Roof Bracing

Richard Doty · 03-26-2011, 08:00 AM

What can you tell me about pulin legs as well as ridge, hip, and valley bracing?

What do you write up as deficient?

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**John Kogel** · 03-26-2011, 08:57 AM

You purlin my leg?

Are you asking someone to write you a book?

Somebody's already don dat, "The Journal of Light Construction". JLC Online - Home

**Wayne Carlisle** · 03-28-2011, 08:04 AM

I'll answer your questions as you presented them. Since you only requested information related to bracing, I will only refer to the bracing of pulins, ridges, hips, and valleys.

1. Pulin legs which most professionals call them "purlin braces" are installed to support purlins. You didn't ask anything about purlins so I will skip right to bracing.

Purlins braces shall be 2 X 4's and shall be installed to bearing walls. The slope (angle) shall not be more than 45 degrees from the horizontal and spaced no more than 48" on center. The length of the purlin brace cannot exceed 8 feet without being braced.

So a question on purlin braces for you. What do you do to a purlin brace that is 10' in length?

2. Ridge bracing. This is an open question because there are too many variables to specifically answer this question. However you will need either ridge straps or collar ties every 48" to resist uplift and placed in the upper 1/3 of the attic. The collar ties shall be a minimum of a 1 X 4. The bracing of the ridge also depends on what pitch the roof is? Is it a ridge or a ridge beam? Flat Ceiling or a cathedral ceiling? 3/12 pitch and under or higher than a 3/12 pitch?

3. Hip bracing. Again a little open ended because you did not offer enough information. However I'll give it my best based on general construction in your area. The only requirement for the bracing of a hip is at the point of connection at the ridge and braced to a bearing partition. OR be designed to carry and distribute the specific load at that point.

4. Valley bracing: Again a little open ended because you did not offer enough information. However I'll give it my best based on general construction in your area. The only requirement for the bracing of a valley is at the point of connection at the ridge and braced to a bearing partition. OR be designed to carry and distribute the specific load at that point.

Now.... a question for you. Are rafters required to be framed opposite of each other? Is a ridge required and if so what is the minimum size?

**John Goad** · 03-28-2011, 08:00 PM

The angle of a brace can be more than 45 degrees, but no less than 45 degrees.

Richard Doty · 03-28-2011, 08:43 PM

Originally Posted by Wayne Carlisle

I'll answer your questions as you presented them. Since you only requested information related to bracing, I will only refer to the bracing of pulins, ridges, hips, and valleys.

1. Pulin legs which most professionals call them "purlin braces" are installed to support purlins. You didn't ask anything about purlins so I will skip right to bracing.

Purlins braces shall be 2 X 4's and shall be installed to bearing walls. The slope (angle) shall not be more than 45 degrees from the horizontal and spaced no more than 48" on center. The length of the purlin brace cannot exceed 8 feet without being braced.

So a question on purlin braces for you. What do you do to a purlin brace that is 10' in length?

2. Ridge bracing. This is an open question because there are too many variables to specifically answer this question. However you will need either ridge straps or collar ties every 48" to resist uplift and placed in the upper 1/3 of the attic. The collar ties shall be a minimum of a 1 X 4. The bracing of the ridge also depends on what pitch the roof is? Is it a ridge or a ridge beam? Flat Ceiling or a cathedral ceiling? 3/12 pitch and under or higher than a 3/12 pitch?

3. Hip bracing. Again a little open ended because you did not offer enough information. However I'll give it my best based on general construction in your area. The only requirement for the bracing of a hip is at the point of connection at the ridge and braced to a bearing partition. OR be designed to carry and distribute the specific load at that point.

4. Valley bracing: Again a little open ended because you did not offer enough information. However I'll give it my best based on general construction in your area. The only requirement for the bracing of a valley is at the point of connection at the ridge and braced to a bearing partition. OR be designed to carry and distribute the specific load at that point.

Now.... a question for you. Are rafters required to be framed opposite of each other? Is a ridge required and if so what is the minimum size?

After 8', the 2x4 brace must be changed to a 2x6 brace with a 2x4 "T" that goes all the way to the top of the 2x6 brace and must come to within at least 6" of the bottom. This is what happens for any brace over 8' in length.

