# Ridge Beam?



## RazrRebel (Apr 16, 2013)

Hey guys, been building my 16' x 24' cabin, now I need some help. I am not a carpenter, but I do my own when I can. Before I ask my cabin is on my private property. It has no road access, so no chance of inspections or anything like that. I need some help on how to size a ridgebeam for the 24' spread. There will be no posts except the ends. I will have a full loft. I started looking at beams and, was surprised to see 2" x 4" stacked, glued, and screwed to make a beam. I was thinking a 2" x 8" x 16' with a 2" x 8" x 12' for length, with OSB in the middle, scewd and glued to make a gluelam beam. This beam would be stood on edge. I saw a guy do a beam with the 6 or 8, 2" x 4" stacked and glued and bolted to span 20'. Anybody think it will be allright. The extra length will be trimmed to fit for overhang.


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## TnAndy (Sep 15, 2005)

First let's talk some carpentry terms.

I assume you will be using a rafter system, not trusses, since you mention "loft".

This is normally done two ways:

1. A ridge *BOARD*.....generally a 2x (though I've seen 1x used) that the ridge end of the rafters butt INTO from each side. The real purpose of the ridge board is to give you something to prop the rafters against while installing them, and to tie the roof together somewhat, end to end wise, until you get the sheathing on the roof (which is what REALLY holds the rafters in place, and prevents the roof from 'racking' out of square).

Here, for example, is a rafter system with 2x6 rafters, a 2x8 *ridge board*, on a 6/12 slope, running into an existing 10/12 sloped roof. 1x6 lumber used for sheathing. (this is actually an addition onto the back of my own garage I now use for a canning kitchen and meat cutting room)










2. A ridge *BEAM*....which can be made several ways....solid lumber (like a 4x8, etc) or built up lumber, like you propose, and so on. The beam usually sits UNDER the joining point of the rafter ends. It does some minor supporting, again, giving you a place to sit the rafters until fasten them together, like the ridge board, it ties all the rafters together end to end, but if your roof slope is steep ( and again, I assume it is because of that loft), the beam is more decorative than structural. The lower the slope of your roof, the more structural a beam becomes (as well as the support points under the beam).

*The rafters butting together bear the majority of the load*...you could leave out a ridge board or a ridge beam, and it would have almost no effect on the strength of the roof, assuming your slope is enough.

So the way you build your beam, if you do decide to use one, pretty much doesn't matter. It's simply NOT doing that much. Unless you want it for decoration, I'd simply go with the ridge board as pictured above and save yourself a lot of effort. 

What probably matters MORE is that you support it someplace near the center of your 24' span with a post or wall of some type....because hanging that extra weight up there will put more downward pressure on the ridge, which in turn will cause more outward pressure on the lower walls the rafters sit on, causing them to move outward, out of plumb, unless you have interior walls running perpendicular to the outside wall that can tie into it. (often cabins are "open concept" )


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## Fishindude (May 19, 2015)

Two ways to do this:

Have a ridge beam like you are talking about that the rafters bear on top of. A 24' Span carrying that entire load is more than can be done with conventional lumber. This will require a glue-lam engineered type beam you can get from the lumber yard, or you will need to field construct a beam using 2x material and OSB all screwed, glued and laminated together to create a deep structural beam. 

If I was just going to wing it, I'd go with (2) 2x10' stacked on edge, (2) layers of 3/4" OSB between, then (2) more 2x10's stacked on edge, the entire works laminated and bolted together (laps staggered) to create a beam 19-1/4" deep x 4-1/2" thick. Somebody smarter than me could give you exact size / materials required.

Another option is to eliminate the beam and have a center ridge board that the rafters butt into. The ridge board can be standard 2x12 or similar material. This requires real accurate cuts of the rafters at the peak where they butt into ridge board, and the notched bottom where they rest on stud wall. Then do horizontal collar beams about 1/3 of the way down from peak tying each pair of rafter to rafter to prevent them from spreading. This will consume a bit more head room.


