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Designing and Installing an Eyebrow Dormer

This past summer, I had the opportunity to create a detail that is now rare in construction. The trade seems to have lost its flair for creative, interesting, and alluring details. All too often we have been transformed into simple assemblers. One of the reasons why I love remodeling is that no job is the same. While some parts of a job are unavoidably familiar, new challenges arise on every project. And some projects push us more than others.

In the winter of 2009, I took a course from Billy Dillon on eyebrow dormers. When I heard about the class, I thought, “Hey, this would be fun to do, and maybe I can learn something that has always intrigued me.” The West Coast seems to have a shortage of schools that teach high-end carpentry. Most of my studies have been on my own, gleaning what I can from books, construction forums, and the occasional carpenter who has graciously shared the true gift: knowledge. I am humbled that these men, who have spent many years honing a skill, would be willing to pass it on.

The class with Billy Dillon opened my eyes to an entirely different world of carpentry. I learned that drawing something can be very, very valuable—up until this point in my career, I had not really drawn things out (my poor chicken scratches don’t count). The second important thing I took from Billy’s class was the power of collaboration: Learning from others and sharing in a free exchange of ideas is unbeatable. The class also reinforced my belief that, over time, we have lost many carpentry methods that were commonplace only a few years ago. Lastly, Billy’s class showed me that we must be willing to teach one another if our craft is to continue to be something that we are truly proud of, and if we want to leave a legacy for future carpenters.

I felt overwhelmed by the end of Billy’s eyebrow class. I didn’t really know if I could actually build one myself, and I didn’t get an opportunity to find out until an unexpected project came my way.

Billy emailed me last year, when someone contacted him to have four eyebrows added to a Seattle home. Billy gave him my contact info, and before long I was in communication with a new client (sometimes jobs can come in the most unexpected ways!). Since Seattle is about four hours north of me (I’m in Portland), I wanted to build as much of the eyebrows as possible before transporting them for installation. I happened to go to Seattle for a tangential handrail course, so I decided to take advantage of that opportunity to meet my new client and see the house firsthand.

The Job

I teamed up with two other contractors to pull off the project: Clint Howes, with Revive Construction, and Lavrans Mathiesen from Mathiesen Woodworking. Once we settled on what size the dormers needed to be, it was time to head to the drawing board (or, in this case, some 1/4-in. plywood). We drew everything full-scale in order to check our work and cut back on errors in the actual pieces. We decided to build curved roof rafters that run perpendicular to the main roof rafters, with both inner and outer valley developments. The rafters would be letting light into a very rough, unfinished attic space that was going to be turned into a playroom.

(Note: Click any image to enlarge)

We used seven full-size drawings as guides in order to work out all of the required geometry.

Each of the drawings in the process is important. Information gathered from one drawing is used in the next drawing to then gather more information. Together, the drawings provide a systematic approach for developing the complex shapes required for this type of dormer. The following animation gives a basic overview of the process.

One of the things that made this project convenient was that we could fit one drawing on one sheet of plywood.

With seven sheets of full-size plywood-drawings, it helps to label them so you can keep them in order.

Once all the drawings were done, it was time to get in the shop and make some sawdust. It was an old house, which meant that the framing conditions were a little unknown. We decided to leave the inner valley drawing for after we set the eyebrows. We also decided to have insulated glass units made rather than ordering a custom window. This allowed us to meet our timeline, keep to the budget, and give a local glass shop some work.

Our goal was to send fully assembled units to Seattle. First, we needed to cut out the outer valleys.

We made templates from the drawings, and then cut our valleys out of 2×12 fir framing material.
We happened to have some leftover Mahogany from another job, and decided to re-purpose that for our window sashes.
We made the primary rafters from Ply-Lam. We cut the secondary rafters from standard framing materials.

In the photo above, you’ll notice that the primary rafters have the bevel of the roof ripped on them. Part of making the outer valley developments is that you need to put the bevels on the valleys to give you a smooth transition from the roof to the dormer. Getting these valleys right is a must.

This is where all the tools in the toolbox come out. A reciprocating saw was used to get the approximate depth of cut for the bevel, and then a grinding wheel was used to shape them fair to the lines.
Once the valleys were shaped, it was time to attach the rafters.

If everything has been done correctly, it should all lay out right (hard to believe we are still just rough framing).

Once the rafters were installed, it was time to put on the sheathing. Since this dormer was on a fairly tight radius, we went with bendy-plywood. We decided on two layers of 3/8, with a good layer of wood glue between, and lots of staples. Due to the size of our windows/dormers, we did not have a design that dictated anything specific in regards to the windows themselves, only the opening in the roof.

Here’s a peek at the process:

Working on cutting out the plywood for the sheathing.
Fitting the sheathing.
Trimming the sheathing to fit.
Sheeted and almost ready for transport.
Ready for the trip to Seattle.

