Vs 26 Rafters: What Is The Difference
Depending on the pitch of your shed roof, you will choose between 2×4 or 2×6 rafters. But what is the difference? Simply put, it comes down to what is needed for your shed. The first thing you need to know is if your roof has a slope that is less than or greater than 3:12. This means for every 12 inches of horizontal run, a roof rises 3 inches. For those that are less than 3:12, 2×4 rafters are not strong enough. These are low-pitched roofs and 2×6 rafters should always be the choice of lumber.
When you want to make a truss you will always use 2x4s webbed together for strength.
While 2×6 lumber will cost you more money, it can be used for almost any type of shed. They can be spaced further apart than the 2x4s. But, if you live in a place that is not subject to strong winds or heavy snowfall, 2×4 rafters are the way to go. They cannot handle a heavy load like a 2×6 but can give you more versatility with the design of your roof.
Drip Edge And Felt Paper
Your shed may not be a livable space, but none the less, it is a structure in which you are going to invest a good sum of money on and you want it to last as long as possible without having to do any major repairs to.Adding drip edge and felt paper to your roof before putting down the shingles is definitely an option, but an option you should not ignore. If you don’t invest the little bit of money it will take for these two items, you are asking for trouble down the road.
Especially if you live in an area of the country where snow and ice are prevelant during the winter months. Freezing and thawing can wreck absolute havoc on a shed roof if it doesn’t have felt paper and drip edge installed.The underlayment will mostly rot over a period of time and you will be looking at an expense of replacing or repairing your roof. Be wise and add felt paper and drip edge to your shed.
Drip edge should be installed over the felt paper on the rake edges or side roof edges, and under the felt paper on the bottom or horizontal edges. An added measure or protection would be to add ice and water peelable rubber membrane along the bottom edges of your roof.
Covering A Slanted Roof
The next step of how to build a slanted shed roof should be the roof covering on a wooden decking. A variety of roof materials give a great fantasy flight. There are some of the most suitable and their distinctive characteristics.
- Floor decking inexpensive and excellent protection from rain and snow.
- Slate long operation for at least 30 years easy installation. The downside is that it is not always advisable to use for small-sized sheds.
- Seam roof very easy to stack, as it is a thin metal sheet easy to install but it is quite expensive.
- Tile or shingle looks nice, but is suitable mainly for large sheds, which are made of stone.
- Different roll materials very simple in styling, perfectly protect a construction from the rain are durable and serve for a long time and differ with the cheapness.
Important! As a slanted roof often has not very big angle of inclination, it constantly accumulates water in the rainy season or winter. In order to avoid various troubles, you should mount in the roof a heating device, heating a roof from the inside and not allowing a large quantity of water to be accumulating at the surface.
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What Is A Good Pitch For A Metal Roof
The performance capabilities of metal roof systems increase in steep-slope applications. A steep slope allows for the fast run off of the moisture. In my opinion, accurate slope for metal roof systems is in excess of 2 1/2:12. However, system manufacturers permit application on slopes of 1/4:12 or more.
What is a 5 degree roof pitch?
Roof Pitch and Corresponding Angles
| Roof Pitch |
|---|
| 22.62° |
How Is Shed Roof Pitch Measured
So far I have referred to the roof slope in degrees. That is the way that my engineering mind works.
However many roofers work on a ratio system which equates the amount of rise in inches for a horizontaldistance of 1 foot . Both systems work and I have a table below that will help you totranslate from one to the other.
Comparison of roof slopes rise:run vs roof pitch in degrees
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Minimum Pitch For Corrugated Metal Roof
by Mountaintop Metal Roofing | Sep 10, 2020 | Residential
For the most part, there are two types of roofs: pitched and flat. Used mostly for industrial, commercial, or manufacturing facilities, flat roofing choices arent as plentiful as pitched roofs. Made mostly of bitumen, rubber membranes, or even tar, these roofs have a very slight slope to ensure the water drains away.
There cant be any spaces, seams, cracks, etc. or else water will find a way through. Ponding is a huge issue, although some flat roofs drain to the middle of the roof to a drain system. There are some residential flat roofs, but slope roofing is much more common.
With pitched roofs, taking water away from the home is a much easier proposition. The steeper the slope, the easier it is for rainwater and other precipitation to find its way to the gutters. If it isnt a very steep slope, water may not drain away as well, causing issues.
