Technical Information

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The role of the Gypsum Products Development Association (GPDA) is to develop and encourage the understanding of gypsum based building materials and systems.

Section 1: Site Storage and Delivery

Action

Likely consequences (results)

Don't leave boards outside without covers

Boards may get damaged

Don't store in the open

Boards will absorb moisture if covers have been damaged, removed or blown off, risking deformation, decoration problems, delay in the jointing process and/or mould growth

Don't place pallets on uneven ground

Boards may deform

Don't place pallets or board on wet ground

Board may absorb moisture

Don't use less than 5 bearers under a pack if not on a wooden pallet

Boards may deflect

Don't use damaged boards

Broken edges & cracked cores are unacceptable


Section 2: Board Handling (Manual Board Handling)

Action

Likely consequences (results)

Don't forget to check board weight

HSE max is 25kg per person. If you exceed this weight
you may get injured

Do lay boards flat

Vertical boards may bend and take on a set deflection

Don't single-handedly try to carry two boards

Injury could result

Don't forget to carry board on edge

Boards may bend if carried horizontally. This may lead to
core cracking

Don't use wet board

It may lose its structural integrity

Don't slide boards off the pack if the paper is damaged

You will get paper 'roll-ups'

Don't damage corners and edges when manoeuvring around

Can't use damaged boards. If damaged cut down to next
lower size


Section 3: Board Fixing

Action

Likely consequences (results)

Do fix boards according to plasterboard manufacturer's recommendations

 

Do follow plasterboard manufacturer's guidelines regarding minimum timber stud/joist dimensions

 

Do stagger the boards on opposite sides

If the boards are not staggered the system may be weakened with reduced fire resistance

Don't fix boards if they are wet

Use of wet board is not recommended (staining, mould or /and sagging may occur)

Don't fix boards if plaster core is cracked

Affects fire rating

Don't use boards with broken corners

End cracks in joints

Don't fix boards to wet timbers

Board joints may crack and nails pop as timber shrinks

Don't screw or nail board to narrow timbers < 38mm

Manufacturer's recommendations cannot be met

Don't forget that screws are better than nails and you need less of them (use screws where possible)

Nail pops are a serious maintenance item

Do use a drill with gauge depth adjustment to fix drywall screws

A drywall screw gun is preferable, otherwise screws may fracture the paper liner and sink below the surface rendering them ineffective

Don't restrict ventilation (ventilate rooms)

Moisture, if not free to escape, may cause condensation and may be absorbed by boards

Don't use a blunt Stanley knife

You get jagged edges to the board and there is more risk of injury

Don't cut service holes with a board knife and hammer

Back of board may have damaged the paper liner. Use a pad saw.

Do use vapour resistant board in a location that is likely to have high moisture (bathroom/kitchen)

Avoids moisture damage

Don't attempt to wet plaster moisture resistant board

Such board is designed to resist moisture and the plaster may not bond

Don't install wallboard onto misaligned timber framing

You may get a ridged joint

Don't use nails to fix ceiling boards to engineered joists eg TJI, JJI, type

You may loosen the floor boards above causing them to creak


Section 4: Direct Bond Drylining

Action

Likely consequences (results)

Don't 'knock up' the bonding compound with more water when it starts to set

It may not bond

Don't use small dabs far apart. Do follow manufacturer's recommendations on dab size and location

Incorrectly fitted board

Don't direct bond onto wet masonry

Dab will dry out into background instead of through board and pattern staining may occur

Do use continuous dabs joined up where specified

Otherwise 'chimney' effect will reduce thermal insulation and sound insulation resulting in the need for a cavity barrier

Don't bridge the joints with dabs

Joints may crack

Don't use vapour control (foil backed) boards with plaster bonding dabs

 

Don't attempt to dab plasterboards if the background material is in doubt

You may get bond failure


Section 5: Fixing Thermal Boards

Action

Likely consequences (results)

Do use nailable plugs in accordance with manufacturer's recommendations if you are fixing by direct bond method

Board may delaminate in a fire, causing plasterboard to fall over and block an access route.

Do fill the gap behind the skirting

Essential for good sound insulation and cavity barrier. Failing to fill the gap will result in thermal loss.

Don't fix these boards with dabs if they are bowed

Linings will be out of range / plumb

Don't use thermal boards on ceilings unless phenolic

Appropriate Building Regulations regarding surface classification of both sides of ceiling boards should be followed

Do check condensation risk, as you may need vapour check layer

Otherwise, condensation problems may result


Section 6: Metal Drylining Systems - Walls

Action

Likely consequences (results)

Do adjust bracket length so that the finished lining will be plumbed and ranged

 

Do use protective gloves when handling metal

Minimise the risk of injury

Don't go wider than 800mm with brackets (unless brackets are adjustable)

Boards may flex too much

Do screw boards to bottom track. Do fix boards to framing in accordance with manufacturer's recommendations.

Joints may crack and sound insulation may be reduced

Don't forget that this system may need a vapour control plasterboard lining in some circumstances

 

Do use a DPC if used on new concrete

Chemical alkaline attack to zinc under J track. Also moisture may travel up the plasterboard core

Don't forget that with 'I' studs you may need special drywall screws

Normal S point screws will not penetrate

Don't forget that if you have an uneven floor surface you need to provide a timber sole plate prior to installation of the floor track

Floor track may bow if not adequately supported along its length

Don't forget that when using mineral wool with this system, the wool goes behind the metal but should not be in contact with the wall

Moisture may track from wall back into wool


Section 7: Metal Stud Partitions

Action

Likely consequences (results)

Don't mix and match boards, studs, accessories and finishings from different manufacturers

No warranty, no performance guarantee

Do read manufacturers specifications first

 

Do use an acoustic sealant under tracks, where specified

Leakage/optimum acoustic performance

Do provide a timber sole plate if you have uneven floor surfaces

Floor track may bow if not adequately supported along its length

Do provide a DPC over new concrete floors

Without a DPC, you may get corrosion of zinc. DPC aims to avoid moisture in the new concrete from travelling up plasterboard core.

