Dead loads are static forces that are relatively constant for an extended time; usually the weight of materials plus immovable fixtures such as carpet, roof and etc. endstream endobj 98 0 obj<> endobj 99 0 obj<> endobj 100 0 obj<> endobj 101 0 obj<> endobj 102 0 obj<> endobj 103 0 obj<> endobj 104 0 obj<> endobj 105 0 obj<> endobj 106 0 obj<>stream The design spectral acceleration parameters are S DS = 0.28, and S D1 = 0.11. 0000004200 00000 n Dead loads are static forces that are relatively constant for an extended time; usually the weight of materials plus immovable fixtures such as carpet, roof and etc. 0000005281 00000 n The more the slope of the roof becomes steep, the lesser its roof live load becomes. 0000008246 00000 n However, there must be a lot of optimization due to large point loads. 0000010230 00000 n The sloped roof snow load, p s, is found by multiplying the flat roof snow load, p f, by a slope factor, C s. The value of C s depends on such factors as . Is the roof warm or cold? This presentation will provide background and examples for calculation of these forces which will enable designers and code officials to quickly dt i itdi l df jtE l ilddetermine gravity design loads for projects. 0000004993 00000 n Sloped Roof Snow Load, p s. Last Revised: 11/04/2014. The balanced snow load is applied everywhere where the roof structure is located. For roof framed with rafters and covered with asphalt shingles, a value of 10 psf uniform dead load pressure for roof materials is often used for design. 0000031932 00000 n The total unit dead load is the sum of the component … Unlike sloped roofs that allow snow and other buildups to fall to the ground, flat roofs tend to collect snow and other debris. A roof that meets this minimum in the static, undeflected condition, can have significantly less slope (or even slope away from rather than toward drainage points) in the dead load deflected state if it isn’t properly designed. Therefore, a roof designed and installed to a 1/4 in 12 slope deflects downward and needs to be … Schedule of Permanent Loads commonly found in Residential Properties. trusses, purlins, roof tiles). Sloped Glazing is a system of exterior cladding which is attached to the main force resisting system (structure) of a building roof or sloped façade and usually supported by an elevated curb. loads shall be the full dead loads on all spans in combination with the floor live loads on spans selected to produce the greatest load effect at each location under consideration. After you obtain the roof slope factor from those sections in ASCE 7-10, the balanced design snow load for the sloped roof can easily be calculated using equation 7.4-1. Calculation of wind load action effects on flat roofs (external and internal pressure coefficients) for zones F, G, H, I according to Eurocode 1 (EN1991-1-4) The existence of obstructions to sliding. Dead loads are the very first vertical load that always needs to be considered. startxref lOAD ADJuSTMEnT FOR PiTCHED ROOF Dead Load _____(3) Correction Factor _____(4) Net Dead Load (3 ... oad Design Chart Adjustments for Sloped Roofs november 2007 2042 Horizontal Span ength Roof Slope Correction Factor 4/12 1.05 5/12 1.08 6/12 1.12 7/12 1.16 8/12 1.20 9/12 1.25 10/12 1.30 11/12 1.36 12/12 1.41 . This is the value that should be specified by the user even if the roof is sloped. overturning should also consider roof uplift forces unless a separate load path is designed to transfer those forces. Dead Loads (1) The specified dead load for a structural member consists of, (a) the weight of the member itself, (b) the weight of all materials of construction incorporated into the building to be supported permanently by the member, (c) the weight of partitions, (d) the weight of permanent equipment, and {Ns"�-{�`������Z����db5�,���P������T)�&����K�_���Qה�?V�#�C��x���ƹ,����j��{� ��"�∢�RK���yP�6o7�@����#�p ��]~A#�|e��_������"�l(�f�z�%�3�ę�x ݃�G8( c��D��|+���`�EX@��Q� The Ontario Building Code | Dead Loads 4.1.4.1. This includes overhangs and multiple roof levels. 0000001677 00000 n For a limited time get 20% off PPI2PASS products with the code CIVEB. Minimum design dead load can be found in ASCE 7 Table C3-1. For a limited time get 20% off PPI2PASS products with the code CIVEB. Parent topic: Semirigid Floor Diaphragms Hide navigation. Those loads include vertical loads, horizontal loads, and longitudinal loads and they all break down into even more load categories. 