This is to prevent indoor water vapor infiltrationInsulation layerLay a layer of airtight and watertight protective materials on the roof.
The purpose of setting vapor barrier is to prevent indoor water vapor from penetrating through roof panelInsulation layerThe heat preservation effect is affected and the coiled material is easy to bulge.Therefore, it is stipulated in Article 4.3.3 of the Technical Code for Roof Engineering (GB 50207 -- 94) that "in the area north of latitude 40" and the indoor air humidity is greater than 75%, or in other areas, the indoor air humidity is greater than 80% all the year round, the insulation roof shall be provided with a vapor barrier ".Therefore, the vapor barrier is required to close the insulation layer tightly and completely cut off the channel for steam immersion in the insulation layer. Therefore, the vapor barrier shall be laid continuously along the wall at the junction of the roof and the wall, and shall be no less than 150mm higher than the upper surface of the insulation layer.
The steam barrier shall be of good water and air tightnessWaterproof materialBecause the condensed water enters the insulation layer through the structural layer gap in the form of water vapor, the vapor barrier should be made of materials with good air tightness, usually single-layerWaterproof roll, full adhesion or empty paving.Also availableWaterproof coatingHowever, water emulsion paint with poor air tightness should not be used.[1]
b. Suitable for cold weather.Cold winter and hot summer, mild, warm winter and hot summer, and hot areas.
c.Dike vapor barrierIt can slow down the emission of indoor water vapor to the insulation layer, and effectively prevent the formation of condensation, so that the waterproof vapor permeable membrane can effectively discharge the water vapor from the insulation layer quickly, protect and maintain the thermal performance of the structure, so as to save energy.[2]
Key points of quality control
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(1) The base course of the vapor barrier shall be flat, clean and dry.
(2) The vapor barrier shall be set between the structural layer and the insulation layer;The steam barrier shall be made of materials with good air tightness and water tightness.
(3) At the connection between the roof and the wall, the vapor barrier shall be laid continuously upward along the wall, and shall not be less than 150mm higher than the upper surface of the insulation layer
(4) When coiled material is used as the vapor barrier, it should be laid empty. The lap joint of coiled material should be fully adhered, and the lap width should not be less than 80mm;When the vapor barrier is coated with film, the coating shall be applied evenly.
(5) The surrounding of the pipeline passing through the steam barrier shall be sealed tightly, and there shall be no damage at the corner;All defective or damaged parts of the vapor barrier shall be repaired.
Vapour barrier design
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The purpose of setting vapor barrier is to prevent indoor wet vapor from entering the insulation layer through the structural layer.Because if the wet steam is trapped in the gap of the insulation layer, it will condense into condensate when it is cold, thus increasing the moisture content of the insulation layer and reducing the insulation effect;When the temperature rises, the moisture in the insulation room will become steam after being heated, which will cause the waterproof layer to bulge.Therefore, the following points should be grasped when designing the vapor barrier:
（1） Setting principles
(1) In the area north of latitude 40, and when the indoor air humidity is greater than 75%, the insulation roof shall be provided with a vapor barrier.
(2) When the indoor air humidity in other areas is more than 80% all the year round, the insulation roof shall be provided with a vapor barrier.
(3) The roof of buildings with constant temperature and humidity requirements shall be provided with vapor barrier.
(4) According to《Code for thermal design of civil buildings》(GB50107), after checking the moisture-proof calculation of the roof structure, it is confirmed that the relevant buildings must be provided with vapor barrier.
（2） Design measures
(1) The position of the vapor barrier shall be set above the structural layer and below the insulation layer, that is, between the two.
(2) The steam barrier shall be of good water tightness and steam tightnessWaterproof material。Various types can be usedWaterproof rollThe water emulsion thin coating with poor vapor tightness shall not be used for paving, and the specific method shall be determined by calculation according to the vapor permeability coefficient of the material.
(3) When usingAsphalt based waterproof coatingWhen making the vapor barrier, its heat resistance shall be 20~25 ℃ higher than the maximum indoor or outdoor temperature.
(4) At the roof flashing, the vapor barrier shall be laid continuously along the wall, and shall not be less than 150mm higher than the upper surface of the insulation layer, so as to seal the insulation layer tightly.
When the thermal insulation materials with through holes are used in the cold insulation project, the damp proof layer must be set. The construction quality of the damp proof layer is related to the cold insulation effect and the life of the cold insulation structure.Before the construction of moisture-proof course, check whether the substrate (heat insulation layer) is damaged, whether the material joints are treated tightly, and whether the surface is flat (hardThermal insulation materialThe surface of the base course shall not have protruding sharp corners and pits). If the above conditions need to be treated, the moisture-proof course shall be constructed.The surface of base course shall be dry before paving.
(1) The moisture-proof layer material shall be closely adhered to the thermal insulation layer, and the sealing shall be complete and good, without defects such as false sticking, bubbles, folds, cracks, etc.
(2) When asphalt felt is used as the damp proof course, the asphalt felt and the base, asphalt felt and asphalt felt shall be pasted with the same petroleum asphalt coating as asphalt felt.
(3) UseGlass fiber clothWhen asphalt coating is used as damp proof course, 3mm thick asphalt coating shall be applied on the surface of the base course first, and then the glass cloth shall be lapped and wound spirally. The lapping width of the glass cloth shall be 30-50mm, and the wool of the glass cloth shall not be left after winding.The horizontal pipe is spirally wound from low to high against the pipe slope, with the seam facing down and fixed.Vertical pipes or vertical equipment shall be spirally wound from bottom to top, and their joints shall be overlapped from top to bottom;When glass fiber cloth is wound.The asphalt coating (cold mastic) shall be applied and wound at the same time.Determine the thickness of damp proof course (several felts and several oils) according to the design requirements.
(4) When the aluminum foil veneer is used as the moisture-proof layerAluminum foil tapeThe aluminum foil surface shall be wiped clean without dust before sticking the adhesive tape.The width of aluminum tape is generally 50-60mm.
(5) After the construction of the damp proof course, it is not allowed to puncture and damage the damp proof course. If there is any damage, it should be repaired with homogeneous materials before making a protective layer.[4]
Construction requirements
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1、Leveling layerset upRevealIt can also be used as exhaust passage;When paving coiled materials, the empty paving method, spot bonding method and strip bonding method should be adopted.
2. The exhaust pipe shall be vertically and horizontally connected, and the same as the exhaust pipe connected with the atmosphere;The exhaust pipe can be set under the cornice or at the intersection of roof exhaust ducts.
3. The exhaust duct should be set horizontally with a spacing of 6m.An exhaust hole should be set every 36 ㎡ of the roof area, and the exhaust hole should be waterproof.
4. OnInsulation layerThe bottom can also be laid with fulcrumPlastic plate, drain water and exhaust steam through the cavity layer.
5. The vapor barrier shall be laid upward along the wall and connected with theWaterproof layerTo form a totally closed whole.
