Minimum Roof Pitch For Every Roofing Material (Full List)

By Roof Online Staff • Updated October 4, 2022

See More Roofing Topics

Scroll down to see the minimum roof pitch chart.

Table of Contents

slope finder helps make sure roof meets minimum roof pitch requirements
Using a slope finder to find the slope of a roof. It’s important to bridge the individual shingles to get an accurate reading.

Introduction: Minimum Roof Pitch

Every type of roof has a minimum roof slope allowed by code. The minimum roof pitch for a material or roof system set by the building code is intended to ensure that the roof will perform the way it should.

Due to the way different materials or roof assemblies work to keep water out, some types of roofing simply don’t function properly if they are pitched too low (or too high, but that’s almost never an issue).

The lowest roof pitch (by code) for any type of roof is ⅛-in-12 (0.60 degrees), applicable only to coal tar pitch roof systems. Coal tar pitch is an interesting case, since it also has a very low maximum recommended roof slope (½-in-12).

All other flat roof materials require a minimum slope of ¼-in-12, which is why flat roofs are properly known as “low-slope” roofs.

Steep-slope roof coverings have a much wider range of minimum pitches. Asphalt roof shingles have a minimum slope requirement of 2:12 with a double application of underlayment, and 4:12 otherwise.

Most other pitched roofing materials, such as clay tile or metal panels, require minimum slopes from 2½-in-12 to 4-in-12.

Read on to learn more about roof slope requirements, or scroll to the end to see the minimum roof slope chart with all the different roofing materials.

Even though building codes state the minimum slope allowed for a material in general, specific roofing products may have different recommended minimum slopes. You should always check the manufacturer’s product data sheets for the actual product you intend to use, and always follow the manufacturer’s installation instructions.

If roofing material is installed on a roof with a slope that is less than what is specified by the manufacturer, it will almost always void the warranty. You don’t want that!

The manufacturer’s slope recommendation should be considered a requirement for warranty purposes.

The manufacturer’s minimum slope recommendation is particularly important to pay attention to when using metal roofing products, such as standing seam metal roof systems. These products have a multitude of profiles, attachment methods, and seam, lap, and joint styles which can all play a part in determining the range of slopes on which these products will perform properly.

The manufacturer’s minimum recommended slope or pitch for a specific product will often be steeper than the minimum that is required by code for that general category of roofing material.

Steeper Roofs Perform Better

As a very general rule, a steeper roof will perform better and last longer than a roof with a lower slope.

A steeper roof will shed water and snow faster and more completely, and is less likely to have debris such as tree leaves accumulate on the roof. They also tend to have less exposure to the sun’s damaging UV rays over the course of a day than a less steep roof.

Minimum Roof Slope and the Building Code

For each type of roofing material, you can see the actual language used in the model 2018 International Building Code at the UpCodes website.

Click here to see Section 1507 (Requirements for Roof Coverings).

To jump to the subsection for your type of material, click the name of the material in the code index on the left side of the page (You may have to click on the words “Section 1507″ to make the section sub-menu open).

For the actual language in the model 2018 International Residential Codeclick here to see Section R905 (Requirements for Roof Coverings).

Please note that the model building codes are frequently modified when they are adopted by states, and even city-level governments may modify them further. This may affect the minimum roof pitch requirements in your area. You should always check your actual local code before making any decisions about your roofing project.

About This Minimum Roof Pitch Chart

The following table shows the minimum required (allowable) roof slope for each type of roofing material mentioned in the code.

The values given here (except for thatch) are taken from the model International Building Code, which forms the basis for almost every building code in the United States.

Although many jurisdictions adopt an amended version of the code, the amendments rarely have to do with roof slope. Still, there’s no guarantee that they won’t, so you should always check with your local code authority in case there are local amendments to the code that affect required minimum roof slopes.

Table: Minimum Acceptable Roof Pitches by Code

If you need help figuring out the slope or pitch of your roof, we recommend this slope finder on Amazon. It’s very inexpensive and very accurate.

Minimum Slope for Roofing Materials
as required by the International Building Code
or the International Residential Code
Roofing Material or System Minimum
Required Slope:
Standard Pitch
(X-in-12)
Minimum
Required Slope:
Degree Equivalent
Asphalt Shingles 4-in-12 18.43°
Asphalt Shingles
With Special Underlayment Requirements
2-in-12 9.46°
Built-Up Roof, Asphalt ¼-in-12
(0.25-in-12)
1.19°
Built-Up Roof, Coal Tar Pitch ⅛-in-12
(0.125-in-12)
0.60°
Clay Tile, Barrel, Mission or Two-Piece 4-in-12 18.43°
Clay Tile, Barrel, Mission or Two-Piece
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
Clay Tile, Barrel, Spanish or S-Shaped 4-in-12 18.43°
Clay Tile, Barrel, Spanish or S-Shaped
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
Clay Tile, Flat 4-in-12 18.43°
Clay Tile, Flat
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
Concrete Tile, Barrel, Mission or Two-Piece 4-in-12 18.43°
Concrete Tile, Barrel, Mission or Two-Piece
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
Concrete Tile, Barrel, Spanish or S-Shaped 4-in-12 18.43°
Concrete Tile, Barrel, Spanish or S-Shaped
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
Concrete Tile, Flat 4-in-12 18.43°
Concrete Tile, Flat
With Special Underlayment Requirements
2½-in-12
(2.5-in-12)
11.77°
EPDM Membrane ¼-in-12
(0.25-in-12)
1.19°
Fiber Cement Shingles 4-in-12 18.43°
Metal: Metal Roof Panels
Non-soldered, No Lap Sealant
3-in-12 14.04°
Metal: Metal Roof Panels
With Lap Sealant
½-in-12
(0.5-in-12)
2.39°
Metal: Metal Roof Tiles
(Metal Roof Shingles, Interlocking)
3-in-12 14.04°
Metal: Standing Seam ¼-in-12
(0.25-in-12)
1.19°
Metal: Stone-Coated Steel
(Metal Roof Shingles, Interlocking)
3-in-12 14.04°
Modified Bitumen ¼-in-12
(0.25-in-12)
1.19°
PVC Membrane ¼-in-12
(0.25-in-12)
1.19°
Roll Roofing, Asphalt 1-in-12 4.76°
Slate Roofing 4-in-12 18.43°
Spray Polyurethane Foam ¼-in-12
(0.25-in-12)
1.19°
Synthetic Shingles/Slates/Tiles
(“Composite”, Plastic)
4-in-12 18.43°
Synthetic Shingles/Slates/Tiles
(“Composite”, Plastic)
With Special Underlayment Requirements
3-in-12 14.04°
Thatch
(see note below)
12-in-12 45°
TPO Membrane ¼-in-12
(0.25-in-12)
1.19°
Wood (Cedar) Shakes 4-in-12 18.43°
Wood (Cedar) Shingles 3-in-12 14.04°

Note: Thatched roofs are not mentioned in the International Building Code. The minimum slope given for thatch in the table is based on best practice standards prevalent in the thatching community.