How to Match an Existing Gable Roof & The Truss Design

Adding on to a house or structure is a great way to get more room without building an entire new house! There are several important things to know about matching existing roofs and how to do it depending on what style of roof you have, the roof truss design, and how you want to add on.

Categories of House Additions

There are two main categories that additions fall under most of the time:

  • T-shape
  • Continued

house trusses

gable roof

Either the addition is added to form a T-shape to the house with the ridge running perpendicular to the main house roof, or the addition is continued on the end of the house making it longer with the ridge running the same way as the existing house.

Gable End Addition

Here we will focus on adding length to the end of a house roof. Now once again, there are several ways to add on.

The addition can be wider than the existing house, narrower, or the exact same width. If you choose to go wider or narrower, there won’t be the challenge of matching up exactly to the old roof and the project will be much easier. With the roof pitch the same, it doesn’t matter if the new addition is slightly off in height or lined up front-to-back because you’re going over or under the old roof.

But it is important that the roof pitch is exactly the same as the existing roof because you will see it from one roof to the other if it isn’t.

If you choose to go with the same width, it will be more difficult to execute without a noticeable difference or bump in the roof between the old and the new. 

Let’s dive into a few more details regarding the roof so we can focus on matching each roof and having a seamless project with beautiful results.

First up, an example…

26-Foot Addition Example 

For the first example, let’s say you have a simple 30’x60’ rectangle shaped house with gable style ends and a 2-foot overhang like this:

And you have decided that you want to add on a 26’ garage on the end of the house like this:

And the finished roof plan when you’re done with matching ridge, overhang and soffit lines should look like this:

But wait…

Do you know how your old roof was built?

Was it built with roof trusses or stick frame? Now is the time to check before you start pouring your slab and building your new walls. If you don’t check, you will likely build your new walls the same height as your old walls but there are reasons not to do so.

What are they?

Let’s explore the differences between stick framing and roof trusses, and how they affect your slab and walls:

The Two Different Roof Framing Styles: Stick Frame & Trusses

If your house was built using roof trusses, then it will look like this above the outside wall of your house:

roof truss system

A stick framed roof will have a rafter member looking something like this:

You’ll notice the difference in how the boards are cut to sit on the wall and create overhang.

Wood roof trusses bring the bottom chord of the truss all the way to the outside of the wall, include a small vertical cut (butt cut), and angles back against the top chord of the truss. The top chord smoothly extends out past the wall to create the overhang.

(If the roof truss has a 2×4 top chord, the heel is shorter than if it has a 2×6 top chord as a general rule. The heel height is adjustable in height by changing how tall the butt cut on the bottom chord is.)

The stick framed roof is a different story. 

Since the rafter has no bottom chord to sit on, it must have a birds mouth cut into the bottom side of the rafter so it has a flat place to sit down on the wall. Now the rafter also has a vertical heel cut that instead of sitting above the wall, actually sits down beside the wall. Depending on what size of rafter is being used, the corner of the birds mouth cut and the top edge of the rafter can get rather thin.

Matching the Two Different Roof Framing Styles

This brings us to the point that putting a rafter beside a wood truss or a truss beside a rafter on the same height of wall may not always work. If the stick framed rafter is a 2×6, it typically has just enough heel height after the birds mouth cut that a regular 2×4 truss can sit beside it and match height.

Any rafter bigger than a 2×6 shouldn’t be a problem unless your roof is pitched fairly steep. A 2×4 rafter just doesn’t leave enough height after the birds mouth to match on any roof pitch.

So now the first step to adding on is to determine how your current roof is built and what the heel height is.

Typically, the best way to find out the heel height is through a vent in the soffit or even pulling a piece of soffit down a bit.

Another way would be to pull off some siding at the top of the wall, on the gable end, right where you are going to be starting the addition. Once you can reach the heel, carefully measure the height of it vertically at the outside corner of the wall to within 1/8 inch.

Also determine how the roof was built while you’re looking at it – roof trusses or stick framed?

