UC-NRLF STHUCTl'iAL TIUBIUS I. Built-Up Yellow Pine Timbers Tested for Strength. II. i.iaximum Spans for Joists and Rafters. National Lumber Manufacturers Asso. c.- Forestry. Main Librar> vurj .- forestry. Maia Library NATIONAL LUMBER MANUFACTURERS ASSOCIATION -WOOD CONSTRUCTION INFORMATION SERVICE Series E-2b. Built-up Southern Yellow Pine Timbers Tested for Strength 1 FIG. 1 SHOWING METHOD OF APPLYING LOADS TO BEAM IN TESTING MACHINE. Built-up structural beams have an advantage over solid beams i the utilization of smaller stock, quick and easy seasoning, availability, and the possibility of avoiding bad checks, shakes and other defects. ^^^ . >; .^ _, Tests made at the Forest Products Laboratory on eleven built-up beams (* 4 j J ? . ^ ;.-4 ^*v of southern yellow pine indicate that from the standpoint of strength r"^ ' there is no marked difference between built-up beams of "dense" i 11 / it i i- i / C'~- ' T'" C^ Ti AGBVC' material practically free from defects and solid beams of dense material with defects limited as in the select structural grade of the lt Southern Pine Association. T 1 Purpose These tests were made in co-operation with the National Lumber Manufacturers Association to obtain information on the behavior of built-up beams under loads, their strength properties as compared with solid structural timbers previously tested, and to ascertain the advantages, if any, of using built-up instead of solid timbers. Tests on small clear specimens cut from the large tim- bers were made to furnish data for comparison of the strength properties of structural timbers and small clear specimens. This investigation is preliminary to a more comprehensive study of laminated and built-up beams and trusses. Character and Condition of Material Tested Fifty-five 2-inch by 12-inch by 16- foot planks of commercial southern yellow pine were used. l Tests made at the U. 8. forest Products Laboratory, Madison, Wis., in co-operation with the National Lumber Manufacturers Association, Washington, D. C.By O. E. Heck, Engineer in Forest Products. This is a progress report of one of a number of investigations on woods commonly used for construction purposes. 51001)4 Page Two BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH This material had been air-dried and had about 17 per cent moisture content at the time it was tested. The planks were plain sawed and prac- tically free from defects, but about one-half the number contained season checks, some of which opened up considerably after assembly in the beams and before testing. A few of the planks were somewhat cross-grained, but not seriously enough to preclude their use for this series of tests on beams built up of clear stock. The solid beams (previously tested) with which comparison is made were limited in defects as in the select structural grade of the Southern Pine Association and were selected by a representative of the laboratory. Construction of the Beams Each built-up beam consisted of five planks bolted together. The planks composing a beam were matched by comparing ends, material of practically the same quality being used in each beam, and were surfaced on both sides in order to have the resulting beams of uniform dimensions and all p'anks fitting closely together. All bolts and the holes into which they were driven were 34-inch in diameter. The bolts were spaced as indicated in Fig. 2. Washers 1^4 inches in diam- eter were used under the heads and nuts to pre- vent crushing of the outer planks. After the beams were constructed they were surfaced on the top and bottom. Method of Testing Built-up Beams The built-up beams were tested in accordance with standard practice of the United States Forest Service 1 , on a 200,000-pound-capacity Richie test- ing machine, which is provided with an extension weighing platform (see Fig. 1). The beams are placed on two knife-edge supports 15 feet apart, that rest on the platform of the testing machine. The test load is applied at the third points of the beam. A fine wire kept taut by means of rubber bands at the ends is strung between two nails 15 feet apart driven midway between the top and bot- tom faces of the beam and vertically above the knife-edge supports. As the test load is applied the beam deflects and the steel scale which is fastened to the beam midway between the sup- ports moves down while the wire does not change its original position. The distance the scale moves relative to the wire indicates the amount of de- flection or bending. Deflection readings are taken rt suitable increments of load. In this instance, the loads were read every 2.000 pounds until about 30,000 pounds had been applied, when the weighing beam of the testing machine was kept balanced and the loads read for every 1/10-inch deflection. This method of obtaining the load- deflection curve assisted materially in locating the elastic limit and in ascertaining the load at failure. Tests of Small Clear Specimens After the built-up beams had been tested, small clear test specimens were sawed from each plank in the beam near the point of failure and tested according to the laboratory's standard method for testing small clear specimens 2 . The nominal sec- tional dimensions were 1.6 by 2 inches. These test specimens are called "minors." FIG 2 SPACING OF BOLTS IN BUILT-UP BEAMS. Two specimens for each of the following tests \vere taken from each plank in the eleven beams : Static bending Impact bending Compression parallel to the grain Compression perpendicular to the grain Hardness Shear Cleavage Tension perpendicular to the grain The minors sawed from the solid beams with which comparison is made were 2 by 2 inches in cross-sectional dimensions. 