Wood Lath

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Author Message Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 32 Registered: 11-2003 Posted on Tuesday, June 14, 2005 - 03:16 pm:    One of my Architects is doing an historical peservation project and has asked that I provide wood lath for remodeled plaster ceilings and walls (the existing lath is wood). Does anyone know where I can find a spec or info for wood lath? I've checked Porland Cement Plaster Manual abd MasterSpec, goose eggs both times. Can anyone point me in the right direction? Lynn Javoroski Senior Member Username: lynn_javoroski Post Number: 222 Registered: 07-2002 Posted on Tuesday, June 14, 2005 - 03:21 pm:    I may have a source of information, but it's at home; I'll check tonight, and if I do, post the information then. Ronald L. Geren, RA, CSI, CCS, CCCA Senior Member Username: specman Post Number: 158 Registered: 03-2003 Posted on Tuesday, June 14, 2005 - 03:28 pm:    Although not very specific, this webpage might give some additional information. It's the GSA Preservation Brief on repairing historical flat plaster ceilings and walls: http://w3.gsa.gov/web/p/hptp.nsf/0/e4fa57e286316eb8852565c50054b317?OpenDocument Helaine K. Robinson CCS Senior Member Username: hollyrob Post Number: 164 Registered: 07-2003 Posted on Tuesday, June 14, 2005 - 05:38 pm:    I think that you may need the old Manual of Lathing and Plastering. I can't find my old copy so good luck! Helaine K. Robinson CCS Senior Member Username: hollyrob Post Number: 165 Registered: 07-2003 Posted on Tuesday, June 14, 2005 - 05:42 pm:    Manual of Lathing and Plastering by John R. Diehl National Bureau of Lathing and Plastering 1965 Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 33 Registered: 11-2003 Posted on Tuesday, June 14, 2005 - 05:47 pm:    I've done some online research this afternoon and found out wood lath is 3/8" x 1-1/2" x 48" cedar or aspen. However, I still need all the other spec data including, spacing?, on furring?, treatment?, etc. Helaine K. Robinson CCS Senior Member Username: hollyrob Post Number: 166 Registered: 07-2003 Posted on Tuesday, June 14, 2005 - 05:51 pm:    Just found and ordered that book (used) at alibris.com Helaine K. Robinson CCS Senior Member Username: hollyrob Post Number: 167 Registered: 07-2003 Posted on Tuesday, June 14, 2005 - 06:27 pm:    You might also want to look at an older edition of Architectural Graphic Standards. Helaine K. Robinson CCS Senior Member Username: hollyrob Post Number: 168 Registered: 07-2003 Posted on Tuesday, June 14, 2005 - 06:33 pm:    From "Repairing & Extending Finishes - Part 1" (H. Leslie Simmons), p. 72: "Wood lath is seldom used today, but old plaster may have been installed using it. Early wood lath was just sticks and tree branches. By the late nineteenth century, however, wood lath had become hand- or saw-split slats 1-3/8 or 1-1/2-inches wide, 5/16 or 3/8-inch thick, and 48 inches long. It was cut from a variety of softwoods." Lynn Javoroski Senior Member Username: lynn_javoroski Post Number: 223 Registered: 07-2002 Posted on Tuesday, June 14, 2005 - 10:45 pm:    From a friend who does preservation work: "First, review NPS Preservation Brief 21, Repairing Historic Flat Plaster: http://www.cr.nps.gov/hps/tps/briefs/brief21.htm Sometimes in dealing with old buildings it's best to review a standard reference like this and then write the spec more or less from scratch. Or you could borrow or steal one from a friend who happened to leave one laying around. Wood lath is good stuff. You can probably get it at Home Depot, although they may call it something else, like surveyor's stakes. I think most of the historic stuff I've dealt with was oak, probably white oak, but I doubt you will find any of that today. It needs to be rough, not smooth. But frankly, I normally read the Preservation Brief and look at old work and then think on these things for a little while before I write the spec. Sample Panels are very important. I like to make the contractor demonstrate that he can do all of the steps in the job. In my office I had framed two plaster assembly panels. They were very pretty. I have an exterior stucco spec around here somewhere too. Let me know if you need anything else." Tom Heineman RA, FCSI, SCIP Senior Member Username: tom_heineman Post Number: 52 Registered: 06-2002 Posted on Tuesday, June 14, 2005 - 11:40 pm:    The age of the building to be remodeled has a lot to do with it. All the information above is good, but I add this: About 1961 I was invited to view an old house a friend had bought in Owings Mills, just NW of Baltimore. He probably told me its age then, but I forget. It was probably close to 1800 or 1820. We went up into a garret that had long