The Install

This is the way the home looked before we installed the eyebrow dormers:

The contract was to put two on the front and two on the back. Our first priority was to strip off the 1×8 sheeting on the inside, and then check out the rafters that would need to be cut.

We had to be careful with the sheeting, since it was going back after the eyebrows were installed. As part of our design, we needed to double up rafters and put headers above the openings. Once that was done, we could peel back some of the roofing and get the eyebrows mounted.
The picture is a little dark, but you can see the new doubled-up side rafters in this photo (left). We added new headers above and below the opening, as well as support running on the bias to support the shrinking width of the eyebrows.

All of the connections were to be attached with various fastening products (I prefer Simpson Strong-Tie.).

I elected to sub the roofing out due to our limited time onsite. This allowed our crew to focus on the carpentry aspects. We primed the exterior sashes with an oil-based paint, but didn’t do any of the finish painting—the homeowner elected to handle that himself.

Once we got the framing done, and the openings created, we were able to set the eyebrows. We used LedgerLOKs to set them into the framing below, and we also used them in the framed nails through the sheeting on the perimeter.

The photo above shows the first one set. It was a little tricky, due to the chimney being so close, but it came out just fine, as did the other three. We had to balance squaring them with the outside look, as well as the inside look. It was one of those “look right” and not necessarily “be right” days. At the end of our first day onsite, we had all four set, the roofed tarped, and a clean job site.

On day two, after we got the roofers set up, it was time to work on the inner valley developments so we could finish the inside. For the roofing, we had the entire dormer covered in Grace Ice and Water Shield. We specifically requested no valley because there was no cut or woven valley on the dormer shingles.
We used some of the drawings that we had previously made, expanding upon them to get the inner valley layout.
These points from a previous drawing allowed us to plot the curve of the inner valleys.
After that, it was time to cut out the templates. We relied on these to guide us in tracing the bevel lines on the inner valley stock. We used a reciprocating saw to get the depth correct on the curve, and then we used a grinding wheel attachment to cut them fair to the lines.

Once the inner valleys were set, it was time to start finishing the interior. We needed something that would take the curve fairly well. We decided to use 1×4 fir flooring to somewhat match the finish that was in the house. We would usually bring in a plasterer to do the curves and blend everything in, but we weren’t in a finished space.

The roofers were wrapping up the outside while we were busy working on the inside.
Once the interior finish was put on, it was time to re-install the original 1×8 sheeting, and then blend it all together.
This is where having a small electric chainsaw would have been helpful. We made do with pull saws, recip saws, Multimasters, Bosch Finecuts, and grinding wheels.
We learned how easy it can be to cut more material than you want to! It’s better to take it slow. Adding material at this point was, shall we say…difficult.

Final Thoughts

Building these in a shop was a great way to go, and extremely efficient. It took us about four days to lay out and build them, and then another three days to install them onsite. If it had been a larger window, I would have probably used a window manufacturer to build the window instead of making it myself.

A few more tools to the arsenal would have also been helpful. As I said before, an electric chainsaw would have been handy when we tackled the re-installation and blending of the original sheeting—the long-cutting action blades of an electric chainsaw would have given us the opportunity to follow some of the roof contours better. Also, if we had used an electric chainsaw, we wouldn’t have had to worry about the fumes in the enclosed attic. Some of the guys mentioned it, but I thought, “A chainsaw? Yeah right!” I guess they get the last laugh.

My wish list for future projects also includes a compass plane, either hand or electric (which would have been useful for shaping some of the rafters), and a Porter Cable Oscillating Spindle Sander, which I actually borrowed to help us fair the curves.

And lastly, though I haven’t used it yet, Festool’s RAS would have probably been a good tool for working to blend the surfaces.

In the end, I’d say that the most important part of the whole project was the drawings. At one point, we laid out the inner valley wrong, and had to do some adjusting before we could finish it up. We went home and re-worked what we did to find the error. The beauty and simplicity of a project like this one is that if you follow the drawings through, it works.

Architectural features like this are missing from our modern buildings. I hope that eventually we can feel like older generations of carpenters did, and know that we’re creating art with our work. I think the tide is slowly shifting toward clients who don’t just want something cheap. I think, more and more, people are truly valuing craftsmanship, art, and beauty.


Special thanks to Lavrans Mathiesen from Lavrans Mathiesen Woodworking and Clint Howes from Revive Construction LLC.

Thanks to Billy Dillon for passing on the craft he loves so much.

And thank you to my family for putting up with me while I learn new skills in the art I love.

(SketchUp animation by Wm. Todd Murdock)

Editorial Note: If you have questions/comments for Billy Dillon, or if you’d like more information about Billy’s eyebrow dormer class, please submit your inquiry through our Contact Page.

