Purlin support or not?

[Jeffery L. Haynes]

Joseph,

I use 10psf for dead loads (loads that are static, ie lumber, shingles rafters, etc.) and 40psf for live load (loads which are not permanent, people, snow, furniture etc).

I have a span book for American and Canadian lumber which I carry in my truck... haven't really used it that much simply because I use SPF to build houses.... don't need to mess with other species.

As to google, I am simply stating that there are many charts and calculators.... the website I used was AWC.
http://www.awc.org/calculators/span/...rcalcstyle.asp
I used 10 as a dead load, 40 as a live load (which doesnt just mean snow).....2x6 at 16" O.C., SPF (southern), 360 deflection, grade 2 (which is the most common grade used), no exterior exposure. It calculates out to 8'-7"

Again, I did not inspect it and simply taking a swag based upon your limited pictures and not knowing the type of roof covering, sheathing, etc.

[Joseph W. Keresztury]

[Marcel R. Cyr]

Joe, that little blue book belonged to my father years ago. That is all he had at the time. I used it for years as a young framer until calculators came out and gained the education to use the darn things.
Just keep it for sentimental value now. Makes me laugh everytime I see how much he paid for it. About the price of a cup of coffee today.

[Jeffery L. Haynes]

AWC use to give a small hand book away to GC's.... I got several from them.

[Marcel R. Cyr]

Jeff, that must have been during the days when GC's new how to build, now they are all Brief Case Contractors, so they have no need of those books.

[Jeffery L. Haynes]

Yeah, your right Marcel.........
I also carry a Framer's Bible in the truck..... great little book.

When I hired people for framing one of the main criteria as to determining what they knew was simply taking a framing square and ask them to explain everything on it to me........the majority of the time they said they never noticed all the data that was on a framing square...................if they got past that I would have them calculate the rise and run for steps...........if they could do all that then I started them off at $20.00 per hour.....however more often than not I ended up taking the younger guys who did not have bad habits and train them.......it was a whole lot less headaches for me.
I will say that the best carpenters I have had work for me were always from the north...typically around the New England area..... those guys were pretty sharp.
I have yet to find anyone in the south who is worth their salt when it comes to framing (nothing personal to my southern friends).

Yep, the majority of GC's are paper contractors......most are relying on their subcontractors and the building inspectors to catch any mistakes.

[Marcel R. Cyr]

And some of those building inspectors don't know what they are looking at so they leave it up to someone else to pick up the mistakes.

[Jeffery L. Haynes]

True, many BI's are looking for the most common mistakes...... that is evident by anyone who does phased inspections........ clients are dumbfounded why a sharp HI will have pages of write up's after a BI has given his blessing to move forward to the next phase.

Track homes by far the the worse............ at the same time I guess with all the shoddy work that has been accomplished over the years we should be thankful........we will have jobs long into the next decade. lol

[Kenton H. Shepard, CMI]

Originally Posted by rspermo

A purlin is used to "reduce the length of the rafter". So if the span of the rafter is within the allowable limits no purlin is needed. If a purlin is used to "reduce the rafter span" it must be supported at least every 4' and the purlin must be equal in size or larger than the rafter. The purlin in the picture looks like it it is not being used for support but as a "hanger"!

That's current code, but many, many homes have been built with 2x6 or 2x8 purlin strongbacks and are doing fine. The stongbacks installed will keep rafters on the same plane but without braces will not cut the rafter span. I don't do any calculations. Look for rafter sagging. No sag, no defect. If it's a newer home, the need for a purlin system is the engineer's call.