Hello all,

I have always been under the impression (mistaken?) that a structural ridge beam is a relatively new addition to TF design, riding the coat-tails of the craft's revival in the 70's.
I happened to be thumbing through the "Red Book" the other day, and on pg. 141, Sobon mentions the presence of a "full length ridge beam" in a 1770's English barn in Western Mass. And it got me to thinking.....

My question: Just how common (or not) were ridge beams in the historic frameworks (houses/barns) of Colonial New England?

I live in an area of N.E. Ohio, the Connecticut Western Reserve, that was settled in the very early 1800's by those leaving New England, and although my viewing opportunities have been limited, I've never seen a ridge beam employed in any of the old frames around here.

So, is there much historic relevance to the ridge beam in house and barn frames of the past, or is it more a part of modern design?

Thanks to all of you who would like to contribute.

The "Red Book" being Timber Frame Joinery and Design Workbook?

If so, the ridge spoken of was not much for structural support. From my understanding a ridge beam was used here and there. I don't see many in down east Maine. A true structural ridge would be supported via a post system, and not allowing the peak to drop. These older type of ridge beams, mentioned, were more to fasten the rafter to, not necessarily to hold the ridge/peak up, they would still exert thrust to the walls.

The next lower down type of historical framing could be the crown post and plate configuration. Still not found in the new world much?

I would say a structural ridge with a post support system would lean toward more modern framing typology.

Tim,
Thanks for the response, and sorry for the lack of clarification concerning the "red book". Yeah, I was referring to the Guild's J & D workbook.
What you describe in your second paragraph matches up with what Sobon goes on to describe, that the commons were tenoned into this ridge and bear on the plate.
This led to a few more questions.
1) Why weren't these ridge beams posted?
2) If these non-posted ridges did nothing to alleviate thrust at the plate, why did the old builders use them, and why not simply m&t the commons to each other?
I'm sure there were some structural benefits that I'm just not seeing.

I have used them on occasion. I found the assembly, perhaps easier than common rafter without a ridge. You are only putting one rafter up at a time, it also aligns the rafters to the proper spacing. I sometimes wonder if cutting a simple mortice in a ridge piece is easier than the tongue and fork, I often cringe when I have a bunch of tongue and forks to do, but don't mind so much a line of mortices and short simple tenons. So my guess would be that building with a ridge could perhaps be easier. But then we don't see a majority of them, do we?

If thrust was handled in other ways such as the dropped tie then they found no need to support the ridge. Have an engineer size a true structural ridge and you will find it to be a large timber. This could also be part of the reasoning not to use one. K.I.S.S. kind of thing.

I am hoping others will add to this......

My understanding (based on a conversation with Jack Sobon)is that these ridge beams were not intended to be "structural" like a posted ridge is.

They facilitated the scribing process by allowing you to lay up each roof plane as a unit with wall plate, ridge, and half the commons. This way to layout and cut the roof you only need to do 2 fairly quick and easy layups. A pentagonal ridge makes this a snap as you have one of the sides to level.

Otherwise, if each rafter joined it's opposite rafter at the peak you would have to lay up each set of commons which might require a dozen or two layups and you still haven't gotten the rafter-plate joint. So you would need to still lay up each of the roof planes. Therefore, adding the ridge eliminated quite a bit of mucking about with the rafters and kept it to two simple layups.


I believe this type of ridge fell out of use with the advent of the square rule which is pretty good circumstantial evidence to support this theory.

I always thought they would be a real pain to assemble.

Thanks, Gabel. I have been playing with Plumb Line Scribe on a small project, and I am now going to add a ridge to it for the reason you pointed out. I had been wondering how the rafter peaks were going to scribe in and this answers the question in the back of my mind. So both the plate and the ridge are set to the lines on the floor and scribed, accommodating both sides with the same lines, too.

I just hold the ridge up with an additional gin pole while the rafters are poked in place. So assembling is a breeze.

I've been thinking about ridge beams a bit lately for a small shed I'm pondering. I'll try to remember to ask Jack when he comes down on Tuesday to the shop. I've seen a few ridge beams here in Western Mass., except for one 1765 barn, I don't really recall what age groups these barns would have been in.

