Roof Rafters?


KnotSquare
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I have a home where we are building a timber frame inside of a conventionally framed home. I have created a small model to figure out how to get the Great Room roof to behave the way I want prior to transferring this data into the actual model.

 

I am running into issues with the 2x14 rafters at 24" o.c. As can be seen in this view, they are turning into a solid block with the bottom outside edge coming to a point instead of flattening out as the fascia board (grey) does.

 

image.thumb.png.ce05bd39787d8de282b413110fb1ca78.png I think I have the default settings correct, but I guess not... (See "Default Framing Settings.png")

 

 

 

I created a custom layer set named Framing Layer Set + Post & Beams to show and duplicate the timber frame members. The timber frame outside the building is designed for the covered deck for the view side of the home with a deep overhang. See "Frmg + Post & Beam.png".

 

I have also attached this small model for trouble shooting.

 

Thanks for any insight.

 

Mark

 

 

Default Framing Settings.png

Frmg + Post & Beam.png

Fisher Roof & Timber Frame.plan

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Michael,

 

No, I am happy with the plum cut. It is not trimmed at the bottom as the grey fascia is. I also do not have 2x14 rafters in the Perspective Framing Overview. It seems to be one solid block of wood, not framing members.

 

I cannot tell if my timber frame beams is confusing the framing program or what is going on.

 

I also expect a grey subfascia per my default settings.

 

Thanks for the compliment on the Perfect Wall System. I have come up with my own method of continuing the insulation to the underside of the roof sheathing. It is nice to work on homes that are for folks that seem aware of the need to reduce fossil fuel consumption.

 

Mark

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Hi Mark,  It seems there are a bunch of issues.  The reason the setting that Ryan is suggesting is not available is because your rafters are not set to be framing.

 

image.thumb.png.bfe16440d8aabeb4d5ea71fed7cfd0c0.png

 

Then if you don't want your rafters showing on the outside you need to make a bunch of changes to your settings.

 

image.thumb.png.b1a02d09f0fd7beea4f57ae4acb5a102.png   image.thumb.png.822e1c23da8310c3ed717c22b3600122.png

 

image.thumb.png.de8bbab6f5ac38d9b601e9e0d4d748bf.png

 

This may not be exactly what you were after but those are the setting to play with to make the adjustments required.

The rafter trim  is based on the sub fascia depth.

 

 

 

 

 

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15 hours ago, KnotSquare said:

I have a home where we are building a timber frame inside of a conventionally framed home. I have created a small model to figure out how to get the Great Room roof to behave the way I want prior to transferring this data into the actual model.

 

I am running into issues with the 2x14 rafters at 24" o.c. As can be seen in this view, they are turning into a solid block with the bottom outside edge coming to a point instead of flattening out as the fascia board (grey) does.

 

image.thumb.png.ce05bd39787d8de282b413110fb1ca78.png I think I have the default settings correct, but I guess not... (See "Default Framing Settings.png")

 

 

 

Mark -

To get your rafters to "frame"...you need to go to the roof structure tab and make sure to check the "framing" box...otherwise chief will not "frame" the structure...it will be a solid block as you have now. 

2022-11-18_10-58-59.thumb.png.40e5c6e48f997ff345dc0c9f3a8391da.png

 

Regarding the soffits...you need to check "Soffits" and "flat under eave sub fascia". Then...on the materials tab, make the soffit material "open no material". This will make Chief trim the rafters flat...but will not create a "soffit". It's there...but you won't see it. 

 2022-11-18_11-00-02.thumb.png.939c4d66cb852f0da79271a7e89909bb.png 2022-11-18_11-00-08.thumb.png.8002c46406494d250c09744c84876bb1.png

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This is getting closer. I am going to attach a couple of custom details developed for how I am managing the continuous insulation. I realize that Chief will never be able to model this automatically, but using enclosed soffits, I feel I should be able to achieve the look. See “Mineral Wool Perfect Wall ISO Det-Layout1.pdf” & “Perfect Wall Rafter System + Applied Eave @ Top Plate Connection.pdf”.

So, I did as both Chopsaw and Steve suggested and whalla, I have the rafters in place. They Full length however and do not have a flat cut bottom. I do not know how to set this. See “Pointy Rafter Tails.png” and “Rafter & Timber Section.png”.

To achieve the look I am after, to scale, the only thing I can think of is no overhang and build these manually to match the detail, but I feel this is good enough at this time unless someone knows a shortcut.

Thanks everyone. Really appreciate the insight,

Mark

Rafter & Timber Section.png

Pointy Rafter Tails.png

Perfect Wall Rafter System + Applied Eave @ Top Plate Connection-KS Calc Sheet.pdf Mineral Wool Perfect Wall ISO Det-Layout1.pdf

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31 minutes ago, KnotSquare said:

So, I did as both Chopsaw and Steve suggested and whalla, I have the rafters in place. They Full length however and do not have a flat cut bottom. I do not know how to set this. See “Pointy Rafter Tails.png” and “Rafter & Timber Section.png”.