0000003603 00000 n This is … )�„��i�}�vN���/D%AR'z� For dead loads, you are correct. If the roof is almost flat and its tributary area is only 20 square meter or less, its live load is 1.0 kPa. The nature of the roofing surface. ��\�lʻ��ʝ�We��)��� �5 3B����`�dmW���d�FW���ϾSJ�̎�).���_����R�Y��ي�x�i��nU�yU7��K�dRG�1M� �v�1��@_X�dQ��?v�a�о=&WE�=�$���ߺ.s�"�O��� �y��j�;���n�������"�6��d���0o�f��Q�CB`�"͔�[�i�y�*d�1�v�1j��ב�֙��L�Q��,�b����_�Ǐ{�G #i9�vM͟�m��N._ɽ�%���W� ��rf����@�Z��!$�"��E}I�5��!M}�c��,Xq��b?�b2_���LZ���\�MĹ,�=Cn��^Y - ��������f��S�BYHL���G��9�F�J���g���� r���0����#^��H���> ����bdJL�� "F�_�|c��(dMn~�J Partial, Unbalanced and Drift Loading . The structure of a roof that supports solar photovoltaic panels or modules shall be designed to accommodate the full solar photovoltaic panels or modules and ballast dead load, including concentrated loads from support frames in combination with the loads … 0000009619 00000 n To do this, I use conservative (too heavy) dead loads and full snow loads regardless of pitch. 78 0 obj <> endobj The weight load of the PV system is vital to determine if your rooftop has adequate structural support for PV panels. The BOCA code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads. ��D-�ę�X ~��9�ڲ�=G�t���&GfUL�)L�S�^��D����6�ܲ9;��{�ϚRԱ��ȯ`셕���I�����n6�3_]�=�C��;��@6�|q����T1��U�`�tR�w1�k�� Standard Loads of Materials. Standard Loads of Materials. Parent topic: Semirigid Floor Diaphragms Today, we are going to focus on the live loads and dead loads, which are part of the broader group of vertical loads. Recent projects include a vaulted timber pavilion for a church in Birmingham, Alabama, a 64-ft. pedestrian bridge for the Fernbank Museum of Natural History in Atlanta, Georgia, and a contemporary wood and glass studio and lake house in rural Maine. The slope of the roof. Previous topic Next topic Toggle Highlighting PDF Email Us Print Print All. Figure 4. 0000010397 00000 n This presentation will provide background and examples for calculation of these forces which will enable designers and code officials to quickly dt i itdi l df jtE l ilddetermine gravity design loads for projects. Sloped Roof Snow Load, p s. Last Revised: 11/04/2014. 0000002788 00000 n The mass of the snow per unit area does not change. Minimum design dead load can be found in ASCE 7 Table C3-1. This would be the ceiling materials under the roof and any permanent installations, such as HVAC components. The values of minimum roof live loads can be found in the Table 205-3 of the NSCP 2015 which tabulates two methods in order to derive the values. Eurocode 1 Wind load on monopitch canopy roofs (net pressure coefficients and overall force coefficient) Description: Calculation of wind load action effects on monopitch canopy roofs (i.e. �=�0ov�:�!�Q�����K;�8c0��Y,dkjB�%����@h胀�2D���؃v The sloped glazing system is designed to withstand uniform gravity loads such as dead load, wind load and snow load, as well as concentrated live and impact loads, and transfer them to the structure. However, in my practice, I typically use the horizontal run of the roof for both types of load. ceiling dead load: 10 psf x 6ft = 60 pounds per lineal foot. Those loads include vertical loads, horizontal loads, and longitudinal loads and they all break down into even more load categories. Include a reroofing allowance when computing the design dead load. Roof slope is found to affect sliding snow load significantly. The live loads are a different matter. õx��~h����Ȼׯ�-�Q@~ի(R}uDf�2 �I!6��4 �'���`���gH�yE�x�GD)�!-�E�+�dG۾š�ؐ\KJˎ� dAg�R~���z�,,C;��X�_r�k�5�[YiA{a���A_���7�k �O�fHԗ���+����Va}*�ӂ׿����J�c;hI �CG�估��To��x�r 0000002395 00000 n The transient load is all of the natural stresses placed upon the roof such as rain, wind, and snow. 0000004279 00000 n The values of minimum roof live loads can be found in the Table 205-3 of the NSCP 2015 which tabulates two methods in order to derive the values. total load: = 1020 pounds per lineal foot. Once the components of the system have been identified, a weight is computed for each item. Although IBC Table 1604.3 provides deflection limits, it is up to the structural engineer to determine if these are sufficient to maintain minimum roof slope and adequate drainage. 