In the Heartwood Cruck class of '09 we used a ridge beam. I think that is why we could small rafters.

Hi Dave,

Cruck and king post roofs are two notable exceptions where the ridge is recognised as being very much a structural load carrying member. As in the cruck photo above we can see that up to half the roof load will head straight to ground via the cruck blades. The actual share will be dependant upon the flexure of the ridge and the type of joints or pegging arrangement employed between rafters and ridge.

Regards

Ken Hume

Interesting, in my little cruck frame I have noticed the crucks have shrunk away from the ridge beam, in effect the rafters are holding the ridge up not the crucks. The crucks are spruce, and such, they tend to shrink a lot. It is configured similar to the one Dave referenced. Now if the walls were to spread via the thrust of the rafters the ridge would then settle back onto the crucks, I hope that does not happen.

Hi Tim,

That is a very interesting observation and I suppose one that is entirely understandable and predictable. You have probably identfied first hand the real reason why ridges are not generally employed in common rafter roofs.

The ridge also stops the rafters from racking and so it is not an entirely redundant component. Did you provide a collar and peg your rafters to the ridge using square pegs driven through the rafter and ridge ideally from opposite sides on each alternate rafter couples ?

I am providing a link to a photo of a 4 sided ridge found on a truncated cruck frame that is located in North East Hampshire that was dendro dated to 1404.

4 sided cruck ridge

Thank you for that valuable practical insight.

Regards

Ken Hume

Regards

Ken Hume

Regards

Thanks for the feedback folks,
I don't mean to take away from the cruck discussion.

I can now see how this non-structural ridge made layout and assembly an easier task, but I'm still wondering:

These old time carpenters MUST have known that placing a post under these ridges would re-direct roof loads away from the plates, so why did they still not use them? As Tim suggested, was it because too large of a timber would be required for the ridge? But it seems to me, that issue was not often a limiting factor in the design of old frames. Or was it?

Tim, your earlier comment about the dropped tie as it relates to roof thrust raised yet another question. I always thought that dropping the tie from its ideal triangular arrangement resulted in an increase of rafter thrust at the plates (relative to how low it was placed) and created the need for tension joinery at tie/post, in effect doing the opposite as you suggested. Or did I misinterpret your explanation? Or am I simply a knucklehead and missing something here?

Gabel, Interesting stuff. Any particular reason why this type of ridge was not used once SR came on the scene?

In two of the later barns (much larger than the crucks shown previous) that I've had the pleasure of dismantling / moving there was evidence of a hay track having been installed. (granted, the hay track came along much later than many of the barns origination dates).

Posting down the center of the barn would have interfered with any operation out the gable ends. These barns had a queen post / purlin roof system - canted if I remember correctly, with posts dropping to the floor below the ties as needed. This kept things open through the upper floor / roof.


Size may not have mattered - here's a pic of me on an oak 'swing beam' on an Ohio barn that was restored into a residence. There were a pair of these and I think they easily hit 12x20 or more in the center (they were tapered from end to middle!). Size was probably easy to come by - but how to get that ridge up in the air might have been a determining factor in not wanting to use large pieces up high...

with square rule there is no time saved by having a framed in ridge.

Think of it this way - if each mortise or tenon is a joint, to join the peak of one pair of rafters requires two tenons and two mortises or four joints. If you delete the ridge and join the two opposite rafters to each other, you only have two joints whether you are doing half laps, tongue and forks or whatever. And since the structural advantage of the ridge is minimal, they just deleted it and I bet the guys that worked through the transition were glad to see it go.

Let's look at the framed ridge's benefit when scribing a little closer in order to understand why they would hew or buy additional timber and cut additional joinery and think of it as a cost saver.

The mortises in the ridge were all laid out and cut by measurement prior to laying up the roof plane. The same is true for the notches in the plate. The plate and ridge were set the correct distance apart, leveled and square to each other. Then the rafters could be tumbled. The process is described in detail in Jack Sobon's series on building his barn in Timber Framing (somewhere around issue 80).

