View Full Version : Proper Attic/Roof Construction Techniques Resources

George Potter
02-16-2009, 10:45 AM
As a new home inspector here in Texas, this is my first posting IN. It looks to be a great resource. I'm looking for authoritative resources addressing roof and attic construction techniques and their acceptable building practices. From an inspector's standpoint it would ideally say that when looking at attic structure, here are the things to tick off on your checklist. (I can dream, can't I?)

What started this was that I came across a new home recently, with a truss roof system, where the ridge and hip boards were all laying on their broad sides, rather than on the narrow side. It was the same for any the rafters present. It immediately raised the JDLR alarm, (Just Don't Look Right). I found this condition on at least two homes in the same development, and thought that maybe this was something that was now thought to be OK. County guys said it's passable only if the engineers signed off on it. I'm pursuing that now, but I'd sure like to be more knowledgeable in proper roof construction. Can anyone suggest any website, book, postings or other that is a good starting point for do's and don'ts of such things as the above example?

Thanks so much.

Jeffrey L. Mathis
02-16-2009, 11:48 AM
Something doesn't compute. I've framed for an awful long time and can't make anything of your description. Got a picture?


Ted Menelly
02-16-2009, 12:29 PM
I think he is referring to trusses made up with the 2x not laid on the flat when built but up on their sides as a wall is. I see this on many occasions with some truss framing the way they bring certain parts of the framing together. Looks to be framed more like a floor truss type joist instead of a roof truss. It is just the engineers way to add to the design of the structure and account for what ever needed to make work.

Mike Truss Guy
02-16-2009, 01:22 PM
You might be looking at what is actually either a purlin gable or bracing that is often laid flat on certain hip systems. What you describe as "ridge and hip boards" may also simply be blocking. A picture would really help.

I would also say that there is probably 50 different ways to frame a hip truss system. All of them are acceptable as long as they have been designed by an engineer. Chances are any metal plate connected trussed roof systems built within the last 25 years were designed by an engineer. Finding a copy of that engineering would be the hard part.

George Potter
02-16-2009, 03:19 PM
Here's a couple of pictures, with each showing a 2x6 on the broad side used along the hip ridge and 2x4s on the broad side for rafters. Is this all cricket?

Ted Menelly
02-16-2009, 03:23 PM
That is not what I described but I see that all the time as well. Again this an engineered design. Is it correct. Who knows. We are not the engineers but I have seen many a plan stamped for construction with this designed in.

Billy Stephens
02-16-2009, 06:07 PM
Is it correct. Who knows.
If Some of The Decking Nails had Actually Hit Home ( instead of Attic Air. ) :D

Ted Menelly
02-16-2009, 06:14 PM
If Some of The Decking Nails had Actually Home ( instead of Attic Air. ) :D

Thanks Bill. I don't know what I would do without you sometime.

I was just commenting on the type of framing I see all the time not on the condition of such. Trying to keep to the one subject and not the crowd.

Billy Stephens
02-16-2009, 06:35 PM
Thanks Bill. I don't know what I would do without you sometime.

Your Welcome. :D

Mike Truss Guy
02-16-2009, 11:52 PM
It's still a little hart to tell what's ahppening. At first I suspected, this was a a typical hip with a purlin gable truss. This involves a "non-structural" truss that serves several purposes. First it laterally braces the top chord. Second, it replaces the need for solid (vertical) hip blocking. This is a common way to frame a hip. You have to remember that the structural trusses are designed to support the vertical loads, and the sheathing alone is adequate to carry the loads to the structural members of the truss. This type of hip is preferred by many framers because it reduces the amount of labor-intensive cutting needed at the site.

What throws me off is that I can not see what is happening beyone the first truss - what would normally be a "hip-master" truss. I can not see any jack framing. Also what I would think was a hip-master truss does not seem to be two plies which is pretty standard practice except on very short spans. The pitch looks pretty steep, which makes me wonder if this is a very short setback hip truss. I just can not tell what ius happening, but it looks like an engineered system and is probably fine. It looks well constructed, except for the air-nails which were referenced above.

Jerry Peck
02-17-2009, 07:23 AM
Well, you can tell it was designed for those purlins to lay across the top of those hip step-down trusses by the off-set allowing for their depth on the hip truss top chord.

A.D. Miller
02-17-2009, 07:34 AM
This type of hip is preferred by many framers because it reduces the amount of labor-intensive cutting needed at the site.

MTG: You mean it reduces the amount of skill required, but increases the number of framing staples shot helter-skelter . . .

Wayne Carlisle
02-17-2009, 08:04 AM
One thing that I noticed is the way they layed the decking in the valley. We right this type of installation up all the time.

The decking is not laid perpendicular to the trusses, allowing some of the joints in the decking to span more than the 24" allowed. We require them to block the joints.

Jerry Peck
02-17-2009, 08:37 AM

Yep, I've written that up so many times it is pathetic.

One would think that builders/carpenters/framers would know what they are supposed to do ... nah, never mind, that would be too much to ask ...

George Potter
02-17-2009, 03:25 PM
Guys, thanks for the discussion on the hip aspect, but what about the other photo with the rafters on the broad side? Is that still okie-dokie?

Wayne Carlisle
02-17-2009, 03:28 PM
Yep! Sure is! As Jerry stated, that's why the 1 1/2" notch is in them. To provide an area where the 2X can lay flat.

The truss manufactuer designed them this way.

Joe Billman
02-24-2009, 06:51 AM
If you are looking for some technical information on Truss construction, you may want to look at these two sites: Structural Building Components Association: SBCA - Structural Building Components Association (http://www.sbcindustry.com/) or Truss Manufacturer's Association of Texas: TMAT - Truss Manufacturers Association of Texas (http://www.tmatchapter.com/) . Just don't expect to see may that are installed in accordance with the guidelines (at least in Houston).

George Potter
02-24-2009, 05:50 PM
Thank you, Joe. I'll take a look.

H.G. Watson, Sr.
02-24-2009, 07:04 PM
George Potter,

When your looking at the SBCA free view PDF documents you might want to pay special attention to Permanent Restraint Bracing, especially wood structural purlins and sway bracing on the top chords.