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Tar paper

Tar paper is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tar paper rather than just read about it. In short: Tar paper, roofing paper, felt paper, underlayment, or roofing tar paper is a heavy-duty paper used in construction. Tar paper is made by impregnating paper with tar, producing a waterproof material useful for roof construction.

Tar paper — main illustration
Tar paper — illustration

Key takeaways

  • Tar paper belongs to engineering; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Tar paper to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Tar paper from memory before moving on to harder problems.

Reference excerpt

Tar paper, roofing paper, felt paper, underlayment, or roofing tar paper is a heavy-duty paper used in construction. Tar paper is made by impregnating paper with tar, producing a waterproof material useful for roof construction. Tar paper is similar to roofing felt, historically a felt-like fabric made from recycled rags impregnated with melted asphalt, and today evolving into a more complex underlayment of synthetic mesh or fiberglass strands waterproofed by synthetically enhanced asphalt.

Description

Tar paper has been in use for centuries. It is defined as a Grade D building paper—a designation derived from a federal specification in the United States. Sometimes anachronistically referred to as "building paper", tar paper is manufactured from virgin kraft paper (as opposed to the fabric-based or synthetic mesh substrates of roofing felt) impregnated with asphalt. The result is a lighter-weight but less durable product with similar properties to felt. Grade papers are rated in minutes: the amount of time it takes for a moisture-sensitive chemical indicator to change color when a small boat-like sample is floated on water. Common grades include 10-, 20-, 30-, and 60-minute. The higher the rating, the heavier and more moisture-resistant the paper. A typical 20-minute paper will weigh about 3.3 pounds (1.5 kg) per square, a 30-minute paper 3.75 pounds (1.70 kg) per square, and a 60-minute paper about 6 pounds (2.7 kg) per square. The smaller volume of material, however, does tend to make these papers less resistant to moisture than heavier felts.

Uses Tar paper is used as a roofing underlayment with asphalt, wood, shake, and other roof shingles as a form of intermediate bituminous waterproofing. It is sold in rolls of various widths, lengths, and thicknesses – 3-foot-wide (0.91 m) rolls, 50 or 100 feet (15 or 30 m) long and "15 lb" (7 kg) and "30 lb" (14 kg) weights are common in the U.S. – often marked with chalk lines at certain intervals to aid in laying it out straight on roofs with the proper overlap (more overlap for flatter roofs). It is typically stapled in place, or held with roofing nails, and is sometimes applied in several layers with hot asphalt, cold asphalt (adhesive), or non-asphaltic adhesives. Older construction typically used a lighter-weight tar paper, stapled up with some overlap, as a water- and wind-proofing material on walls, largely displaced in recent decades by breathable plastic housewrap, commonly in 8-or-10-foot (2.4 or 3.0 m) widths.

In the 19th and early 20th centuries, shacks of wooden frames covered with tar paper were a common form of temporary structure or very low-cost permanent housing in the rural United States and Canada, particularly in the temperate American South.

References

Illustrations

Tar paper: Tar paper on a wall exposed by tornado damage in Oklahoma, used as a moisture-resistant backing for a masonry veneer exterior wall
Tar paper on a wall exposed by tornado damage in Oklahoma, used as a moisture-resistant backing for a masonry veneer exterior wall
Tar paper: Workers using roofing shovels to remove asphalt shingles from a roof. They are standing atop a layer of what appears to be tar paper, a bitumen or asphalt impregnated waterproofing layer between the shingles and the wood roof sheathing.
Workers using roofing shovels to remove asphalt shingles from a roof. They are standing atop a layer of what appears to be tar paper, a bitumen or asphalt impregnated waterproofing layer between the shingles and the wood roof sheathing.
Tar paper: Tar paper shack in Minnesota in 1939
Tar paper shack in Minnesota in 1939

Worked examples

Example 1 — a first encounter with Tar paper

Start with the simplest possible case. Write down what Tar paper claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tar paper before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tar paper ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tar paper

In research
Tar paper appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Tar paper in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Tar paper is common in secondary-school and first-year university syllabi. It links to neighbouring topics Building materials, Moisture protection, Paper, so understanding it makes those chapters shorter.
In everyday life
Look for Tar paper outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Tar paper in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Tar paper means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Tar paper out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tar paper in simple terms?

Tar paper, roofing paper, felt paper, underlayment, or roofing tar paper is a heavy-duty paper used in construction. Tar paper is made by impregnating paper with tar, producing a waterproof material useful for roof construction.

Why does Tar paper matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tar paper?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tar paper.

Tags

  • Building materials
  • Moisture protection
  • Paper
  • Roofing materials
  • Roofs

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