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Joshua Farrand, of Eight Inch Nails Construction LLC, is based in Portland, OR. He is always in search of new approaches and techniques, and ways to improve the trade that he enjoys. Someday, he hopes to build furniture, and teach others the wonderful craft that is carpentry.



32 Responses to “Designing and Installing an Eyebrow Dormer”

  1. Joe 'the Pro' Sainz

    Nice article, and nice job on the construction. It looks like you really took some pride in the work. May I use 1 or 2 of the photos on a blog post at pointing people towards the article here?

    • Tristan Katz

      Hello Joe,

      You are welcome to republish photos or text from the article, as long as you credit Josh Farrand, the author, and

      For more information, please read our Reprint Policy.

      Thanks, and best regards,

      Tristan M. Katz
      Associate Editor,

  2. Dan Ackermann

    Wow! It’s really nice to know that there are actual craftsmen out there. How many carpenters actually know how, or could be bothered to find out how to do this. Many of them just say
    “They don’t do that anymore.” Keep up the good work.

  3. Joshua Farrand

    Joe and Dan,
    Thanks for the nice comments. We had a ton of fun building them and take a lot of pride in building something that adds so much and blends so seamlessly. One of the things that I love about carpentry is always trying to learn something new. We are eagerly anticipating the next set.

  4. keith mathewson

    Brilliant article Josh. I remember hearing about it on JLC and thinking since I don’t do window work it wasn’t revenant to me, a real opportunity missed. Well executed and presented, I hope you get a chance to do more. If Billy Dillon teaches any more classes I suspect I will attend regardless of subject matter.

    As a side note I want to express my thanks to Gary Katz & team for the forum & Youtube presentation, it takes a great deal to time to put together and helps greatly in understanding the concepts.

  5. Joshua Farrand

    I highly recommend the class that Billy teaches. He is fantastic at relating concepts and is patient which helps guys like me who don’t get things quickly. Plus you get to hang with other guys who totally digg crazy carpentry. A pretty cool bonus!

  6. J.R. McCaulley

    WOW. Beautiful job. It’s nice to see carpenters in action rather than butchers with tools. The geometry use is spectacular. Only thing I would recommend next time is cutting back the tar paper further on the roof to allow for ice and water shield on the main deck as well. Think that makes a more permanent seal around all that fantastic craftsmanship.

  7. BobboMax

    We also need to give kudos to the homeowners who were willing to invest in the work of craftsmen- that’s even rarer than the craftspeople these days.

  8. Jeff T

    Thanks for a great article and the way you laid out some of both the pros and cons of the project. Your looking back and explaining what went well and what could have gone better is just as helpful as the design and construction parts.

    Were you happy with the work the roofers did? It doesn’t look great in the pic, especially on such a focal point of the house but maybe it turned out better in the long run. You mention that you purposely spec’d the roofing to run through rather than have cut valleys.


  9. Joshua Farrand


    I was happy with the work the roofers did. I think it turned out very well on their end. Having cut valleys is problematic and not recommended from what I have been taught. The overall look I think transformed the house into a really cool look but more importantly you would never know that they were new dormers and hadn’t been there for a 100 years.

    • Joshua Farrand

      You are so right! Todd did a magnificent job of making it clear and understandable. He is a wizard with Sketchup, and I hope that I can learn a little of his tricks from him.

  10. Mike Cunningham The Eyebrow Construction Company

    Very interesting article, we have made 100’s of these eyebrow dormers in all shapes and sizes. I couldn’t agree more with the artisanship of our trade becoming lost. We are an East coast outfit and send these dormers all over the country, and Canada. My experience has shown tha Architects are afraid to incorporate eyebrow dormers in thier designs, as one Architect put it to me, “one out of ten looked like they should, so I stopped drawing them”, articles like this may help sway them.
    Try a 7″ grinder with a 16 grit pad, fast carving!

    • Joshua Farrand

      Thanks Mike for the tip on the 7″ grinder. We will definitely try that on the next ones. It looks like you have a great company. Keep up the good work. I agree with you that most guys would just try and wing it. These along with many other things in carpentry lay out so easily with just a little math and it makes all the difference between clean looking/spectacular and something that is just shoddy and made up. Hopefully as guys learn some more of the techniques that are out there we can gain a little more respect for the trade and see some of these great details come back!

    • Keith Mathewson

      Nice work Mike, its good to see you are making a business of it.. Something I noticed is that Josh’s trim and glass match the window profile. A small detail but makes a noticeable difference.

    • Billy Dillon

      Mike, I understand your comment about architects not knowing how to draw the curves correctly . That is why in the class we spend almost 1/2 a day developing the different forms of the front elevation . I am also intrigued, why do you not offer an inner valley? The inner valley when done properly is elegant.
      I may be down your way this winter and would love to stop by and say hello.

