🇲🇳 Mongolia · SMM-influenced unit-price bill · Work section
Roofing in a Mongolia bill of quantities
In Mongolia, the roofing section of a Bill of Quantities (BoQ) is measured to SMM-influenced unit-price bill (Southeast Asian 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 "BILL NO. 3 — ROOFING".
Roofing is one of the sections every Bill of Quantities (BoQ) in Mongolia is built from. This page sets out what belongs in it, the unit each item is measured in under SMM-influenced unit-price bill (Southeast Asian 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 Mongolia
- —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 Mongolia
Quantities for this section on a representative single-storey house, computed from Mongolia 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 (boq) in the SMM-influenced unit-price bill format, priced in MNT (₮), with every rate source-cited.
Generate my Mongolia BoQRoofing — frequently asked
What goes into the roofing section of a bill of quantities in Mongolia?
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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 SMM-influenced unit-price bill 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 Mongolia 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 SMM-influenced unit-price bill format, grouped by section with roofing priced in MNT (₮), and every unit rate carries a source so a Mongolia quantity surveyor can check it.