Setting the joints on FireCrunch is a simple process. It is very similar to standard plasterboard joint setting, however there are a few things to note.

PRO BASE 40 Base Coat – Use Pro Plaster PRO BASE 40 faster 40 minute set. (warranty). This is a specifically formulated extra bonding adhesive for embedding paper tape to FireCrunch Joints and internal angles.

Tape – Use paper tape internally not fiba fuse typesExternal see Fire jointing instructions and use fire sealant on external wall joints. Do not use the fire sealant between internal board joints, just run 3 beads of fire sealant down face of internal stud faces prior to fitting boards, set to 1 mm pressured sealant fit, screed off excess with damp cloth.

Fire Sealant Internal walls K-Clad TE10 ( AS1530.4 type ) will take 24 hours to cure. Ensure all internal perimeters of the internal wall are fire sealed if part of an FRL rating IE 30 60 or 90 minutes.

MgSO4 materials are more absorbent than plasterboard, on warm days ensure rebated joint areas are well soaked with water prior to setting base coats and tape, to counter the higher absorption rate of the MgSO4 board, do not dry set joints to avoid cracking USE the Pro Base 40 only (warranty).

Fire Manual

For warranty instructions on plaster setting base coats tape and joints.


Pro Plaster base compound Pro Base 40 and 4T Topping compounds should be stored at room temperature for at least 24 hours prior to use. Mix lightly and test apply. Do not over mix as this can cause pocking. Add water 250 ml at a time as necessary; remix and test apply before adding additional water.


Any surface imperfections or damage that may have occurred should be repaired to the board surface prior finishing. Apply over dry surfaces only and allow each coat to dry completely before applying another coat. Maintain minimum air, joint compound and surface temperature within working area until joints are completely dry.

Class 4/5 Finishes

Vapour permeable clear sealer Klass Si AquaCrunch To obtain a class 5 finish mix an amount of 4 x diluted mix of plaster base coat and either roll or spray on the installed sheets. Apply light fine grade sand after 24 hours which will produce a class 5 finish.

Note: After the total finished plaster set is completed it is essential (warranty) to roll on the Vapour permeable clear sealer Klaas Si AquaCrunch, before applying recommended DULUX Precision, max adhesion under coat and then finish, with DULUX recommended tested water based paints (system).

General Information / Hand Tool Application

Special important note

Magnesium oxide boards are more absorbent than plasterboard. Ensure each rebated edge is well soaked by generously sponging prior to each joint being set and only use the Pro Base 40 minute faster set base coat compound (Warranty)

Embed “plasterers paper tape” to the FireCrunch board; make sure no fasteners protrude above the FireCrunch panel surface using a broad steel finishing knife.

Use Pro Plaster Pro Base 40 taping compound to fill the channel formed by the rebated edges of the FireCrunch Centre and lightly press paper tape into fresh joint compound. Working within a convenient arms-reach area embed tape by holding knife at an  angle to panel, draw knife along joint with sufficient pressure to remove excess compound, above and below tape and at edges.

Leave sufficient compound under taper for proper bond, while embedding, apply a thin coat of Pro Plaster Pro Base 40 compound over the tape. This thin coat reduces edge wrinkling or curling and makes the tape easier to conceal with following coats. Allow to dry completely.

Fill Coat Application

After the Pro Plaster tape embedding coat is dry, apply a topping using Pro Plaster 4T Multi Purpose or similar approved compound, fill second coat approx 180mm to 250mm wide over taped joint. Feather edge of second coat 50mm beyond edge of first coat. Allow to dry.

Finish Coat Application

After second coat is dry, apply a thin finish coat of 4T Multi Purpose Compound over joints. Finish compound, should be applied at a slightly thinner consistency. Feather edge of third coat at least 50mm wider than second coat.

Finishing Inside Corners

Apply a thin layer of compound to either side of the corner. Crease centre of tape and press into corner. Tightly embed tape with knife on both sides removing excess compound and apply it as a thin coat over tape. Apply second coat over one side at a time allowing it to dry before finishing opposite side.

Sanding Application

Light sand with a wet sponge to eliminate dust and scuffing . Remove high spots using as few strokes as necessary. Clean sponge often. If dry sanding, use 180 grit sandpaper or finer. Avoid scuffing tape.

If dust is generated wear suitable protective clothing including PVC gloves (AS 2161), Eye protection (dust resistant AS/NZS 1336), and a respirator (AS/NZS 1715 and 1716.Wash clothes regularly.

On completion of all plaster set and ready undercoats use only Klaas Si AquaCrunch  vapour permeable sealer on FireCrunch MgSO4 sheets.

Klaas Si AquaCrunch “vapour permeable” primer sealer (Warranty)  see recommended products. Available from


FireCrunch will not be liable for incidental and consequential damages, directly or indirectly sustained, nor for any loss caused in application of these materials other than to the manufacturers specified instructions. Our liability is expressly limited to replacement of defective goods.

Any claim shall be deemed waived unless made in writing 7 days (7) days from the date it was, or, reasonably should have been discovered following delivery of the FCA products. Photo POD will be in evidence and once picked up by carrier the damage liability rests with purchaser.

Health and Safety

For further health and safety handling instructions, refer to the (SDS) Safety Data Sheets for these products.