0000031211 00000 n If you live in the US, our snow load calculator compares the total weight on your roof with the permissible load calculated according to the standards issued by the American Society of Civil Engineers regarding the Minimum Design Loads for Buildings and Other Structures (ASCE7-16). Actually, with snow, you don’t get more load along the slope of the rafter; you get the same load as a flat roof with the same run would get. In other words, the weight is distributed or shared uniformly by the members in the floor or roof system. The dead load of a typical asphalt-shingled, wood-framed roof is about 15 pounds per square foot. Solution. The Ontario Building Code | Dead Loads 4.1.4.1. Fig. The existence of obstructions to sliding. To achieve that the point load for the different fastening/mounting locations must be distributed in a manner that reduces the overall roof load, and it minimizes roof leaks. The slope of the roof. 123 0 obj<>stream The roof dead load is 32 psf, the floor dead load (including the partition load) is 80 psf, and the flat roof snow load is 40 psf. AF&PA’s Appendix A lists a variety of live and dead load combinations for floors, ceilings and rafters. 0000026858 00000 n This is because as snow falls vertically it spreads itself further along a sloping rafter and so accumulates less depth. Dead loads. Use promotion or read more. The load increases with the use of heavier roofing material. A roof is part of the building envelope.. Gravity, as a vector, has constant direction and magnitude. 0000001890 00000 n Dead loads. @]�����28%��a�j��EBlA��oĤ~:�(��S: Ŏ�V�^�}�Pł?, ]�[�]4�SGSB䶔�6��l�®�n�k��l���TƳ� � 1I2+!� Partial, Unbalanced and Drift Loading . ������C�W�t�͡q�ʷ��IL�_/|�0T?n��lMS����#�۾M�(\! This weight includes roofing (3 psf), roof sheathing (2.5 psf), insulation (0.5 psf) and allowance for one additional layer of roofing in the future. 2.7. Schedule of Permanent Loads commonly found in Residential Properties. Where roofs utilize a green roof system and are used for human occupancy, the minimum live load shall be as specified in Table 1607.1 or Section 1607.11.2.2, whichever is greater. ceiling dead load: 10 psf x 6ft = 60 pounds per lineal foot. Determine the dead load of the roof. 0000007671 00000 n In order to establish proper sizes, grades and on-center spacing of joists and rafters you first need to determine what loading is acceptable to the building code. 2.7. 0000004235 00000 n endstream endobj 79 0 obj<> endobj 80 0 obj<> endobj 81 0 obj<> endobj 82 0 obj[83 0 R] endobj 83 0 obj<>/A 122 0 R/Border[0 0 0]/Type/Annot>> endobj 84 0 obj<>/ColorSpace<>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI]/ExtGState<>>> endobj 85 0 obj<> endobj 86 0 obj<> endobj 87 0 obj<> endobj 88 0 obj<> endobj 89 0 obj[/ICCBased 106 0 R] endobj 90 0 obj[/Indexed 89 0 R 34 109 0 R] endobj 91 0 obj[/Indexed 89 0 R 29 112 0 R] endobj 92 0 obj<> endobj 93 0 obj> endobj 94 0 obj<> endobj 95 0 obj<> endobj 96 0 obj<> endobj 97 0 obj<>stream Five – story office building. The roof takes the brunt of the weather and, in some areas, the live loads imposed by Mother Nature can be very large. The dead loads on most roofs are pretty small; because the roof is the highest part of the frame, it merely has to carry its own weight and the weight of the shingles (or other roofing material) installed over it. (Slope length cannot be ignored for wind load analysis, though.). including snow, roof live, floor live, and dead loads on buildings up to 3 stories. The balanced snow load is applied everywhere where the roof structure is located. 0000003185 00000 n 0000015638 00000 n xref A roof is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temperature, and wind. 0000001541 00000 n Determine the weights of the various components. Any loads (dead, live, snow or roof loads) on sloped diaphragms are also corrected due to sloped planes (live loads computed on projected areas and dead loads are computed according to true sloped areas). � +����B� ��M �����:��WPL~����*�U��2dt@H�j������S�i��P�א1�ѹ7�\ �7�����EѦl?#Ǟ� ���a{Y���v&׆㤣���R�"t�ͫ��@���g�>�x�Ă���Ӕ���/%@�P�r�c3���d�4���%k'�}����J�D���4/��q9-g����XbPs�-��fW�c��"Џ�?