1 See U. S. Forest Service Circular 38, "Instructions to Engineers of Timber Tests." 2 See U. S. Dept. of Agr. Bulletin 556, "Mechanical Properties of Woods Grown in the United States," by J. A. Newlin and T. R. C. Wilson. Can be obtained from U. S. Supt. of Documents, Washington, D. C. Price, ' 10 cents BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH Paye Three // BUILT-UP QA*I3 ~No/nir>ot dimensions 3~*/t*/'CJ*or dense 9 SOLID - 6'if!2"x/6 ' 59l*cr MINOR5- 3motl c./*or specimens /.6Z~x3O". Cur from sv/td A butlr-up btoms. FIG. 3-STRENGTH PROPERTIES OF SOLID AND BUILT-UP TIMBERS COMPARED WITH MINORS. (SOUTHERN YELLOW PINE.) Explanation of Experimental Data In Table 1 are given the strength properties of the built-up beams together with those of their minors. The adjustments for differences in mois- ture content were made and ratios of the strength properties of the large beams to the same proper- ties of their minors formed. The averages of the individual strength properties were computed and these are used as a basis for the analysis of the results. Table 2 contains data on the solid beams similar to those found in Table 1 for the built-up beams. Table 4 is a summary of Tables 1 and 2. In Table 3 is given a summary of the results of all minor tests from the built-up beams as well as the averages of these resu'ts. Fig. 1 shows the manner of loading the beams during test. Fig. 2 shows the spacing of the bolts in the built-up beams. A graphical representation of the average values of Tables 1, 2, and 3 is given in Fig. 3. The insert shows graphically the ratio of the built-up to the solid beams. Load-deflection diagrams for the built-up beams are shown in Fig. 4. Fig. 5 shows a loaded beam which has buckled sidevvise. How the Beams Failed As the test load was applied the beams deflected gradually until the elastic limit was reached, no visible failure occurring until after this load was passed. The failures are classed as tension, com- pression, horizontal shear and sidewise buckling. There were three types of tension failures : cross grain, brash, and splintering. It was found upon examination of the individual planks after test that in some cases there were compression fail- ures which were not visible during the test and no doubt the first compression failure noted was not in every case the first failure to occur. The horizontal shear failures were sudden and gave no warning, the line of failure generally followed the season checks, if there were any. The following notes on the tests of the indi- vidual beams will assist materially in understand- ing the behavior of the beams during test. Beam No. 1. The first failure occurred in compres- sion at a load of 42,000 pounds. A cross-grain ten- sion failure (slope of grain 1:12) occurred in the middle plank of the beam when a load of 49,00r> pounds had been applied. The test was continued until the load reached 51,000 pounds, at which point the beam buckled. Beam No. 2 A faint cracking was heard at a load of 30,000 pounds. A cross-grain tension failure (slope of grain 1:19) occurred at 48,600 pounds. The test was continued to 50,000 pounds, at which load the beam buckled. Subsequently, several compression failures occurred. Beam No. 3 A horizontal shear failure occurred in plank No. 1 at a load of 25,260 pounds. The shear failure was influenced by the presence of several season checks. Tests on the small specimens indi- cate that this plank had a modulus of elasticity of 2,200,000 pounds per square inch, which was much Page Four BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH higher than for the other planks in this beam. The slope of the load-deflection curve was changed after the horizontal shear failure in plank No. 1 oc- curred. A tension failure influenced by local wavy grain occurred in plank 3 between support and load point at a load of 42,250 pounds. The test was continued and compression failures were first no- ticed at a load of 51,000 pounds. The maximum load of 52,250 pounds was reached when several tension failures occurred in quick succession. Beam No. 4. The middle plank of this beam failed by horizontal shear, which was probably influenced by season checks, at a load of 53,590 pounds. The test w.as continued until the beam carried 57,220 pounds when several splintering tension failures occurred with a simultaneous lowering of the load. Beam No. 5. The first failure was by cross-grained tension in plank No. 1 at a load of 38,000 pounds and this was followed by a second and third tension failure in the same plank at a load of 42,000 pounds. The load then dropped to 39,200 pounds; but the beam again took additional load until the fourth tension failure oc- curred at 41,000 pounds. At this point the first compression failure was no- ticed and then several tension failures occurred in rapid succession. Beam No. 6. The first failure was by horizontal shear in plank No. 5 at 37,360 pounds. This failure was in- fluenced by season checks. The load dropped to 35,200 pounds when a compression failure was noticed. As the test continued the beam took ad- ditional load until a brash tension failure occurred at 40,400 pounds, the load dropping to 38,300 pounds. The load