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| Nom De La Marque: | SUNHOUSE |
| Numéro De Modèle: | 1220x244m-12mm |
| Nombre De Pièces: | 800 |
| Conditions De Paiement: | LC, T/T |
Moisture resistant gypsum board is frequently specified for bathroom, kitchen, laundry, hotel and hospital ceilings. Reduced water absorption does not automatically provide sufficient sag resistance for every ceiling. Long-term stability depends on the exact board type, thickness, framing spacing, installation direction, fastener pattern, surface finish, insulation load, ventilation and moisture conditions during construction and service.
Confirm that the exact moisture resistant product is approved for ceiling installation and the required framing spacing.
Channel spacing, alignment, stiffness and suspension stability directly affect the board span.
High humidity, wet finishes, condensation and unsupported insulation can increase temporary or permanent deflection.
Board direction, screw spacing, edge support and joint arrangement must follow the approved ceiling system.
Moisture resistance describes reduced water absorption or improved performance in humid interior conditions. Sag resistance describes the ability of a horizontally installed panel to limit deflection between supporting framing members over time. A board can satisfy a moisture resistance classification while still requiring closer ceiling framing than a specially engineered sag-resistant ceiling board.
Core additives and treated facings help the panel resist moisture uptake compared with standard gypsum wallboard. This property is important in humid rooms but does not define the maximum unsupported ceiling span.
Sag resistance depends on the panel core, facing composite, thickness, width, orientation and distance between supports. Specialty ceiling boards may use an engineered formulation to provide improved performance at wider framing centers.
Wet texture, multiple finish coats and insulation resting on the back of the board can increase loading. These loads must remain within the limits of the exact board and ceiling design.
A high-quality board can still sag when ceiling channels are spaced too widely, poorly aligned or inadequately suspended. Fastener spacing and edge support are also critical.
A moisture resistant board approved for vertical partitions may have different limitations when installed horizontally. Before ordering, confirm the ceiling application, minimum thickness, board direction, maximum framing spacing, fastener spacing, surface finish and insulation loading permitted by the manufacturer.
Sagging normally appears as visible downward deflection between ceiling framing members. It may develop gradually under sustained humidity and load, or become noticeable after wet spray texture, water leakage or insufficient framing support.
Board remains flat between correctly spaced and aligned supports.
Minor movement begins under humidity, finish moisture or sustained load.
Uneven reflected light makes the deflection noticeable across the ceiling.
Severe deflection may lead to cracked joints, screw stress or damaged finishes.
This diagram is illustrative. Acceptable deflection and inspection criteria should be defined by the product manufacturer, project specification and ceiling-system requirements.
A wall-grade moisture resistant panel may be installed where a dedicated sag-resistant ceiling board is required.
Thin panels are more sensitive to horizontal span, wet finishes and high-humidity conditions.
Increasing the distance between channels increases the unsupported span of the board.
Parallel installation may create a different effective span and joint arrangement from perpendicular installation.
Prolonged humidity can reduce panel stiffness and increase time-dependent deflection.
Water-based texture, wet plaster or heavy coatings add moisture and temporary weight before drying.
Unsupported batt or loose-fill insulation can create a sustained downward load.
Wide screw spacing, over-driven screws or damaged paper can reduce effective attachment.
Twisted, bowed or misaligned channels can create an uneven ceiling before finishing begins.
Plumbing leaks, roof leaks or condensation can saturate local board areas and cause permanent damage.
The following table is a procurement framework rather than a universal installation schedule. Exact limits vary by board formulation, manufacturer, framing type, finish and local installation standard.
| Nominal Thickness | General Ceiling Position | Main Purchasing Concern | Recommended Action |
|---|---|---|---|
| 6.4mm / 1/4 Inch | Generally used as a covering or curved-surface layer, not as a normal unsupported single-layer ceiling. | Very limited stiffness when used alone. | Do not specify as a single ceiling layer unless an approved system expressly permits it. |
| 9.5mm / 3/8 Inch | Used in selected ceiling systems with relatively close framing and controlled finishes. | Greater sensitivity to framing spacing, humidity and water-based texture. | Confirm that the exact board is ceiling-approved and review all product limitations. |
| 12mm Or 12.5mm | Common international wall and ceiling thickness. | Standard MR board and sag-resistant ceiling board may look similar but have different span limits. | Request a ceiling application table for the exact product. |
| 12.7mm / 1/2 Inch Standard Board | Suitable for ceilings only within the manufacturer's permitted framing and finish conditions. | Ordinary board may not support wider framing centers or additional wet finishes. | Do not apply performance data from a specialty ceiling board. |
| 12.7mm / 1/2 Inch Sag-Resistant Board | Engineered specifically for ceiling use and potentially wider framing centers. | Product recognition may depend on orientation, insulation and finish restrictions. | Verify the current technical data sheet and system approval. |
| 15mm Or 15.9mm / 5/8 Inch | Greater stiffness and commonly used in fire, acoustic or robust ceiling systems. | Higher board weight increases handling and framing loads. | Confirm framing spacing, fire assembly and suspension capacity. |
| Multiple Board Layers | Used for fire, acoustic or impact performance. | Increased dead load and longer fasteners affect the entire ceiling system. | Review hanger, channel, screw and perimeter requirements. |
Framing spacing determines the unsupported span between ceiling channels, joists or furring members. Wider spacing can reduce material and installation cost, but it increases bending demand on the board and makes the ceiling more sensitive to humidity and additional load.