90% of all collar ties are 4' in length (and the other 10% are 5'-6') and 2x4's are used now. They are not used for uplift, they are to keep the rafters from spreading, as well as the "shear force" of the winds here locally in my area. If it is a cathedral ceiling, the size of the ridge depends on the pitch and the lenth & size of the rafter, & the load it must carry, especially if it carries roof load.

The hips or valleys do not actually require bracing at the ridge. If there was a purlin required for that span, then the hip and/or valley would need a brace where the purlin runs into it.

Rafters are required to be opposite each other at the ridge with the exception of the triple rafters put in to carry the load for brick.

Ridges are required and the depth of the ridge must be equal to or greater than the pitch cut on the rafter. Even if trusses are installed, blocking is required between each truss at the peak in order to stiffen up trusses and provide solid blocking for the roof sheathing.

Question for you: What is the code for purlin location for comp roof & for slate & tile roof?

Richard Doty · 03-28-2011, 08:47 PM

Originally Posted by John Goad

The angle of a brace can be more than 45 degrees, but no less than 45 degrees.

John,

Double check that information please. Maximum angle for any brace is 45 degrees. Braces can be 90 degrees to 45 degrees compared to the wall. The perfect angle, at least for roofs up to a 12/12 (45 degrees) is to be at 90 degrees off the rafters, and when this is done, the pitch cut on the brace, is the pitch of the rafter.

**John Goad** · 03-29-2011, 04:17 AM

At any angle more than 45 degrees you are getting closer to being vertical, any angle less than 45 degrees you are getting closer to being horizontal, so the angles of a brace should be no less than 45 degrees.
Collar ties are in the upper 1/3 of the rafters & help to resist wind uplift, rafter ties are in the lower 1/3 & resist rafter spread.

**Wayne Carlisle** · 03-29-2011, 07:17 AM

Originally Posted by Richard Doty

After 8', the 2x4 brace must be changed to a 2x6 brace with a 2x4 "T" that goes all the way to the top of the 2x6 brace and must come to within at least 6" of the bottom. This is what happens for any brace over 8' in length.

Code section please.

Originally Posted by Richard Doty

90% of all collar ties are 4' in length (and the other 10% are 5'-6') and 2x4's are used now.

Possibly common practice. I see 4' 2X4's all the time also.

Originally Posted by Richard Doty

If it is a cathedral ceiling, the size of the ridge depends on the pitch and the lenth & size of the rafter, & the load it must carry, especially if it carries roof load.

Not true. If the ceiling is a cathedral ceiling then the ridge must be a beam/girder or a wall to support the loads.

R802.3.1Ceiling joist and rafter connections.
blah blah........Where ceiling joists or rafter
ties are not provided, the ridge formed by these rafters shall be
supported by a wall or girder designed in accordance with accepted engineering practice.

Originally Posted by Richard Doty

The hips or valleys do not actually require bracing at the ridge. If there was a purlin required for that span, then the hip and/or valley would need a brace where the purlin runs into it.

That is also not true.

R802.3 Framing details.
Rafters shall be framed to ridge board or to each other with a gusset plate as a tie. Ridge board shall be at least 1-inch (25 mm) nominal thickness and not less in depth
than the cut end of the rafter. At all valleys and hips there shall be
a valley or hip rafter not less than 2-inch (51 mm) nominal thickness
and not less in depth than the cut end of the rafter. valley rafters shall be supported at the ridge by a brace to a bearing partition or be designed to carry and distribute the specific load at that point. Where the roof pitch is less than three units
vertical in 12 units horizontal (25-percent slope), structural
members that support rafters and ceiling joists, such as ridge
beams, hips and valleys, shall be designed as beams.

Originally Posted by Richard Doty

Rafters are required to be opposite each other at the ridge with the exception of the triple rafters put in to carry the load for brick.

The code does not actually specify that the rafters be framed opposite each other. However placing them opposite of each other provides a stronger roof. The code only specifies "framed to a ridge board or"

R802.3 Framing details.
Rafters shall be framed to ridge boardor to each other with a gusset plate as a tie.

Originally Posted by Richard Doty

Even if trusses are installed, blocking is required between each truss at the peak in order to stiffen up trusses and provide solid blocking for the roof sheathing.

Please provide a code section where this is required.

Originally Posted by Richard Doty

Question for you: What is the code for purlin location for comp roof & for slate & tile roof?

