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Porch Roof Construction (In Simple Steps)

Updated
Build a porch roof from scratch and save a packet on professional fees.

Your new porch will add value to your home and give you additional relaxing space outdoors. However, building a porch roof requires the necessary skills. It is not a task that a novice could undertake.

We show you how to build a porch roof, discuss different roof designs, and offer hints and tips for the best outcomes.


What Kind of Wood Do You Use for a Porch Roof?

Redwood is an ideal building material to use for porch roof supports. It resists shrinking, warping, and cracking. It also takes any treatment you want to apply.

Plyboard is another product widely used in roof construction. It makes a perfect platform to attach shingles or other roof coverings.

What to Consider when Building a Porch Roof

Like all major building projects, you can’t just dive right in without planning. There are several considerations to bear in mind before you pick up your tools.

Roof Pitch

Most porch roofs follow the same pitch as your existing roof. However, this is not always the case. Flat roofs are harder to waterproof but easier to construct, while pitched roofs improve water drainage.

While deciding which roof you prefer, consider the aesthetics, curb appeal, and cost. Flat roofs are cheaper to construct due to their simplicity.

Important Point

Your local building code might prohibit flat roofs if you live in a cold environment with heavy snowfall.

How to Determine Roof Pitch

Roof pitch is graded as a number determined by the rise and run. For example, a 7/12 roof has a rise of seven inches for every horizontal (run) 12 inches. A flat roof is 2/12, while a steep roof has a rise and run of 9/12.

Here’s a handy guide:

Run and Rise (Inches) Roof Type
2/12 Flat roof (not suitable for extreme weather conditions)
4/12 Low-pitched roof (not suitable for snowy areas)
9/12 Standard roof pitch
9/12 plus Steep roof
12/12 Extremely steep roof (requires a taller chimney stack)

Roofing Material

The pitch of your roof typically dictates the roofing material. A rise of four or more means you can use almost any roofing material. If the pitch is below three, you should use asphalt shingles.

Top Tip

Where possible, the roof coverings should match the existing roof of your house for aesthetic reasons.

Attaching the Roof to the House

The ledger board is a crucial component of any porch roof. It attaches horizontally to the house wall and supports half the roof’s weight. Metal flashing between the house and the ledger board prevents water ingress.

You can attach the porch roof to an existing roof, but it is more common to butt it against an exterior wall.

Header Beams and Posts

Every eight feet, 6×6-inch vertical support posts are set in concrete footers. The header beam runs horizontally along the top of the posts, just below the ledger board. The header beams and posts take the rest of the roof’s weight.

The height of the ledger board and the header beam determine the pitch and run of the roof.

Codes and Permits

Wherever you live, building codes and regulations must be adhered to when constructing an extension. When you attach a structure to your home, your local permitting office may demand to see the architect or engineer’s plans.

You cannot proceed without the necessary permissions, so it’s always a good idea to prepare first to get an idea of what they will and won’t allow.

Simple Porch Roof Framing Diagram

Here’s a simple design diagram that explains what’s involved in porch roof construction.

How to Build a Porch Roof

summer wooden house in a birch grove. camping in the woods. tourist base for travelers ' recreation. eco-friendly construction

As with all significant building projects, you will need to gather the right tools and materials. Investing time to prepare will mean the project runs smoothly with fewer errors.

What You’ll Need

  • Drill.
  • Ratchet wrench set.
  • Circular saw.
  • Square.
  • Ladder.
  • Hammer.
  • 1-1/2-inch wood nails.
  • Spirit level.
  • 2×6 lumber (seven).
  • 2×10 lumber (one).
  • 10 ft 6×6 lumber (two).
  • 15 lag screws with washers.
  • Joist hangers for 2×6 (six).
  • Quick-set concrete (four bags).
  • Two bags of gravel.
  • 1/2-inch plywood sheathing.
  • 8 ft drip flashing.
  • Post hole digger.
  • Roof shingles.

1. Install the Ledger Board

Remove the siding and sheathing to expose an eight-foot by 5-1/2 inch section of the structural framing. Drill pilot holes with the drill and install the 2×6 board using the wrench and lag screws.

Important Point

Ensure that the ledger board is secure because it will need to take half the porch roof’s weight.

2. Attach the Joist Hangers

Screw the rafter hangers to the ledger boards at 16-inch intervals, ensuring that you have one on each end of the roof.

3. Support Posts

Dig two holes in the ground opposite the ledger board and drop in the support posts. Use a post hole digger to speed up the process.

Your local building codes dictate the depths of the posts. If you live in a cold climate, you may be required to dig below the frost line.

Fill each hole with gravel to four inches. Mix up the concrete according to the manufacturer’s guidelines and pour it into each hole. Use a length of wood to pat the concrete to remove air holes.

Ensure the support posts are upright with a spirit level and build temporary bracing to hold them steady while the concrete sets.

4. Cut the Posts to Size

Once the concrete sets, grab the square and mark the height of the support posts. This is crucial for finding the rise and pitch of the porch roof. Grab a saw and make notches in the top of the posts to 1-1/2 inches deep and 9-1/2 inches high.

5. Install the Header Beam

Place the header beam on top of the two support posts, ensuring that it fits the notches snugly. Drill pilot holes at each end of the header beam and attach it to the posts using lag screws and washers.

