Ceilings
MF suspended ceiling grid: primary channel, ceiling section, hangers and perimeter
- where
- number of MF7 primary channel runs
- room width (m)
- MF7 centres (mm)
- number of MF5 ceiling section lines
- room length, direction of the MF7 runs (m)
- MF5 centres (mm)
- MF7 stock lengths
- waste and overlap allowance (%)
- stock length (m)
- MF5 stock lengths
- hangers
- hanger centres (mm)
- MF6 perimeter channel stock lengths
Explain this equation
Gives the MF7 primary channel, MF5 ceiling section, hangers and MF6 perimeter channel for a rectangular suspended plasterboard ceiling.
n7 is the number of primary channel runs across the width W at centres s7; they run along the length L. n5 is the number of MF5 lines along L at centres s5, each spanning W. N7, N5 and N6 turn the total run lengths, plus waste and overlaps w, into stock lengths Ls. Nh puts hangers along each MF7 run at centres sh, with one extra so there is a hanger near each end.
The 1000 converts metres to millimetres. Rounding up keeps every bay at or below the published centres. The perimeter channel follows the room perimeter, 2(L + W).
Sense check: at 1200 mm × 1200 mm a ceiling needs about one hanger per 1.4 m², and MF5 at 450 mm is about 2.2 m of section per m² of ceiling.
Watch out: heavy multi-layer ceilings need MF7 at 900 or 600 mm; check the load table first.
Take-off for a British Gypsum GypCeiling MF (or similar) suspended plasterboard ceiling in a rectangular room.
Enter your values to see the result.
Good to know
GypCeiling MF hangs from suspension points at 1200 mm centres each way. MF7 primary channels are at 1200 mm centres for ceilings up to 30 kg/m², closing to 900 or 600 mm for heavier ceilings (Table 1); MF5 ceiling sections clip under them at 450 mm centres for Gyproc boards, and boards are always fixed perpendicular to the MF5. MF6 perimeter channel is fixed to the walls at 600 mm centres. The count puts one MF5 line at each end wall and one more hanger than bays on each MF7 run, which errs on the generous side. Hangers are strap (MF8, up to 1000 mm drop) or steel angle (up to 5600 mm).
Common mistake
Spacing MF5 at 600 mm because the boards are 1200 wide, or ignoring the reduced MF7 centres needed when the ceiling carries two or three layers of fire board.
Limits
Rectangular rooms only. Setting-out end distances, splice overlaps and connecting clips follow the White Book details; the waste allowance covers overlaps. Check the total ceiling weight against the system load table and fix suspension to the structure with suitable anchors.
Sources
- British Gypsum, White Book: GypCeiling MF (suspension points at 1200 mm centres each way; MF5 ceiling sections at 450 mm for Gyproc boards; MF7 centres 600–1200 mm by load, Table 1; boards fixed perpendicular to MF5; MF6 perimeter channel at 600 mm centres)
- British Gypsum, GypCeiling MF GCMF-1L-WB12 specification (hangers and MF7 at 1200 mm, MF5 at 450 mm, screws 230 mm reducing to 150 mm at board ends and perimeters, 30 kg/m² maximum load)
Results are calculations from the published methods and manufacturer figures shown, and depend on the data you enter. Always follow the manufacturers’ system and product data, BS 8212, BS EN 13914 and Building Regulations. Coverage rates vary by product, background and thickness. Check prices, VAT and CIS rules with your own records and HMRC.