 

18 hours ago, rgardner said:

AE18A56F-7212-418C-AE32-992FACBF7743.thumb.jpeg.a02986d5f91657b6a2d1fd57e498eb16.jpegtry setting it to trim framing to soffits in roof dbx

 

15 hours ago, Chopsaw said:

The reason the setting that Ryan is suggesting is not available is because your rafters are not set to be framing.

 

image.thumb.png.bfe16440d8aabeb4d5ea71fed7cfd0c0.png

 

Then if you don't want your rafters showing on the outside you need to make a bunch of changes to your settings.

 

image.thumb.png.b1a02d09f0fd7beea4f57ae4acb5a102.png   image.thumb.png.822e1c23da8310c3ed717c22b3600122.png

 

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Steve,

 

If you view the attached details attached as PDFs you will see that the soffit will show. I do believe that if I want it dimensionally correct, and not directly connected to eliminate thermal bridging through the rafters I will have to model them independently and paste them on. The work around for presentation will be to fuss with depths on the overhang, height of the soffit, etc. to at least appear correct in the Perspective Full Overview for determining window heights, rendering, etc. to please the client.

 

If you know any shortcuts, please share.

 

Thanks,

 

Mark

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That message was four hours ago with to images in the text body and the detials were named, "Perfect Wall Rafter System + Applied Eave @ Top Plate Connection-KS Calc Sheet.pdf" and "Mineral Wool Perfect Wall ISO Det-Layout1.pdf" if you are interested in my method of doing this in the field. Now I just need to represent it in Chief, but I am close.

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3 hours ago, KnotSquare said:

Thanks,

 

Mark

Hey Mark, thanks for giving me the resolution thumbs up yesterday, however it looks like Glen, Steve, Ryan and Chop actually gave you the correct resolution.  One of them should get the credit.  I'm glad they figured it out for ya!

 

I'd def be interested in the two methods (pdf's) you mentioned.  How can I find these?

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@KnotSquare Mark - I looked at the PDF's you attached. I'm not clear on the "furred" framing detail. Is the framing meant to be attached to the surface of the insulation? Is the furring meant to be horizontal or vertical? The detail is not clear as to the "furring"...unless it's just another stud wall and the insulation is placed in between each stud? 

 

Is the siding attached directly to the furring strips?

 

Just FYI...Chief will always place the soffit directly against the main layer....so, that is unavoidable. However, in a detail you could use a cad mask to hide this...or, like you said you could use a molding polyline to create the soffit. 

 

Also...the 2x member of the fascia should be the "eave fascia"...not the "sub facia". The only way you will see the "sub-fascia" in elevation is if you turn the rafter layer on in a layer set. I'd probably make the fascia a 2x and use a "shadow board" for the other piece of fascia trim...and make the sub-fascia 1/16" thick to make it disappear. 

2022-11-19_10-10-12.thumb.png.ea004a2021aa433b8823e32fcd6a0d93.png

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Michael Leach,

Here is the full set of solutions as I have them so far.

If you use AutoCAD, I would be happy to supply you with .dwg files. Anything for an attempt at solving my Chief problems.

Hit me up at mark@knottystudios.com. I would like to talk Florida a bit with you. Considering Snowbird action.

Thanks Michael

Mineral Wool Perfect Wall ISO Det-Layout1.pdf Perfect Wall Common Truss @ Top Plate Connection-KS Calc Sheet.pdf Perfect Wall Rafter System @ Top Plate Connection-KS Calc Sheet.pdf Perfect Wall Rafter System + Applied Eave @ Top Plate Connection-KS Calc Sheet.pdf

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Steve Nestor,

 

Great information on the eaves, especially understanding how soffit works.

 

I had already determined that using subfascia was not going to work and did just as you suggested.

 

As for the furring or firring, not sure which is correct actually and I have been in this industry since 1994, the 1x4s hold the mineral wool in place. You run the bottom course and then attached 1x4s and slide in the remaining insulation behind them for a quick assembly and it saves you on buying Rockwool's plastic, large washer "buttons".

 

I prefer (2) layers of 1.5" over a single layer of 3" so I can lap the seams for better air-tightness. Comfortboard 80 now comes with a slightly tapered edge, so they like to state that a single layer is plenty air tight. I guess it just depends on your client. On the house I have been trying to resolve in this thread, we are going for PassivHaus standards, so (2) layers is better.

 

There are images on Rockwool's site, but you can see plenty of damaged edges either due to shipping or builders not handling with care.

 

Thanks for your tips,

 

Mark

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