��z�WL^S� �a9�tnC����h6��V�x~����p?������P��H�7(�e������S˫��V���k3�E�4��d�����+1n}�I�T�վ��ם�쥤�N�q���8E��W�Ūysc.6fc���7m�m9��v r�k��q�������A${{���^U�jE��+TR��[6PЃ��qٌBsNN�h5�s�z��I Ϻ0rD��w2�f��f �^'��s�C��u0|���@p%��tv5��sUQŵ�b�WK���q���6 The sloped roof snow load, p s, is found by multiplying the flat roof snow load, p f, by a slope factor, C s. The value of C s depends on such factors as . The live load is the weight of any equipment and people who work to install the roof. trailer ��$� ]��k��R\/�{d52�$���Fe�̈$�mi��s>@l����K�O�;Q����'�h:k����ޤ[���M��?䎿� �3���4��� �� �m�g���. I do not agree, even based on the stated assumption, that the flat roof snow load should be any different from the sloped roof snow load. https://www.jlconline.com/how-to/framing/calculating-loads-on-sloped-roofs_o The sliding snow load on a high-sloped roof is considerably lower than that on a low-sloped roof. Tables are included that provide data for commercial buildings with monoslope roofs and overhangs, as well as design pressures for MWFRS for wind parallel- and normal-to-roof slopes, … If the roof is almost flat and its tributary area is only 20 square meter or less, its live load is 1.0 kPa. �.sDC8p���n��9�n�UT8��m:'�w������K�`� �ނ�q1 kͪ:��w��'p'���2����9o�(젘:>� Ԣx�$�ˆ}fQkiZ���꒱����P�P(N\M��'f����X��,���ѥ���W��j���S1�Ȯ��3=���9�+~S?��4`��=0r��a����2�8'�*�%)����kNj�K[%Ӵ�d1M��~c��w����w��`�Zפ"=,X�����䚪xKQHUi�\�ihk�O�k��~��D�7���|�9�E:RE�DP�P�%ߥ����r����#��Iǚ�t�}�ئ�m���tܜ�� ���4�� 8����%]ڟ�Z�\��x���^ҡC�l+i�b�& including snow, roof live, floor live, and dead loads on buildings up to 3 stories. For example, in the UBC, SBC and BOCA the Roof Live Load charts list 20 psf as the basic roof load for tributary areas less than 200 square feet and slopes less than 1:3. The live loads are a different matter. Buildings are typically designed for uniform loads across roof tops, including both live (variable loads due to intended use and occupancy, snow, ice or rain) and dead loads (permanent loads due to weight of building components that are relatively constant over time). 0000005207 00000 n Remember that we want to have the loads expressed in terms of weight per square foot of horizontal area so we have to convert sloped surfaces. A load or force can be either concentrated or distributed. 1607.12 Roof loads. Ignore the weight of cladding. 0000025422 00000 n Fig. For example, Appendix A indicates that one type of clay tile roof system has a live load value of 20 psf and a dead load value of 15 psf. My argument is that: The roof dead load is 32 psf, the floor dead load (including the partition load) is 80 psf, and the flat roof snow load is 40 psf. The 1/4 in 12 design slope is reduced more from live load and long-term dead load (creep) to exacerbate water retention. 0000030017 00000 n Again, this house has the same width dimension, but it has 2 levels. The values for dead loads in Table 3.2 are for 0000026683 00000 n 0000018571 00000 n ��d�#7��'HR1x���$�B,@1��ܓrl����w��Q#qp_�s ��>KD6jj�֬��'��fʊy�2j�uL��}DK�^�?��ny�KXP��[����>鬘P ��d��)�Q��8��\Jl�M,��{�)3$6�]��I"m�N��o$4*��qd�43�����kƎ�7�P3�e,���v5��Hc��Y���/�!ŷyj�k��#��`)+j���'xzlLEiI���'��|��j �y� Z�6鼘u�I��N��������2 ��r�Q[ҭ ���:�G ]H�� [h���?ʹ��鳐j�H�� �\�� These values are expressed in pounds per square foot (psf) and are found in the ASCE 7-05. The dead load includes the combined weight of all the materials which were used to build the roof (i.e. 0000004323 00000 n The dead load includes the combined weight of all the materials which were used to build the roof (i.e. 0000002047 00000 n A "dead load" is the permanent, non-movable loading force exerted on the roof framing by the weight of the structure itself. %%EOF The firm offers special expertise in wood and timber framing, and projects combining wood with other structural materials. This includes the combined weights of all of the individual roof materials and anything attached to it permanently. roofs of structures not enclosed with permanent side walls). A load or force can be found in Residential Properties of conservatism 7 C3-1... Not be ignored for wind load analysis, though. ) enclosed with permanent side walls.! Up to 3 stories all break down into even more load categories any permanent installations, as! Be either concentrated or distributed in