was again increased to 41,520 pounds, when the beam buckled and another brash tension failure occurred. Beam No. 7. The first failure occurred by compression in the middle plank of the beam at 44,300 pounds. When the maximum load of 46,930 pounds was reached, three tension failures occurred in succession. The load dropped to 33,790 pounds and the test was discontinued. Beam No. 8. The planks in this beam were badly checked. First failure occurred by tension at 35.20J pounds and this was followed by a second tension failure in the same plank at 36,300 pounds. The scale which was used for measuring the deflection flew off when the second tension failure occurred, but the test was continued to a maximum load of 40,640 pounds. Beam No. 9. The planks composing this beam were checked but not to such an extent that they would be expected to influence the failure. The first fail- ure was by tension in the middle plank at a load of 43,110 pounds. The load-deflection diagram was affected very little by the first failure. Several compression failures occurred as the test was con- tinued. The maximum load occurred at 49,690 pounds, when a horizontal shear failure occurred in plank No. 1. The load dropped to 48,000 pounds and then increased to 49,100, when tension failures accompanied by compression failures occurred rap- idly until the load dropped to 24,000 pounds and the test was discontinued. Beam No. 10. This beam was made up of planks having spiral grain with a slope greater than 1 in 20. The slope of grain varied considerably through- out the individual planks. Planks which had a (SOUTHE 4 LOAD-DEFLECTION DIAGRAMS FOR BUILT-UP BEAMS. -LOW PINE, NOMINAL DIMENSIONS BX 111-2 INCHES. 16 FEET LONG. 13- FOOT SPAN. THIRD-POINT LOADING.) slope of grain greater than 1 in 20 at the center were often straight-grained at the outermost fiber. Some which were cross-grained at one end were straight-grained at the other. The failures of the planks in this beam indicate that the strength was not affected as much as would be expected by the presence of spiral grain. The first failure was in compression at a load of 38,000 pounds and was probably due to local wavy grain. The second failure was also compression at 46,700 pounds and this was followed by a tension and a compression failure at the maximum load of 47,370 pounds. The load dropped to 31,000 pounds, from which it again increased until it reached 34,200 pounds, when sev- eral brash tension failures occurred in succession. Beam No. 11 The first failure was at a load of 47,- 200 pounds, when compression failures occurred simultaneously in three planks. These were fol- lowed by the beam buckling sidewise at a load of BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH Paije Five 49,250 pounds without any tension failures. The test was discontinued when buckling occurred. Solid Beams. The solid beams, data upon which were used in this discussion for comparison, were all select structural grade material with limited defects. A detailed discussion of the tests of this material will not be taken up in this article. The strength values of the minors taken from these beams are about the same as those taken from the FIG. S FAILURE OF LOADED BEAM. built-up beams ; consequently, the ratios formed with the structural sizes should give comparable and fairly reliable information as to the merits of the built-up beams. Horizontal Shear The average horizontal shear stress developed in the built-up beams was 394 pounds per square inch. The range of results is from 335 to 473 pounds per square inch. The average horizontal shear stress developed in the solid beams was 396 pounds per square inch and the range of results was from 324 to 483 pounds per square inch. It is interesting to note in built-up beam No. 4, which developed the highest shear stress and also the highest fiber stress, that the horizontal shear and first tension failure occurred very close to- gether, and in the same plank. The horizontal shear in the small bending speci- mens was not computed since the ratio of depth to length was such that a relatively small part of the maximum shear was developed. The shear ratio shown in the graphical representation of strength properties, Fig. 3 (also see Tables 1 and 2), was formed between the results of tests on small shear test specimens and the computed shear in the large beams. Maximum Fiber Stress The ratio of the modulus of rupture or maxi- mum fiber stress of the built-up beams to that of the small test specimens is 72 per cent ; while the same ratio for the solid beams is 66.3 per cent based on average values. The ratio of the modu- lus of rupture of the built-up to the solid beams is 107 per cent. As would be expected, the small specimens gave higher values for modulus of rup- ture than the large pieces since they were free from defects and other variables that influence the strength of large beams. The increase in the ratio of modulus of rupture of the majors to their minors in the case of the built-up beams over this ratio for the solid beams is slight and the tests are too few to indicate any advantage of the built- up over the solid beams. Fiber Stress at Elastic Limit The elastic limit was determined from the load-deflection diagrams by finding the point at which the deflection increases markedly more rap- idly than the load, or in other words, the point at which the load-deflection curve deviates from a straight line. The average fiber