  11. Billy Dillon

    I forgot to say how well the graphics worked . Josh I know you and the crew at TIC worked long and hard ,nice work .
    Also great to hear from Sim ,and Keith .

  12. Gary Randone

    Beautiful project and very nicely done. It’s all in the details and it shows.

    I do disagree about your statement: “trade seems to have lost its flair for creative, interesting, and alluring details”

    It has nothing to do about the trade, (to a degree) only the depth of the clients pockets and their appreciation for fine craftsmanship and architectural details. There were many man hours involved with your project and unless that was a pet project, that would be out of most homeowners budget.

    • Joshua Farrand


      Thanks for the comments and I do agree that part of the issue is clients pockets and their willingness to spend. However, I strongly feel that by in large our trade is very willing to settle for being cheap assemblers as opposed to craftsmen. The standards have been lowered that most people really don’t know what a carpenter can or should be able to pull off.

      A recent example of this is that I was asked to build a part of a set for an upcoming trade-show for a designer. Part of her design incorporates two ellipses and a large oval. When I went to meet her she commented that she had done a pretty good job of laying out the oval based off of her cad drawings and that she suspected it was close enough for me to just copy the “good” quarter that she felt was the best. I just told her the oval was simply two ellipses and we would lay it out based off of mathematical points and use a router to make it accurate. She seemed amazed by this and the ease with which I suggested it. We are the second set of carpenters on the project- the first ones didn’t offer this solution and seemed mildly overwhelmed.

      Don’t take from this that I am a genius but I do try to learn new things. I for one am thankful for websites like This is Carpentry
      and magazines such as JLC and Fine Homebuilding because I think that the more we educate ourselves and get better at the trade the more we will see projects more in line with what I have done here and that is a win/win for everyone- architects/designers, homeowners, and carpenters!

  13. John C

    Wow. I’m sure nobody in my area is doing this type of quality work. I think it’s fantastic that you guys are doing this type of work. Great job. Keep it up!

  14. John C

    However, eyebrow dormers are about the last thing that house needs. How about a good shrub trimming??? ; )

  15. Arnold

    Wow, that was fantastically interesting.

    Given that (to my knowledge) there are no prescriptive codes for something like this, do you have to get an engineers stamp? How did the inspections go?

    Also, how did you find out about and register for Billy Dillon’s class?

  16. James Joyce

    Great article, good to see how this is done in the real world. I am an Associate Architectural Technologist (in the UK) and I have just landed my first eyebrow dormer project. It is one thing to draw it up on CAD but refreshing to see it in the digitised ‘real world’ with a proper explanation. Very informative. Cheers!

  17. Kirk Harmon

    Billy Dillon referenced a inner valley. I am curious to know what this is. I am getting ready to build a new how that will have a eyebrow dormer with sheatrock finish on the in side. I would like the eyebrow shape to come through as opposed to just a radius circle.

    • Joshua Farrand

      Hi Kirk,

      The inner valley is similar to the outer valley shown in the article and it is developed from the drawings. It is what helps tie in the rafters to the eyebrow to bring the shape through. I would highly recommend one of Billy’s classes on the east coast if you are out that way. Starting probably next year we will have a class in OR is my goal if you would like to learn how to do the developed drawings. Cheers, Josh

  18. Jeff Tyler

    Hi Josh,
    Very much enjoyed your article. Perhaps I am just not picturing it correctly, but I think the dormer “plan view” drawing you provide is inaccurate. The rafters should lean toward the top of the bell curve, not away, right?

  19. Shaheen Alikhan

    Thank you! I worked professionally doing carpentry for a few years; I’m doing all my home reno myself, and studying architectural history. I fully agree that pride in workmanship and unique details are sadly lacking, esp in the US. I want to add an eyebrow dormer for the window I just acquired, and like EVERYthing on Youtube is just how to draw one in architectural computer programs. The two that address physical construction of a curve have one pic of the window frame, and the next pic the rafters are on, sheathed, and shingled. This is great, including your learn-as-you-go moments. My project will differ slightly (as they all do!) because that particular sloped roof doesn’t exist yet. Thanks!!

  20. Steve Wakeham

    Just built a eyebrow roof on my front porch . Was about 9 foot wide and about 30 inches high . It went very well.
    Now i’m ready to do the shingles and have been seeing a few different ways to go about that . Any tips on how to go about the layout would be appreciated.
    I noticed on some sites i was looking at that it looks like you could start the first row on the eyebrow with a full course and most likely shrink each course as you are going up or you could run the first course at an angle as it is going up the side of the eyebrow .
    Any tips would be appreciated.
    Thanks Steve Wakeham


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