If the roof is built with trusses, congratulate yourself that you have a good roof and that the project will be easier 🙂 

We can match another truss, and who knows, we may have even built the truss your looking at. And if it was stick framed, don’t lose hope! We can do this together!

Floor & Wall Height Considerations

Now back to wall and floor heights.

If the heel height is too short and we can’t match it, there are a couple things that can be done. If the ceiling of the new addition can be lowered an inch or 2, this gives us room to build a truss to match on the roof top.

Or if the addition is for a garage, a lot of times the floor is lower than the house floor anyway and it can be adjusted up or down to make a regular framed wall come out slightly lower than the existing house wall.

The other option is to make the walls taller than the existing house and just make the new roof higher than the old with a higher ceiling. Going up and higher than the old roof means you don’t have to match exactly anymore which is also easier. However, this may not be the look you want.

Plan Your Roof in Advance – Give Us A Call!

At any rate, this is a great time to call Timberlake TrussWorks about your project at 580-852-3660! (We service Oklahoma, Kansas, and North Texas) 

After reading this article, you will be up on most everything we would tell you! There are a few tricks left in the bag that can be pulled out if for some reason your project doesn’t fall under these general examples.

When you call, we will want to know the heel height and roof pitch and can begin to help you with matching up and getting a design to work. Contacting us at this stage will also give us a chance to stay with you throughout your process. Keeping on top of the details and planning ahead makes it go much smoother for you and us! By planning ahead and knowing your building schedule as well, we can make sure we have the trusses to you on time so when you rip into the existing structure, you don’t have to keep it uncovered for very long.

Matching Existing Truss Worksheet

Want a worksheet to make this easier?

Email us to get your downloadable worksheet:

This is the complete list of details we need for a perfect match. Some of the details will may not be available until the floor and walls are complete. Filling out as much of this worksheet as possible will only speed the process up and make it go that much quicker and smoother.

Thanks for choosing Timberlake TrussWorks for your quality-built trusses and hardware! We appreciate your business!

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Premanufactured Wood Trusses Provide a Solution for Labor Shortage

Premanufactured wood trusses offer a solution to the building industry labor shortage. There is currently a significant labor shortage among home framers and carpenters. Contractors find it increasingly difficult to keep up with the housing demand and operate in a cost- and time-effective manner.

Framing Labor Shortage

“Eight-five percent of builders reported a shortage of framing subcontractors, compared to “only” 77 percent who reported a shortage of framers directly employed,” according to July 2017 NAHB/Wells Fargo HMI study.

This is significant, considering that new home sales were 8.3 percent higher in 2017 than in 2016, reaching 608,000 homes in 2017. This is part of a steadily rising trend since 2011. (Reference)

NAHB/Wells Fargo HMI Study Results on labor shortage

Industry leaders currently focus their efforts on attracting the next generation of builders, but the needs of the industry are changing. Stick framing is both time and labor intensive. Building the American dream is becoming increasingly difficult as job openings are wide-spread. Component manufacturing is providing a solution.

Structural Building Components Offering a Solution

Structural building components such as wood floor and roof truss options provide a significant cost and jobsite man-hours reduction for your home building project.

The WTCA conducted a study “Framing the American Dream”, building two identical homes. Contractors built one home using stick framing, the other using structural building components, including premanufactured wood trusses, both floor and roof.

The home built with premanufactured wood trusses required 183 less jobsite man-hours to erect with a labor cost savings of $3,150. Overall, the home built with premanufacutred wood trusses resulted in a 23 percent total labor and material cost savings, equal to $3,015.

Benefits of Using Premanufactured Wood Trusses

premanufactured wood trusses from Timberlake Trussworks Using wood trusses offers additional benefits.

  • Every product is designed to the exact specification of your project.
  • The latest technology is used when engineering components.
  • Weather is not a factor as wood trusses are manufactured in a temperature controlled environment. As a result, callbacks on materials are reduced.
  • Material shortage delays are reduced, keeping your project on schedule
  • Theft of components from a jobsite is rare.
  • Using wood trusses is environmentally sound as waste is minimal.