The purlin location depends on the size of the rafter used and the dead load of a comp roof or a slate/tile roof. If the rafter is sized to carry the load for the length of the rafter a purlin is not required.

You know Richard...it sounds like you have a lot of "framing" experience but do not have any "code" experience.

Richard Doty · 03-29-2011, 11:27 AM

Originally Posted by Wayne Carlisle

Code section please.

Possibly common practice. I see 4' 2X4's all the time also.

Not true. If the ceiling is a cathedral ceiling then the ridge must be a beam/girder or a wall to support the loads.

R802.3.1Ceiling joist and rafter connections.
blah blah........Where ceiling joists or rafter
ties are not provided, the ridge formed by these rafters shall be
supported by a wall or girder designed in accordance with accepted engineering practice.

That is also not true.

R802.3 Framing details.
Rafters shall be framed to ridge board or to each other with a gusset plate as a tie. Ridge board shall be at least 1-inch (25 mm) nominal thickness and not less in depth
than the cut end of the rafter. At all valleys and hips there shall be
a valley or hip rafter not less than 2-inch (51 mm) nominal thickness
and not less in depth than the cut end of the rafter. valley rafters shall be supported at the ridge by a brace to a bearing partition or be designed to carry and distribute the specific load at that point. Where the roof pitch is less than three units
vertical in 12 units horizontal (25-percent slope), structural
members that support rafters and ceiling joists, such as ridge
beams, hips and valleys, shall be designed as beams.

The code does not actually specify that the rafters be framed opposite each other. However placing them opposite of each other provides a stronger roof. The code only specifies "framed to a ridge board or"

R802.3 Framing details.
Rafters shall be framed to ridge boardor to each other with a gusset plate as a tie.

Please provide a code section where this is required.

The purlin location depends on the size of the rafter used and the dead load of a comp roof or a slate/tile roof. If the rafter is sized to carry the load for the length of the rafter a purlin is not required.

You know Richard...it sounds like you have a lot of "framing" experience but do not have any "code" experience.

I have over 30 yrs of framing experience, Framing houses as big as 15,000 sq ft and for the past 15 yrs prior to 08, never framed anything smaller than 6,000 sq ft. Framed big commercial as well - structure codes are even more strict. You kept asking me for the exact code, but I don't know that information, I do know those are the facts for IRC structural code enforcement of wood construction. Those are all multi-million dollar homes and commercial structures. The schools I framed fall under what they classify as "F5", which means the strictest and most structurally sound building for wood classification that there is. Residentual is not near as tough. All framers with my experience, know all structure codes by heart, we just don't know the "numbers" of the codes because we know too many and they far exceed the codes we are required to know for home inspection.

The end of the ridge is braced, and that supports the hip. I may have told you wrong about the valley bracing, we do put a brace, within 4' is the actually code specifics, to support valley. The hip, because of the intersection design, does not have to have a brace near the top, as long as the ridge itself is braced, ON THE VERY END though.

Purlin location is 11' 6" on rake run of rafter. That distance can't be exceeded from collar tie to purlin, from purlin to purlin, or from purlin to plate. Slate/tile the run is 9' 6" and that is for upsizing the rafter to 2x8 and 2' centers - for 2x6 rafters can be used , but at 16" centers.

If rafters are not across from each other at ridge, you will always get a red tag - means you must fix it.

The ridge on cathedral ceiling, again, depends on span and load. Some are small enough, that 2x8 ridge is just fine.

This is the difference between a book, and real life practice. Everything I have stated is in the SBC (Southern Building Code for states in the south) and in the IRC as well. These codes have to be applied to "live loads" , never a "dead load". The live loads we use, are for max loads, in order to carry x - amount of this or that, depending on what part of the house you are talking about.

As an "elite class" framer, I can move load bearing walls, turn one story into two-stories and frame any plans in front of me. The codes you know for stairs, for example, are a little incomplete as well. It will be that way for all you know about structure. You have to actually experience it every day, with actually building it - not just inspecting it.

I will have to say, you are knowledge is pretty good if you haven't framed before.

Ask me any question you like under the complete structure section. I can take the codes that you know, and add to them and finish them to explicit details.

**Jerry Peck** · 03-29-2011, 04:39 PM

Originally Posted by John Goad

The angle of a brace can be more than 45 degrees, but no less than 45 degrees.

