Common Purlins again
#21804
11/21/09 12:11 PM
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Will Truax
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Had anybody come across this ? http://www.fairbankshouse.org/barn_frame.pdfThe most interesting aspect of it for me is that the roof is Common Purlin. The barn had stood in Essex County Mass, and I've been informally trying to learn how common that roof system was there on that bank of the Merrimack. Took in a bunch of the house museums in neighboring Ipswich last Autumn (though I believe the season is over now) which boasts of holding more 17th ca homes than any other town in America, and over fifty First Period homes. The only one I was able to talk my way into the attic of, the Whipple House, had Common Purlins in its original wing, but common rafters in a mirror image wing built just a few years later. I almost broke the no flash photography rule up there, the docent had no interest in climbing around in a grimy attic with a crazy person and stayed downstairs with Molly.
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Re: Common Purlins again
[Re: Will Truax]
#21816
11/22/09 01:43 PM
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TIMBEAL
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Will, did you take pictures?
Why is it they do not want photos take of the interior of these buildings. I have come across this locally, the photo taking part.
Tim
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Re: Common Purlins again
[Re: TIMBEAL]
#21821
11/23/09 03:42 AM
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Will Truax
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I have some shots of the outside of the buildings, but no, none of that attic, and had I taken any, I guess I would be reluctant to post them here, where I lack any real anonymity... More about the Whipple House here - http://www.ipswichmuseum.org/whipple.phpI do have some of visible framing in the NH Royal Governor's Mansion which we visited in the same stretch of time, and which is maybe only twenty miles north of Ipswich http://en.wikipedia.org/wiki/Wentworth-Coolidge_Mansion I've a friend who is a docent there, and he wanted help in answering what are common questions about the framing there. I'll see what I can find when I visit my desktop over the holiday and see if there is anything worth sharing.
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Re: Common Purlins again
[Re: Will Truax]
#21822
11/23/09 03:56 AM
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Will Truax
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Oh forgot,
Always guessed the no flash thing was about undue UV, and how light and time fade everything, but that's a guess.
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Re: Common Purlins again
[Re: Will Truax]
#21825
11/23/09 09:45 PM
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OurBarns1
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Hi Will,
Interesting find. Nice and old, even dendro-dated.
It does seem like there ain't much rhyme or reason to the whole purlin vs common rafter thing. This befuddled me greatly in the begining of my poking around here in Maine. Always wondered if it was a cultural choice or something else.
But I'll hazard a guess that common rafters were employed over a major-rafter / purlin system at times simply because they're easier to construct: no joinery to really contend with... I don't know...or maybe sawn stock was cheap and easy in a given cicumstance, vs hewing major rafters ?? What are your thoughts?
At any rate, the photos of that old barn frame look almost like a connected girt type...almost. The plate is quite small, more like its neighboring purlin stock, perhaps used more like a nailer for the wall/roof boards. But there does seem to be a jowled post. So far I've yet to see a CG w/ jowled posts.
Speaking of dendro-dating, anyone know where one can get this done (do you ship a sample, etc)? Is it expensive?
Don Perkins Member, TFG
to know the trees...
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Re: Common Purlins again
[Re: OurBarns1]
#21834
11/24/09 02:49 AM
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Gabel
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Jack Sobon told me that he thinks purlin roofs were built when a board roof was to be used and rafters were used with shingles. Makes sense to me.
Looking at your example, Will, perhaps when the extension was built the owners had more money to build with and could choose the pricier shingle roof, hence the common rafters. Perhaps at the same time they even upgraded the original house to shingles, replacing the worn out (or perhaps just "low class") board roof.
Last edited by Gabel; 11/24/09 02:54 AM.
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Re: Common Purlins again
[Re: Gabel]
#21836
11/24/09 04:00 AM
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Will Truax
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I guess I don't get that, while yes, it would be more expensive to shingle a purlin than a rafter roof because you would have to first board over the purlins and then apply skip for the shingles, it would require no fewer layers to do board roofing over purlins - Though you can do board roofing over common rafters with no sheathing whatever, doesn't get any cheaper than that.
And it doesn't explain the regional dominance Common Purlins hold in much of Northern New England. Just across the river from where that 1715 barn stood you're in common purlin land, which is why I have a curiousity for how common they were on the south bank.
And as I have said in other threads, they are (and were hereabouts for a good 200 yrs) a perfect marriage with ETJ's - No load path whatever for thrust to reach the Plates.
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Re: Common Purlins again
[Re: Will Truax]
#21868
11/26/09 03:20 PM
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Gabel
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I don't think you can get any cheaper than a single layer of boards nailed to the purlins. Not a great roof, but it gets you a few years in the dry. I don't know if they were shiplap or feather-edged or exactly how they kept the wet out.
I guess the shingles were pricey by comparison. There is certainly more labor in the install and more work in the making of them.
I'm not an expert on this, but it is interesting.
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Re: Common Purlins again
[Re: Will Truax]
#21869
11/26/09 06:07 PM
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Dan from Maine
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This was one of the most interesting buildings I think I have ever been a part of dismantling. What he web site doesn't show is that it was a "ground bound" building in that it had no sills, just a HUGE lower girt that was half lapped into the posts and pegged. The tie beams all were tapered as were the plates. It looked as if they simply squared up the trees and used them as is. If I remember right, one of them was very curved. Some of the purlins were straight, some curved. All of them were hewn flat on one side. Also, if memory serves me right, most of the frame was oak and chestnut. Whatever the species, it was really heavy. Back to the original question. . .I do see a lot of common purlin roofs on barns and house from that era in that geographic reigon. Mostly on buildings before the 1760's. Also, in many cases, the purlins run the length of the building uninterupted.
