Roof installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What roof installation is

A roof installation replaces an old roof, or covers a new build, with underlayment, flashing, ventilation and a new roof covering. People call when the roof is near the end of its service life, has damage across many areas, or has been patched so often that repairs no longer hold.

Signs you need it

  • Shingles curling, cracking or losing granules across most of a slope, not just in one spot
  • Sagging or soft decking visible along the roof line when you look at it from the yard
  • Daylight through the attic boards, or dark stains on rafters in several places
  • Leaks in different spots after heavy rain, which points to a covering that is worn everywhere
  • Moss or algae that has lifted shingles or stayed wet long enough to break down the surface

What the pro does

  • Strip the old roofing down to the decking and haul it away, then check the boards for rot, delamination and popped nail heads
  • Replace damaged decking and fasten the new boards to the spacing the roof covering calls for
  • Install drip edge at the eaves and rakes, then run the underlayment in courses with the laps shedding water down the slope
  • Set step flashing, valley metal and pipe boots, then install ridge vent or other vents so the attic can breathe
  • Lay the new shingles in the manufacturer's pattern, nail them to the spec, and magnetically sweep the yard for stray nails

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Roof size and pitch, since steep sections need more fall protection and more crew time
  • Roofing material, from asphalt shingles to metal, tile or wood, each with different material and labor needs
  • Number of layers to remove, and whether the old roof can be covered or must be torn off
  • Condition of the decking, since rotted boards are replaced as a separate line
  • Complexity, such as valleys, dormers, skylights, chimneys and the total count of penetrations
  • Ventilation work, including ridge vent, soffit vents and any powered attic fan
  • Permit, inspection and disposal needs

What a written quote should spell out

  • Roofing product, color, weight class and warranty, with the manufacturer named
  • Whether the old roofing is removed or covered, and how many layers are being removed
  • Underlayment type, drip edge and flashing details, including valleys and each penetration
  • How decking damage is handled, with a stated price per sheet for replacement found after tear-off
  • Ventilation plan with the ridge vent, soffit vents and any powered vent listed
  • Cleanup, magnetic nail sweep, haul-away, and who pulls the permit and schedules the inspection

Questions to ask before you hire

  • Will you tear off to the decking or cover over the existing roof, and why is that the right choice for my roof?
  • What underlayment are you using, and how is the drip edge installed at the eaves?
  • How do you handle decking that is rotten once the old shingles come off?
  • Who are the crew members on my roof, and who supervises them on site?
  • Who pulls the permit, and will you handle the inspection?
  • Can you show me a recent install with ridge vent and flashing details similar to mine?
  • What is the manufacturer warranty, and what does your crew warrant for workmanship?

Red flags

  • A proposal to cover an old roof when the decking is soft or more than one layer is already on it
  • A bid with a single total and no line-by-line detail for underlayment, flashing or ventilation
  • A price that does not say whether the old layers will be torn off or covered
  • Full payment requested before the shingles are delivered
  • A crew with no proof of insurance and no clear answer about who will be on the roof

What you can do yourself

You can safely check the attic for blocked soffit vents and note the roof's condition from the ground. Roof installation is work at height with heavy materials and sharp tools, so leave the tear-off, decking and shingling to a pro. Call a pro as soon as you see sagging, soft spots or several leaks, and ask for a written plan before any work begins.

Licenses and permits

A licensed roofing contractor commonly handles roof installation, and a permit is often required for a full reroof. Check with your state and local licensing and building offices for the rules that apply to where you live.

Roof installation questions

Can a new roof go over my old one?

Sometimes, depending on local rules, the number of layers already in place, and the condition of the decking. A pro should inspect the roof and explain why a cover-over is or is not right for your house.

How long does a roof installation take?

It depends on the size and complexity of the roof, the material, and the weather. A good pro gives a schedule that names the work days and explains what happens if rain interrupts the job.

What should I do about the attic and the rooms below during the work?

Clear items from the rooms under the work area and ask the crew how they protect insulation and ceilings. Dust and debris from tear-off can reach the rooms below.

Do I need to be home during the work?

Usually not, but you should be reachable. Ask the crew how they will secure the yard, where they will stage materials, and how they will handle a weather delay.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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