Need a formula to calculate:

-underpurlin top edge and side cut.  It is the roof member that
supports the roof load underneath rafters.  Runs into hips and valleys

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Request for Question Clarification by websearcher-ga on 16 Jun 2005 06:28 PDT

Hi jonoslee:

The following document was the most detailed I could find. Please let
me know whether it contains the information you require.

Span Tables for Residential Building
URL: http://www.chhfuturebuild.com/uploads/Hyspan_structural_laminated_veneer_lumber_span_tables.pdf

Thanks. 

websearcher

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Request for Question Clarification by redhoss-ga on 16 Jun 2005 06:58 PDT

I think that websearcher might be on the wrong track. It sounds to me
that you want a formula to calculate angles required on various cuts
that must be made on purlins and rafters. There are published tables
for this and several tools used by builders to make these cuts. Is
this what you are looking for.

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Clarification of Question by jonoslee-ga on 17 Jun 2005 22:20 PDT

Hello,

websearcher, unfortunately that is not the information I require.  The
attached link is a manufacture's specifications for a factory
developed building product containing span tables and loads.

redhoss, you are definitely on the right track.  There are a lot of
tables on the market that provide the angles in a roof for different
roof pitches, either in degrees or in a rise over run ratio, but I
need the actual formula to be able to calculate it myself.  If there
is a way for me to e-mail further information in the way of diagrams,
please let me know.

Kind regards, Jono

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Clarification of Question by jonoslee-ga on 19 Jun 2005 02:03 PDT

Hello redhoss,

Good find, but unfortunately it does not have the formula I require. 
I bought the most likely manual, but no luck.

Kind regards, Jono

I couldn't believe this website when I found it. This guy has done an
amazing job of explaining your question.

http://www.josephfusco.org/Articles/Roof_Cutting/raftercutting.htm

This is free and he offers some more info that is not. However, seeing
how he explains things, it might be worth a few dollars to buy these:

http://www.josephfusco.org/article_donations_page.html

If you want me to post this as your answer, let me know. If not, I understand.