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## RazrRebel (Apr 16, 2013)

I'm always so confused when trying to figure this out. One reason for the homemade gluelam beam is the length, another is for headspace in the loft. I can't figure out your measurements. I searched glulam beams on you tube and confused myself even more when I saw people and companys turning their lumber flatside down and stacking it and glueing and bolting it to make a beam. I can get how you get 4 1/2" , where does the 19 1/4" deep come from.


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## Fishindude (May 19, 2015)

*where does the 19 1/4" deep come from.*

(2) Vertical 2x10's (9-5/8" true depth) standing on edge, stacked on top of one another.


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## RazrRebel (Apr 16, 2013)

I see now, that would tie up almost two foot of headspace right in the middle.If I can get by with a ridge board I'd rather do that. Would I just use a homemade gluelam beam to have the length and use that for a ridge board, or just splice and plate a 2 x 12 for length? If my outside wall are tied together with the loft joists, would I still need collar ties? Theres no way my walls can spread with the loft joists every 16 inches.


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## Fishindude (May 19, 2015)

*I see now, that would tie up almost two foot of headspace right in the middle.If I can get by with a ridge board I'd rather do that. Would I just use a homemade gluelam beam to have the length and use that for a ridge board, or just splice and plate a 2 x 12 for length? *

The ridge board can be just standard 2x material, needs to be as deep as the end cut on rafters so they have full bearing against the ridge board, see Tn Andy's photo.


*If my outside wall are tied together with the loft joists, would I still need collar ties? Theres no way my walls can spread with the loft joists every 16 inches.*

Shouldn't need collar ties with rafter joists tying things together at the bottom.


Do some internet searches and you can find most of this information, as well as info on how to properly size these members.


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## RazrRebel (Apr 16, 2013)

Thanks guys. I think I'll go with a ridge beam to get the length, but use it as a board with the rafters tied into it.


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## wy_white_wolf (Oct 14, 2004)

Since you plan on a full loft no ridge beam or board is needed. The loft floor joists should be tied to the sides of the rafters. They will them act as collar joists to keep the rafters from spreading the exterior walls.

WWW


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## Terri (May 10, 2002)

Speaking of ridge boards: I have one on my greenhouse, and I got I up without help. The fist end went up easily, but when I went to put up the second end the first end fell on top of me leaving a nasty bruise. 

Later I was talking to someone, and she said that she had used a bungee cord to secure the first end before lifting the second end, and that sounded very much better than what I had done. In fact I used one years later when I was ding a little repair work, and it was very helpful.

Since you are wanting to use a ridge beam instead of a board, you might want to use something stronger than one bungee cord: perhaps 2? Or???

Sorry for the thread drift!


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## Beest (Nov 7, 2014)

Ditch the beam.. Go with what we call a ridge pole. As in the referenced pic. use 2x material as you will be able to keep it straighter than 1x. As mentioned, your loft joists will act as collar ties;.


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## beenaround (Mar 2, 2015)

lumber yards will often size/engineer the beam for you for free and provide the necessary paperwork if needed for BD approval.

The last open space I did like that (24lx18w) required 3-26' 1-3/4x16" micro lams nailed/screwed together. The requirements on how to put them together is also provided (there is a recomended method that must be followed) ***very important*** no holes are allowed to be drilled anywhere in the beam.

I used 2x12 for rafters to get the needed insulation space and it was an 8/12 pitch.

I wouldn't build one up like you're thinking.


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## Evons hubby (Oct 3, 2005)

No beam required. I have taken down 200 year old buildings to be moved that had only poles for rafters notched together at the peak with a single wood peg holding them together. Ridge beam adds virtually no structural strength, just make settin rafters a little easier.


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## beenaround (Mar 2, 2015)

Yvonne's hubby said:


> No beam required. I have taken down 200 year old buildings to be moved that had only poles for rafters notched together at the peak with a single wood peg holding them together. Ridge beam adds virtually no structural strength, just make settin rafters a little easier.


I have too and put them back together. We don't use native lumber cut on site anymore (I did when I built my place) and standard lumber is no where near capable at doing what old lumber did, we don't even allow the same techniques anymore. I've seen first hand why. I have seen many structures built poorly. Many structures that I have repaired.


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