Ridge Board

[Energystar]

This question concerns R802.3 Ridge. If we are using 2x12 rafters (for extra insulation), does the ridge need to be 1-piece? The pitch is 5:12 and a 2x8 is enough to support the load (cathedral ceiling). Can we use a 2x8 stacked on top of a 2x6 to cover the ends of the rafters or must we use a 14" LSL?

 

[Sifu]

If it is a ridge board, not a ridge beam (very important distinction), then yes. Way back in the day we often installed additional members to provide the rafter with full bearing.

 

[bill1952]

Based on what I've observed, with 2x12 rafters, often a 1x12 (or 2x12) will be accepted, even though code requires the full depth of the rafter plumb cut.

 

[TheCommish]

hold the ridge board down to the botom so the heal of the plump cut is supported and there space is more open at the top for the ridge vent

 

[SCBO1]

If it is a ridge board, not a ridge beam (very important distinction), then yes. Way back in the day we often installed additional members to provide the rafter with full bearing.

We have allowed a 2x2 to be applied to the bottom edge of the ridge board to bring it down to catch the rafter heel. But as Sifu has noted a beam and a ridge are two different applications.

 

[Energystar]

The ridge is 6 feet long and is a ridge beam. There is no ventilation with >R-15 polyiso on the roof deck (2 layers of 1.5"). It is in CZ-4.

 

[Sifu]

We have allowed a 2x2 to be applied to the bottom edge of the ridge board to bring it down to catch the rafter heel. But as Sifu has noted a beam and a ridge are two different applications.

That is what we did 100% of the time. But, I like the commish's method too.

 

[Sifu]

The ridge is 6 feet long and is a ridge beam. There is no ventilation with >R-15 polyiso on the roof deck (2 layers of 1.5"). It is in CZ-4.

That might change things. The beam has to be sized to carry the load AND provide full bearing. First, size the beam, second, provide it with full bearing. For example, if the beam would require a 9 1/4" LVL, then you could add a piece of 1 3/4" under it to give full bearing. You would not need to upsize the beam just to get to the full bearing in my opinion. Or maybe the commish's method with the beam set to the bottom of the plumb cut.

 

[Energystar]

As I said initially, the load can be supported with only a 2x8. Maybe we put a 2x6 on top and a 2x8 on bottom?

 

[bill1952]

I'd probably use a 2x12, and set based on how you want ceiling to look. You might set it up so bottoms of rafters aligned with bottom of ridge beam. I'd think you either want a crisp crease between planes, a beam, or if a utility building, not care.

 

[Energystar]

Thanks for the good tips. I sounds like no one is overly concerned. Hope the inspector isn't either, or he doesn't look up.

 

[chief-inspector]

Yes but a horizontal drag strut metal tie should tie the pieces together.

 

[Genduct]

This question concerns R802.3 Ridge. If we are using 2x12 rafters (for extra insulation), does the ridge need to be 1-piece? The pitch is 5:12 and a 2x8 is enough to support the load (cathedral ceiling). Can we use a 2x8 stacked on top of a 2x6 to cover the ends of the rafters or must we use a 14" LSL?

If only a Ridge BOARD vs a Ridge Beam as pointed out,
WHY NOT 2 RIPS oF Plywood, STAGGERED FOR A CONVENIENT WAY TO ALIGN THE RAFTERS?

Also, why the extra expense of 2x12's when some "ISO Board could reduce the thickness of the roof assembly especially if it were continuous with a top layer of 1/2 plywood to nail shingles. More effective, don't you think?

 

[Genduct]

The ridge is 6 feet long and is a ridge beam. There is no ventilation with >R-15 polyiso on the roof deck (2 layers of 1.5"). It is in CZ-4.

With the Iso on top, then the inside temp of the sheathing would not hit dewpoint temp and therefore won't need to be vented. I believe