ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

How to Build a Porch / Canopy Roof

Updated on September 15, 2014

Build your own porch roof the easy way

Here we are going to show you how to build a porch roof the easy way which can save you hundreds by doing it yourself.

First we will go through a few roof basics.

what and how we use run and rise.

how to find the angle of a potential roof,

making a simple but effective rafter square,

how to work out lengths of rafters

and a simple way to mark angle cuts

For more how to do it yourself

click here

Roof Basics

Before we can start to build any kind of roof it helps to know a few basics.

Below the figure shows the main componets of a gable roof followed by a porch roof

Gable Roof

Gable Roof
Gable Roof
Stanley 45-910 24-Inch x 2-Inch Steel Rafter/Roofing Square (English)
Stanley 45-910 24-Inch x 2-Inch Steel Rafter/Roofing Square (English)

frame any roof with this and no need for rafter table book

 

Porch Roof

Porch Roof
Porch Roof

Run and Rise

run rise
run rise

The next thing we need to know is how to work out the angles, Now before you faint and say i hate trigonometry i couldn't do that in school, you may be pleased to know that most of the best old traditional roofers couldn't do maths either, so they devised this method,a roof was worked out by run and rise

Run and Rise

A roof is calculated by foot per run, for you that are not familiar with imperial measurements there are 12 inches in a foot (1ft) so calculations are worked out by how much the roof rises per foot or every 12 inches.

In the next picture you will see that for every inch a roof rise it equals an angle eg if a roof rises 10 inches after travelling 12 inches (1 foot) the angle of the roof would be 40 degrees,if it rises 12 inches after travelling 12 inches it would be a 45 degree pitch roof.

How do we work out angles - To work out the angle of our we need to find the distance it travels (run) and the height (rise)

If we look at the picture on the left this is the basic construction of our porch roof the run would be the distance out from the wall along the ceiling joist, less the thicknes of the ridge, the rise would be the height from the top of the ceiling joist to the top of the ridge, the formula to work out the angle is the rise in inches divided by the run in feet, so if the run was 26 inches (distance out from the wall) minus a 2 inch thick ridge board that would give us 24 inches = 2 ft, if we had an rise of 20 inches (height from top of ceiling joist to top of ridge) we would divide the 20 inches by 2 ft giving 10 this would be equal to a 40 degree pitch roof.

Make a Roofing Square

The next thing we need to do is make a roofing square (unless we have one) and the easiest way to do this is to cut the corner off a sheet of ply board etc.making it roughly 24" one side and 16" the other side then starting from the corner in both directions mark it out at 1 inch intervals

My recommended roofing squares

Checkout my favourite roofing Squares

Swanson Tool S0107 12-Inch Speed Square Layout Tool with Blue Book
Swanson Tool S0107 12-Inch Speed Square Layout Tool with Blue Book

We have the Speed Square (like the one you can make out of plywood) This Square is 12" X 12'' and marked out down both edges in inches, It is marked out in degrees from 0-90 also showing its Equivalent In inches as per foot run eg. 40° = 10"

 
Stanley 45-910 24-Inch x 2-Inch Steel Rafter/Roofing Square (English)
Stanley 45-910 24-Inch x 2-Inch Steel Rafter/Roofing Square (English)

Here me have the traditional roofing square which is 16" x 24" the blade of the square is mark out with the length of every rafter, Hip rafter, Jack rafter and valley board per foot run for any angle roof, No need for rafter tables book

 
Johnson Level & Tool 405 Stair Gauge 2-Pack
Johnson Level & Tool 405 Stair Gauge 2-Pack

these stair guages fit on the above square and are to hold the square at your desired angle for ease of multiple marking out

 
Stanley 46-052 Adjustable Quick Square Layout Tool
Stanley 46-052 Adjustable Quick Square Layout Tool

Similar to the speed square we have the quick Square or Squ angle this is the same as the speed square but has a moveable arm that Locks on the angle making Plumb and Seat cuts quicker

 

How do we work out rafter lengths

How do we work out the rafter lengths ?

Well we have a couple of ways, we could buy a rafter table book - expensive, can be complicated.

We can use pythagoras theory, which would be the run squared + the rise squared find square root which i would recommend for major roofs , in our example porch roof it would be 24 squared = 576 + 20 squared = 400 add together = 976 square root = 31.24 so your rafter length would be 311/4 inches

The best way is to do it the same way on our square as our roof is a 10 in 12 we do 10 x 10 =100 then 12 x 12 = 144 add them together = 244 find square root 15.62 this means that for every 12 inches our roof travels the rafter will 15.62 inches longer,but as not all roof runs work in to exact mutiples of 12 we need to take it a step further to make it easier, so once we have our square root of 15.62 we need to divide it by 12 = 1.30 this now means that for every inch our roof travels our rafter will extend by 1.30 inches, so if our roof run is 24 inches we would mutiply 24 by 1.30 = 31.2 inches or 311/4 inches. so if we were doing a big gable roof with a span of say 20ft that would be 240 inches - a 2 inch ridge board = 238 inches half it = 119 inches multiply by our 1.30 would make our rafter 1543/4 long,if we look at the figure below of our square if you drop a tape measure across our square between the number 12 and number 10 you will see it measures exactly 15.62 multiply this by 10ft as in our big roof and minus the 2" ridge you would get 154.75 or divide 15.62 by 12 you get 1.30 change our 10ft into inches =120 x 1.30 - 2" ridgde =154.75, so in our porch example we would multiply our 24" by 1.30 would give us a rafter length of 31.2 or 311/4.

Now look at the figure below, to cut our rafter we place our square on to our timber lining up the marks 10 and 12 level to the top we draw a line down the top cut side (no 10 side) we then measure down the timber 31.2 inches put our square back on lining up the 12 and 10 again but making sure this time that the no 12 is on our bottom mark then draw a line for our bottom or seat cut,rafter is now ready to cut.

Get the new ebook covering basic roofing with practical examples

Chocolate fudge Cake
Chocolate fudge Cake

Once your'e finished your roof

Chocolate fudge Cake Click Here

Stanley Rafter Square Review

In my opinion if you a building any kind of roof this is the best square to use and maybe a cheap calculater for a couple of bucks the stair guages are a useful added extra for speed of marking out but not essential, with this square you can work out anysize or and any angle of roof without the use of fancy roofing calculators or books of rafter tables, just this square and a cheap calculator. This square has stamped on it rafter tables to work out rafters,hips,jacks and valleys so it's not going to get damaged by a bit of rain like your rafter book.check out my lens on how to use a rafter square

Recommended reading

if you want to learn roof framing or improve the skills you have I recommend these from firsthand experience

New Guestbook Comments

    0 of 8192 characters used
    Post Comment

    • profile image

      Timothy Macg 

      3 years ago

      it is a great article i enjoyed it,my porch is going to build by my self and a help i find on http://iwilldo.co keep up good work

    • roofingvancouve1 profile image

      roofingvancouve1 

      5 years ago

      I like the way you have laid it out in sequence. Nice job

    • profile image

      jp_smith86 

      5 years ago

      Thanks for sharing. High performance reinforced EPDM flat roofing systems from AR Systems. We supply Duoply, new reinforced EPDM flat roofing systems to roofing contractors for residential, commercial and industrial projects.

    • profile image

      sandra65 

      5 years ago

      easy and simple guide lines

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)