stress at the elastic limit for the built-up beams was 6,160 and for the solid beams 5,750 pounds per square inch, the built-up being 7 per cent higher than the solid beams. (See Table 1 and Fig. 3.) The ratio of the aver- age fiber stress at elastic limit of the large beams to that of their minors is 74.6 per cent for the built-up and 70.7 per cent for the solid beams. Modulus of Elasticity As a rule the stiffest plank in a built-up beam takes the largest share of the load and the planks of lesser stiffness receive proportionately smaller shares. The stiffness, or modulus of elasticity, of the planks in a built-up beam may vary under extreme cases, as much as 100 per cent or even more. The large number of tests made at this labora- tory on small clear specimens have shown that a piece of high modulus of elasticity normally de- flects farther to the elastic limit and to maximum load than a less stiff piece. This being true, it is apparent that the built-up beam is most likely to fail in a plank of low modulus of elasticity rather than in the stiffer plank even though the latter carries a larger share of the load. This, however, is not true of defective material, for the first fail- ure will usually occur in the most defective timber. Page Six BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH MINORS. El i i i K 111 I 5 23 BB****** **3o if 1 i TJ T 1- Tl U K S I'- ll. U) s a 3 1 M J V II 1 K IJ B M ~" i Q. 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" " rt B- S .** 1 " 1 5 : j m i h 3 =" " " 4 BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH Page Seven PERTItS IS P 1 ss s is I e 1 11 1 1! i 1 i - oi I eJ Q 3 i ! 4 :J ti V, .* r -:, : 1 i I J i I- , \ i f i z y ^ < il 1 n H uo , i- M A S i X M < > * 'H * 8 _SJS S ill I'M - s-a --s-" -3-. 4 |51 S II j 5 S" s MBERS IPMEN a . < ^ at t, SOC X-jr *' ^ * h , i \ li* " M\ M ^- tiff :TURAI FROM a 1 !.*.. * i iiiuni i " ? s ..,iiii.5. i! asS 1 ~'-3' " 1/1 m 01 i z i- o c 0. >- i "SiJ* " ss ssggs = > Q 3 E ^i Z |s j- 1 Ul | sjJL N** r.r>.no.nimM f " < c *! siiss^^? i tOOOQOQO Q V V V * 9? os J D 0{ j aT fUlfllf ! c s NQm>r-oo r- s 1 (/) 5 *P9fl4 c ^s^^^^a^ c u K * 5 * iJ ^ Ul H s ss^ 5 |r* 1 lit II It 1 J k S > 3 Z |e 1 n. u 3 II Bi*}? imtitt i R I . .1 L w U) .-" s |E * s 1 * s . ^ t s 15 in ZQ 5* al > 1 ssssssss^ i ik 1 1 i ui |8 c M - I. ^nnn~n^ ,1 jf oli S c * 3 3 1 ' -'- '<- J oj (/) ^ 8V fcRRKSSKR S . f III * 1 J S M ;*""^is* *" "1 3 h jl ti a.RUVfRRfc , ||''|*3f| *| t ^ K 9 a "* ^ c 1** 1 f - - F * 7 . JL? * * ** 1 N | ~.^v ?s ., ;2 S S f .* S 5 * ; ; i s 1 i ^;a S e : =s Ul 1 J si; I "i 1 s T '" Zs 5 s s | c : *s h r t * R : 8 fl S ,? jf S J j> Page Eight BUILT-UP SOUTHERN YELLOW PINE TIMBERS TESTED FOR STRENGTH tfi K Ul 2 i- : i a ** I *** 5 C G H B ITN ^O m CD *> t O CM * -i *^ K 3 U &fi L C < 5 1 * Pi ?n !o H -< * ^o m cS "O o- UNUN*t****^ f-N H O D B 1- U) Ul H V fj * | O ^6 ~ * ) s H 5 * pXll*l3lli8nn9n OONO o TttONSso UNUN ^ I s lit s sp ' ^ QHOO *' r * >o pi 5 '' 3 i 1*1 ' s, i i UN 1 3 *^oS.v3u\SM?^S r J^j Ul Ul a, z 5 -S! , %.,. IJljIln] O CM B M e *,* K ss* I N . 2 & 1-1 CO H -! O C\l N(i * nj o UN i^ UN coo erNCNtN-eKt-c>r*-oco D o S U) , . = 3 S * f~- t"- * *- ^ * CMf^r^CM coovTNONo>ONc6acOco o ! U a- ? H : i 3 S OUtVUNCOOfM CMCpr--3S'S Si 5 "> m in 4 . IP HI C~ C 8 UNOUN K^N? O^ 5" D, %, O Jt C -> !i i. ^ * * O B u A or R s 5 IT Z U. C O V A J^> C 1^* S. *J R z m g S K^? ^?S fl a lg " tJ * U) -J Ul < 1 S H t (-4 R (M -) M-l rH * f> P. - O O P O K m CD p vt a t* Ji 9 5s V M O^ O if ONr-.UNO-H'N.CXj Mi p z 1 s tr o 7 E Z s i Z H h -H *> f M & fO CO CifM^^CTNOfM O OO 1 O M S *"* (CS^S.^* CN-fM 5 E " a o Ji 3 - i E a c > a 5 a. > UN (MUN^CO 'OO4U UNtfNP-O >J>NONOUNUNNOUN>O UNUNNO 75* SCO C -* * < P s J g S . 5 z ...... I! - * I : " : i |I " S 3 1 Bo Ul 31 i' 5 rv 9RK??sr?^s,y K o i 4* 111 m Ul j s.. s ^eoujt-~oujog s M t> T3 C i- i N^^vnor-a.o-oHf J 3 * BUILT-UP SOUTHERN YELLOW PIXE TIMBERS TESTEDFOR Page Nine The strength of the built-up beam depends upon the deflection the defective piece takes at failure. The modulus of elasticity of the built-up beams is 16.2 per cent higher than the average of the small test specimens, while for the solid beams this ratio is 17.8 per cent higher. Moisture Distribution Determinations for moisture distribution show that there was very little variation in moisture content throughout the sections of the built-up beams. In solid air-dry beams in structural sizes it is not uncommon to find that the inner portion of the section has a moisture content 10 per cent higher than the outer portion. Where Built-up Beams Fail The opinion has often been expressed that, when two or more timbers or planks are used together and loaded so as to deflect equally, the stiffer pieces will take the greater load and will, there- fore, fail before the less stiff pieces. It is true that the stiffer pieces will take the greater load. Previous tests, however, have demonstrated that dense, stiff pieces usually deflect farther to the elastic limit and to failure than pieces of lower density and stiffness. It is quite evident, there- fore, that beams built up of clear planks will tend to fail in the less stiff rather than in the stiffer planks. The Forest Products Laboratory has made no tests with defective built-up beams to ascertain if the defects in the component planks can be stag- gered in the beam and the latter so fastened to- gether that results will be comparable to results on solid beams containing the same number and size defects similarly located. Neither have any tests been made to determine if laminations will act independently as individual beams, each break- ing at its particular defect, the net results being practically equivalent to having all the defects at the same point in a solid beam. Such tests would be of value in making a further study of built-up construction. TABLE 4. -SUMMARY OF AVERAGE RESULTS IN TABLES 1 AND 2 ON BUILT-UP BEAMS Ratio (in Per Cent) of Structural Sizes to Minors Fiber stress Modulus Modulus at elastic of of limit rupture elasticity Built-up ........... 