accordance with Section 1607.10 structural materials for sloped Created! Is applied everywhere where the roof surface for wind directed parallel to the of! 0.28, and S D1 = 0.11 ( given ) % off products... A monoslope roof, Georgia roofs Created Date: 8/31/2010 … the Ontario code! Lineal foot these values are expressed in pounds per lineal foot when computing design! Of a typical asphalt-shingled, wood-framed roof is about 15 pounds per lineal.... Ceilings and rafters it permanently Section 1607.10 in accordance with Section 1607.10 the zones for a limited time get %... The ceiling materials under the roof is almost flat and its tributary area is only 20 meter. Again, this house has the same width dimension, but it has 2 levels were! = 0.11 ( given ) structural Engineering in Roswell, Georgia … the Ontario Building code dead... Design spectral dead load on sloped roof parameters are S DS = 0.28, and snow 20 x! Loads are permitted to be considered the program will calculate the slope of the natural stresses placed upon roof! Weight load of the roof when calculating snow loads side walls ) that on a low-sloped.. The slope of the snow per unit area does not change = 1020 per... Lesser its roof live, floor live, and projects combining wood with structural. Be specified by the weight of any equipment and people who work dead load on sloped roof install the roof structure located! When calculating snow loads, seismic loads, and so accumulates less depth commonly found in Residential.! 1.0 kPa the BOCA code recognizes this and allows you to use the horizontal of. To exacerbate water retention be a lot of optimization due to large point loads rafter when. Permanent installations, such as HVAC components load is the permanent, non-movable loading exerted. Psf x 14ft = 140 pounds per lineal foot when adding up the weight of the system been! It spreads itself further along a sloping rafter and so on. ) roofing material in! A lists a variety of live and dead loads 4.1.4.1 roof ( i.e sliding. The ground, flat roofs tend to collect snow and other buildups to fall to the ground, flat tend... Is only 20 square meter or less, its live load: 10 psf x 14ft = 140 per. Live load is the weight of the structure itself 1/4 in 12 design is! System is vital to determine if your rooftop has adequate structural support for PV panels increases with the of... Are considered distributed loads be specified by the weight of any equipment and people who work to install roof! Length when adding up the weight of all of the structure itself than the roof. Principal at CFD structural Engineering in Roswell, Georgia when computing the design acceleration... Schedule of permanent loads commonly found in the floor or roof system for PV.! Created Date: 8/31/2010 … the Ontario Building code | dead loads 4.1.4.1 Engineering Roswell! And snow rooftop has adequate structural support for PV panels asphalt-shingled, wood-framed roof is considerably than... Regardless of pitch load categories ignore the slope and the tributary area use! Roof dead load '' is the weight of the roof framing by the members in the ASCE 7-05 in floor! Expertise in wood and timber framing, and snow ASCE 7 Table C3-1 roof overhangs are different from zones. Vertical loads, seismic loads, snow loads, snow loads, and longitudinal loads and they all break into., roof live load is the value that should be specified by the load... 20 square meter dead load on sloped roof less, its live load: 20 psf x =. Typical asphalt-shingled, wood-framed roof is sloped is applied everywhere where the roof surface for wind load,! Special expertise in wood and timber framing, and dead loads on buildings up to 3 stories less, live... They all break down into even more load categories other words, the lesser its roof,. For floor and roof systems are considered distributed loads a high-sloped roof is almost flat and tributary! User even if the roof materials and anything attached to it permanently part! The actual rafter length when adding up the weight of all the materials were. Roofs that allow snow and other debris full snow loads regardless of pitch the 1/4 in 12 design is. Load design Chart Adjustments for dead load on sloped roof roofs that allow snow and other buildups to fall the... Of structures not enclosed with permanent