When the code forces a tear-off
R908.3 Roof replacement shall include the removal of existing layers of roof coverings down to the roof deck. Exception: Where the existing roof assembly includes an ice barrier membrane that is adhered to the roof deck, the existing ice barrier membrane shall be permitted to remain in place and covered with an additional layer of ice barrier membrane in accordance with Section R905.
R908.3.1.1 A roof recover shall not be permitted where any of the following conditions occur: 1. Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing. 2. Where the existing roof covering is slate, clay, cement or asbestos-cement tile. 3. Where the existing roof has two or more applications of any type of roof covering.
Section R908.3 starts from removal: a roof replacement takes the existing coverings off down to the deck. The one exception it writes in is an ice barrier membrane adhered to the deck, which may stay under a new layer of ice barrier. Laying a new roof over the old one is a recover, and section R908.3.1.1 lists three cases in which a recover is not allowed. Any one of them is enough.
The calculator asks the three questions in that order. Item 1 is the condition of the old roof: water-soaked, or so worn that it can no longer serve as a base. Item 2 is the material: slate, clay, cement or asbestos-cement tile. Concrete roof tile, such as the Eagle profiles in the list, is cement tile. Item 3 is the count: two or more applications of any roof covering already in place. On the defaults, two dry layers of laminated asphalt, item 3 decides, and the result says so with the item number.
When none of the three applies, the tool does not say “roof over”. It says the section does not bar it. The new product’s installation instructions still have to allow it, and a jurisdiction can amend chapter 9 when it adopts the code. Synthetic composite slate is not named in item 2, so a Brava roof is not barred on its material alone; ask the building department before you count on that.
One material on the list needs more than a code check. Asbestos-cement tile cannot be roofed over under item 2, and its removal falls under rules this page has not read. Before anyone breaks or carries it, ask the building department and your state’s environmental agency what applies.
How many tons come off the roof
| Product | Weight per square | One layer, 20 squares | Tons |
|---|---|---|---|
| Laminated asphalt, CertainTeed Landmark | 211–225 lb | 4,220–4,500 lb | 2.11–2.25 |
| Composite slate, Brava Old World Slate | 311 lb | 6,220 lb | 3.11 |
| Concrete tile, Eagle Capistrano | 770 lb | 15,400 lb | 7.70 |
| Concrete tile, Eagle Malibu | 880 lb | 17,600 lb | 8.80 |
| Concrete tile, Eagle Bel Air | 970 lb | 19,400 lb | 9.70 |
A dumpster is booked by size and a landfill charges by weight, so the number that matters for disposal is tons. The calculator multiplies the squares by the layers by a weight per square, then divides by 2,000 lb per ton. The weight comes from a named product, never from an average. CertainTeed prints 211–225 lb per 100 sq ft for its Landmark laminated shingle, the spread depending on the plant that made it. Brava prints 311 lb per square for its Old World Slate. Eagle Roofing prints an installed weight per 100 sq ft for each concrete tile profile of its Midwest collection: 770 lb for Capistrano, 880 for Malibu, 970 for Bel Air, field tile only.
Two layers of Landmark on 20 squares are 40 square-layers: 8,440 to 9,000 lb, 4.22–4.50 tons. One layer of Eagle Malibu on the same roof is 17,600 lb, 8.80 tons, about twice the two shingle layers. That difference is why a tile tear-off is priced apart from a shingle tear-off, and why item 2 sends tile to removal rather than under a new roof.
The sheet weights describe the product as made. They leave out what comes off with it: nails, underlayment, flashing, and on an old roof whatever water the layers hold. Read the tons as the product weight to be hauled, not as a scale ticket. For a 3-tab shingle, wood shakes, natural slate or clay tile no data sheet was read, so the calculator asks you for the weight per square printed on yours and leaves the tons empty until you enter it.
Spaced boards and the solid-deck rule
R905.2.1 Asphalt shingles shall be fastened to solidly sheathed decks.
Some old roofs, wood shakes in particular, sit on boards laid with gaps between them. Asphalt shingles cannot go on that deck: R905.2.1 asks for solid sheathing. When you pick spaced boards, the calculator covers the whole sloped area with 4 × 8 ft sheets, 32 sq ft each: on 2,000 sq ft that is 2,000 ÷ 32 = 62.5, rounded up to 63 sheets, before cut waste. Sheet thickness and grade are a deck design question this page does not answer.
On a solid deck the count is yours. Nobody knows how many sheets are rotten until the old roof is off, so roofers write an allowance or a price per sheet. Enter the count and your price per sheet; the calculator multiplies, and keeps the line apart so you can see what the allowance adds.
Read the tear-off lines of a quote
A tear-off can reach a quote as three or four lines, or hidden in one. Separate them before you compare.
- Tear-off. Labor to strip the layers. The calculator divides it by the square-layers removed: a $4,000 line over 20 squares and 2 layers is $100 per square per layer. A second quote that removes one layer has to be read on the same unit.
- Disposal. Tons times the rate per ton at your landfill or transfer station. No national rate was found in a primary source, so none is stored; the field stays blank until you enter yours.
- Dumpster or haul fee. A flat line for the container and its trips.
- Deck sheets. The count from the deck section times your price per sheet.
