Hi,

Roof is covering small 11x13 outbuilding. Slope is 4:12. Using 2x8 ridge
board and 2x6 rafters.

No problems with the rafter trig - got that covered. No problem with the
span of the 2x6 rafters either. A mere 11 ft / 2 = 5.5 feet (roughly) - all
to code. Overkill, but I want an R-19 roof.

My question is this: I've looked at a bunch of codes, and I can't seem to
find anything that covers the span of the *ridgeboard*, especially as it
applies to the roof slope. I'm certain the ridgeboard can not span as far
on a 4:12 as it could on a 6:12, for example.

I'm probably overkill like the rest of the roof, but I'd like to know for
100% certain. Snow and 100 mph wind load codes apply at this location.

I know a steeper roof would be more bomber, but I want to match the house.

Any references?



Thanks,

- Nate

"Nate B" wrote in message ...
Hi,

Roof is covering small 11x13 outbuilding. Slope is 4:12. Using 2x8 ridge
board and 2x6 rafters.

No problems with the rafter trig - got that covered. No problem with the
span of the 2x6 rafters either. A mere 11 ft / 2 = 5.5 feet (roughly) - all
to code. Overkill, but I want an R-19 roof.

My question is this: I've looked at a bunch of codes, and I can't seem to
find anything that covers the span of the *ridgeboard*, especially as it
applies to the roof slope. I'm certain the ridgeboard can not span as far
on a 4:12 as it could on a 6:12, for example.

I'm probably overkill like the rest of the roof, but I'd like to know for
100% certain. Snow and 100 mph wind load codes apply at this location.

I know a steeper roof would be more bomber, but I want to match the house.

Any references?



Thanks,

- Nate

I don't think there is a code for it. The 'span' in a properly built
roof is only from one rafter to the next. Collar ties (or joists)
keep the walls from spreading and the rafters support the ridge board.

Harry K

On 29 Aug 2004 07:49:47 -0700, (Harry K)
wrote:

"Nate B" wrote in message ...
Hi,

Roof is covering small 11x13 outbuilding. Slope is 4:12. Using 2x8 ridge
board and 2x6 rafters.

No problems with the rafter trig - got that covered. No problem with the
span of the 2x6 rafters either. A mere 11 ft / 2 = 5.5 feet (roughly) - all
to code. Overkill, but I want an R-19 roof.

My question is this: I've looked at a bunch of codes, and I can't seem to
find anything that covers the span of the *ridgeboard*, especially as it
applies to the roof slope. I'm certain the ridgeboard can not span as far
on a 4:12 as it could on a 6:12, for example.

I'm probably overkill like the rest of the roof, but I'd like to know for
100% certain. Snow and 100 mph wind load codes apply at this location.

I know a steeper roof would be more bomber, but I want to match the house.

Any references?



Thanks,

- Nate

I don't think there is a code for it. The 'span' in a properly built
roof is only from one rafter to the next. Collar ties (or joists)
keep the walls from spreading and the rafters support the ridge board.

Harry K

I'm not a structural engineer, but...

What Harry says is true unless the OP is planning a structural ridge,
meaning no joists or collar ties. In that case, I believe the ridge
supports one-half the total load of the roof, and the walls support
the other half. Posts under the ends of the ridge carry the load to
the foundation.

A steep pitch increases the total weight of the roof system (because
of longer rafters and more sheathing). The snow load stays the same,
so the ridge carries more load (in the case of a structural ridge).

HTH,

Paul

"Paul Franklin" wrote in message
...
On 29 Aug 2004 07:49:47 -0700, (Harry K)
wrote:

"Nate B" wrote in message
...
Hi,

Roof is covering small 11x13 outbuilding. Slope is 4:12. Using 2x8
ridge
board and 2x6 rafters.

No problems with the rafter trig - got that covered. No problem with
the
span of the 2x6 rafters either. A mere 11 ft / 2 = 5.5 feet
(roughly) - all
to code. Overkill, but I want an R-19 roof.

My question is this: I've looked at a bunch of codes, and I can't seem
to
find anything that covers the span of the *ridgeboard*, especially as
it
applies to the roof slope. I'm certain the ridgeboard can not span as
far
on a 4:12 as it could on a 6:12, for example.

I'm probably overkill like the rest of the roof, but I'd like to know
for
100% certain. Snow and 100 mph wind load codes apply at this location.

I know a steeper roof would be more bomber, but I want to match the
house.

Any references?



Thanks,

- Nate

I don't think there is a code for it. The 'span' in a properly built
roof is only from one rafter to the next. Collar ties (or joists)
keep the walls from spreading and the rafters support the ridge board.

Harry K

I'm not a structural engineer, but...

What Harry says is true unless the OP is planning a structural ridge,
meaning no joists or collar ties. In that case, I believe the ridge
supports one-half the total load of the roof, and the walls support
the other half. Posts under the ends of the ridge carry the load to
the foundation.

A steep pitch increases the total weight of the roof system (because
of longer rafters and more sheathing). The snow load stays the same,
so the ridge carries more load (in the case of a structural ridge).

HTH,

Paul


So many books show a gable roof with a ridge beam, that isn't really a ridge
beam kind of roof. I guess this is one of those things where there isn't
really a cookie cutter standard design one can follow.

I'm probably way overbuilding the thing, but I've decided to add in some 2x6
ceiling joists, providing a flat ceiling about 9 inches above the top of the
framed wall. It will look like a capital "A", with the same 4:12 pitch. I
was shooting for a cathedral roof, but that's not to be at this stage. This
will be a best guess at an engineered truss design, I suppose.


- Nate

"Paul Franklin"

What Harry says is true unless the OP is planning a structural ridge,
meaning no joists or collar ties.


Okay - did a quick redesign. This is what I have going on now:

http://www.geocities.com/j_mironescu/roof.doc

Still using a ridge board. Probably should just build these things on the
ground and skip the ridge board, but the former sounds like a little bit
less work. We'll see.

Thanks,



- Nate

On Sun, 29 Aug 2004 11:25:20 -0600, "Nate B" wrote:


"Paul Franklin"

What Harry says is true unless the OP is planning a structural ridge,
meaning no joists or collar ties.


Okay - did a quick redesign. This is what I have going on now:

http://www.geocities.com/j_mironescu/roof.doc

Still using a ridge board. Probably should just build these things on the
ground and skip the ridge board, but the former sounds like a little bit
less work. We'll see.

Thanks,



- Nate

Ok, now you've got collar ties, and you don't need a structural ridge.
The collar ties counteract the force that would otherwise try to push
the walls out due to the roof load. Using collar ties instead of
joists will give you more headroom.

You are right that now you don't need a ridge board; you could build
them as trusses if you like.

Just remember that the collar ties will be in tension, so overlap the
ties and the rafters and nail them off good.

It will be fine, it's just not that big a roof!

Good luck and have fun,

Paul

"Paul Franklin"

Just remember that the collar ties will be in tension, so overlap the
ties and the rafters and nail them off good.

Probably squirt some PL100 in there, too.

It will be fine, it's just not that big a roof!

Like playing with Tonka toys. Fun stuff.




- Nate