Congratulations, if you’re looking into lining walls then you’re a proper DIYer. This is a fair sized job, but don’t be put off, it is still something that’s within the capabilities of a competent handyman. Follow the process step-by-step through this guide and before you know it you’ll be inviting your friends around to admire your work.
Before You Start
Matched linings or lath and plaster (plaster laid over timber) or, in some cases plasterboard, often provide structural bracing as well as a finish to a wall. In this case an engineer or builder will be required before replacement. If there is any doubt when removing old linings consult a professional.
IMPORTANT NOTE: When plasterboard is required to provide bracing performance, this is now “Restricted Building Work” and must be carried out or supervised by a Licensed Building Practitioner.
Handling & Storage
Handling
Plasterboard is a finishing material and as such should be treated with care. Do not walk or sit on stacks of plasterboard. Carry plasterboard on its edge. Apart from being easier to carry, sheets are less likely to crack or break. When taking sheets from a stack, avoid dragging a sheet across the one below it as this can damage the face paper.
Storage
The sheets should be stacked in neat flat stacks, clear of the floor, to avoid damage to edges, ends and surfaces. Stacks of plasterboard should be limited to stacks of 20 sheets on non-concrete floors to minimise the risk of structural damage due to point loading. If plasterboard is being stored on new concrete floors the plasterboard should be elevated to prevent it from picking up moisture from the concrete or on a piece of waterproof polythene sheet.
Preparing The Wall
Preparation is paramount to achieving a good finish. Take the time to ensure that the surface is as flat and straight as possible before applying plasterboard.
Remove any nails, old glue or other fixings that are protruding from the timber.
Using an 1800mm straight edge, check the flatness of the wall. There should be no deviations in the framing greater than 2-3mm from the straight edge.
Plane any high areas flat or straighten any misaligned nogs/dwangs.
Check the timber is dry. The moisture content of the timber should be 18% or less. Timber with a moisture content outside these limits is prone to movement causing problems with joint distortion.
When fixing vertically all joins will need to be made over timber. Plan where your joins will be and make sure these will be over timber.
Horizontal is the recommended method of fixing plasterboard, however, there are times when this is not possible.
Plan The Layout
Fix the plasterboard horizontally. This will ensure that joints are below eye-level and as a result any imperfections are more difficult to see. Any glancing light from windows or lights is less likely to show a shadow line if joints are finished slightly raised. Screwing and gluing reduces the number of mechanical fixings in the face of the board, decreasing the number of possible imperfections from problems such as ‘popping’ which are often caused by wet timber.
When fixing horizontally, using taper edge/square edge board makes subsequent installation of skirting and cove/cornice easier.
If end joints are required when fixing horizontally, these should be staggered a minimum of one stud apart, 600mm. Stud spacing should be at a maximum of 600mm.
For older, existing homes, stud spacing may require that plasterboard sheets be trimmed when fixing vertically. Horizontal # fixing is the preferred method.
NEVER make joints above or below or within 200mm of the corners of windows or doors.
Cutting & Attatching
Cutting
Place the sheet with the face paper side up. Measure and mark the sheet to the size desired.
Line a straight edge up with the marks and hold firmly against the sheet. Draw a pencil line as a guide for scoring. Score through paper and lightly into the core using a drywall or craft knife.
To break the sheet core, securely grasp the board edges on both sides of the score line and snap the board with a quick, firm movement. Alternatively, break the sheet over the end of the working surface or a length of timber.
Complete the cut by running the knife through the back paper of the sheet and snapping back to the face.
Cut Outs
For openings such as an electrical outlet or switch box use the following method.
Measure from where the side of the sheet will be located to the near and far sides of the installed box.
Measure from the top or bottom edge of where the sheet will be located to the top and bottom of the box.
Trace the outline of the electrical box at the appropriate position on the sheet.
Cut with a keyhole saw.
Attaching
The best practise for fixing plasterboard involves the use of plasterboard screws and glue. Plasterboard screws are used around the perimeter of the sheet and glue should be used in other areas that contact wall framing.