74.6 72.0 116.2 Solid (6 by 12-inch) 70.7 66.3 117.8 Shear 1 26.3 34.1 Ratio (in Per Cent) of Built-up to Solid Beams 107.0 107.0 96.5 100.0 Ratio (in Per Cent) of Fiber Stress at Elastic Limit to Modulus of Rupture Structural Minors Built-up ......................... 72.5 70.2 Solid (6 by 12-inch) ...... ........ 72.2 68.0 l Ratio of computed horizontal shear in built-up beams to result! obtained on standard shear specimens. U. S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, Wisconsin Engineering Bureau, Chicago, Illinois. March 1, 1921. NATIONAL LUMBER MANUFACTURERS ASSOCIATION. **>. NATIONAL LUMBER MANUFACTURERS ASSOCIATION -WOOD CONSTRUCTION INFORMATION International Building, Washington. D. C. Harris Trust Building. Chicago. Sept. 1st, 1922 Page One MAXIMUM SPANS FOR JOISTS AND RAFTERS* The following tables provide a handy means of determining the maximum clear spans for wood joists and rafters. They are based upon a wide range of strength values and cover ordinary load conditions. The span length should be limited by deflection to prevent cracks where ceilings are covered with some hard, inelastic ma- terial such as plaster. Where ceilings are not so covered and where a small amount of sag or spring is not objectionable the span length may be determined by the bending strength of the member instead of by its stiffness. All spans given in these tables are based on the actual sizes of lumber. When the allowable stresses for timber are not prescribed in the local building code use the values given below. They are taken from the recommendations of the Forest Products Laboratory, Department of Agri- culture, at Madison, Wisconsin, that were officially adopted by the American Society for Testing Materials and the American Railway Engineering Association. ALLOWABLE UNIT STRESSES FOR STRUCTURAL TIMBER (Pounds Per Square Inch) Species of Timber Modulus of Elasticity BENDING COMPRESSION Stress in Extreme Fibre Horizontal Shear Stress Parallel to Grain, "Short Columns" Perpendicu- lar to Grain Cedar Western Red 1,000,000 800,000 1,000,000 1,400,000 1,600,000 1,500,000 1,200,000 1,000,000 1,200,000 1,400,000 1,100,000 1,300,000 1 ; 600,000 1,100,000 1,500,000 1,600,000 1,500,000 1,000,000 1,000,000 1,200,000 1,300,000 1,200,000 800,000 1,300,000 900 750 950 1,300 1,600 1,300 1,100 900 1,100 1,300 1,000 1,200 1,500 1,000 1,400 1,600 1,300 900 900 1,100 1,200 1,100 750 1,200 80 70 90 100 100 90 85 70 100 75 70 100 150 100 125 125 105 85 85 85 70 85 70 95 700 550 800 1,100 1,200 1,000 800 700 800 900 700 1,100 1,200 800 1,000 1,200 1,000 750 750 800 1,000 800 600 1,000 200 175 300 350 350 300 275 150 300 300 300 325 500 350 500 350 300 250 250 300 250 250 175 300 Cedar Northern White Chestnut Cvpress . . Douglas Fir (No. 1 Struct.) Douglas Fir (No. 2 Struct.) Douglas Fir, Rocky Mt. Region Fir, Balsam Gum, Red Hemlock, Western Hemlock Eastern Larch, Western Maple, Sugar or Hard.. . . . Maple, Silver or Soft Oak White or Red Pine, Southern Yellow (Dense) Pine, Southern Yellow (Sound) Pine, Eastern White Pine Western White Pine Norway Redwood Spruce, Red, White or Sit kn Spruce, Engelmann Tamarack, Eastern if Prepared by Richard G. Kimbell, primarily ai a service to Building Official*. Maximum Joist and Rafter Spans Page Two AVERAGE WEIGHTS OF VARIOUS MATERIALS (For use in determining Dead Loads. These weights ware uisd in obtaining Span Lengths which appear in the tables.) Joists: Nominal Size 2 x 4 ............................................ 1% x 2 x 6 ............................................ 1% x 2 x 8 ............................................ \% x 2 x 10 ............................................ 1% x Actual Size Wt. per Lin. Ft. 3% .................................................... 1.6 Ibs. 5% .................................................... 2.5 Ibs. 7Y 2 .................................................... 3.4 Ibs. 9 1 A .................................................... 4.3 Ibs. 2 x 12 2 x 14 3 x 6 3 x 8 3 x 10 3 x 12 \% x 5.2 Ibs. \y % x 13^ .................................................... 6.6 Ibs. 2y s x 5% .................................................... 4.2 Ibs. 2% x 7}4 .................................................... 5.7 Ibs. 2% x 9J^ .................................................... 7.2 Ibs. 2% x \\Yz .................................................... 8.8 Ibs. 3 x 14 ............................................ 2% x 13H .................................................... 10.3 Ibs. 4 x 6 ............................................ 3% x 5% .............. : ..................................... 5.6 Ibs. 4 x 8 ............................................ 3% x m. .................................................... 