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How To Extend A Roof Overhang | Comprehensive Guide

how to extend a roof overhang

A roof overhang is a great way to extend outdoor living space. It can be used as an extension of the house, or it can provide protection from the elements for an outdoor kitchen.

A properly designed and installed roof overhang will last for many years without any problems.

It’s very easy to extend or retract a roof overhang. You can do this by cutting the rafters in your existing roof, adding new rafters, and then cutting trusses to fit between the two sections of rafter.

If you’re looking to build an overhang on your roof, here are some things that you’ll need for the project.

What is a Roof Overhang?

A roof overhang is the protective covering above a doorway or window, consisting of an exterior side of a building which projects outwards.

The purpose of an overhang is to repel rainwater so that it falls well away from the sides of the structure (usually on beams supported by posts) and does not erode the foundation.

Overhangs protect windows from sun damage and avoid moisture seepage into the wall cavity.

How To Extend A Roof Overhang | Comprehensive Guide

Planning And Preparation

If possible, choose a day when rain is not forecasted in order to prevent any mishaps with construction materials.

Once you have decided upon where exactly you want your overhang to be built and how long it will be, you need to take some measurements.

This includes the length of your overhang and how much roof pitch you have in that area.

Next, determine what lumber you are going to use for framing by looking at three things: The span between supports (usually 24″ on center), the load capacity needed per square foot based on the type of material you are going to use, and the size needed for your framing lumber.

After that it’s time to get all necessary materials together in order to start construction: roofing felt, drip edge flashing tape (for asphalt shingle roofs), nails or screws with washers depending on what types of insulation will be used underneath and how much wind is in your area, utility knife for cutting insulation and flashing tape, chalk line to mark the extension’s shape on the ground before you actually start working.

Common Materials Used for Roof Overhang Extensions

Roof overhangs can be extended with basic materials found at most home improvement centers. Materials used typically include:

1. Lumber / Wood – There are actually two types of wood used, either shingles or square cut boards.

  • Shingles are the most common material to use when extending roofs overhang.
  • They are easy to work with, usually less costly than square cut boards and come in a variety of colors.
  • Shingles can be glued together to create a larger piece for support, or left as individual pieces to suit your needs. There is also a smooth side and rough side which will determine if the roof overhang has a smooth look or not.
  • Square cut boards can be glued together and nailed into place for support, or left as separate pieces to create a different look.
  • These are more costly than shingles but come in a variety of colors and sizes.

2. Trim boards – These boards are usually 1×4 or 1×3 creations, glued together to extend a roof overhang out several inches.

They come in a variety of shapes and styles so they will look more natural on your home. These boards can be painted or stained to suit your preferences.

3. Cut shingles/batten strips – These are cut shingles or batten strips that are glued together to extend the roof overhang out several inches.

This is a less costly method of extending your roof overhang since you are using cut pieces of shingle.

4. Glue and nails or screws (fasteners) – There are a few different types of fasteners that you can use in this project.

Wood Glue is typically used in most carpentry projects to hold things together where the nailed area is too large. Wood Glue acts as a bonding agent and will not be used in this project unless otherwise specified by the owner.

Nails, screws, and other types of fasteners are used to keep wood attached to other pieces of wood and should be driven into the 1x2s (the outside frame) to secure them together.

Steps on How to Extend a Roof Overhang

1. Measure and cut pieces of lumber for roof overhang extension (the side you will be working on first) including the length of the existing roof overhang.

2. Measure the height of the existing roof overhang at each end and cut appropriate pieces of lumber to extend it, using a circular saw to make straight cuts.

Make sure that all pieces are level with one another (use a small spirit level).

3. Attach the side boards for extension along both edges of the existing roof overhang using the roofing nails.

Try to angle the side boards so that they overlap one another or are staggered, if possible. If you have a lot of space between the beams, you can skip this step and just attach plywood sheets directly to them.

4. Attach the 2 × 6 lumber pieces for trimming along the lower inside edge of the new roof overhang using roofing nails.

5. Attach one or more layers of tar paper over the top of all lumber pieces that are exposed on the bottom side (tape them together along their edges if needed).

This is to protect both your house and the extension from moisture damage. If you have shingles on your roof, you can attach new shingles over the tar paper.

6. Attach a few nails along the inside of all exposed beams using a hammer and an appropriate spacing.

Make sure that they are not flush with the top surface of the beams but stick out by at least 2”. This will support the roofing felt and shingles.

7. Attach the roofing felt over these nails following the next steps:

  • Place one end of the roll at the bottom corner of your house where you will be starting (leave about 20″ of extra material for later).
  • Fold the rest of the roofing felt over the first piece and align it with the inside of the existing roof overhang.
  • Attach it to your house using several roofing nails along its edge, close together so that there’s no space between them.
  • Cut off any extra material from the edges if they are not flush with one another or will be covered by new shingles.
  • Continue along the entire length of your roof cover extension with a few more nails, half of them on a straight line and the other half staggered from the first.
  • Leave about 20″ extra material for overlap at each end (if you have shingles over your existing roof overhang it will get in the way while you attach the felt, so it’s better to leave an extra foot of roofing material for each end).
  • For all other overlaps along the extension make sure that the edge of one strip is parallel with or 1″ below the bottom edge of another.
  • Fold over any excess felt around the outside edges and nails using a hammer.

8. Cut two strips of roofing felt 2″ wider than the width of your existing roof overhang and about 4′ longer than its length.

Use these to cover the lower edge of the extension where it meets the original roof overhang, folding them under so that they overlap one another by at least 1″.

9. Attach them to the bottom of the extension using a hammer and a spacing like what you used for the roofing felt.

The nails should stick out from under the new roof covering by at least two inches, but not come too close to lower edge or angled boards.

10. Attach shingles over the tar paper for the entire roof extension (if you didn’t do that in step 7).

For each shingle, start at one end of your roof cover and secure it to the eave with two nails. Make sure you get about 3/4″ overhang on both sides.

11. Continue placing shingles until you reach the other end overlapping your previous row by a few inches.

12. Cut a few vent holes over the peak of your roof cover to help reduce moisture buildup and replace any broken or loose shingles as needed.

If your roof overhang faces west, it might be a good idea to install ‘solar fans’ on one side of your house that will allow you to direct airflow through your attic and keep the temperature even.

13. Make sure you have a good ventilation system in your attic that allows air circulation between the extension and original roof overhang, just like you do it around the rest of your house.

14. If you plan on living under the extension for an extended period (more than several weeks) it’s recommended to reattach or install new shingles over the lower edge of your house where the extension meets the original roof overhang.

Final Thoughts

Building a roof overhang extension can increase the value and appeal of your property. It is usually constructed with wood or metal supports and attached under the existing roof line.

This creates a nice transition from your house to the exterior walls that will provide shade for windows or doors. In addition, it protects the area from rain and snow when the roof is sloped in that direction.

Extending a roof overhang can be done by anyone, but it may make sense to consult with someone who knows how to do it. You might even want to hire professionals if you are unsure about the whole process.

However, you should consult with your local building permit office before completing the project.

This will allow you to get important information on building codes and zoning regulations for your area of the country. You may not need to submit plans or get a permit, but it is better to be on the side of caution.

How To Extend A Roof Overhang | Comprehensive Guide