• DRYWALL BOARD

    In the sixties and early seventies you could not begin taping and finishing a project until after the city drywall boarding inspection had been passed. This is an area that is overlooked and builders and developers should be demanding self inspection

    Drywall board should be inspected on delivery for defects and the that the delivery is complying to the manufacturers recommended sheeting schedule and this should be signed off to confirm that the proper material list has been delivered.

    Standard drywall board used on construction

    • 1/2” standard
    • 1/2” ceiling density board (CD board)
    • 5/8” type x
    • 5/8” standard

    There are many types of water resistant board for around showers or bath areas and are normally specified.

    Drywall should be applied to meet the Canadian standards, ASTMs, and the manufacturer’s recommended sheeting schedule.

    Recommended CD board on all ceilings regardless of O.C.s (On Centers)or 5/8” only

    This is where many contractors will cut corners and use 1/2″ std. on ceilings, which shaves off 15 cents a square foot but you get a ceiling that will show deflection much sooner and is not recommended by the manufacturers.

    1/2” std or 5/8” on walls.

    Even under the recommended sheeting schedule drywall has a 15 year life span and will then start showing deflection.

    Low impact and scratch resistance and filling compounds are very soft and not moisture resistant.

    There is an option for a higher quality board that is much more durable and has a much longer lifespan. (see Plaster Board.)

  • DRYWALL BOARDING BY CANADIAN STANDARDS

    Upon delivery all materials should be inspected to ensure they meet specifications and free of defects. (should be signed off)

    Board ceilings with 1/2″ CD (ceiling density) board or 5/8″ board only.

    Board sheeting must be from framing to framing without gaps and with proper overlapping.

    Proper screw patterns: new lightweight board reps have agreed upon the old screw spacing of 7” on ceiling perimeters, 5-6” on butt joints, and 3 screws in the field. Walls are 8” on perimeters and same as ceilings on the butt joints with 2 screws in the field.

    This is an area where a day or two can be shaved off the total time spent boarding by not overlapping properly, pre cutting sheets, stacking sheets, and improper screw patterns. Boarding by the Canadian standards will take 1-2 days longer per 10000 square feet. This is the most important inspection and should be signed off after completion.

    All gaps must be pre-filled prior to taping and all areas where corner bead will go should be pre-filled square and signed off by contract manager that this has been completed.

    This is another area where many contractors will cut corners to save time by not pre-filling gaps. this is the second most important inspection due to it being the base for all finishing and should be signed off after completion.

    It is recommended to bed all tape and beadwork with taping compounds as they are harder, have more glue, and hold better. close attention should be taken to  the taping process as half the time can be shaved off this procedure. In the sixties and early seventies high end government contracts would specify absolutely no hand taping with taping jigs. Taping jigs do not provide enough compound to fill the voids and there is no control over the taping finishers. It is in a contractors best interest to get the job done quickly so they have a tendency to adjust the compound very thin in order to move quickly, this is the leading cause of Beading (a raised line in the seams). If a hand taper were to use enough compound to properly fill the voids it would slow them down so badly it would take them twice as much time to tape a job. Hand tapers using low quality corner flushers will leave excess compound in the corners.

    Taping with high quality mechanical taping tools provides enough compound to fill the voids and corner rollers force the tape down to the wall board squeezing out the excess compound and mechanical corner flushers will leave the corners square and will leave only enough compound to cover the tape.

    Taping must be carried out in a manner in which there is enough compound to fill the voids and the compound is thin enough to saturate the spark tape.

    All must be carried out to the Canadian standards and the manufacturer’s recommended applications.

    We use the highest quality taping and finishing equipment available, to ensure there is enough compound to fill the voids, and corner finishing tools, to ensure the highest quality performance in the industry

  • STANDARD CORNER BEAD WORK

    standard corner bead can vary in price and in quality from 95 dollars per box to 200 dollars per box and should be specified, and the application methods can be two and three times more labour intensive depending on the quality of workmanship. A high quality application requires mitring the corner bead to match one another and filling the corner bead full of compound and rolling down to set the bead in place providing a solid corner. A lower quality application would be cutting the corner bead square and applying only a thin track of compound on either side of the corner leaving the bead hollow in the centre. this application would take less than half the time.

    fillers being used in all corners and seams vary in hardness, the hard ones are more durable and impact resistant where as the soft ones are faster to apply.

     

  • DRYWALL FINISHING LEVELS 1-5 AND A LEVEL 6 STRAIGHTENING OUT SUBSTRATES.

