Architectural Flashing Supply
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Basic blueprint reading · Lesson 4 of 4

Basic blueprint reading: defects, verification and case study

The common reading defects, why an AFS drawing must never be measured with a ruler, how revisions and bubbles are misread, a sloped-edge example, what a maker's print-approval sheet is, and a worked case study with its evidence record.

You will be able to: Spot the common ways a print is misread, choose a corrective option that keeps the design professional in charge, and write an evidence record that lets someone else check the reading.

10 min · 10 slides · 7 questions

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Slide 1 of 10

Reading defects at a glance

Common reading defects: scaling an NTS or fitted drawing, using the wrong scale on a reduced print, swapping the two halves of a bubble, using a superseded sheet, using plan length as metal length, reading the hem side from the wrong figure, and treating a maker's value as a project requirement.

The card on the figure turns each one into a question to ask before you order.

Before-you-order checklist for reading a printNine cards, each a coloured heading with two lines. Scale: 1/4 in = 1 ft is 1 to 48, and 1 to 50 is close, not equal. Print size: full or half size, trust the bar scale. NTS and AFS drawings: read the printed number, never the paper. Bubbles: upper is the view number, lower is the sheet. Revisions: cloud and delta, then the revision block. Spec section: Division 07, read the project's own contents. Feet and inches: 12 feet 7 1/2 inches is 151.5 in. AFS limits: girth 24.25 in against a 48 in limit, piece 10 ft standard and 126 in maximum. Hem side: read it on this order's drawing, new hems default to the inside.Before you order from a printScale1/4 in = 1 ft is 1:48.1:50 is close, not equal.Print sizeFull or half size?Trust the bar scale.NTS, AFSdrawingsRead the printed number,never the paper.BubblesUpper: view number.Lower: the sheet.RevisionsCloud and delta, thenthe revision block.Spec sectionDivision 07: read theproject's own contents.Feet andinches12'-7 1/2" = 151.5 in(12 x 12 + 7.5)AFS limitsGirth 24.25 in; limit 48 inPiece 10 ft; max 126 inHem sideRead it on this order'sdrawing; new hems: inside.Ask the design professional about anything doubtful.

Nine cards, each a coloured heading with two lines. Scale: 1/4 in = 1 ft is 1 to 48 and 1 to 50 is close, not equal. Print size: full or half size, trust the bar scale. NTS and AFS drawings: read the printed number, never the paper. Bubbles: upper is the view number, lower is the sheet. Revisions: cloud and delta, then the revision block. Spec section: Division 07, read the project's own contents. Feet and inches: 12 feet 7 1/2 inches is 151.5 in. AFS limits: girth 24.25 in against a 48 in limit, piece 10 ft and 126 in maximum. Hem side: read it on this order's drawing.

A teaching card, not an AFS inspection procedure. Card colour groups the checks: blue for measuring, teal for finding and tracking, green for AFS numbers. The girth is the worked example's 24.25 in; the 48 in and 126 in limits are AFS's own.

Sources

Glossary

Superseded sheet
A drawing sheet replaced by a newer issue. A revision cloud and delta mark a change after issue, and the title block keeps the revision history, so the revision block shows which issue is newest.
Print approval
A maker's standard product sheet that the buyer fills in, signs and returns, such as Drexel's Econo-Coping form, whose approval block asks for an Effective Date, Drawn By and Approved By.
True length
The length of metal along a sloped edge, which is longer than the plan length by a factor of the square root of 1 + (rise / 12) squared.
Evidence record
A short written note giving the sheet identifier, revision, detail number, spec section, who verified a number and the date, so another person can check the reading.