Originally Posted by Richard Doty

Double check that information please. Maximum angle for any brace is 45 degrees. Braces can be 90 degrees to 45 degrees compared to the wall. The perfect angle, at least for roofs up to a 12/12 (45 degrees) is to be at 90 degrees off the rafters, and when this is done, the pitch cut on the brace, is the pitch of the rafter.

The angle can be more, or less, than 45 degrees, all you need to do is specify 'from where' ... the angle can be 45 degrees or greater from horizontal, or, the angle can be 45 degrees or less from vertical.

**John Goad** · 03-30-2011, 04:19 AM

... & the code does specify,...at a slope not less than 45 degrees from the horizontal.

**Wayne Carlisle** · 03-30-2011, 06:33 AM

Richard, I understand where you are coming from when it comes to building things "to code". However a lot of the things you did were "above" code. Yes your construction methods are quite superior to other but with me being a building official I cannot require some of the things that you are stating as code.

Like the purlin braces for a slate roof. IF you used a specific size of rafter and the span tables in the IRC specified that the particular rafter would only span X amout of feet, then you would be required to install purlins. If the rafter was sized to carry the load of slate for X amout of load and you did not overspan that length then a purlin would not be required.

I too framed for several years and was taught by a real carpenter. I remember he used to take a 2X4 and ram it against the roof sheathing to see if I nailed it good enough.

Again...several of the statement you make are not code however it is good quality construction.

As far as the purlin braces go here is what the code actually says about the angle.

R802.5.1 Purlins.

Installation of purlins to reduce the span of rafters

is permitted as shown in Figure R802.5.1. Purlins shall be
sized no less than the required size of the rafters that they support.
Purlins shall be continuous and shall be supported by 2-inch by
4-inch (51 mm by 102 mm) braces installed to bearing walls at a
slope not less than 45 degrees from the horizontal.

**Jerry Peck** · 03-30-2011, 02:34 PM

Originally Posted by John Goad

The angle of a brace can be more than 45 degrees, but no less than 45 degrees.

Originally Posted by John Goad

At any angle more than 45 degrees you are getting closer to being vertical, any angle less than 45 degrees you are getting closer to being horizontal, so the angles of a brace should be no less than 45 degrees.
Collar ties are in the upper 1/3 of the rafters & help to resist wind uplift, rafter ties are in the lower 1/3 & resist rafter spread.

Originally Posted by John Goad

... & the code does specify,...at a slope not less than 45 degrees from the horizontal.

And this "from the horizontal" was not included in your previous posts, see above, and which is why that needs to be specified.

The lack of that reference lead to Richard stating:

Originally Posted by Richard Doty

John,

Double check that information please. Maximum angle for any brace is 45 degrees.

Richard did give a reference point, albeit a confusing one; "Braces can be 90 degrees to 45 degrees compared to the wall."

The braces are not "90 degrees ... to the wall", the braces would be parallel with the wall (i.e., vertical) to 45 degrees from vertical - which is just another way of saying that the braces must be 45 degrees or more from horizontal.

I could see the lack of communication between you two from way down here

, so I posted clarification of the angle and its reference point. No angle means anything without a given reference point, which is typically related to "level" (i.e., "horizontal") ... but not always referenced to horizontal.

Richard Doty · 03-30-2011, 05:12 PM

Originally Posted by Jerry Peck

And this "from the horizontal" was not included in your previous posts, see above, and which is why that needs to be specified.

The lack of that reference lead to Richard stating:

Richard did give a reference point, albeit a confusing one; "Braces can be 90 degrees to 45 degrees compared to the wall."

The braces are not "90 degrees ... to the wall", the braces would be parallel with the wall (i.e., vertical) to 45 degrees from vertical - which is just another way of saying that the braces must be 45 degrees or more from horizontal.

I could see the lack of communication between you two from way down here

, so I posted clarification of the angle and its reference point. No angle means anything without a given reference point, which is typically related to "level" (i.e., "horizontal") ... but not always referenced to horizontal.

Thanks Jerry, I did sound a little confusing there didn't I?

Just like one of the Minyans on Dispicable Me sais "Whaaaaaaaaat?"

My 2yr old grandson goes around saying that all the time. When he's over, it's Dispicable Me time. He makes me laugh so much. Grandkids are so great. I do my best to feed him all kinds of candy, a pot of coffee, and whatever else I can think of (just kidding) and send him home to mom. Ha, Ha!!