| Framing Condition | General Stability Effect | Purchasing Decision |
|---|---|---|
| 305mm / 12 Inch Centers | Provides close support and can be required for selected thin boards, resilient systems or heavy finishes. | Confirm whether close spacing is necessary for the specified board, tile finish or ceiling detail. |
| 400–406mm / 16 Inch Centers | Common ceiling support range for many gypsum board systems. | Verify board thickness, direction and screw pattern. |
| 600–610mm / 24 Inch Centers | Creates a wider board span and generally requires a suitable thickness or engineered sag-resistant product. | Require explicit manufacturer approval rather than assuming every 12.5mm or 12.7mm MR board is suitable. |
| Irregular Framing Centers | Creates inconsistent spans and can produce visible waves. | Correct framing before board installation. |
| Misaligned Furring Channels | Forces the board to follow uneven supporting surfaces. | Inspect ceiling level, channel straightness and suspension. |
| Unsupported Board Edges | May create joint movement, cracking or local deflection. | Add framing or follow an approved perpendicular-edge detail. |
Some engineered ceiling boards are approved for framing at approximately 600 or 610mm centers under defined conditions. This allowance should not be copied into a quotation for a generic moisture resistant board. The product name, thickness, orientation, finish, insulation load and fastener method must all be verified.
Board direction is defined by the position of the long board edge relative to the framing. Perpendicular installation is commonly preferred because it distributes joints across multiple framing members and can provide a more favorable span arrangement. However, some approved products and systems also permit parallel installation.
The board's long dimension crosses the ceiling framing. Each sheet spans across several channels, and end joints can be offset between adjacent rows.
The board's long dimension follows the ceiling framing. This arrangement may be permitted for specific products but can have different framing and edge-support requirements.
Do not change from perpendicular to parallel installation merely to reduce cutting or waste. Board direction may affect maximum framing spacing, edge support, fastener arrangement and the validity of a fire or acoustic ceiling system.
Ceiling fasteners support the dead weight of the board and help keep the panel in close contact with framing. Fasteners that are too widely spaced, too short or over-driven can reduce attachment reliability.
Ceiling boards carry their own weight vertically downward and often require closer fastening than wall boards. Use the ceiling schedule stated in the applicable installation standard, product guide or tested assembly.
Moisture resistant gypsum board improves tolerance to humidity but cannot prevent condensation caused by poor ventilation, cold surfaces or uncontrolled vapor movement. Long-term humidification can increase deflection and may damage finishes or joints.
| Moisture Condition | Effect On Ceiling Stability | Recommended Control |
|---|---|---|
| Short-Term Bathroom Humidity | Normally manageable when the board and ventilation are suitable for the room. | Provide effective extraction and allow the ceiling to dry. |
| Persistent High Relative Humidity | Can reduce panel stiffness and increase long-term deflection. | Review the board's service limits and upgrade the system if necessary. |
| Surface Condensation | Repeated wetting may stain finishes and soften local areas. | Improve insulation, air sealing, ventilation and temperature control. |
| Concealed Cavity Condensation | Can wet the back face without immediate visible warning. | Review vapor control, insulation continuity and service penetrations. |
| Roof Or Plumbing Leak | May cause local saturation, severe sag or board failure. | Stop the leak, isolate the area and assess the affected boards. |
| Construction Moisture | Wet screeds, plaster and concrete can raise humidity before the building is ventilated. | Dry the building before closing and finishing ceilings. |
| Unconditioned Roof Space | Temperature cycling may increase condensation risk. | Confirm whether the board and ceiling design are approved below unheated or unconditioned spaces. |
Water-based spray texture, veneer plaster, heavy coatings and multiple finishing layers can temporarily add both moisture and weight. The board may be most vulnerable before the finish has fully dried.
Some thin or standard gypsum panels are not recommended at their maximum framing spacing when a water-based texture is applied. Always check the exact product table instead of approving the ceiling based only on dry board weight.