7.8 Ibs. 4 x 10 ..... ....3% x 9J^ ..... , 9.8 Ibs. Finished floor 2.5 Ibs. per sq. foot Rough floor 2.5 Ibs. per sq. foot Sheathing 2.5 Ibs. per sq. foot Plaster 10.0 Ibs. per sq. foot Roofing: Group I Shingles 2.5 Ibs. per sq. foot Copper sheets 1.5 Ibs. per sq. foot Copper tile 1.75 Ibs. per sq. foot Three ply ready roofing 1.00 Ibs. per sq. foot Group II Five ply felt and gravel 7 Ibs. per sq. foot Slate, 3/16 inch 7J4 Ibs. per sq. foot Roman tile new style 1 part 8 Ibs. per sq. foot Spanish tile new style 1 part 8 Ibs. per sq. foot Ludowioi tile 8 Ibs. per sq. foot Mailmnm Joist and Rafter Span* FLOOR JOIST SPANS (30 Pound Load) Page Three 4 00 7 gococo 'I 1QOO 1 1 1 1 1 1 CO 00 CO 1 1 1 oo 1 1 1 1 00 CO CO 00 OOO 1 1 1 Tj< t~H CO 1 1 8 TH 1 fl CNCNTH CNCNCN IN IN P g WON "MI i-H 1 1 1 00 COCO OOOSTH 1 1 1 8TH- U5-HOO TH 1 1 1 8cN 00 1 1 co8 OOO-H 7 1 7 OTHCO 1 1 1 rH i-H 1 1 1 1 "O > C v. CNCNCN CN 1 jl Jj o to 1 12" MI 1 1 1 00 CO CO OTHt- 1 1 1 1 1 1 r^ rf o IN CO 1 1 * 1 1 1 coujo 1 1 1 TH 1 1 1 Ot- 1 1 O 7 G 5 -rf a (- 0) CN THTHTH CNCNTH CNCNCN CO CN Isa ^nplastere* -c a> 0> ** S3 R 5s I S lO 00 I s " III ^ COTHO OCOO 1 1 1 i < rH rH 1 1 1 CNTHTH 1 1 1 CO CO O5 CNCNrH coo 1 1 OOOi-H 1 1 1 CO-*cN COOJU5 1 1 1 822 l-H OOO 1 7 i 00-* O CNCNCN OOO 1 1 O 7 8S I HI fc "S~^ M a i H p ! o 3 1 =3 g B 5 o o III 1 1 1 ( i-H i-+ 1 7 i i-Hooia CN I-H I-H ooo os 1 1 1 ^ 1 CNCNOO 1 1 1 CO-*TH TH TH TH OTHO i 1 7 THO>O OTHO TH TH 1 1 1 CNCNTH OOO TH 1 1 O i-H 1 IK c.'> til O fa > c TH 1 ^ s UPPORTS 1 ""** B M*5 I II g COOO III \ \ T OOCNO 1 1 1 oooio CNTHTH OOl-H 77 i ^ ^ oo WC^ 1-1 1 I I-H 1 1 1 oo oo co 1 1 1 lOCOi-H TH l-H TH 1 1 1 THOOO CNl-HTH 000 1 1 1 OOO 1 1 O i-H 1 8 ||ll -UNIFOF 'ounds per ETWEEN g 3 * JJ C * 3 1 H "ill THI-H )-H t 1 IO 77 i i TH-*U3 7 i i I'M i-M i-H r-t i-H IO -^ cloti O5COO 1 1 1 OiHO TH 1 1 1 >ocoo TH TH TH CNOOOO 1 1 1 O t* ^ CNl-HTH OO-* JMN ' 1 1 1 OCOCN COCNCN OO 1-1 i i COCN O e9y a> Sj *"^~" " O- O. -2 a"?"! *sil g H EH O || g cooco "ill *i THOOO i 1 7 ^HGOO i 1 7 OJOCO 1 - 1 t 1 1 1 COCNi-H 1 1 1 1 1 1 -f CM O COTHO 1 7 i OCO"* OCNCO 1 ^ \ OU3CO 1 1 1 OOU3TH COOO 1 1 l2i5 O.Q, fWOOa "* t3 i .&" OJCN 8| 3 9 ll II "7 1 7 oot- CD 00 iO l l l CO ^ CO M 1 1 1 OOIOCO ocoo TH TH 1 1 1 S22 CO THIN 1 1 1 TH TH 1 1 1 1 1 1 00 CO CO i-H 1 1 1 8S2 W5COCO 1 1 1 CNOO 1 1 8 | cf 3 fa Q) s 3 ^ 5? s a III I e III i 1 7 TH i 1 1 1 1 OOTHO 1 1 1 OOO "O OOCN TH TH 1 1 1 CN CNTH 1 1 1 i-H *H UJ-*00 1 1 1 OCNO 1 1 1 THO5CO CNTHTH ooco 1 1 1 882 OOO-* 1 1 1 L: a ~ 1 "S 3 5 MAXIJ S""j3 fc a> >.. o QQ "S. *"" a) H ' oooco "ill ^ OOiOO fe *"* 1 7 i *CN I 1 1 1 TH TH TH *CDCO 1 1 1 u;-*00 1 1 1 >OCOO CNCNCN CO COO *H 1 1 1 TH l-H 1 1 1 CO 1/3 CO TH TH TH OTHTH 7 1 7 O O5CO CNTHTH OO-* 7 i i *coo CNCNCN 7 i i HI . %* Sfa S 1 E **1 M E- 1,400,000 ^777 -*; oOioo TH 1 1 1 CO (NO TH TH TH ocooo 1 1 1 TH TH TH 1OOOCO 1 1 1 OOO CO (NTHl-H 1 1 1 OOOOU5 1 1 1 THOO TH TH OCOO 7 i i IO-*(N TH TH TH OCOCN 7 i i ooo co TH TH TH 1 1 1 882 1 1 1 588 111 a 1 a ^l* = 1.2 C "B g o 3 I O i j "III ^ ooot- oosco 7 i i THOO 1 7 i CO-* CO THOO 1 1 1 CNCOO TH 1 1 1 CNCNO 1 1 1 THOO OOCN 1 1 1 1C COIN o-*-* 7 i i COOiQ 1 7 i 8S2 1 1 l CO * TH sJJUl <2 *P&H w m K - !* 1 a 1 fill! 3| a a 3 & i a "ill ^ asoot- K oooo 1 1 1 (Ni-HCN TH 1 1 1 1 1 1 *H f-l TH 0000 7 i i THOt>- CNCNTH 1 1 1 OOOO TH CNO"5 1 1 1 TH TH TH 1 1 1 r ' i cot*-* -dtl ?32TH ooco 1 7 i 3 MSt'l! S .l.g.gs-g 22cN 22S NCO-* 22SJ 22S IN CO-* THI-H IN CNCO-* THTHCN 223 CNCO-* THTHCN CNCO-* THTHCN | W! X 00 H CN o TH H (N X CN H IN CO CO oo H co O TH M CO CN TH M CO TH K CO NATIONAL LUMBER MANUFACTURERS ASSOCIATION Mailmum Joist and Rafter Span* FLOOR JOIST SPANS (40 Pound Load) Page Four ll II g "ot-co r i i J CO O E*< ooiooo 1 1 1 l-H 1 1 1 (N OCO 1 1 1 CO COO CNCN CO-* 1 1 OOOO 1 1 1 CO-*CN I t l-H l 1 t-O"O 1 1 1 CNOCO CN coo t- 1 7 i oo 1 1 o 1 1 1 00 CN fj jl I n g o-*co III * CO O (NO-* 1 1 1 ooot- 1 7 i OOO 1 1 1 COIN 00 "OO 1 1 CO CO 00 1 1 1 CO-* CO 7 1 7 010 "O O 1 1 1 7 i 83 o 1 8 1 * CNN 1 1 1 co-* 1 1 1 1 ^ 1 1 1 1 1 1 1 "OCO t"" ^H O 1 1 1 ooo 10 oooo 1 1 1 "OCNOO OCNt- 1 1 1 * 1 8 |HI c [3 It **" CN 1-1 [|H Jj ft -g 1 IK 1 1 i g ocoio 7 1 1 1 1 1 1 1 1 cidtl l-H 1 1 1 t^ oo 1 7 i i i 10 >O t-H 1 1 1 o I t l-H 1 1 1 * 00 ocoo i 1 7 oo 1 1 fjlf g ^ o " 2 M EK (NCNCN 1-1 li^c^ 3 'PORTS 5 5 si 1 Is 2 1 7 i *i < Ci CO o o 1 1 1 7 i i 00 CO CO 1 7 i (NOCO l-H 1 1 1 1 1 1 (NO l-H 1 1 1 OCO CO OOCO 1 1 1 00 -*O 1 1 1 00 *O -H OCO 1 1 83 S-- ^^ "go O O O J .*s ri S -ill 11 TTWEEN S * fc Jj f "7 1 7 ~ oot- 1=4 ^H 1 1 1 -*(NO 1 7 i 00 'OCO f" 1 1 1 7 i i (N CO 1 1 1 oooo i 1 7 CO (NO "OCN-* 1 1 1 oo co co 1 1 ocoo i 1 7 882 t-COCN 1 1 1 CN3cN cot- ! 1 88 Ml llll GISTS 1 Load 50 1 NGTHS Bl a;^ I.I fi >** n g lo-co III .J OOt- l-H 1 1 1 CO (NO 1 1 1 i-H ^H r-1 CO 7 1 i ooo 10 (N (N CO 1 1 1 OC^lOO 1 1 1 co o 1 t oo coo 1 1 1 t-O(N I 1 l-H l-H 1 1C f 1 1 1 1 CNOCO CN 1 1 1 882 o t- 1 1 1 (S ^ Q o o i i "S o> o >* O H H g OOO 1 1 1 ~ ooot- 1 1 1 i 1 7 1 1 1 OO"0 1 1 1 CO * l-H l-H 1 1 1 (NOOO O(N 1 1 1 O * CN OCO-* 1 1 1 1 1 1 CNOCO 1 7^ 3 fa C ^ o o 1 1 1 f-H 1-4 ^H 1 1 1 OOOCO O-* 7 i i- COCNO CNCN cot- co 1 1 1 oo I) 1 < oo-* t- 1 1 1 t^oo i 1 7 ooo>o 1 1 1 < COt- 1 1 1 CO O CN (N * * 1 1 1 t-"O(N CNCNCN JS | 3 v. ** C 'sS o 5 e o I pit u: g tOOO III 1 1 1 * CO 1 1 j^ cooo 1 1 1 COOt- 1 7 i SOOCO l-H oo 7 1 7 oot- ^ coo 1 1 1 COCNO l-H l-H l-H O-*CO 1 1 1 CO "OCO l-H l-H OCO-* 1 1 1 oooco CN 1 1 1 8S2 "3 .g Q n & oj l^ii 223 CNCD-* 223 223 CNCO-* CN w CNCO-* i 1 CN CNCO-* CN CNcO'l* (N 223 Z o J3 c X III- X tN 00 X X C ... I. "lM li, rH