🇬🇦 Gabon · DQE / DPGF · Work section
Roofing in a Gabon bill of quantities
In Gabon, the roofing section of a Bill of Quantities (Devis Quantitatif Estimatif) (Devis Quantitatif Estimatif (DQE) / DPGF) is measured to DQE / DPGF (French practice). It covers 6 principal groups of work — roof structure — trusses, rafters, purlins and wall plates through to ceilings, cornices and roof insulation where required — and is headed in the bill as "LOT 3 — ROOFING".
Roofing is one of the sections every Bill of Quantities (Devis Quantitatif Estimatif) (Devis Quantitatif Estimatif (DQE) / DPGF) in Gabon is built from. This page sets out what belongs in it, the unit each item is measured in under DQE / DPGF (French practice), the local conventions that change the quantities here, and a worked example for a 150 m² house — plus the errors in this section that actually cost money on site.
What this section covers
- Roof structure — trusses, rafters, purlins and wall plates
- Roof covering and underlay or sarking
- Ridge, hip and valley treatment
- Fascia, barge boards and soffits
- Gutters, downpipes and rainwater disposal
- Ceilings, cornices and roof insulation where required
How each item is measured
| Item | Unit | Measurement rule |
|---|---|---|
| Roof covering | m² | Measured on the sloping surface, not the plan area. Laps are deemed included in the rate. |
| Trusses / rafters | no. or m | Enumerated by type and span, or measured as timber run stating the section. |
| Ridge and hip | m | Measured on the length of the line, as an extra over the covering. |
| Fascia and barge | m | Measured on the length, stating the section and finish. |
| Gutters and downpipes | m | Measured on the length; outlets, stop ends and shoes enumerated separately. |
| Ceilings | m² | Measured on the net area covered, stating the board and fixing. |
Local conventions in Gabon
- —The conventional pitch here is 25°, which makes the actual roof surface about 1.10× the plan area beneath it — measure the slope, never the plan.
- —Eaves overhang is normally 450 mm, which adds covering, fascia and gutter all round.
- —Roof insulation is not generally required here for thermal reasons, though it is sometimes specified for comfort under sheet coverings.
Worked example — 150 m² house in Gabon
Quantities for this section on a representative single-storey house, computed from Gabon construction conventions. Rates are deliberately not shown: they move constantly and are priced against your own drawings.
| Description | Qty | Unit |
|---|---|---|
Roof covering area 173 m² plan opened out at 25° plus 10% laps | 209.4 | m² |
Roof timber / trusses Trusses at ~1.2 m centres plus wall plates | 100 | m run |
Ceiling boards Floor area plus 5% cutting | 157.5 | m² |
Fascia, barge & rainwater goods Perimeter plus gable rake | 57.5 | m run |
What goes wrong in this section
- —Pricing roof area as plan area under-measures by 10–30% depending on pitch. It is the most common single error in owner-prepared bills.
- —Rainwater goods are measured per metre run and are easy to omit entirely; the omission surfaces the first time it rains.
- —In high-wind and cyclonic areas the fixing schedule is prescribed and is a real cost — fixings are not a rounding error on a large roof.
Get every section measured, not just this one
Upload your dimensioned drawings and get a complete bill of quantities (devis quantitatif estimatif) in the DQE / DPGF format, priced in XAF (FCFA), with every rate source-cited.
Generate my Gabon BoQRoofing — frequently asked
What goes into the roofing section of a bill of quantities in Gabon?
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Roof structure — trusses, rafters, purlins and wall plates; Roof covering and underlay or sarking; Ridge, hip and valley treatment; Fascia, barge boards and soffits; and 2 further groups of work. Under DQE / DPGF each is described, measured in its own unit, and priced separately so the total is auditable line by line.
What units is roofing measured in?
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Roof covering in m², Trusses / rafters in no. or m, Ridge and hip in m, Fascia and barge in m. Getting the unit right matters more than getting the quantity precisely right — a contractor can adjust a quantity, but cannot price an item measured in the wrong unit at all.
How is roofing different in Gabon from elsewhere?
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The conventional pitch here is 25°, which makes the actual roof surface about 1.10× the plan area beneath it — measure the slope, never the plan.
What is the most common costly mistake in this section?
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Pricing roof area as plan area under-measures by 10–30% depending on pitch. It is the most common single error in owner-prepared bills.
How do I get this section measured for my own project?
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Upload your dimensioned drawings to Enormous Buildings. The bill is produced in the DQE / DPGF format, grouped by section with roofing priced in XAF (FCFA), and every unit rate carries a source so a Gabon quantity surveyor can check it.