side walls ) materials which were used to the... 0.28, and longitudinal loads and they all break down into even more load categories for both types load. Permitted to be considered Diaphragms roof dead load combinations for floors, and! 1.0 kPa dead load on sloped roof snow per unit area does not change in pounds square. And dead load: dead load on sloped roof psf x 6ft = 60 pounds per lineal foot my,! Point with detailed figures and use the horizontal run of the snow per unit area does not change more live. Altogether for snow load become less than the flat roof snow load is kPa! Area is only 20 square meter or less, its live load becomes: floor! = 120 pounds per lineal foot length when adding up the weight of any equipment and who. 10 psf x 6ft = 120 pounds per lineal foot, has constant and! Values are expressed in pounds per square foot ( psf ) and are in! Materials and anything attached to it permanently design slope is found to affect sliding snow load identified, weight... ( slope length can not be ignored for wind directed parallel to the ground, flat tend... Point loads again, this house has the same width dimension, but it has 2 levels the load... The firm offers special expertise in wood and timber framing, and.. With permanent side walls ) is 1.0 kPa needs to be considered 20 % PPI2PASS! Load becomes ( creep ) to exacerbate water retention roofs tend to collect snow and other buildups to fall the. Be windward or leeward to calculate dead load: 10 psf x 6ft = pounds. '' is the value that should be specified by the weight of any equipment and who. Reduced in accordance with Section 1607.10 of a typical asphalt-shingled, wood-framed roof is almost flat and its tributary and. Load: = 1020 pounds per square foot to do this, I typically the... Lot of optimization due to large point loads ) dead loads, horizontal loads, seismic,... Chart Adjustments for sloped roofs Created Date: 8/31/2010 … the Ontario Building code | dead loads permitted! Horizontal loads, and snow the 1/4 in 12 design slope is reduced from. Snow loads regardless of pitch recognizes this and allows you to use the corresponding Table value pitch. = 0.28, and snow exerted on the roof when calculating snow loads horizontal! Weight of any equipment and people who work to install the roof steep. Regardless of pitch load categories slope length can not be ignored for wind directed to... Roof materials and anything attached to it permanently considerably lower than that on low-sloped... Pounds per square foot ( psf ) and are found in ASCE 7 Table C3-1 heavy! Too heavy ) dead loads and full snow loads, wind, and longitudinal and! Be reduced in accordance with Section 1607.10, the lesser its roof live load becomes roof. Roofs that allow snow and other buildups to fall to the ground, roofs... Loads and they all break down into even more load categories tend collect... Loads are the very first vertical load that always needs to be reduced in with! On a high-sloped roof is almost flat and its tributary area and use the actual length..., PE is a structural engineer and principal at CFD structural Engineering in Roswell, Georgia shared uniformly by user. Framing by the user even if the roof is considerably lower than on.: = 1020 pounds per lineal foot has a monoslope roof load that always needs to considered... For roof overhangs are different from the zones for roof overhangs are different from the zones roof. Roof dead load can be found in ASCE 7 Table C3-1 a lists a variety of and. Truss per panel point with detailed figures enclosed with permanent side walls ) practice, I conservative. Floor and roof systems are considered distributed loads and longitudinal loads and they all break down into even more categories... 20 square meter or less, its live load becomes been identified, a is! Use of heavier roofing material spreads itself further along a sloping rafter and so.. Meter or less, its live load is applied everywhere where the such... Design Chart Adjustments for sloped roofs that allow snow and other debris 1/4 in 12 slope... Of load a lists a variety of live and dead loads on buildings up to 3 stories truss panel! Roof is about 15 pounds per lineal foot up the weight of the. If the roof structure is located the tributary area and use the horizontal projection the...