Doug_N

Roof Lookout Framing Modelling

Recommended Posts

When doing instructions for framing a roof I realized that the CA framing model is somewhat strange for the outlook detail.  Maybe I am doing something wrong but here is what I was hoping for, VS what CA is generating.

2044110849_SuggestedFramingforOutlook.thumb.jpg.503122b95bcb0db741753a66898934fb.jpg

 

Something like what I was expecting.  

 

685425840_CAOutlookFraming.thumb.jpg.81434bbe3b6b2925b1a1652f035cf5e2.jpg

 

How Chef actually models it.

 

Here is a clip from a framing manual.

 

474292628_RecommendedFraming.thumb.jpg.ac57a010690e91de9f0c3683a8f337d3.jpg

 

And finally here is a cross section of what I was hoping for and what I got.

1214483450_RoofLookoutFramingComparison.thumb.jpg.6ba7373c3de35d7c71ef4306ba609bbe.jpg

 

So a couple of questions:

1) How have you detailed outlooks - what is the practice in your area?

2) Have I overlooked some setting in CA that does this automatically?

 

Edit:  When playing with the roof structure DBX here is what I discovered.

Here is the original DBX 

879177594_RoofStructureDBXStanding.thumb.jpg.627293eed511db13bbab54b8e2973f17.jpg

 

And here is a revised DBX Swapping the dimensions for width and depth.

 

571120025_RoofStructureDBXFlat.thumb.jpg.dec6e2f92ec91f51553e55ffa259ea8e.jpg

 

And a much better result!

 

298487081_LookoutFramingFlat.thumb.jpg.791c1201268c4c867e57faba5a9be812.jpg

This still would require a note about notching the rafters I suppose or manually reducing the depth of the rafter to make the outlook members more like purlins.    Any comments?

 

Outlook Framing.plan

 

Share this post


Link to post
Share on other sites

I think Chief does what you want OOB.

Post a plan so we can see what you are doing.

Screen Shot 2021-01-02 at 8.11.55 am.jpg

Share this post


Link to post
Share on other sites

Hi Glenn, Happy New Year!

Not really if you look at the details that I have posted.  The way that the outlooks were modelled were out of correct rotation.  Why?  I have no idea because when I fiddled with the roof structure DBX it stopped doing it, and rotated them to the correct angle.  The OOTB copy still requires notching the gable rafter.  Most framers around here reduce the depth of that rafter so that the outlook can cross the rafer without cutting.

Share this post


Link to post
Share on other sites

This is a long standing bug Doug.  Not sure I remember all the nuances, but I believe it's always triggered by having Auto Rebuild Roofs toggled on and Automatically Build Roof Framing toggled off.  To fix, you have to group select the offending items (using Match Properties makes this quick) and then Cut/Paste Hold Position.  I would also recommend turning OFF Auto Rebuild Roofs or you'll just have to keep fixing it. 

Share this post


Link to post
Share on other sites

Yes, I can duplicate this by turning off auto rebuild roof framing, auto roofs on, editing the plan, and then

selecting a roof and then Build framing for Selected Objects. 

Screen Shot 2021-01-02 at 8.36.17 am.jpg

Share this post


Link to post
Share on other sites
6 minutes ago, glennw said:

Yes, I can duplicate this by turning off auto rebuild roof framing, auto roofs on, editing the plan, and then

selecting a roof and then Build framing for Selected Objects. 

Screen Shot 2021-01-02 at 8.36.17 am.jpg

 

You can also just hit Undo or Save and reopen the plan. 

Share this post


Link to post
Share on other sites

I wrote up a suggestion last fall to be able to manually draw lookouts.  It might be moot if we can draw purlins in X13.

 

As for extending the top plate of the framed gable wall, to reach the subfascia, Chief won't do this, but you can, when editing the wall framing detail.