Gypsum board should not be used as an unverified support platform for insulation, cables, pipes or mechanical equipment. The ceiling suspension and building structure should carry service loads independently unless the system documentation expressly permits a defined load.
| Over-Ceiling Item | Potential Risk | Recommended Design Response |
|---|---|---|
| Batt Insulation | Poorly supported batts may rest unevenly on the board. | Support insulation independently or follow the board manufacturer's permitted loading. |
| Loose-Fill Insulation | Creates a distributed sustained load over the ceiling. | Verify maximum permitted loading and uniform installation. |
| Wet-Installed Cellulose | Adds both moisture and weight before drying. | Use only where the exact board and system expressly permit it. |
| Electrical Cables | Cable bundles can create concentrated pressure points. | Support cables from framing or approved cable supports. |
| Pipes And Ducts | Can transfer dead load, vibration or condensation water. | Suspend services independently from the building structure. |
| Light Fixtures | Heavy fixtures can overload cut openings and board edges. | Provide independent support and reinforce openings as required. |
| Access Panels | Interrupt board continuity and add concentrated frame loads. | Use a framed, system-compatible access panel detail. |
Ceiling boards and channels are not intended to support stored tools, tile boxes, duct components or workers. Temporary site loading can permanently deform the ceiling or damage the suspension system.
| Application | Typical Moisture Condition | Board Selection Approach | Key Stability Check |
|---|---|---|---|
| Residential Bathroom Ceiling | Short-term humidity and possible condensation. | Ceiling-approved moisture resistant board. | Ventilation, framing spacing and sag performance. |
| Kitchen Ceiling | Cooking vapor, heat and periodic cleaning humidity. | MR board or approved ceiling board according to room conditions. | Extraction ventilation and surface finish. |
| Laundry Room Ceiling | Humidity and appliance-related condensation. | Moisture resistant ceiling system. | Dryer exhaust, plumbing leaks and ventilation. |
| Hotel Bathroom Ceiling | Frequent use with repeated humidity cycles. | MR or mold-resistant ceiling board with documented span. | Daily drying opportunity and maintenance access. |
| Hospital Washroom Ceiling | Cleaning moisture and controlled indoor humidity. | Product selected for moisture, mold, cleaning and fire requirements. | Joint finish, access panels and service penetrations. |
| Commercial Kitchen Ceiling | Heat, grease, cleaning vapor and potentially high humidity. | Specialist washable ceiling system rather than generic MR board. | Hygiene finish, ventilation and exposure classification. |
| Indoor Pool Ceiling | Persistent humidity, condensation and chemical exposure. | Specialist corrosion- and humidity-resistant ceiling system. | Board, framing, hangers, screws and coating compatibility. |
| Steam Room Ceiling | High temperature and continuous vapor pressure. | Purpose-designed steam-room system. | Vapor barrier, waterproofing and temperature resistance. |
| Exterior Soffit | Outdoor humidity and possible wind-driven moisture. | Exterior soffit board specifically approved for exposure. | Weather limits, framing, fasteners and exterior coating. |
Humidified deflection testing is used to evaluate the relative ability of gypsum panel products to resist sagging while horizontally supported in a high-humidity environment. The result should be reviewed together with the product specification and installation limits.
| Test Or Document | What It Evaluates | Buyer Interpretation |
|---|---|---|
| ASTM C473 Humidified Deflection | Deflection of a horizontally supported specimen under specified high-humidity test conditions. | Useful for product qualification and comparison when the same method and specimen conditions are used. |
| ASTM C1396 Product Compliance | Applicable gypsum board product classification and physical property requirements. | Confirm whether the board is identified as ceiling board, water-resistant board or another category. |
| Manufacturer Ceiling Span Table | Permitted thickness, framing spacing, orientation and finish conditions for a specific product. | This is the primary document for selecting the actual ceiling configuration. |
| Fire Rated Assembly | Complete board, channel, hanger, fastener and insulation build-up. | Ceiling stability changes must not invalidate the approved fire system. |
| Suspended Ceiling Design | Main channel, furring channel, hanger spacing, perimeter support and structural load capacity. | Board data does not replace structural design of the suspension system. |
| Batch Physical Test Records | Current-production dimensions, flexural properties, weight and other specified quality indicators. | Helps verify that bulk production matches the approved board specification. |
A supplier's internal hanging test cannot be compared directly with a standardized laboratory result unless specimen size, support span, board direction, humidity, duration, loading and measurement method are equivalent.
Identify room use, humidity level, ventilation, condensation and possible water exposure.
Review the manufacturer, product name, classification, thickness and ceiling approval.
Match channel or joist spacing with board thickness, direction and surface finish.
Include board layers, insulation, fixtures, access panels and finishing materials.