Without the ridge, you still have to tumble the heel to the plate, but you also have to lay up each pair of commons to mark out the peak joint.

Mike, I'd like to know more about that swing beam. Looks a lot like a Dutch anchor with what looks like pent roof mortises. It looks like it is going into a corner post. Is this frame going back up fairly close to its original state, or is it made up from salvaged pieces? Do you have any other photos of that frame? Looks very interesting. Thanks.

My intentions were not that the size of the beam would be difficult to find but that it is a bugger to handle and in upper reaches of the frame, at that. All in all it's just me speculating. I would add to Mike's points of the king post getting in the way. When ever I construct a king post truss it is always in the way if you are using the attic space, barn, home or what ever, and any strut work makes it even more so.

Ron, I think you interpreted my words well. To clarify a bit more, most dropped ties are within a foot of the top plate, so it is still in the ball park. They had to create a joint there anyway, so to making it a through tenon with an extra peg and/or even a wedge on a half dovetail would be less work and material than the ridge and post set up. There is a lot of functioning dropped tie barns out there with common rafter, so it works.

Another approach would be the english tie but, from my perspective that does not handle thrust from common rafters well. The english tie gets your tie right where it is ideal and to top it off barks for a principal rafter and common purling roof system, changing how the roof system works in comparison to a common rafter system.

Ken, how were the rafters tied at their peaks if at all, other than the peg through the ridge? I used mortice and tenon to connect the rafter to the ridge. They were not laid on top as in the photo. I like that as an alternative, as long as I was not having to join the rafters at the peak. This example has me wondering if the cruck was to shrink than did the ridge drop too? It's like chess, 3 moves ahead and I stall out due to to many options, then you can go back over the game and follow the notations to see what happened.

Dave, I'll have to dig for some more pics. I helped for about a week with misc joinery and then raising. Location is near Columbus, Ohio. Pretty sure owner had 3/4 of an intact barn and we used pieces from a nearly identical barn for the remainder. I don't think they traveled far to get to his site.

The swing beams were in the center bay. In that photo the bent is being assembled for raising. Posts were gunstocked in the direction of the plate. Tie dropped on and then plate interlaced on top with a horizontal tenon coming in from the tie, then the whole assembly dropped 1 1/2" or so. If memory serves those pockets were from the loft floor.

Thanks Mike. A lot of the pieces in that photo are very much like the Dutch barn I'm working on. I'll have to get some photos up. I know we all like photos.

Thanks to all who contributed, I learned a lot, and it was much appreciated.

I talked to Jack a little about ridge beams today. He said it was builders choice pretty much. They don't indicate any particular period. Advantages and disadvantages are pretty much as described above. They do help straighten the lines of the ridge, but every joint in the beam is an extra joint. I'm working up an idea for a small shed we need here on the farm, and I want to incorporate a ridge beam in it. It might be somewhat cruckish, have to check the tree supply here.

I believe it was Eric Sloane who put a date range on frames with and without (non-structural)ridge beams. And I believe it was Jack that debunked that theory (among others).

Yes, I recall reading that in the Sloane books.

Missed this threads rollout because the Forum is still running squirrely, and things still seem to appear only willy nilly like. If you don't happen by when a when a recent post appears out of place, typically in the general forum questions section, you may not see it at all.

Historical structural ridges - done a lot of looking at a lot of frames in alot of locales, and I've not seen one ever, and I don't expect to.

Here in Common Purlin Land, one finds a four sided Ridge Purlin, (Rectilinear not square - With one of the two shorter sides clipped at roof plane) in frames on either side of the transition from Scribe to Square. This serves as nailbase, and like the other Common Purlins, to carry the thrust and dead/live loads of small subsections of the roof deck laterally to the Principal Rafters

will -

go to 'active topics'.
select 24 hours, 48 hours, 7 days.

bookmark that page.
next time you want to come back, hit that bookmark... and you'll see the latest and greatest active topics.

That is the first thing I do when open up the Forum, punch Active Topics. And if some activity has happened in Northern Hewers thread I have a couple of extra hoops to jump through. Any tricks for that one?