been used as an extra bedroom, and some of the old lime/sand plaster on the sloping ceiling had fallen away from the lath. The original roof joists were about 16 or 18 in. oc, and spanning them were lath strips, likewise about 16 or 18 in. long. Each lath strip varied in width from 3/8 to about 3/4 in. - often wider at one end than the other. The wood was chestnut, and had undoubtedly been there for 150 years. Blight-destroyed chestnut boles that fell to the forest floor circa 1910 were still being hauled to sawmills for their beautiful and decay-resistant wood late in the century. The thickness of the laths varied a little too. Each strip was fastened in some way that I forget, probably two small handmade iron cut nails, to the bottoms of the rafters. They had spaces between about equal to the spaces between wood laths nailed up in the 20th C. Why 16 or 18 in.in length? My Westinghouse engineer friend had done a little reading up, and said that to split laths from a short billet of chestnut, 18 or 20 in. was about as long as mallet and froe could easily manage. I think Siegfried Gedion says somewhere in his fascination with the development of balloon framing in America's early and mid 19th C, that the 16 in. joist and rafter spacings we are so familiar with today come from the early limitation in the length of furring. Perhaps we had not moved far enough west to discover cedars tall enough and straight enough to be easily split into 48 in. laths. An 1885 rowhouse I lived in had 48 in. cedar laths just like what you get today, holding the same 2-coat lime/sand plaster (with lime-rich whitecoat). I hope that what this city boy passes on is truly old country practicality and not urban legend. Richard Baxter (Unregistered Guest) Unregistered guest Posted on Wednesday, June 15, 2005 - 11:54 am:    An important issue with wood lath for plaster is to ensure that the wood, whether new or existing, is either sealed, thoroughly wetted, or sufficiently green before application of the plaster. This is to ensure that the wood does not absorb moisture from the curing plaster. Reduced moisture will weaken the plaster and may break the keys that hold it to the lath. Robin Dale Rund (Unregistered Guest) Unregistered guest Posted on Wednesday, June 15, 2005 - 12:16 pm:    The following may be of interest. It's from "Architectural Specifications" by Harold Sleeper (copyright 1940) Under the heading of "Lathing and Plastering" "Materials-Lathing and Furring" "Wood Lath: (a) Wood lath shall be 1-1/2" by 1/4" with key between and 32" or 48" long and shall be of non-staining wood, #1 grade pine or spruce, free of knots, sap or bark and shall be reasonable well air seasoned. (b) Nails shall be 3d blued nails. (c) Supports for lath shall be not over 16" o.c." and under "Erection of Metal [sic] Lath" "Wood Lath: (a) Shall be spaced 3/8" apart at the edges, 1/4" apart at ends, and shall be nailed securely at right angles to wood supports (spaced not to exceed 16" o.c.) with 3d fine, #16 gage blued nails, full driven. (b) joints shall be broken every seventh lath. (c) Lath shall not run through from one room to another. (d) Conerite shall be securely nailed through the lath to supports at all interior angles." I agree with Tom Heineman's comments regarding time and place determining the material one finds in place. My personal experience with lath matches the material description I quoted above(midwest/ houses dating from 1910 to 1930). On the other hand, in the examples I've seen the lath always seems to run between rooms, which complicates renovation work. John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 369 Registered: 03-2002 Posted on Wednesday, June 15, 2005 - 02:07 pm:    Robin's description fits nearly perfectly the wood lath in my c. 1890 house in the Boston area, including the sizing and spacing. It is also rough-sawn, as mentioned in another post. I've disposed of tons of it and horse-hair plaster over the years. I think I still have some grains of plaster between a couple of back teeth. Russell W. Wood, CSI, CCS Senior Member Username: woodr5678 Post Number: 34 Registered: 11-2003 Posted on Wednesday, June 15, 2005 - 02:19 pm:    Thank you one and all for being so helpful! Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 60 Registered: 10-2002 Posted on Thursday, June 16, 2005 - 03:43 pm:    While the type of material, width, length, and thickness may vary, it seems to me that the two most important factors are the roughness for adhesion (as Lynn pointed out) and the spacing between the lath members. The lug effect of the plaster between the lath is what holds, or "locks," the base coat into place. The 3/8" spacing listed by Sleeper coincides with the measurements I have taken in the past.