Define screw type, length, spacing, edge support and joint arrangement.
Confirm whether texture, plaster, tile or overlaid insulation changes the permitted configuration.
Match product data, test reports, fire assembly and ceiling drawings before purchasing.
Check framing level, board condition, screw spacing, joints and room moisture before finishing.
| Inspection Item | Acceptable Review | Potential Defect |
|---|---|---|
| Framing Alignment | Channels form a flat and consistent supporting plane. | Bowed or twisted channels create visible ceiling waves. |
| Framing Spacing | Within the approved maximum center-to-center dimension. | Excessive spans increase deflection risk. |
| Board Direction | Matches the approved perpendicular or parallel arrangement. | Incorrect orientation may exceed the permitted span. |
| End Joint Position | Joints are supported or installed according to an approved detail. | Unsupported joints can move and crack. |
| Fastener Spacing | Within the specified ceiling maximum. | Wide spacing reduces attachment and may increase movement. |
| Screw Head Condition | Slightly recessed with facing intact. | Broken facing reduces fastener-head resistance. |
| Board Surface | Flat, dry and free from visible damage. | Distortion before finishing may remain visible afterward. |
| Insulation Position | Independently supported or uniformly placed within permitted loading. | Concentrated insulation creates local sagging. |
| Joint Treatment | Compatible tape and compound applied under suitable drying conditions. | Trapped moisture or weak joints can lead to cracking. |
| Final Ceiling Level | Inspected with appropriate straightedges and lighting. | Grazing light may reveal waves not visible during installation. |
Water absorption performance is incorrectly used as proof of ceiling stiffness.
The product has no documented ceiling application or span table.
A specialty ceiling-board allowance is applied to a generic panel.
Temporary finish moisture and weight may cause noticeable deflection.
The board direction may fall outside the approved configuration.
Ceiling attachment may be insufficient for board dead load.
The facing can no longer provide proper fastener-head support.
Sustained loading may exceed the board or suspension limits.
Pipes, cables or ducts create concentrated loads and vibration.
Moisture-damaged panels may retain permanent deformation.
Humidity from construction and wet finishes remains trapped.
Uneven channels are concealed and transferred to the finished ceiling.
Cut openings become overloaded and may crack or deflect.
Changing board thickness or framing spacing may invalidate the assembly.
Moisture And Mold Resistant Gypsum Ceiling Board, Exact Manufacturer And Product Designation, Specified Thickness And Dimensions, Approved For Horizontal Ceiling Installation At The Specified Framing Centers And Board Direction, With Applicable Moisture Resistance, Humidified Deflection And Physical Performance Data, Compatible Fasteners, Installation Instructions, Product Marking And Batch Traceability.
Combined Fire And Moisture Resistant Gypsum Board For The Referenced Ceiling Assembly, Exact Board Type, Thickness, Manufacturer And Product Designation As Listed, Installed On The Specified Suspension System With Approved Channel Spacing, Fasteners, Joint Treatment, Insulation And Surface Finish.
No. The exact product must be approved for horizontal ceiling use. Confirm board thickness, framing spacing, direction, fasteners and finish conditions.
Not necessarily. Water absorption and humidified deflection evaluate different properties. Review both when selecting a board for humid ceilings.
Only when the exact board and installation conditions are approved for that spacing. Do not assume all 12.5mm MR boards have the same span.
Increased thickness generally improves stiffness, but an engineered 12.5mm ceiling board may outperform a standard heavier panel under particular test conditions. Compare product data.
Perpendicular installation is commonly preferred, but the approved product instructions control the decision. Some specialty boards permit either direction.
Do not assume so. Ceiling boards often require closer attachment. Use the ceiling fastener schedule from the approved installation guide.
Only within the loading and installation conditions permitted by the exact board and ceiling system. Services and heavy items should be independently supported.
It can add temporary moisture and weight. Some board configurations have stricter framing limits when water-based texture is used.
Additional screws may not reverse permanent board deformation. Identify moisture, framing and loading causes before deciding whether the boards require replacement.
Assess them according to manufacturer guidance. Permanent bowing, soft core, paper separation, mold or damaged fastener areas may require rejection.
No. Fire classification and sag resistance are separate. The complete fire assembly and the product's ceiling-span data must both be reviewed.
Confirm the board product, ceiling approval, thickness, framing centers, board direction, fasteners, humidity exposure, finish, insulation load, fire assembly, packaging and batch identification.
Provide the room type, humidity level, board thickness, ceiling framing, channel spacing, installation direction, surface finish, insulation load, fire requirement and project quantity. The moisture resistant ceiling board and complete suspension system can then be reviewed for sag resistance, compliance and total installed cost.
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