When choosing a roofing covering, its important to know what the slope of your roof is. Although different jurisdictions may have different regulations, even flat roofs must have a general slope of at least ¼ inch rise for every 12 inches. From there, different roof surfaces need different slopes.
For aluminum shingles, the slope reaches 3 inches for every 12 inches. There are more seams and fasteners with shingles, so it makes sense to have a steeper pitch than with the panels. However, this slope can be minimized if additional sealants or special underlayments are used.
Whats The Best Type Of Fasteners For Low Slope Metal Roofing
With the moisture problems that low slope roofs suffer from, your best bet is probably roofing screws with neoprene washers. There are those manufactured with plastic washers, but the plastic degrades after a time when exposed to sunlight.
If youre installing a standing seam roof, you dont have to worry about the washers as much. Your roofing panels will be fastened with clips underneath the panels and not with screws that will puncture the panels themselves.
If your roofing panel supplier doesnt supply fasteners as well, ask which ones are recommended. Fortunately, many roofing screws come with various colored heads meant to match your metal roofing.
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How To Find The Rafter Length
Youll also need to find the length of your roof from the eave to the ridge, also known as the rafter length. How to do this? Remember your middle school math! Use the Pythagorean theorem a^2 + b^2 = c^2. So for our 8×10 shed, youll do 4^2 + 2^2 = x. The answer is 20. But you have to take the square root of 20 to find the length, and it ends up being around 4.5.
Whats The Best Roof Pitch For A Loft
Having a steeper pitched roof allows for more space in a shed loft. This image shows a relatively shallow roof pitch of 15 degrees. The loft space would be much larger with a roof pitch of 45 degrees.
Which is the correct ratio for roof pitch?
So, if your roof rises 4 inches for every 12 inches of horizontal length, then the pitch of your roof is expressed as 4:12. A ratio is the most common way of expressing roof pitch or roof slope, but degrees are also possible. A 4:12 pitch is around 18.5 degrees, but not exactly.
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How Far Can You Overhang Metal Roofing
If youre strapping your roof and using metal roofing you can extend the metal roofing 2 to 4 inches past the facia board. However, this will leave the unsupported metal subject to damage from ladders and ice damps. Depending on the thickness and rib design of the metal roofing your using will determine if you can extend the metal the maximum 4 inches pass the framing.
The Final Point Influencing The Roof Slope Is The Preferred Choice Of Roofing Material
Traditional roofing materials such as traditional clay tiles and timber shakes/shingles needa relatively steep pitch in excess of 40 degrees to be waterproof. More modern tiling andfelt shingle systems can achieve lower slopes down to about 20 degrees.
For slopes below 20 degrees systems such as epdm, fibreglass, metal roofing can be used.For lots more information on which roof finish to use for which slope and indicative costs.Visit the shed roofing page
This image shows a shed with a roof pitch of 30 degrees with a covering of cedar shingles.
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What Type Of Roof Do You Want To Build
Long before you start to worry about your shed roof pitch, you must decide on what type of shed roof you are going to cap all of your hard work with.
Obviously, if you are going to install a flat roof on your shed, you won’t have to worry about any amount of shed roof pitch as a flat roof has a pitch or 0/0, in other words, it rises zero inches for every zero inches of run.
Beyond this there are several different styles worth considering, including:
- Barn or Gambrel style roof
- Gable style roof
- Salt Box style roof
- Standard pitched roof
Each of these styles of shed roof has one or more slopes to them. This means that you must be ready to calculate both the shed roof pitch and any snow load in your area if you are going to build any of these roofs.
However, you should also figure in your own construction abilities as you look the different types of roof. Take a more detailed look at the different types of shed roofs here.
How Roof Pitch Determines Suitable Roofing Systems
Flat and nearly flat roofs cannot be covered with shingles or shakes of any material since there is not enough angle to combat the danger of blow-off. For that reason, flat roofs are limited to these types of covering materials:
Built-Up Roofs
Tar and Gravel. Alternating levels of hot asphalt and heavy roofing felt finished with a gravel coating can be applied to a flat roof for protection. Typically, between three and five layers are built up. The cost for this utilitarian roof covering lies mostly in the labor and will vary greatly depending on the location of the building.
For a 2,000 square foot roof expect to pay around $3,500 for materials and supplies and upwards of $9,500 for professional labor. Built-up roofs are not a DIY project and will require professional installation but the waterproofing for flat roofs cannot be beat. A built-up roof can be expected to last 20 years.