Share this post


Link to post
Share on other sites
20 hours ago, Alaskan_Son said:

This is a long standing bug Doug.  Not sure I remember all the nuances, but I believe it's always triggered by having Auto Rebuild Roofs toggled on and Automatically Build Roof Framing toggled off.  To fix, you have to group select the offending items (using Match Properties makes this quick) and then Cut/Paste Hold Position.  I would also recommend turning OFF Auto Rebuild Roofs or you'll just have to keep fixing it. 

 

IIRC you noted this action in your Roof Purlin Video about a year ago ?  or at least in that Thread.....

 

M.

Share this post


Link to post
Share on other sites

               I know things are done differently in other parts of the country but this is the way we do our lookouts. 2x6 fly rafter with 2x6 lookout nailed to the end truss. Sheathing applied  and then set on wall.

 

               Hope all have a Happy New Year, Ken

 

 

Roof Lookouts.PNG

Share this post


Link to post
Share on other sites
12 minutes ago, NRST8TRKR said:

               I know things are done differently in other parts of the country but this is the way we do our lookouts. 2x6 fly rafter with 2x6 lookout nailed to the end truss. Sheathing applied  and then set on wall.

 

               Hope all have a Happy New Year, Ken

 

 

Roof Lookouts.PNG

Hi Ken,

Where is your part of the country?

I have seen it done this way in our locality here in Ontario Canada, and it is called a ladder outlook system.  The inspectors are cautious about it because to resist vertical loading past the gable it relies upon the pull-out strength of nails resisting shear loads. I think they make the builders install gang nail plates at the gable joint.    Do you have uplift problems with wind loading with this construction method?  

Share this post


Link to post
Share on other sites
Just now, Doug_N said:

Hi Ken,

Where is your part of the country?

I have seen it done this way in our locality here in Ontario Canada, and it is called a ladder outlook system.  The inspectors are cautious about it because to resist vertical loading past the gable it relies upon the pull-out strength of nails resisting shear loads. I think they make the builders install gang nail plates at the gable joint.    Do you have uplift problems with wind loading with this construction method?  


We do basically the same thing and have no problems whatsoever.  I would note that I only use that method when the barge overhang is under 2 ft. though.  

Share this post


Link to post
Share on other sites

Hello Doug,

 

      I am in the Shenandoah Valley in Virginia No problem with uplift or inspectors here (so far). Never know when that might change.

In the case of a Prow Gable (which is only occasionally for the guys I work with) we build the gable low and run the look outs back to the next truss.

 

   Ken

We just call it a Chicken Ladder

 

Share this post


Link to post
Share on other sites
6 minutes ago, NRST8TRKR said:

Hello Doug,

 

      I am in the Shenandoah Valley in Virginia No problem with uplift or inspectors here (so far). Never know when that might change.

In the case of a Prow Gable (which is only occasionally for the guys I work with) we build the gable low and run the look outs back to the

the next truss.

 

   Ken

 

 

13 minutes ago, Alaskan_Son said:


We do basically the same thing and have no problems whatsoever.  I would note that I only use that method when the barge overhang is under 2 ft. though.  

 

Thanks for that Ken and Michael.  Good to know. 

 

Doug

Share this post


Link to post
Share on other sites

Here's how I handled the lookouts on my duplex garage. 

No worry about shear load strength or sagging since the

2 x 8 fascia boards are sitting on the wall top plate. :)

1743079082_RoofFraming.thumb.JPG.3929be76fc13f56ddc6a0acdb0233869.JPG

12 hours ago, Doug_N said:

...I think they make the builders install gang nail plates at the gable joint.

Not to digress, and I don't claim to know more

than Simpson, but as a woodworker the notion

of gang nail plates drives me crazy. Nails and

nail plates are intrusive wood splitters. Unlike

fastening metal, when joining wood more is not

necessarily better. And if you really want to make

a secure joint a few well places screws will hold

better than a forest of nails. JMHO 

 

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now

  • Member Statistics

    28886
    Total Members
    9156
    Most Online
    DVLOffice
    Newest Member
    DVLOffice
    Joined