Will, do you think it makes sense to scribe all the rafters on one side of the roof and then the other side with a ridge, or scribe rafter pairs? Then you have to deal with the rafter foot to plate aspect all over again, on both sides. And so, you don't see a decline in ridge beams, even into the late 1800's early 1900's?

When I do see a ridge in my parts it is usually on common purlin roofs, and the ridge is let into the fork and tongue principal rafters, just like all the purlins, via daps, cut into the top side of the rafters. No ridges with common rafters. All of the frames are scribed as well, houses and country side barns and out buildings. It is the larger community building which I can find square rule, churches for the most part. Also usually common rafters suggest the roof may have been changed at some point in the buildings history, but not always the case.

Excuse me if I am rehashing this.

not sure what you mean. i see the northern hewers thread just like the rest... depending on how often i log in, and how active the forums have been.

Mike - I know active topics is there, and thanks. My comment was more about the Forum being messed up, and for months now. (not the first time I've mentioned it and there are others who share the same problem) This squirrel in the attic has made the Forum far less navigable, and is the root of my comment.

Tim - Common rafters are not my norm, but I have done it both ways. From purely a layup and efficiency viewpoint, a roof system with a ridge is easier and requires less layups -

If you're scribing a frame without a ridge you must do multiple quick layups of the pairs at the ridge- If using a Five Sided Ridge you have the ridge taken care of in the same layup in which you scribe the commons to the Plate, avoiding the layup of all the pairs.

I have seen but two historical Five Sided Ridge / Common Rafter combinations north of the Mass line, and both were in border towns, though neither was in the border region of the Merrimack Vally where I came up.

Not being from a Common Rafter part of the world, I never considered if the advent of Square Rule led to a change in their use ? Interesting question.

Hi Guys;

I live in an area, Mid-Coast Maine, with five-sided ridge beams. I know they are common in the Connecticut river valley too.

I have seen a couple of references for these ridge beams in England, but I do not have much information on their origin or distribution.

As for ancient history, posts supporting a structural ridge beam is one of the fundamental ways structures were built in prehistoric times. They were common and widespread. The name for one type in Danish is a sulehus, sule being a name for a post. Another name for these posts is a gavel from Latin gavala, meaning forked stick, and this is where our word gable comes from!!

In Germany buildings with a structural ridge beam and supporting post are called a Firstsäulenbau, Firstständerbau, Hochsäulenbau, or Hochfirstsäulen sometimes translated as a “Ridge Pillar House”. I am not aware of American examples of this building type.

Here is a web page in Danish with a drawing of an interesting example of a sulehus if you scroll down: http://www.kulturarv.dk/information-om-b...kik-paa-landet/

Here is a German page with good photos of a reconstruction:
http://presse.aoeza.de/2010/06/neuer-hausnachbau-im-steinzeitpark.html

If you use Google you can translate the text and almost understand what it says. There are some other types of historic framing presented on this page.

Take care;
Jim

Here's another good paper on types of frames of ancient (Greek and Roman) design where the ridge is important.

http://www.pierreseche.com/poteaux_de_faite.htm

What?! You cant read French! (I'm just learning)

Jim

The German Firstständerhaus is one type of the Low German hall-house, and is typical of the post built Germanic style, the style predating the frame-built house. It is an important step in the development of framing traditions across the Germanic world.

In the early middle ages, most houses that were built were built this way, or with a variation with 2 posts supporting mid-span purlins instead of ridge beams. This is called in German Zweiständerbau. In this style the exterior walls are non-loadbearing, but the weight of the roof is born by the mid-span posts. This works only for very small buildings of course. This was replaced by the 4-posted house, or vierständerhaus, which allows for much wider buildings. In these houses the middle hall is the living quarters while the outer aisles function as animal stalls with the space above being used as hay lofts. This basic style of the aisled barn is still used to this day in America. A bit of a side track from structural ridges, but it illustrates how the structural ridge is related to other building styles. IT seems that the simple structural ridge leads to the development of a pair of purlins, which in turn leads to more complex roof framing.