Dan Boyle Preservation timber framing, inc. South Berwick, Maine
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Re: Common Purlins again
[Re: Dan from Maine]
#21878
11/27/09 03:45 PM
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Jim Rogers
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Dan: Welcome to the Forum.....
Whatever you do, have fun doing it!
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Re: Common Purlins again
[Re: Jim Rogers]
#21882
11/27/09 09:04 PM
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OurBarns1
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Yes, welcome Dan. Glad to see someone from PTF here. How's the Abyssinian coming along?
Speaking of "board roofs," that really is a fascinating thing to ponder. Never heard of them before. But makes sense that they'd have been used on the out buildings of poor homesteaders. Not sure I buy them being used in town on homes, but there is much we don't know about history.
Shiplap does make sense, as does tongue & groove, board & batten, etc. What might be most problematic would be hiding/covering nails as exposed nails will always leak water.
Tongue & groove allows "blind nailing"...but exposed boards would move and shrink in the weather considerably...must have been a loosing battle. I thought early roofs in the "New World" were often thatched.
Would be interesting to see if anyone could find and post a reference to plain old "board roofs"
Don Perkins Member, TFG
to know the trees...
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Re: Common Purlins again
[Re: OurBarns1]
#21886
11/28/09 02:46 AM
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Housewright
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Hi Dan and Everyone; An earthfast barn! That makes three...I have heard there are still two of thse in Saint Mary's City, MD. Board roofs were common on all types of buildings including houses, though probably most common on outbuildings. I have seen some good photos of these, but I could not find one to post. The boards were sometimes set with the edges on a thin batten or protruding nail to force a U shape and then the top edges covered with a batten. Even if they were not forced into a U shape, they curled that way naturally with the sun beating down on the top surfaces. There could also have been two layers of boards without battens. I was just reading about the Stanley-Lake barn which is an ancient (pre 1718?) barn in Topsfield, MA on the Ipswitch River. It, like the Giddings-Low barn in Essex, MA (before 1702) have common purlin roofs and may have been "single boarded and battened" as is a reference to "The 1667 Nelson barn in Rowley...". Most of this information is from the linked article by Robert Blair St. George. http://departments.umw.edu/hipr/www/resource/pva1stgeorge.pdfJim
The closer you look the more you see. "Heavy timber framing is not a lost art" Fred Hodgson, 1909
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Re: Common Purlins again
[Re: Housewright]
#21888
11/28/09 02:57 AM
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Housewright
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More thoughts;
Some board roofs probably did develop leaks (but only when it rained) and were soon shingled over.
Please keep an eye out for vertically boarded roofs which appear weathered, especially if there is evidence of a batten applied to the edges of the boards, that is if the edges are less weathered than the middle part of the boards.
Also, a barn near me had closly spaced common purlins and could have been shingled directly onto the purlins with no sheathing, but was vertically boarded whin it was disassembled a few years ago.
Jim
The closer you look the more you see. "Heavy timber framing is not a lost art" Fred Hodgson, 1909
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Re: Common Purlins again
[Re: Housewright]
#21896
11/28/09 06:58 PM
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Will Truax
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Dan - Glad you’ve piped in…
Gabel - Not having heard of such a roof before, I was envisioning, and thought we were discussing something more akin to a clapboard roof , only of riven boards, (A common product here in colonial times) and being on the cheap, maybe “seconds”, something that split out with a slight taper but with so-so grain, not worth dressing/planing into an a-class clapboard.
Jim – Good stuff as always. I have not seen such a batten ghost, though I have stripped more than a few Purlin roofs down to their original sheathing. But I will keep an eye out. Should be easy to spot, as I’m guessing though such a roof would only buy you a few years before it needed proper roofing lain over it, I’m also guessing the weathering between the battens, would be deep and distinct, as compared to the protected surfaces below the battens. Nor have I seen a Purlin roof sheathed RB&B style, though it is a common sheathing/siding methodology for early barns, and I’m guessing it would be a much more durable board roof than one with a batten over.
As far as close spacing of Purlins intentionally for shingles. That would be a tough one, I have lain a number of “board shingle” roofs on bridges, (Cedar ½” X 6 X 3 times the length of exposure - Common to bridges in that they have a long service life and are exceedingly light) but these still require nail-base at every exposure (11” being typ) and I’ve not seen nor heard of a board shingle being longer than 48”, which would require Purlins @ 16” OC
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Re: Common Purlins again
[Re: Housewright]
#21907
11/29/09 10:12 PM
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OurBarns1
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I was just reading about the Stanley-Lake barn which is an ancient (pre 1718?) barn in Topsfield, MA on the Ipswitch River. It, like the Giddings-Low barn in Essex, MA (before 1702) have common purlin roofs and may have been "single boarded and battened" as is a reference to "The 1667 Nelson barn in Rowley...". Most of this information is from the linked article by Robert Blair St. George. http://departments.umw.edu/hipr/www/resource/pva1stgeorge.pdfJim That's a great article, Jim. Thanks for posting. I haven't finished it in its entirety, but can't seem to find a reference for "board roof." Looked for both "roof," "boarded" and "purlin" in the PDF search window--all came up zero. Perhaps I'm missing something? Do you have a page # for the "single boarded and battened" reference? Enjoying the topic.
Don Perkins Member, TFG
to know the trees...
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Re: Common Purlins again
[Re: OurBarns1]
#21909
11/30/09 12:36 AM
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Housewright
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Sorry Don, there is not a reference to board roofs in that article.
If you google "board roof" or "plank roof" you will find some info.
Jim
The closer you look the more you see. "Heavy timber framing is not a lost art" Fred Hodgson, 1909
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