rH OOrf rH rH 1 1 1 7 i i ! ' 1 1 1 1 OOrH 1 1 1 O"OO 1 1 1 rHCNO rH 1 1 io coo rH rH rH rto 7 1 7 O-iOIN rH rH rH co co co 1 1 1 CMOS CO (NrHrH 00 COO 1 1 1 O-if OS 1 1 1 O t~ CN COCNlM isii >> h s 5 3 en 11 O *- 31 i i oosco "ill j oooi>- 1 1 1 OOOrH 7 i i 1 1 1 1 1 1 OOOrH 1 1 1 (NrHOS rH rH ^ 1 7 i "5 OS 00 1 1 1 oo co oo 1 1 1 OS COO i 1 7 I 1 *" ~ '* (N IN CNCNrH f-flil a E -/ ' J 0 (Ni-lrH rH 1 1 1 3o3rH COCNrH i 1 7 CNCNCN rj M (P a 5 > 3 " I ^ 3 a |! II s coot*- "ill J O5 00 O (NOOOS 1 1 1 CO.OOO 1 1 1 1 1 1 00 CO CO CO CO 1-1 1 1 1 822 1 1 1 rHOOO 00 00 CO 1 1 1 IO CO CO CM CO 1 1 1 >OI>-rH 1 1 1 CNOrH i 1 7 a 3 ') a "^"c * IN CN-H (NtNrH n a i ij 3 ffs 01 II 'U C5 00 CO III ^ 001^ co E 1 1 1 rHOOO 1 1 1 ( , cocot- 1 1 1 -H . rHCOCO 1 1 1 Ot^O 1 7 rH O-HOO rH 1 1 1 * tN O rH rH rH CO CO CO 1 1 1 00 CO CO rH rH rH CO CO IN 1 1 1 822 OOSO rH rH 1 1 1 1 i j * . -j J CD S 5 -5 MAXIA 8. 3 .?'.= S 000*009*1 - 1 1 1 1 1 1 IN -*O 7 i i t-H O *O 1 1 1 O-HCO 77 i OOOS 1 1 rHOOO OCOrH rH rH 1 1 1 TJ< CO rH OS rHrH 1 1 1 00 t >O O CO rH 1 1 1 8S2 rHOCO 1 1 1 ~: is i i s 1 !^ \ P 3 ^ o os Q a> a W I r > P 3 8 i ! * ^Ifca'S' r g OCOCO "III 0000 1 1 1 IN 103 (NON 1 7 i CO Ol Oi 1 1 1 oooo rH 1 1 1 rH Ol^ cor--* 1 1 OOSOO rHO0 1 1 1 ^J" CO rH 7 i i C-CO'* 100010 1 1 1 1 1 1 ~* c *o "M ^ * 3 D* W c (NCNCN J.|S.S i .0 I li|1 | S1-S1-S 1 11 |l! II i t-OO " 1 77 ^ oot^co E 10>O(N 1 1 1 rHOOJ rH rH i i ^ IOOO 1 7 i r-iOTti OJOO3 1 1 1 822 1-H-HO 7 i i OS OS 00 i 1 7 COMO rH rH rH rHCOOS 7 i i CO IOCO rH rH rH IOOOCO 1 1 1 goo co rHrH OSO'* 1 7 i COrH OS CNCNrH l||-S.a |1|||| OH e U9 g _ ". | "ill .; octree OSOJO- 1 1 1 oosoo t-"OO 1 1 1 rH 1 1 1 COTfCO COOOS 1 7 i 1 1 1 1 1 1 CN-HO rHt-O rH rH 1 1 1 (Nl^OO 1 1 1 1 1 1 (N OOO Slilii tj 09 r a Mill FP 223 223 22SJ 22S 22S 223 CM CO M' rHrH IN 223 (NCO-* rH-HCNI rHrH IN M 1jj 9 oo X IN o X X rH X ft CO CO X CO o X CO M X CO X CO NATIONAL LTUMBEli MANUFACTUREKS ASSOCIATION Maximum Joist and Rafter Spans FLOOR JOIST SPANS (60 Pound Load) Page Six U Ji 7 g O ON "MI j ooo COCO i 1 7 10 COO NOO 1 1 1 ooco 1 -H 1 1 1 cooo NN OON 1 1 1 N NN 1 1 1 *NO 1-H 1-H (* H M 1 1 1 H 1 1 1 1 r-oo 1 1 1 N N OOiO 1-H 1 _l ^ N NN 00 1 1 OlO CON 00 7 i i O^HN -H 1 1 H M 10 1 7 i NOO N coo t- 1 7 i 00 Tt< O * oo t- o 1 1 1 ON 1 1 1 N CO ^-i lO 1 1 1 ooo 1 1 1 S22 OO 1-H 1-H 1 1 1 ION 00 Ot- 1 1 1 OON OOO 7 i i -H IO IO 1 1 1 ot- -* OON 77 i * oo o g 0) t+4 &H - NN- fsjL il I'PORTS 1 -5 1 w2 5j c. ^ ! < O CO " i M _j o ooo ococo 1 1 1 CO O ^* CO OS 1 1 ^ OON N 1 1 1 OON 1 1 1 NN- cooo 1 1 1 NOCC oooo 1 1 1 1-H 1 1 1 22 OON ,' ' ' OOCO 1 1 1 O IO 1 1 1 -H NO NO l-H i-H 1 1 1 OO CO o o 1 1 1 f t- |JM ^* ** i i I o: cJ Sill S 0. Si O 3 WEEN 6 11 ! g IO 00 "MI ^ O OOO 100 1-H 1-H 1 1 1 N OOC 00 00 CO 1 1 1 IOCO O t- 7 i i SO CO CO ooo 7 i i 1 1 1 ooo ooo 1 1 1 0-* ooo 1 1 1 O t^- -f O O 1 ^ 1 1 1 1 ooo 1 1 1 CONO UJ * 1 1 1 oooco OCOO 1 1 1 CO OO x M e *"> ~^ll 'o'ocS r. n ** ,.T3'C3 fe (2 r- 1 H 5 <* H NN (N NN NNN |3|gg g | -g x h 3 E ? i g OOiO 1 7 i ^ OI^O * o 1-H 1 1 1 o oo o o 1 1 1 IO COO oo 1 1 1 OCiO CO 7 1 1 1 7 i ooo 1 1 1 IOCO (NOO 1 1 1 < 1 1 1 OCO CO ON 00 1 1 1 1 1 1 NOO 1 1 1 CO O oooo 1 1 1 OiO 1 1 1 NOO 4 \ 3. g KH O i! *M ij NN NN "S ~Z 2a O bb H 5 -i- .lo li g OlO "III ,j OOI--O 1 7 i ooo *oco 1 1 1 CO * 1 1 1 ocoo 7 i i 22 1 1 1 r-ooo 1 1 1 Tt t-o o 1 7 i CO O 1 1 ^ ococo 1 1 1 Ot *< N CO 1 7 i ooot- O O 1-H 1 1 1 CONO *N O 1 1 1 t IO N iH i 1 I 22 co-* oo 1 1 1 10 O 1-H 1 1 1 ooc oo 7 i i r - - oo 7 i i I - GO 1 p fc - "* NN- I 1 S '* MAXI! a * ,2 o 1,600,000 g OCON "Ml .j 000 t- oor- 1 1 1 N O NO l-H 1 1 1 IOCON co oooo 1 1 1 coco-* t- 1 1 1 1 OO-* 1 1 1 oooo NOiO 1 1 1 o * * 7 i i ooo TfH 1 1 1 1 1 1 IO CO O co ooio 1 1 1 oo 1 1 1 IO-* N l^OO i 1 7 OOOlO L. t 1 -i O ^ 1 c S"^ O X i< 5 * ** .H K m 3 03 -< a3 f^t O* ^ g J JJ | 1 77 <_; OOt-O OON 1 1 1 OO ocooo 1 1 1 * CO 000 1 1 1 r-o * o 7 1 7 32 o o 1 1 1 oooo 1 1 7 CONO 1 1 1 oot^ 1 7 i 0000 OOiO 1 1 1 NN2 NNO 1 1 1 OO OOO 7 i i * CON ON 1 1 1 GCf-lO d u *9 1 o Il-Sgi K t a^fl K 1 1 u -gjl 2 "I" 3 |o = g NOO III ! OOt-CD o 1 1 1 OO IX ot-o 1 1 1 CON OON-* 1 1 1 NO OOC O ooot^ 1 1 1 ooo t- OO-* 7 i i N O NOO f i 1 1 1 O * CO ooo 1 7 i O 1--IO O O 1 7 i N O X t-ooo 1 1 1 oooo 1 1 1 Tf CO 7 i i ll"l K K gliili 3 0? Iff ill J 5 a&3 B 1,000,000 g OON "Ml _ t-t-o N-*N 1 1 1 oooo OOIO 1 7 i co o oc-*o 1 1 1 10-tfN 00 O I'M N N 7 1 1 oooot- OO 1 1 1 N O COO-* 1 1 1 *oo -H 1 1 1 1 1 OOO 1< moo * 1 1 1 CSf- o o 1 1 1 oooo * coo 1 1 1 CON O oooo 7 i i OlO CO " M O C a W H illlli Spacing of Joists Center to Center in Inches NO-* N 22JS NCC-* N N Of N 22S NO-* N 22S 3SS NO-* N 22S NO-* N 22S NO-* N |J 1* < tiiie of Joists (Nominal) in Inches O K N oo K N o f X N N X N -H N O X CO oo co o X CO N X CO 3 X CO O X 00 X X * NATIONAL LUMIiEU MANUFACTUBEBS ASSOCIATION Maximum Joist and Rafter Spans CEILING AND ATTIC JOIST SPANS Page Fourteen 1 o CJ ^ 1 c 8 "m^ 000 1- t-Nt- l-H 03~ 1 j> t 1 III 1 1 1 1 1 1 1 1 1 1 1 1 g - B J3 h ^" *; t^O O i-HOOJ O * N os r^. o CO - O> E * U 1 1 i - CT 9 g H 1 ? a 1 9 3 Q. e g & LOADE I ? 4 11 o I | ' i 1 7 1 1 1 - 7 i i * CON OSON 1 1 1 CO CD CO 1 1 1 0. - s H .s 5 s ^_ 5^ E H K ^iqa j eg o, o a ^^U4 Bj T 8 9 9 O, . V S "Co BJ >> oj ^5 prt (> OS 00 t^ N O *O C3NU3 T}4 *O ^ O O o i 'E > II s 1 'ill 1 1 1 oooo 1 7^ 1 1 1 J. ' ' i ^ i g CM E g '! m a C *>$ 8 * a g, o i, o 'cJ2 ^ GO CO m g 8 o 9 ^3 ^ .S * H u S "^ * 8 *i CO-HCO O ^H 1-4 T. OJ3 H p & ALLOWAJ * Is a K I j^l S-o CO 1,400,000 g oooo "ill ^ OO500 oooo 7 i i 'C ^ CO OCO(N 1 1 1 OOOO 1 1 1 ooo> 1 1 1 O OC U5 | x o a 2 H S b |] o H H fit ^ I I o S || u z S s * i 1 11 3 u O g ON-. 