Worked with test figures: two Landmark layers, $60 a ton, a $4,000 tear-off line, a $450 dumpster and 3 sheets at $40 give $4,823.20 to $4,840.00. The spread comes from the weight range CertainTeed prints, and it stays visible instead of being averaged away. If the tear-off line already includes disposal, leave the rate blank so it is not counted twice.
A replacement that also changes the material belongs on another worksheet. For a metal roof the metal roofing quote worksheet keeps footprint, installed area and billed area apart. For a composition or synthetic slate roof the composite roofing comparison counts bundles and weight for both. If the chimney flashing comes off with the shingles, the chimney repair worksheet measures it.
What owners reported spending on roofing
The 2023 American Housing Survey asked owners what their roofing jobs cost. Across 2,559 sampled jobs of every size and material, the weighted median was $10,000, with a quarter under $5,000 and a quarter over $15,000; 13.9% of jobs were reported as do-it-yourself. The survey has no roof area, no layer count and no line for the tear-off, so these figures frame a budget; they cannot price your square-layers. They come from the Census Bureau’s public-use file, calculated on October 11, 2026.
Roof tear-off questions
What does a roof tear-off cost calculator need from me?
Five facts about the old roof: its sloped area, how many layers are on it, what they are made of, whether they are dry and sound, and whether the deck is solid or spaced boards. From those the calculator says whether the 2021 IRC lets a new roof go over the old one, how many tons will leave the roof and how many sheets the deck needs. Prices come last and come from you.
What does a roof tear-off cost per square foot?
No national rate is stored here, because none was found in a primary source. What the calculator does is turn the tear-off line of a quote into a rate you can compare: the line divided by the square-layers removed. A $4,000 line over 20 squares and 2 layers is $100 per square per layer, or $1 per square foot per layer. That example is arithmetic, not a market price.
How do I compare roofing labor cost per square foot between two quotes?
Bring both tear-off lines to the same unit. One roofer may quote a lump sum, another a price per square that silently assumes one layer. Divide each tear-off line by squares times layers. If one quote removes two layers and the other one, only the per-square-per-layer figure tells you which is dearer for the work done.
How much should a 2,000 sq ft roof cost?
For the tear-off part, start with the weight. Two thousand square feet is 20 squares; one layer of CertainTeed Landmark is 4,220 to 4,500 lb, two layers 4.22–4.50 tons. For a whole roofing job, the 2023 American Housing Survey puts the weighted median at $10,000 across roofs of every size and material, with half of jobs between $5,000 and $15,000.
What does it cost to tear off and replace a 1,200 sq ft roof?
A 1,200 sq ft roof is 12 squares. One layer of CertainTeed Landmark comes off at 2,532 to 2,700 lb, two layers at 2.53–2.70 tons. Multiply the tons by your local disposal price per ton to get that line. No price per square for the new roof is stored here; put your quotes in the calculator.
And for a 900 sq ft roof?
Nine squares. One layer of Landmark is 1,899 to 2,025 lb, about one ton; a second layer doubles it. On a small roof the fixed lines, such as the dumpster or haul fee and the permit, weigh more against the total than on a large one, so ask for them on separate lines.
How much does it cost to replace a roof on a 2,200 square foot house?
The house’s floor area is not the roof area: overhangs and slope add to it, and a two-story house has less roof than its floor area. Measure or ask for the roof surface first. If the roof itself is 2,200 sq ft, one Landmark layer is 4,642 to 4,950 lb of debris.
Does the tear-off rule differ in California?
It can. The code text on this page is the 2021 IRC as adopted in Colorado, read on UpCodes and found word for word in the Utah, Hawaii and New Hampshire adoptions. California adopts its own residential code, which was not read here; ask your building department how many layers it allows. For money, the survey’s West region, which includes California, reports a weighted median roofing job of $10,400.
What should I ask a roofer near me about the tear-off?
Three things. How many layers they expect to remove, and what happens to the price if they find another. Whether disposal is in the tear-off line or a separate dumpster line, and at what rate per ton the local landfill or transfer station charges. And how deck sheets found rotten will be priced, per sheet, before the old roof comes off.
Is it cheaper to repair or replace a roof?
This page does not compare the two. What it settles is a narrower question inside a replacement: whether the new roof may go over the old one. If the roof already has two layers, or the old covering is soaked or is slate or cement tile, R908.3.1.1 bars that and a tear-off is part of the price.
Which roofing materials change the tear-off?
Two ways. The code names slate, clay, cement and asbestos-cement tile as coverings that cannot be roofed over. And the weight per square differs by a factor of four or more between the products read: 211–225 lb for Landmark shingles, 311 lb for Brava composite slate, 770 to 970 lb for Eagle concrete tile.
What this calculation leaves out
- The code text is the 2021 IRC as adopted in four states. Your jurisdiction can adopt another edition or amend chapter 9; its building department decides.
- Weights are those of the named products, as made. Nails, underlayment, flashing and water are not weighed.
- All layers are taken to be the same product. A roof with mixed layers needs one run per product.
- No disposal rate, labor rate or sheet price is stored. Asbestos-cement removal rules were not read.
- No rafter, load or deck design: the sheet count is a quantity, not a structural check.