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Mansard roof with flat eaves. 3 roof pitches per side?

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Hello! I'm trying to achieve the look of a mansard roof with a flat eave that extends out 2' or so. I want the high pitched roof plane to stop at the wall, and then extend straight out 2' for the eave. Is doing 3 roof pitches per side the best way to achieve this look? With the eave basically being a flat roof plane. Or, is there a better way to do this? Attached are some examples. Thank you for your help!

 

Monty

 

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That element of the building is called a Cornice.  As such, its not so much part of the roof, though in the example you show it does feel like an extension thereof.  I'd build it with solids and 3d molding profiles.

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You could manually add a roof plane and make it flat -- or a very low pitch then add brackets.

Alan

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Monty............Building a basic Mansard roof style in CA is fairly easy, using three roof planes, especially with the roof improvements CA has added with the last couple of versions. The complexity comes in when you start adding all the molding details that are usually associated with this type of style. One thing to remember is that the overhang does not have a flat pitch. Almost 100% of the time this overhang had a "built-in" gutter and the overhang was pitched accordingly to pitch the water to the gutter. I've seen not only a low pitch coming off the steep pitched roof to the gutter, but also a slight pitch from the outside edge of the of the cornice back toward the gutter. This all can be shown correctly in CA, but is quite time consuming to get everything correct. It's much easier to show a well drawn out cad detail of this and just get it "close" in the 3D model. As for myself, being and experience user showing a lot of historical detail on my projects, I would consider it a challenge. If you are a fairly new user, well-- good luck.

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Thank you for the tips! This is where I'm confused. A few questions:

 

1) With a cornice in this style, is the eave a massive piece of molding or part of the roof? 

2) What are the pros/cons doing the eave section as a roof plane vs solids and molding profiles? 

3) What's the minimum pitch for a roof plane to properly move the water? 

 

For the 3D model I was thinking of doing an almost flat roof plane. Then, use the shadow board setting for the rake trim, the frieze board for all the other trim except the corbels, then, place the corbels manually.

 

Or,

 

Not use a roof plane, and do it with solids and molding profiles.

 

Any more thoughts would be appreciated! I have "Get Your House Right" coming which I'm hoping details how a very large cornice with built in gutters is actually constructed. 

 

Monty

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Monty..........I would design it just like you would build it. The pitch on the overhang area should be no less than 1.5/12 and 2 to 2.5 even better. It depends on where you locate the gutter and how deep you make your overhang. The material for roofing this overhang should be either flat seamed tin or copper. The use of any other material and I'm sure you with run into water problems in short order. Before doing a project like this, do your "homework". If at all possible study some actual Mansard roofs up close. If that isn't possible, you should be able to find info on the internet. What area of the country do you live in? Snow load & ice damming could be a factor you should think about also.

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If you plan to model the cornice the same way you build it, then you may want to draw up a section first to work out all your connections.  There are many different ways you can build a wood cornice in your examples.

 

However, if want to model it visually for presentation purposes first... id personally use molding 3d poly-lines and do a build-up.  Later you could come back and do 2D details or remodel sections to get your working drawings done.  In fact, you may want to get an engineer or architect to review your work before completing the structure.

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Thanks Larry and Johnny! 

 

This is just my first draft. I'll definitely be taking my plans to the experts for issues such as this.

 

I'm in Utah, so snow and ice is a factor.

 

I'll be doing more research. I took a look at a mansard roof on a porch today. The gutter is "built in" and the shingles appear to be made out of a stone material. It's a 100 year old building that has been recently remodeled. The top had a drain in the middle. We have a lot of Victorian houses around here but they were built 100 years ago so it will be interesting to learn the differences between old and new construction. I'm just getting started so I appreciate the help!

Monty

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From your pictures it's hard to tell what I'm looking at. This looks like some type of new construction and not a typical Mansard style roof. The "stone" material is slate. Slate normally is installed on much steeper pitches. In the picture it's hard to tell what the pitch is, but it doesn't look steep enough for the use of slate. Slate was used quite often (if not always) during the time when the Mansard style was poplar, but only on the steep pitched area. The flatter top and overhang sections were almost always flat seamed tin. To save on cost today these less sloped areas would probably be covered by rubber membrane roofing. One thing most people don't think about is that a flat seamed tin roof, properly installed and taken care of, can last 100 years. A rubber membrane roof won't last a third of that time.

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Thank you for the info! Yes, I couldn't get on top of the building so that was just the porch roof that I could see from the second floor. I'm sure the only reason the porch used slate on the sides was to match the slate on the high pitched roof.

 

OK. So flat seamed tin roof with slate. Got it!

 

Monty

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You only knew some IDIOT was gonna do it. And that be me..!

 

Using polylines solids, trim moldings, roof tool, some symbols scrounged from the WWW, and hot pockets, I swizzled my way through this monster in 10 minutes. Of course I only dressed up 2 sides. But who's counting. Then I thought, hummm maybe I should make a video, but who the H  E  Double Hockey Sticks is gonna want to do something like this crazy thing again... Oh Yea And That Be ME....!

 

So no vid, but here are all the cool items loaded up in the plan.

 

--Dave 

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Untitled 1.zip

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Thank you Dave! I'm already a fan of yours so this was a major surprise. Awesome!

 

Monty

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Nice touch and a beautiful job Dave!!! :)

 

Thanks -

 

Toodles...!!

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Thank you Dave! I'm already a fan of yours so this was a major surprise. Awesome!

 

Monty

 

 

Glad I was able to help..!

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