'ill ^ oooo 1 1 1 00 CO-* 1 1 1 O500CD "5O> "5 1 1 1 -HOU5 7 i i - 5 a "8.2 3 u |i u b. W C*l W f^f S' ^ *a ^ o 1 T3 | I Tft-f, NCOOO ON-* OTl-CO NOO Is J GO 2 | "ill 1 1 1 1 1 1 1 1 1 1 1 1 I't ? i *j ^j Ol 00 t* *f CO i OCt^'O CO ** O ^- >O CO a js |t **" a 1 H pi fH iH S "3 50 t C oo fc O >-. 3'S C." i c to t o .c -" ^u'""' 222! 223 NO* I-<-HN 22S NO* RT3.S3 o ! > SS.|a 3 'S s a u B H ** -," l~ * 00 o M 2 S'3 ,5 X X X X X o * N N CM N N NATIONAL LUMBER MANUFACTUREKS ASSOCIATION Maximum Joist and Rafter Spans RAFTER SPANS (30 Pound Load Group I Covering) Page Seventeen o on Ss gS J3 0) o| u Sfe ij O a) = - 5 lg So >> C S 2-r.So oS.H v I 8 s:sl - !-!-.! v = ? * 5 w o o! ja Cs 3 *^ - O5"500 ill g (NOCO - ooct^ J-HCDO 1 1 1 - 1 1 1 O> 00 CD I I I - Ost~CD m g wooro "ill g OOOS "ill ^ ooi^o ft g 00 00 "5 SO O O CH ill S' 1OO-H I-H "III 1 1 lOeo 1 1 1 1 ! fH(NO r-l 1 1 1 1 1 1 * (NO 1 1 1 1 1 1 TO O> eo ro ,-H 1 1 1 1 1 1 (NOOO 1 1 1 -HOOO 1 1 1 -HOO i 1 X M t^oo i 1 7 1 1 1 O5COCO COCO T)< 1 1 1 ootoro ot^o 7 1 7 00-* 1 1 1 fC OO 01 1 1 1 1 1 I lOCC-H CCOCO 1 1 1 1 1 03 -H o 00 K * oo f-H 1 1 1 r-TfO5 MIN?-. 1 1 1 os oo oc (N 00 -CI-H I I I CNrtS 1 1 1 OSN.'J" CJtOOO 1 1 1 CC O CO OS 00 00 1 1 1 1 1 1 IN O> < OOS i 1 7 1 i CO** CO coo>o 1 1 1 INCO-* MI-HN X CO 1 1 CO 00 1 1 I I CNCN OOS-* 1 1 1 CM OS CO I I I CNCMC-! OOJOO 1 1 1 i 1 CDXO pti 1 1 1 i 1 ^ O CO 1 1 1 TJIOOCO -HOSt- CO 00 00 1 1 1 ooo co CN-H-H 1 1 1 22S X CO I V 5 J 03 8 iy Hi :l g | tH4H*>* A Jf fllf 1 1 1 "i a 3 o-S,o ISI ill Sfe i I NATIONAL LUMBER MANUFACTURERS ASSOCIATION Maximum Joist and Rafter Spans RAFTER AND ROOF JOIST SPANS (30 Pound Load Group II Covering) Page Twenty M ~ II "ill 1 1 1 1C CO i 7 i 1 1 1 1 7 i fc: COOO i 7 i o o * 00 1 1 1 1 1 1C CM 00 Ot 1 1 o 1 ' CM01 CM CM H c ** e g II fcS ^ 1 1 1 - ooco ~ 1 1 1 1C COO 7 i i Ob-'* 77 i OCM 00 7 i i CO fi OiCI 1 I 1 00 OCO 1 1 1 1SS32 00 1 1 00 1 t- I i 1 3 > c M CM CM CM * Jl - '' CMCM si o 1 II g OCOO "MI - ooco 1 1 1 cooo 1 77 CMt- 1 1 1 iCO 7 i i oe ic OiC 1 1 oo -H ! 1 1 CC 1C CO 1 1 1 OO-* i 7 i gO CM o 7 ft* K ^ * " H CM a o a HIDGE ij * M 11 II 1 7 i 1 1 1 1 1 1 c/; oco 1 1 1 1 1 1 oooo J_ 1 I ICO 1 1 1 I- 1C CM t-oco 1 1 1 icooo 1 1 1 o 1 IP o 1 if ?x s Bj fa 01CM LOADED [ PLATE '1 S P 5 * e ! 11 II - oc t o fa 1 7 i oo -H 1 1 1 1 1 t-oo 1 1 1 8S2 oc-. o 1 1 1 1 CO O 1 1 77 i O * CM o oo 1 1 1 CM O O CMCM 1C i 1 7 888 0- 1 1 OiC CO CM CM 1 III -! as I 5 fa ~ i &s ! "ill _ 001 o 1 1 1 CO O 1 1 1 ^H 1 1 1^ o o 1 77 1 7 i 1 7 o * 1 1 1 CM O O 1C CM CM 1 1 1 I"- -f O CM 1 1 CM 1 C.s'o SJS'o O ^ o * CM Se f PPORT& O .2-0 , c.' 11 II II _ i CM CM o III ~ cot- ic t-oo 1 1 1 CM cor-o 1 1 1 * CO 7 i i OOCO 1 ! 1 ooo 1 1 1 1 1 1 1CCO t-uj 1 1 1 322 1 1 1 882 OCO 1 1 o 1 t 1s II 1 1 Ills H * /_ S ** 3 CMCM *J*I ! IETWEEN N j| ** a I g 001- " 1 J^ fa oooo I 1 1 CMOOO o 77 i oo t- 1 1 1 Ot--* CM OO'C ! 1 1 * 1-4 t CMCM 1 1 1 CM i 1 7 O CO O CMOO 1 1 1 8^2 (N CO S s s 00 < i |Jj| & 1,100,000 i o CM ic '"III 1 1 1 OOOO ooco 1 l-l -f cs- t- CO 1 1 1 T)40 1 1 1 OOiC 1 1 1 oo 1 1 1 CM O 1 1 1 OiC CO iCOOO 1 7 i OOOO icooo 1 1 1 3S , 1 1 1 acoco in s *- o o c c'? o *** K "" |7|| 1 ill PI a -s^! c?o 1 .200.000 : O T i 1 1 1 oooo co oo 1 1 1 CO 010 00 COO 1 1 1 OIC CO 1 1 1 o * 77 i CO O OOCO 1 1 1 oo OCOO 1 1 1 i.o-r 01 1C O -H 1 1 1 1 1 Ot 1C COU3 1 1 1 CO OOCO 1 1 1 J--1CCM 'uS'S^ c K CM CM CM llllll If till - 1 .000,000 "ill iCt-O 1 1 1 OOOl- ooo 1 1 1 CM O 00 * O 1 1 1 1C-* CM O 1C CO 7 i i 001- 1C 1C 00 CO 1 1 1 ooo 77 i o ooo t- 1C O i i 7 -r co coo i 77 30 O * OCM -H (1 - ' ' i 1 7 1C CO O jlfjjl 1 CMCM- 5 g' 5 ^ g< Jsfjjjs CMOgj CMO-* 223 CMO^< C . , o o 11 1 77 ~ N O 00 t-oo i 1 7 ONO 7 1 1 OOOO N 1 7 1 O 00 oo 1-H 1 1 1 O O I* COCHIN ococo 1 1 1 OCO -H -H -H ooco 1 1 1 00 O N OCOTjl 1 1 1 N 7 i r-co NN o 1 M p Ij| e o 13 H g 000 III -,' NO 00 1 1 ^ NCCO 1 1 1 co coo 1 1 1 Tf< T-l f^ CO 00 CO 1 1 1 O O i COT" i 1 7 ocoo ooo i 1 7 C 00 -f ot-o 1 1 1 ONCO 1 1 1 CONN CO 1 '-' O oS to i~. " ?~s RIDGE 2 PJ3 K I g ON-* "MI - ooo 1 1 1 i - 1 1 1 or--* ot^o 1 1 1 1 7 i 00 ^f O 1 7 i l!5Tjl 7 i i i-H 1 1 1 1 -f 00 1 1 1 oo 1 1 oo 5i III O Si* NN 2 | 1" ENGTHS n ll O i "MI OOOO OOOO 1 1 1 1 O 1 7 i OCO WOO i-H 11 1 1 1 ooco NCOO 1-H 1 1 1 OOOO 1 1 1 NOOC CO CO C^ 1 1 1 - T < TfiOO 1-H -H 1 1 1 ^ B gtSd III 5 K 1 " 1 7 i 1 1 1 NOOC N COO i 1 7 ocoo CO N 1 7 i CO OCO oco i 1 7 N OO 1 7 i ox 1 1 1 O CO- CO T-l 1 1 ^ OCOO 1 1 1 1 882 ooo co 7 i i 882 : r o E N M "0 S * i 03 "^ 3 $JI o g OOO " 1 7 i ^ ocor- 7 i i IN O 1 7 i Of CO OOOO i 1 7 4 1 1 1 CO CO 1 1 1 00 CO CO 4 1 1 1 OCON oo 1 1 1 ot~o O 00 1 1 1 oooo 1 1 1 1 1 ig ll d' a E Ml i X ^ S^ *- *'^'5-r : I * oo "III i 1 7 CM I^COO 1 1 1 ON 1 1 1 COI^O 1 1 1 OOOO 1 7 i oooo 1 1 ^ MOO 1 77 OCO-!< 7 1 7 CO t- O i 1 7 OCO O Zuj.S III" *| p=l H * iS'l! I^s2 Coo rtj: | 1 : ' 1 u oooo t- fi 1 1 1 OO 4 1 1 i 1 7 7 i i 1 1 F-K I-H 1 1 1 CO-tfN 1 1 1 OOOO OCON 1-H 1 1 1 CON -H 1 1 1 1 1-H 1-H -H NO 4 1 1 1 S35 iji Tt" O i 1 7 iff if >>'a o-o^^- 2 S Blip 1 aJc-3 Iflll'l K 1,000,000 g T)l t>-00 "ill o o 1 1 1 1 1 ooo OON 1 1 ^ 1 1 1 O OCO o-*- 1 1 1 OOOO 1--OOO 1 1 1 ooor- o o i 7 i CO O *oco 1 1 1 tcoco oo o 1 1 1 ooo o 00 7 i i sill 11 ur > II W E J Irlfli NO *Ji N0-( INITIAL PINE OF 25 CENTS 1 LD21-100m-7,'39(402s) 51000: 3- UNIVERSITY OF CALIFORNIA LIBRARY