Partnering with Timberlake Trussworks

Premanufactured wood trusses are a proven solution to save you time and money when building your home or office building. We would love to partner with you. Please contact us today at 580-852-3660 to discuss your project and get a quote.

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Pros and Cons of Trusses vs Stick Framing


When comparing two things, it’s best to compare apples for apples. If you are trying to decide if you will use Trusses vs Stick Framing, there are things to take into consideration that will make a difference in your decision making.

Although we want to compare apples for apples, some things can’t be compared equally because it’s actually not possible to do it as both trusses and stick framing have some situations where one isn’t an option.

[Read more…]

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Pricing Wood Trusses for Any Project: A Step-By-Step Guide

We wish we could provide an exact answer to the question – how much will my trusses cost?

Although we can’t provide the exact bottom-line number (without further consultation), what we can provide is a thorough pricing guide to help you understand how wood trusses are priced for homes, buildings and all projects.

Below you’ll learn about the most common truss design and how it’s priced for projects. You’ll also learn about other designs and how pricing is affected by the change in design. And to conclude, we’ve provided a simple home design with common dimensions as an example to help you understand the complete pricing process.

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Why Geographic Location is So Important in Truss Design

wood trusses

Geographic location is an important factor for truss design. Depending on your geographic location, your trusses will have to account for different amounts of wind and snow.

Timberlake TrussWorks has customers all across Oklahoma, Texas, and Kansas. That means we have lots of different climates and codes we need to consider.

When a customer orders trusses, we can’t proceed without knowing their geographic location. By analyzing the weather patterns and climate history in this geographic location, we can get accurate information about wind and snow loads in the area.

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Designing Wood Trusses to Accommodate Appropriate Spacing

Kansas wood trussesWhen it comes to designing wood trusses, the spacing of each truss according to each design is crucial. If you miscalculate any bit of the spacing and don’t consider the use of the building you’re constructing, then you’re likely to end up with a compromised structure that can present a hazard.

Today, we want to run through a design scenario to discuss how we approach design and our consideration of spacing. If you have any questions along the way, please don’t hesitate to reach out to our team. We’re happy to help – 580-852-3660

Here’s the design scenario:

Take trusses that are spaced 4’ apart. They are loaded for a post frame construction that has purlins on the top cord with metal screwed down to that.

The bottom of the truss is open and exposed from underneath although the building will be completely enclosed. So on this 30’ span truss, it is resting on 5 ½ inches at each end.

On that small surface, there is 1560 lbs. of weight on the bearing point. This is every 4’. So if the trusses were spaced out to 8’, there would be double that amount of weight.

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How Much Do Trusses Cost? – An Approximate Guide

Roof truss framing is a cost-effective way to build a roof. Today, more and more homebuilders use roof truss framing to save costs and build stronger roofs.

But how much do trusses cost? Today, we’re going to explain how pricing is evaluated and calculated by truss manufacturers and what you can expect when you consider purchasing a truss system for your next project.

An average 2,600 square foot house costs…

According to the study discussed below, we can give you some approximate pricing information for truss framing. These are general figures and will change according to whichever supplier you’re working with:

-Labor costs: 112 man-hours x $20/hour average = $2,240

-Equipment costs: Crane = $500

-Total bd. ft. lumber: 10,500 x truss manufacturer’s selling price per board foot:  $9,000 to $12,000

-Scrap disposal cost: 3 yards of lumber x $15/yard plus labor costs: $77

Total cost:  $11,817 to $14,817

Keep in mind that these statistics are for a 2,600 square foot house. Also, these are only approximate values. Labor, equipment and materials vary in price due to cost of living in varying locations. Since cost of living is much lower here in Oklahoma and the Midwest, these prices will be lower than the national average.

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How Prairie Winds Affect Wood Trusses in Kansas

Storm Clouds SaskatchewanKansas is notorious for its prairie winds. Engineers have always had to take these winds into account when designing structures across the state.

Prairie winds can be downright dangerous if you’re working with the wrong building materials.

