Roofing guide

Everything worth knowing before you order a roof.

General guidance written in plain language. It deliberately avoids quoting prices, gauges or warranty periods — those depend on the product and must be confirmed for your order.

Start with the building, not the sheet

The right roofing product follows from the building and how it will be used — not the other way round. Four questions settle most of the decision before anyone talks about profiles.

What is the building for?: A family home, a shop front, a warehouse and a livestock shed have different priorities. Appearance matters more where the roof is seen from the street; span and durability matter more on a large utility building.
How big is the roof, and what shape?: Simple rectangular roofs are quick to set out and generate little offcut waste. Hips, valleys, dormers and multiple levels mean more cutting, more flashing and more sheets than the plan area suggests.
What is the pitch?: The pitch affects how much sheet you need for the same footprint and which profiles are sensible. Low pitches place more importance on lapping and detailing — say so early, because it can change the recommendation.
When does it need to be on site?: Roofing is ordered against a build programme. Tell Manasseh your target date at the start and ordering can be planned backwards from it, instead of chasing at the last minute.

Understanding profiles

A profile is the shape rolled into the sheet. It determines how the roof looks, how stiff the sheet is across a span, and how it is set out and fixed.

Corrugated (rounded wave): The most familiar profile. Easy to source, familiar to every roofing crew, and simple to replace sheet by sheet later. A sensible default for homes, extensions and outbuildings.
IT5 trapezoidal (box rib): Square-shouldered ribs with flat pans between them. Reads as crisp parallel lines rather than a soft wave, which suits contemporary residential and light commercial buildings. Flat pans also show colour more evenly.
Tile profile: Pressed into a stepped pattern so a metal roof reads like a tiled one from ground level, while staying lighter than concrete or clay tiles. Common where an area's character or a planning expectation calls for a tiled appearance.
Choosing between them: If the roof is highly visible, start with appearance and check availability second. If it is a functional building, start with span, durability and cost, and treat appearance as a bonus.

Colour and finish

Finish affects how a roof looks in strong sunlight, how visible surface marks are, and how the colour ages.

Matte finish: A low-sheen surface that reduces glare and reads as a flat, solid colour. It tends to look more restrained on large roof areas and hides light surface marking better than a high shine.
Gloss finish: A reflective surface that reads brighter and keeps colour looking vivid. Effective on smaller roofs and where a crisp, new appearance is wanted.
Coloured aluzinc: Coated sheet available in a range of colours, so the roof can be matched to walls, joinery or an architect's palette. Confirm the current colour range at the time of ordering — availability changes.
Always check a physical sample: Screens do not reproduce roofing colour accurately, and a colour that looks right on a small swatch can read very differently across a whole roof in direct sun. Ask for a sample before committing.

Working out quantities

A rough quantity is easy to estimate; a final order quantity needs measurements. Getting the difference right avoids both shortfalls and expensive offcuts.

Plan area is not roof area: A pitched roof is larger than the footprint it covers. The steeper the pitch, the bigger the difference — which is why a rough estimate should always be adjusted for pitch.
Cover width, not sheet width: Sheets overlap at the sides, so the width that actually covers the roof is less than the width of the sheet. Quantities are calculated on cover width.
Laps, cuts and wastage: End laps, hips, valleys and cut-in details all consume material. Simple roofs waste little; complex ones can waste a lot. This is one of the main reasons a real quotation beats an online estimate.
Do not forget the accessories: Ridge caps, barge and edge flashings, valley trays, fixings and sealing all form part of a complete roof. Ask for them to be listed on the quotation so nothing is discovered mid-installation.

Buying without regrets

A few habits that consistently make roofing purchases go smoothly.

Get it in writing: A written quotation stating profile, finish, colour, quantity and availability lets you compare offers properly and removes any argument later about what was agreed.
Compare like with like: Two quotations at different prices are often for different products. Check that the profile, coating and thickness match before treating a lower number as a better deal.
Confirm before you cut: Measure the structure as built, not as drawn. Frames move during construction, and a final check before ordering costs nothing.
Order in one go where you can: Sheets from the same production run match most closely in colour. Splitting an order across dates can produce a visible difference on a large roof.

Area estimator

Get a rough idea of the roof area.

A quick way to sanity-check the scale of a job before asking for a quotation. It is arithmetic on the numbers you enter — nothing more.

Your roof

Roof length (m)

Roof width (m)

Plan width, measured on the ground

Roof pitch

Sheet assumptions

Change these to match the sheets you are considering. Confirm the real cover width and lap for your chosen product with Manasseh.

Sheet length (m)

Cover width (m)

End lap (m)

Estimated result

Enter your roof length and width to see an estimated roof area and an approximate sheet count.

This calculator provides an estimate only. Final roofing quantities should be confirmed using project measurements and a professional quotation. It does not allow for wastage, cuts, hips, valleys, ridge and edge flashings, or product-specific lap requirements.

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