Modified Bitumen. Historically, the word bitumen has been used interchangeably with asphalt and tar. It is a naturally occurring goo that develops from millions of years of decomposing organic material and has been used since prehistoric times as a sealant.
In modern roofing, bitumen is infused into plies of polyester or fiberglass to create a weatherproofing roof material. The installation technique is similar to building up with tar and gravel, but the plies are less expensive by half about $2,000 for materials and supplies. Labor is a bit faster and expect a tab of about $8,500.
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Introduction: Minimum Roof Pitch
Every type of roof has a minimum roof slope allowed by code. The minimum roof pitch for a roofing material or roof system as prescribed 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 dont function properly if they are pitched too low .
A truly flat roof with zero slope is both undesirable and generally prohibited by code. Some minimum amount of slope is required to ensure that water will drain off the roof.
On a dead-level roof, the slightest bit of deck deflection or any obstruction will lead to water ponding in place on top of the roof. Long-term ponding water is detrimental to almost every type of roofing material.
The lowest roof pitch allowed by code for any type of roof is -in-12 , 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 .
All other flat roof materials require a minimum slope of at least 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.
How To Calculate Shed Roof Pitch Using A Formula
Calculating the roof pitch is straightforward. Remember that pitch is calculated as the height or rise of a roof pitch over 12 inches of horizontal run. Therefore, if your roof rises 4 inches over the course of 12 inches of horizontal run, then your roof pitch is 4:12.
Constructing a new shed roof at the desired pitch is as easy as knowing how to use a speed square. As stated in the video, speed squares have useful markings on them from 0 to 12. Each number represents a pitch, so 1 would indicate a pitch of 1:12, 2 would be 2:12, and so on. Line up the pivot on one end of your rafter, at the corner. Then rotate the square until the desired pitch number is lined up with the top edge of the rafter. Make your line.
Do this with the other end. Then you use the speed square and same pitch number to cut the birdsmouth joints learn how to do that from my shed roof framing guide.
Once you are done with your cuts, youve not only calculated roof pitch but also constructed rafters to fit your shed at the pitch you want.
Now, lets say you want to build an 8×10 shed with a gable roof. Since the ridge of our gambrel roof will run the length of the shed, down the center, that leaves us with about 4 horizontal feet from the ridge to the outside edge of the shed.
Next, multiply both numbers by 12. That gives us 6:12. And there is your pitch.
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Prepare The Construction Site
Once I decided on the site for my shed, I cleared the area of ground cover. I added 2 on each side of the shed perimeter and hammered in wooden stakes at the corners to give me the area I needed. I removed any sod and the top layer of soil, and then slightly compacted the site to pack down any loose soil.
Build A Skillion Roof
The material you chose to cover your roof with is very important. It is what keeps water or snowmelt from percolating through into your shed. It protects the wood of your shed from rot and bug and rodent damage, and from the elements. An important decision with many choices asphalt, steel, aluminum, clay, slate, or cedar shake.
There are advantages and disadvantages to all roofing materials, do your research and make your decision. I chose asphalt shingles. The price was right, color acceptable, and with the single slope roof design and direction my shed faced, only my neighbor would see them.
Advantages:
- Cheap! Asphalt shingles are one of the least expensive roofing materials. They frequently go on sale too.
- Easy installation even for a beginner. Follow the instructions on the bundle wrapper or check out videos online.
- Asphalt shingles are widely available in different colors and textures.
Disadvantages:
- Will degrade with time may last 7 to 20 years before needing to be replaced.
- Are a petroleum product so an environmental issue and cost when disposing of them.
- Susceptible to wind and heat damage. They transfer the solar gain into your building.
Ventilation
If your shed is fairly airtight, youll need to put in ventilation especially if storing gasoline or pesticides in it. No sense poisoning yourself. Add a vent in each gable end near the roof line.
The Roof
I used 2x6x16ft pine for the rafters.
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Understanding The Minimum Roof Pitch
International building code guidelines recommend a minimum roof pitch of 1/4:12. This means that for every 12 inches of the roof’s runwhich is the horizontal distance it travels as it covers a homethe elevation of the roof should change by at least 1/4 of an inch.
Keep in mind that the building code requirements for minimum roof pitch may vary from one location to the next. Similarly, maximum roof slope rules can vary by municipality and may be determined by the type of building being constructed. In general, it’s rare for a roof pitch to xceed a 45-degree angle, or a pitch ratio of greater than 12:12.
