2x4 purlins/braces

What year did it start being required that purlins be at least as large or larger than the rafters they support?

Also what yr was the peak ridge board required to be as larger than the rafters it supports? This home was built in 90.



Question 1: It has been standard practice / building principle since I have been framing in the late 70’s…can’t quote code and it may be a local thing as well.

Question 2: The ridge board (when required) must be a minimum of 1" nominal or 3/4" dimensional however when rafters can be framed to each other with a gusset or approved tie its not required. R802.3

The problem with the rafters are that they heel of the rafter is not touching…the bracing you are showing is acting more as a kee wall and not purlin bracing where the braces are more perpendicular to the rafters.


Richard, being in Texas as you are, with all due respect to Jeffrey 2X4’s were still being used as purlins in the 80’s. My guess to your purlin question is the late 80’s for the change, but a purlin then and now needs to be on edge not flat. As Jeffrey would agree lumber is stronger on edge than flat.
As far as the ridge goes I thought as current code is now that always the ridge should line up w/ or past bottom of rafters. For instance 2x6 rafters woud need a 2x8 ridge.
Also, your picture 2 shows no collar ties which i assume and know were required back then as they are now at every other rafter at ridge connect.

Even with the pitch this roof has?

Yes, the collar ties prevent uplift. With the steep roof the rafters are already headed in that direction.

Joe & Jeffrey,

Thanks for the explanations. I did not even think about the collar tie issue. Some of these homes have so many issues (attic alone) that you can’t seem to keep track of them all. What’s more amazing is that this is a well known custom home builder in the 750k and up range.:roll:

I understand collas and purlins prevent rafter spanning . And collars are under tension. Is purlins concierge to be under comprestion . I thank it on the exam
Text me if you have this answer. Or reply here. 614 496 0468 thank you

Just keep in mind that TREC doesn’t care when the house was built.

In most jurisdictions, collar ties are only required where the designer has specified them.

Collar ties help prevent uplift, but except when the wind is blowing hard enough to produce uplift, collar ties are in compression from the weight of the roof.

The weight of the roof is trying to spread the walls, pulling each end of a rafter tie in opposite directions, meaning that rafter ties are in tension.

Purlin systems reduce the distance that the rafters have to span, but don’t “prevent rafter spanning” unless you mean "over-spanning’…

Most jurisdictions where? You’re in Colorado and I’m in Texas? ? And what designers ? Are you kidding ?
Original poster is in Texas and so am I that you are responding to. Please explain why you know all of this better than I that has local knowledge and experience for over 30 years, as Builder, inspector, consultant !
P.S. and Plan designers around here sure the hell don’t dictate whether collar ties are required ! ! They Draw - Design Plans / Layouts.
Aren’t you the one that calls Purlins - Strongbacks ?

Aren’t you the one that calls purlins- strongbacks ?

In North America. I’m not talking about local knowledge. I’m talking about in general, across North America. Requirements vary by jurisdiction.
No, I’m not kidding. No one plans designs, they create designs and draw plans. Generally, the need for collar ties is called out by the architect ( who usually designs the roof framing) and maybe the engineer.
I was a carpenter in CA, CO, and WA for 32 years, a framing and finish contractor for 5.
I’m not in Colorado. As for you asking me whether or not you’re in Texas… I don’t know where you are. Judging from your snippy attitude, I don’t care where you are.

Why are you getting all bent out of shape?

I didn’t ask you if I was in Texas - I told you I was- As far as you being in Colorado it says you are from there top of your post. I responded to you telling me how- From my quote things are done in local jurisdictions- original poster was from texas and so am I.

Responses above are in response to your quote above a few places above contradicting my statement: Qoute " In most jurisdictions, collar ties are only required where the designer has specified them." Which is not true. How am I being snippy - because I don’t agree w/ you? You disagreed w/ me from post I made 2 years ago ! . Kenton, is it OK that you don’t agree w/ me but not if I don’t agree with you I’m -“Snippy” ? How am I getting bent outa shape you ask, because I don’t agree w/you? I do have respect for you- You have shown none for me!

Joe, this… ?.. is a question mark. It follows a question. You should contact some of those posters who like circular squabbling, you’ll fit right in.