Roof with collar ties fails

I’m new to ClearCalcs and not a structural engineer but the app is very helpful.

Things look good until Governing… what’s up?

Bending: 73%
Shear: 70%
Bearing: 0%
ST Deflect: 12%
LT Deflect: 3%
Governing: FAIL


I have raised this topic previously on this forum. The calc is checking the overall rafter deflection but setting the limit based on the length of the exposed portion of the rafter only. It throws the comparison off to the point that it has to be ignored. Something like that… I suggest adjusting your deflection limit in the settings to very atypical ratio, like L/20 instead of L/180 or L/240 or other. That way, it won’t show an error.

**Please consult an engineer to verify this recommendation for your own use. This is not a professional opinion and I don’t want to offer advice on a situation that I may be misunderstanding. It is just my own experience that this module can be glitchy.

1 Like

Hi @jim4clearcalcs, welcome to Blueprint! And thanks for the reply @WilsonEngineers :wink:

In this case, I don’t think the issue is related to the deflection limit, but I agree with you @WilsonEngineers, we need to improve the deflection check logic of the calculator.

It looks like the problem is that the Depth of Second Tie = 9.86 ft is greater than the Maximum Tie Depth = 9 ft 4 in. You can see more details about what’s failing by hovering over the red “FAIL” on the top bar – check the screenshot below. We need to improve the visibility of these messages, and I’ll bring this issue to the team.

I hope this helps!