[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-664155-105":59,"doc-detail-664155-en":129},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":122,"head_meta":124,"extra_data":126,"updated_unix":128},105,"en","roof-truss-span-tables-reference","Roof Truss Span Tables - reference","","Roof truss span tables for Alpine truss designs specify allowable roof spans based on total load, live load duration factor, and roof pitch configuration. The tables cover common truss configurations such as mono-slope, scissors/vaulted, and flat roofs, listing top and bottom chord lumber sizes and span limits. Notes reference NDS 91, bearing conditions, spacing, deflection limits, and material properties, and include guidance on special loading, shipping tall trusses, and possible span reductions.",{"@graph":69,"@context":121},[70,84,104],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":30,"@type":76,"position":81},"https://docshare.wps.com/document/technology/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/roof-truss-span-tables-reference/664155/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":98,"encodingFormat":97,"isAccessibleForFree":99,"interactionStatistic":100},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/roof-truss-span-tables-reference/664155.png","ImageObject",300,407,{"name":92,"@type":93},"Boyslovefans","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-29",true,{"@type":101,"interactionType":102,"userInteractionCount":4},"InteractionCounter",{"@type":103},"ViewAction",{"@type":105,"mainEntity":106},"FAQPage",[107,113,117],{"name":108,"@type":109,"acceptedAnswer":110},"What parameters do the roof truss span tables use to determine allowable spans?","Question",{"text":111,"@type":112},"They use total load (PSF), live load (PSF) with a duration factor, and the roof type/pitch configuration, along with truss chord sizes.","Answer",{"name":114,"@type":109,"acceptedAnswer":115},"Which truss configurations are included in the tables?",{"text":116,"@type":112},"The tables include common configurations such as mono-slope, scissors (cathedral/vaulted), and flat truss options.",{"name":118,"@type":109,"acceptedAnswer":119},"What do the notes say about design basis and limits?",{"text":120,"@type":112},"Overall spans are based on NDS 91 with specified bearing, spacing, and deflection limits, and trusses must be designed for special loading such as concentrated loads and snow conditions near parapets or sliding from higher roofs.","https://schema.org",{"og:url":83,"og:type":123,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":125,"canonical":83},"index,follow",{"doc_id":127,"site_id":62},664155,1793241482,{"code":4,"msg":5,"data":130},{"doc_id":127,"user_id":131,"nickname":92,"user_avatar":132,"doc_module":4,"category_id":29,"category_name":30,"doc_title":65,"doc_description":67,"doc_content":133,"file_id":134,"file_url":135,"file_type":136,"file_size":137,"view_count":4,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":8,"language":138,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":139,"faqs":140,"seo_title":141,"seo_description":67,"update_tm":128,"read_time":81},1374410101428,"https://ap-avatar.wpscdn.com/davatar_3d24733baf745e90a7e4bdd5f77d97b2","Roof Truss Span Tables  \n| Alpine truss designs are engineered to meet specific span, configuration and load conditions. The shapes and spans shown here represent only a fraction of the millions of designs processed by Alpine engineers. | Total load(PSF) | 55\u003Cbr>1.15\u003Cbr>40 snow shingle\u003Cbr> 55 \u003Cbr>1.15\u003Cbr>30 snow tile |  47 \u003Cbr>1.15\u003Cbr>30 snow\u003Cbr>shingle |  40 \u003Cbr>1.15\u003Cbr>20 snow\u003Cbr>shingle |  40 \u003Cbr>1.25\u003Cbr>20 **\u003Cbr>shingle\u003Cbr>**construction\u003Cbr>or rain,\u003Cbr>not snow load |\n| --- | --- | --- | --- | --- | --- |\n|  | Duration factor\u003Cbr>Live load(PSF) Roof type |  |  |  |  |\n|  | Top Chord | 2x4 2x6 2x6 | 2x4 2x6 2x6 | 2x4 2x6 2x6 | 2x4 2x6 2x6 |\n|  | Bottom Chord | 2x4 2x4 2x6 | 2x4 2x4 2x6 | 2x4 2x4 2x6 | 2x4 2x4 2x6 |\n\nCommon--Truss configurations for the most widely designed roof shapes.  \nPitch Spans in feet to out of bearing  \n2/12  \n2.5/12 3/12  \n3.5/12 4/12 5/12 6/12 7/12  \n24  \n29  \n34  \n39  \n41  \n44  \n46  \n47  \n24  \n29  \n34  \n39  \n43  \n52  \n60*  \n67*  \n33  \n39  \n46  \n53  \n59  \n67*  \n69*  \n70*  \n27  \n33  \n37  \n41  \n43  \n46  \n47  \n48*  \n27  \n33  \n39  \n44  \n49  \n58  \n67*  \n72*  \n37  \n45  \n53  \n61  \n64  \n69*  \n71*  \n72*  \n31  \n37  \n40  \n44  \n46  \n49  \n51  \n52*  \n31  \n38  \n44  \n50  \n56  \n66  \n74*  \n77*  \n43  \n52  \n60  \n65  \n69  \n74*  \n76*  \n77*  \n33  \n39  \n43  \n47  \n49  \n53  \n55  \n56*  \n33  \n40  \n46  \n52  \n57  \n66  \n74*  \n80*  \n46  \n55  \n64  \n70  \n74  \n80*  \n82*  \n83*  \n\n|  |  |  |  |  |  |  |  |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |\n| Mono--Used where the roof is required to\u003Cbr>slope only in one direction. Also in pairs | 2/12 2.5/12 3/12 3.5/12 4/12\u003Cbr>5/12 | 24\u003Cbr>28\u003Cbr>30\u003Cbr>33\u003Cbr>35\u003Cbr>38* | 24\u003Cbr>29\u003Cbr>33\u003Cbr>37\u003Cbr>41\u003Cbr>47* | 33\u003Cbr>40\u003Cbr>45\u003Cbr>49*\u003Cbr>52*\u003Cbr>57* | 25\u003Cbr>29\u003Cbr>31\u003Cbr>34\u003Cbr>36\u003Cbr>39* | 27\u003Cbr>32\u003Cbr>37\u003Cbr>41\u003Cbr>45*\u003Cbr>51* | 38\u003Cbr>43\u003Cbr>47\u003Cbr>51*\u003Cbr>54*\u003Cbr>59* | 27\u003Cbr>31\u003Cbr>34\u003Cbr>36\u003Cbr>39\u003Cbr>42* | 31\u003Cbr>37\u003Cbr>42\u003Cbr>46\u003Cbr>50*\u003Cbr>56* | 41\u003Cbr>46\u003Cbr>50\u003Cbr>54*\u003Cbr>58*\u003Cbr>63* | 29\u003Cbr>33\u003Cbr>36\u003Cbr>39\u003Cbr>42*\u003Cbr>45* | 32\u003Cbr>37\u003Cbr>42\u003Cbr>46\u003Cbr>49*\u003Cbr>54* | 44\u003Cbr>49\u003Cbr>54\u003Cbr>58*\u003Cbr>62*\u003Cbr>68* |\n| with their high ends abutting on extremely long spans with a\u003Cbr>support underneath the high end.\u003Cbr>\u003Cbr>|  |  |  |  |  |  |  |  |  |  |  |  |  |\n|  |  |  |  |  |  |  |  |  |  |  |  |  |  |\n\nScissors--Provides a cathedral or vaulted ceiling. Most economical when the difference in slope between the top and bottom chords is at least 3/12 or the bottom chord pitch is no more than half the top chord  \npitch.  \n6/12-2/12 ‡  \n6/12-2.5/12 ‡  \n6/12-3/12 ‡  \n6/12-3.5/12 ‡  \n6/12-4/12 ‡  \n40  \n37  \n33  \n28  \n22  \n43  \n38  \n33  \n28  \n22  \n59*  \n52  \n45  \n38  \n31  \n42  \n38  \n35  \n32  \n26  \n49  \n44  \n38  \n32  \n26  \n62*  \n57*  \n52  \n44  \n36  \n45  \n41  \n38  \n34  \n30  \n56*  \n50  \n43  \n37  \n30  \n66  \n61*  \n56*  \n50  \n41  \n48  \n44  \n40  \n36  \n32  \n57*  \n52  \n46  \n39  \n32  \n‡ Other pitch combinations available with these spans  \nFor Example, a 5/12-2/12 combination has approx. the same allowable span as a 6/12-3/12  \n71*  \n66*  \n60*  \n54  \n44  \nFlat--The most economical flat truss for a roof is provided when the depth of the truss in inches is approximately equal to 7% of the span in inches.  \n| Total load(PSF) Duration factor\u003Cbr>Live load(PSF) |  55 \u003Cbr>1.15\u003Cbr>40 snow |  47 \u003Cbr>1.15\u003Cbr>30 snow |  40 \u003Cbr>1.15\u003Cbr>20 snow |  40 \u003Cbr>1.25\u003Cbr>20 rain or constn. |\n| --- | --- | --- | --- | --- |\n| Top Chord | 2x4 2x6 2x6 | 2x4 2x6 2x6 | 2x4 2x6 2x6 | 2x4 2x6 2x6 |\n| Bottom Chord | 2x4 2x4 2x6 | 2x4 2x4 2x6 | 2x4 2x4 2x6 | 2x4 2x4 2x6 |\n| Depth | Spans in feet to out |  | of bearing |  |\n| 16\" | 23 24 25 § | 25 § 25 § 25 § | 25 § 25 § 25 § | 25 § 25 § 25 § |\n| 18\" | 25 27 28 | 27 27 29 § | 29 § 29 § 29 § | 29 § 29 § 29 § |\n| 20\" | 27 28 30 | 28 28 32 | 31 30 33 § | 32 31 33 § |\n| 24\" | 29 30 33 | 31 31 35 | 34 33 38 | 35 34 40 |\n| 28\" | 32 32 36 | 34 33 39 | 37 36 42 | 38 37 44 |\n| 30\" | 33 33 38 | 35 35 40 | 38 37 44 | 40 39 45 |\n| 32\" | 34 34 39 | 36 36 42 | 39 39 45 | 41 40 47 |\n| 36\" | 36","cbCaipPgFm6SKyw3","https://ap.wps.com/l/cbCaipPgFm6SKyw3","pdf",67760,"English","# Roof Truss Span Tables\n## Total Load and Live Load Parameters\n## Common Truss Configurations (Mono, Scissors, Flat)\n## Notes and Design Limitations","[{\"question\":\"What parameters do the roof truss span tables use to determine allowable spans?\",\"answer\":\"They use total load (PSF), live load (PSF) with a duration factor, and the roof type/pitch configuration, along with truss chord sizes.\"},{\"question\":\"Which truss configurations are included in the tables?\",\"answer\":\"The tables include common configurations such as mono-slope, scissors (cathedral/vaulted), and flat truss options.\"},{\"question\":\"What do the notes say about design basis and limits?\",\"answer\":\"Overall spans are based on NDS 91 with specified bearing, spacing, and deflection limits, and trusses must be designed for special loading such as concentrated loads and snow conditions near parapets or sliding from higher roofs.\"}]","Roof Truss Span Tables - reference | PDF"]