Every day, truss designers need to take a variety of factors into account when building for the prairie winds in Kansas. Here are some important things to know about how truss systems are affected by Kansas prairie winds:

Truss builders need to calculate wind pressures using two blended methods

There are two broad ways to calculate wind pressures: Main Wind Force Resisting System (MWFRS) and Components & Cladding (C&C).

MWFRS applies to a structural frame or an assembly of structural elements that work together to transfer wind loads to the ground.

C&C applies to components that directly receive wind loads – like wall coverings, roof coverings, fasteners, and girts. Components and Cladding are typically exposed to higher wind pressures than MWFRS elements.

Trusses fall into both categories. Thus, the industry-standard practice is to design the truss to handle both MWFRS loads and C&C loads.

Truss builders need to consult wind maps to identify correct wind speeds

Building codes typically require the use of a 90-mph wind speed for inland areas of the United States. However, you’ll need to consult local wind maps and government building codes for region-specific information.

Experienced builders don’t settle with just the 90-mph wind speed standard. Experienced builders increase the durability to handle wind speeds around 100 and 110 mph. With wood trusses in Kansas, increases wind speed durability is a major consideration. All trusses must be designed to withstand substantial wind, more than the average structure.

Building usage affects wind pressure calculations

Buildings fall into a number of different usage categories. Specifically, there are three broad categories of building usages:

-Category I: A building that will have a low hazard to human life if it fails

-Category II: A building that presents a substantial hazard to human life if it fails

-Category III and IV: Buildings that are critical facilities or present a substantial hazard to human life in the event of a failure.

Different building exposures affect truss design

Buildings located on empty, flat land are more affected by wind pressure than buildings surrounded by trees and other buildings.

Building codes classify these buildings in four different ways:

Exposure A: Buildings located in downtown areas or city centers.

Exposure B: Urban and suburban buildings that are surrounded by similar-sized buildings and trees.

Exposure C: Buildings in an open area with scattered obstructions.

Exposure D: A building exposed to unobstructed wind for at least one mile over flat land.

Good truss builders take all of these factors into account

Ultimately, truss builders have a lot of responsibility. In Kansas, flat plains let wind travel unobstructed for hundreds of miles. Rural buildings and even many suburban buildings are rarely protected against substantial wind.

To take truss manufacturing to the next level, Timberlake TrussWorks builds wood trusses capable of withstanding strong winds. The key to a sound structure requires the builder to guarantee trusses are fastened tightly against the wall. This is accomplished by installing TimberLOK Screws, which we happily provide.

These screws are hurricane ties – able to withstand the brunt force of harsh winds caused by severe storms. TimberLOK Screws keep trusses and roofs stable and secure during harsh weather conditions experienced on the plains of Kansas.

If you’re shopping for wood trusses in Kansas, then you can’t settle for average. Kansas’s prairie winds chew up average wood trusses and quickly reduce the lifespan of structures. If you’re looking for wood trusses in Kansas that offer a higher level of quality and longer-lasting support, then order from Timberlake TrussWorks today.

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Designing for Truss Deflection in Oklahoma

91370356268-mediumUnderstanding deflection within the design of trusses is one of the most important aspects when considering a truss system.
We spend considerable time determining the deflection, load amount and span of a truss. We review the specs again and again so our customers receive considerable spans, but spans that are deflected safety and effectively.

But first, let’s discuss the basics of deflection of our Oklahoma wood trusses a bit more:

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Package Discount Offer

Boehs Building Supply and Timberlake TrussWorks feel privileged to offer you a special discount for your building supplies! This discount covers your complete exterior package on your project. If you will purchase the materials from Boehs Building Supply and the wood trusses from Timberlake TrussWorks, we will both Discount your order 5% to bring you a SPECIAL SAVINGS on your project!

Just give us a call for more details or to order your package deal, and we will be happy to serve you!

Doug Boehs — Boehs Building Supply (580) 852-3664

Brad Unruh — Timberlake TrussWorks (580) 852-3660

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Timberlake Truss Works LLC