected every 100m2, and each area will be 10m2. Seam sealing and waterproofing shall be randomly inspected every 50m, 5m per location, and no less than 3 locations. All detailed structures are inspected according to the contents of the sub-projects.
The main hidden contents of the roofing project: the base layer of the waterproof layer; the parts for sealing and waterproof treatment; details such as gutters, eaves, flashing and deformation joints; the overlap width and additional layers of the waterproof layer.
The quality of the roofing project should meet the following requirements: no leakage or water accumulation; the materials meet the standard requirements; the surface of the leveling layer is smooth, and there must be no looseness, sanding, or peeling; the thickness of the insulation layer, The moisture content meets the requirements; the structures such as gutters, eaves, flashings and deformation joints meet the design requirements; the laying method and overlap width of the waterproof layer are correct, the joints are tight, and there must be no wrinkles, bubbling or warping; inlays The seam sealing material should be firmly adhered to the base layer on both sides. The sealing part should be smooth and straight, and there should be no cracking, bubbling or sagging.
Check whether there are any leaks on the roof, whether there is water accumulation, and whether the drainage system is unblocked. After all water storage tests have passed the supervision and acceptance, do a good job in the acceptance of concealed projects and the compilation and inspection of engineering data.
Roof waterproofing occupies a very important position in house construction, because it is related to the use function of the building, as many examples have shown. Waterproofing is a problem that is both simple and complex. If you operate it according to the specifications and requirements, it will be very simple, otherwise the remaining problems will be very complicated.
Picture (1) Worker applying grease (2) Worker using flame burner to lay membrane
Picture (3) Using six-petal method to waterproof downspout< /p>
Picture (4) Using the patch method to deal with hollowing and damage of the roll
Picture (5) When placing heavy objects on the top of the paved roll, pads need to be added to protect the roll< /p>
Picture (6) Place heavy objects on top of the paved membrane without taking protective measures