Do use protective gloves when handling metal

Minimises the risk of injury

Do use the appropriate deep (or extra deep) leg track where high partitions and / or deflection heads are specified. Obtain manufacturer's advice if necessary

 

Do use the correct width, gauge and spacing of stud to suit the height

Partition will not be strong enough if incorrect framing members are used

Don't use blunt tin snips with thin metals

Metal will have corners like 'fish hooks' and you risk personal injury

Don't provide less then 600mm overlap when splicing studs

Joint will be too weak

Don't start screwing boards near return flange side

Screws may push stud away and cause a step in the joint

Do back support horizontal board joints with a suitable section

Joint can crack and give reduced fire resistance

Don't have vertical joints above each side of door opening

Joints may crack when door slams

Don't screw boards to top track if there is a deflection head

Deflection may be restricted

Don't forget that there are special details for movement joints and service baffles

Otherwise technical performance of partition will not be maintained

Do screw boards to resilient bars ensuring the screw does not penetrate through to studs

Otherwise, acoustic insulation will be short circuited

Do comply with all relevant guidelines / legislation relating to electrical installations and use of electrical tools

 

Don't forget special detail at T junctions when fixing acoustic partitions

Sound insulation expected will not be achieved


Section 8: Ceilings

Action

Likely consequences (results)

Do follow manufacturer's advice regarding board thickness, joist size and spacing, noggings, suspended ceiling framework

 

Do use protective gloves when handling metal

Avoids the risk of injury

Do use correct screw type and screw length as specified by the manufacturer

Avoids risk of loosening of the ceiling boards

Don't fix boards direct to ceiling joists if they are not level

Joints may crack and nails may pop, use metal furrings or counter battens instead

Don't use plaster skim or undercoat more than 6mm thick on ceilings

Boards may get too wet, core may soften and ceiling could fall down

Do start board fixing from the centre of the board

Otherwise unsupported ends may sag down and cause board core to crack

Don't use single layer 9.5mm wallboards if fire rating is required

No fire rating with these boards

Don't fix suspended ceiling hangers to concrete soffits with shot fired pins

Ceiling may fall down

Don't overload ceilings with services - follow manufacturers recommendations. Contact the manufacturer for advice.

Ceiling may fall down

Don't use heated ceiling panels and membranes behind MF ceilings

Joints may crack and board may calcine, depending on temperature


Section 9: Jointing and Finishing

Action

Likely consequences (results)

Don't start jointing and finishing if the temperature is below 4°C

Joint cements may not dry and set

Do address any protruding nails or screws prior to the jointing process but don't sand nail and screw heads (may give a rust spot)

 

Do use plasterboard manufacturer's proprietary drywall primers

These have been specially developed to achieve the best finish

Do apply finish coat plaster to the prepared face. This face has been prepared to accept finish coat plaster. Do consult the plasterboard manufacturer if applying an undercoat plaster to a plasterboard

 

Don't mix and match fillers and finishes from different manufacturers

There might be a compatibility problem

Don't use watered down emulsion paint as a primer or so called 'mist coat'

It puts too much water into the paper & core and can cause staining

Don't fill and tape with air drying compounds then finish with setting compounds

Tapes may peel off. Bedding compound cannot dry out

Don't use fibreglass tape if you wish to reduce the risk of hairline cracks. Do use paper tape rather than fibre mesh.

Fibre tape does not bond strongly to board. Paper tape achieves a stronger joint

Do box out as wide as you can then sand and leave to dry fully before painters come

Joints may shrink and become visible

Don't think that you have to use square edge boards for skimming and texturing

Joints between TE boards are generally stronger

Don't use air drying compounds for corner beads

They will not stick


Section 10: Painting

Action

Likely consequences (results)

Do use a drywall primer before painting

Suction of joint and paper liner will not be equalised without a drywall primer

Do use drywall sealer if the wall is to receive wallpaper

Without sealer, wallpaper cannot later be removed without damaging board liner paper


Section 11: Repair Work

Action

Likely consequences (results)

Don't try to repair boards which have been subjected to flood damage

Even when dried out the boards may have deteriorated. Use new boards

Don't try to repair boards where there has been fire or smoke damage

Board will have been subjected excessive heat. Black soot will not wash off. Use new boards

Don't try to straighten or level up sagging ceilings where there has been high humidity

Boards will have taken on 'set' and cannot be flattened. Remove and fit new boards

Don't repair holes by plastering with scrim tape over hole

Hole area may be too weak. You should use a backer board bigger than the hole

Don't try to repair damage to fire rated drywall systems

Fire rating cannot be achieved from damaged boards. Use new boards

Don't re-use nails and screws if they have been in wetted area, even if they look OK

They may rust or corrode later. Use new screws or nails

Don't start repair work after flood or fire damage until the building is absolutely dry

You may get sagging boards, nail pops, mildew and rusting fixings

Don't try to use more layers of emulsion point if the boards show signs of striping and staining

Staining may still come through. You should use an oil based alkali resistant primer


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