Gluing
Use GIBFix® All Bond or GIBFix® One for the appropriate surface. Make sure that the framing is clean and free from oil, dirt or a combination of the two. Apply adhesive using a gun at the appropriate spacing. A glue daub approximately the diameter of the framing timber stud should be used. Fix the sheet immediately after applying the glue to avoid the glue from ‘skinning’, resulting in poor adhesion.
Screwing
Hold the sheet tight against the framing. Sink plasterboard screws to just below the sheet surface, leaving the paper intact.
Installation
Install the lower panel first as this will help support the top panel during fixing. If the wall-ceiling junction will be square-stopped then it may be preferable to fix the top sheet first as this will form a neat edge at the top of the wall.
Measure and cut the sheet to fit around any windows or doors.
Apply glue daubs to the studs 300mm apart. Do not place glue where the edge of the sheet will be located.
Place some small off-cuts of plasterboard at intervals along the wall-floor junction and then rest the sheet on these.
Press the sheet firmly into place at the location of each glue daub.
Screw using 25mm x 6g GIB® Grabber® plasterboard screws along the top edge of the sheet in the tapered area on each stud, starting in the centre and working toward the ends.
Continue screwing the perimeter of the sheet with fixings 300mm apart. Do not plasterboard screw around windows and doors where glue has been placed.
Cut the top sheet to fit around any windows or doors.
Lift the top sheet into position and rest on top of the bottom sheet and attach as per the first sheet.
When fixing vertically, start at a window or door and cut the first sheet to fit so that any joins are further than 200mm from the corner of the window or door. Also ensure that joins extend a minimum of 200mm beyond the corner of the edge of the window or door.
Dealing With Grooved Jambs
For best practise, architraves should be used. However, if the use of grooved jambs is unavoidable there are a couple of tips to remember to help achieve the best results.
Ensure that best practise has been used to installwindows and doors, i.e. the back edge of the groove and the front face of the timber line up. The plasterboard should have 1 - 1.5mm clearance in the groove.
Do not try to force the plasterboard into the groove.
Keep joins to a minimum. It is usually possible to cut into an entire sheet and fit this around windows and doors.
Remember to allow for the groove when measuring.
The same rule of extending joins a minimum of 200mm beyond the edge of windows and doors applies.
Dealing With Internal Corners
To join sheets at an internal corner, butt the second sheet against the first and fasten the second sheet to the stud.
Dealing With External Corners
To join sheets at an external corner, lap the end of the second board over the end of the first. Make sure the sheets overlap neatly and that the second board does not extend past the face of the first. Fasten both sheets to a common stud. After sheets have been fixed in position, fix metal or plastic external corners in place to provide a clean edge for stopping. These will protect the edges of the plasterboard and also make stopping easier.
Stopping
Preparation
Ensure that all fixings, screws or nails are seated below the surface of the plasterboard. Fill any areas greater than 2mm deep with a setting compound such as Gib Tradeset® and leave to dry.
First Coat
Using a 150mm broad knife, fill the recess formed by the edges of the sheets with jointing compound.
Centre the paper tape along the joint and using a 150mm broadknife press the tape down into the compound.
Draw the broad knife, held at approximately 45 degrees, to the board surface along the joint to remove any trapped air bubbles beneath the tape. Ensure that sufficient compound is left behind the tape to achieve a good bond.
Immediately apply a thin coat of compound over the surface of the tape. This reduces the possibility of the tape curling and wrinkling which can lead to edge cracking.
When the compound is set (or dried) scrape back any build-up of compound along the joint.
Second Coat
Apply a second coat of jointing compound with a 200mm trowel. Ensure that this coat extends outside the area of the first coat.
Allow to dry thoroughly (24 hours) and scrape back any build-up of compound along the joint.
Top Coat
Apply a finishing coat of compound with a 280mm trowel. Joint edges should be feathered at least 50mm beyond the edges of the previous coat.
Allow to dry for approximately 24 hours.
Lightly sand in the same direction as the joint using 220 grit, or finer, sandpaper.
After sanding, mark any defects and imperfections with a pencil, then retouch these areas with compound. Leave to dry and sand. Repeat this process until the desired finish is achieved.