6. Construct the Rafters

Place the 2×6 rafters in the joist hangers on the ledger board and rest the other end on the header beam. Nail the rafters in place using the holes in the joist hangers.

To attach the rafters to the header beam, drill angled holes and nail them to the beam. This is a technique known as toenailing.

7. Install the Sheathing

Nail the 1/2-inch plywood sheathing to the rafters. If you want to speed up your work rate, invest in a nail gun, like this Porter-Cable 20V Cordless Brad Nailer. It increases your budget, but at least you can work at double the speed.

8. Lay the Shingles

Cover the sheathing with the shingles. Start at the base of the roof and work upward in rows until you reach the house’s exterior wall.

9. Install the Flashing

Nail the flashing to the exposed framing on the side of the house. Ensure it covers the joint between the house and porch roof, with an overlap on the top of the shingles.

10. Replace the Siding

Nail the siding back in place to cover the exposed structural beam and drip flashing.

How to Build a Gable Porch Roof

Maybe a flat or low-pitched roof doesn’t cut it, and you want something more aesthetically pleasing. Building a gable porch roof is more complicated, but the principles remain the same.

Luckily, the framework of the gable roof is the same as a low-pitched roof. However, we will need to make the support posts the same height as the ledger board because we don’t want the pitch. Follow the instructions in the previous section up to step five.

Lay the rafters across the top of the frame, securing the wooden struts through the joist hangers with nails. Do the same for the beam-end.

Now it’s time to build the A-frame supports. Determine the pitch of your roof before making any cuts. Most gable roofs have a rise of between 4/12 to 7/12.

Measure the wooden struts to the required dimensions and then cut each end at 45 degrees (ensure that the angles are reversed on the top and bottom ends). You can use a framing square to find the angles.

Screw the two pieces together to create the A-frame, and attach it to the support beam. Repeat this process, adding an A-frame to the center of the roof and one butting against the house wall.

Nail the 1/2-inch plywood sheathing to the framework, covering both sides of the roof, and cover it with shingles.

Finally, nail the drip flashing to the exposed structural framework and ensure it overlaps the shingles. Replace the wooden siding, ensuring that you cut the lengths to accommodate the span of the new gable roof.

Small Porch Roof Designs

With so many roof designs to choose from, which one looks the best on your house? It can be challenging to find the one that complements the aesthetics and adds value to your home.

Flat Roof

Group of worker installing tar foil on the rooftop of building.

Flat roofs are not everyone’s cup of tea, but they are simple to construct. They typically have 2/12 pitch, so they are not entirely flat but give that illusion. Remember that flat roofs are less robust than other designs because of limited water runoff.

They also need greater maintenance to address sagging. However, they are cheaper and faster to construct.

Open-End Gable

Red door under gable shelter in stone wall

Open-end gable roofs have (wait for it) an open front-facing end. They are ideal for small porches or when you want to create the illusion of height.

Lean-To Roof

Lean-to roofs give the impression that it leans against the house wall. It is one of the most common porch roof types and the cheapest to construct. Lean-to roofs are perfect for small to medium porches but have a limited span due to their simplicity.

If you live in a mobile home and want the easiest DIY roof project, this design is ideal. You can also create simple structures to enclose a patio or outside seating.

You can get creative with your choice of roof covering, including polycarbonate sheeting and tiles.

Hip Roof

Hip porch roofs are another popular design. They add a touch of class to the exterior of your home and enhance curb appeal. As you can see, they contain a long slope and two triangular slopes at either end of the roof.

Tips and Tricks For Building a Porch Roof

Porch roof construction can be complicated, so getting an insight into industry tips and tricks can make life so much easier. Here are a few to get you started:

Draw a Plan

You may have a clear idea of what you want, but no one else will have a clue unless you commit the design to paper. This is especially important when working with a team. Secondly, what you envisaged may change as the project progresses, muddying the vision.

A plan keeps you on the right track, helping you stay focused.

Decide on the Pitch

The pitch determines your timber lengths and the type of roof covering you need. It also allows the water to drain away more efficiently, preserving the roof and limiting water damage.

Consider Using a Nail and Screw Gun

Automated tools vastly improve your work rate. They also reduce repetitive strain injuries. Nail guns and screw guns take practice, but you will never look back once mastered.

Pre-Cut Your Lumber First

Once you determine the design and commit it to paper, you can then work out the dimensions of your porch. Use the measurements to pre-cut the lumber so that you can assemble the porch in kit form.

Number the Components

When you draw the design, number each section to make it easier to identify. Then, number the corresponding pre-cut lumber pieces. Think of it like flat-pack furniture instructions, and you are on the right track.

Now, you can refer to your instructions during assembly and work methodically towards completion.


Final Thoughts

Knowing how to build a front porch with a roof requires skill and knowledge. It is not something a novice should attempt without assistance. One of the best ways to learn is on the job, but not at the expense of accidents or a poorly constructed porch.

Also, check the local building codes before you begin to remain on the right side of planning laws.

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About the Author

Mark Weir

Mark spent 24 years working in real estate, so he knows his way around a home. He also worked with contractors and experts, advising them on issues of planning, investments, and renovations. Mark is no stranger to hands-on experience, having renovated his own home and many properties for resale. He likes nothing better than seeing a project through to completion.