    Level 1:

    all joints and interior angles shall have tape set in joint compound, tool marks and ridges are acceptable.

    Frequently specified in plenum areas above ceiling, in attics, in areas where the assembly would generally be concealed or in building service corridors, and other areas not normally open to public view. Accessories optional at specifier discretion in corridors and other areas with pedestrian traffic.

    Some degree of sound and smoke control is provided; in some geographic areas this level is referred to as “ fire-taping.” Where a fire-resistance rating is required for the gypsum board assembly, details of construction shall be in accordance with reports of fire tests of assemblies that have met the fire-rating requirement. Tape and fastener heads need not be covered with joint compound.

    Level 2:

    All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. joint compound applied over the body of the tape at the time tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.

    Specified where water-resistant gypsum backing board (ASTM C 630) is used as a substrate for tile; may be specified in garages, warehouse storage or other similar areas where surface appearance is not of primary concern.

    Level 3:

    All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. fastener heads and accessories shall be covered with two separate coats of joint compound. all joint compound shall be smooth and free of tool marks and ridges. Note: it is recommended the the prepared surface be coated with a drywall primer prior to the application of final finishes.

    Typically specified in appearance areas which are to receive heavy- or medium-texture (spray or hand applied) finishes before final painting, or where heavy-grade wall coverings are to be applied as the final decoration. This level of finish is not recommended where smooth painted surfaces or light to medium wall coverings are specified.

    Level 4:

    all joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. Note: it is recommended the the prepared surface be coated with a drywall primer prior to the application of final finishes.

    This level should be specified where flat paints, light textures, or wall coverings are to be applied.

    In critical lighting areas, flat paints applied over light textures tend to reduce joint photographing. Gloss, semi-gloss, and enamel paints are not recommended over this level of finish.

    The weight, texture and sheen level of wall coverings applied over this level of finish should be carefully evaluated. Joints and fasteners must be adequately concealed if the wall covering material is lightweight, contains limited pattern, has gloss finish, or any combination of these finishes is present. Unbacked vinyl wall coverings are not recommended over this level of finish.

    Level 5:

    all joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. fastener heads and accessories shall be covered with three separate coats of joint compound. a thin skim coat of joint compound trowel applied or a material manufactured especially for this purpose and applied in accordance with manufacturer’s recommendations shall be applied to the entire surface. the surface shall be smooth and free of tool marks and ridges. Note: it is recommended the the prepared surface be coated with a drywall primer prior to the application of final finishes.

    This level of finish is highly recommended where gloss, semi-gloss, enamel, or flat paints are specified or where severe lighting conditions occur.

    This highest quality finish is the most effective method to provide a uniform surface and minimize the possibility of joint photographing and of fasteners showing through the final decoration.

    Level 6:

    Taped seams only then Rod and Feather edge to achieve a fully flat surface with no waves or shadows. Then corner trim is applied then finish ready for painting.

  • COMMENTS

    Skim Coat. A skim coat of joint compound is intended to conceal small imperfections in joints and on the surface of the gypsum board, smooth the texture of the paper, minimize differences in surface porosity, and create a more uniform surface to which the final decoration can be applied.

    A skim coat is essentially a film of joint compound and is not a readily measurable thickness, there is no specific mil thickness that constitutes a proper skim coat. A skim coat is described in the foregoing text as being trowel applied with the intent being that the consistency (viscosity) of the joint compound be such that it can be applied by a trowel if that is the tool chosen for the task. Other tools may be used for application so long as the trowel consistency is achieved.

    The objective of the application is to achieve total coverage if the entire surface with the skim coat. this is typically accomplished by delivering the compound to the surface and using a drywall broad knife to force the compound into the surface pores and imperfections while shearing off excess compound from the surface.

    A skim coat will not approximate a plastered surface. Once the skim coat dries, the gypsum board paper may show through the treated joints, filled voids, and spotted fastener heads will likely be visible.

    Critical(severe) lighting areas

    wall and ceiling areas abutting window mullions or skylights, long hallways, or atriums with large surface areas flooded with artificial and/or natural lighting are a few examples of critical lighting areas. Strong side lighting from windows or surface mounted lights fixtures may reveal even minor surface imperfections. Light striking the surface obliquely, at a very slight angle, greatly exaggerates surface irregularities. If critical lighting cannot be avoided, the effects can be minimized by skim coating the gypsum board surfaces, by decorating the surface with medium to heavy textures, or by the use of draperies and blinds which often soften shadows. In general: gloss semi-gloss, and enamel finishes highlight surface defects; textures hide minor imperfections.

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