Find the right fire-rated assemblies and design details drawings for your architectural plans. From the homepage, select Products, Systems or Assemblies > Building or Fire Systems > Fire Rated Walls, Floors, Beams and Columns > Search by Assembly Number. Search the catalog for the Standards you need and then purchase them on our Standards sales site. Learn more about Product iQUL Solutions' source for certification information. with 1 (25 mm) Type S corrosion resistant bugle head screws 8 (203 mm) o.c. Joints staggered 24" each layer and opposite sides. Opposite side: Base layer 5/8" (15.9 mm) ToughRock Fireguard C gypsum board or 5/8" (15.9 mm) DensArmor Plus Fireguard C gypsum panels applied at right angles to studs with 1" Type S screws 24" o.c. Base Layer: 1/2 (12.7 mm) ToughRock Fireguard C gypsum board or 1/2 (12.7 mm) DensArmor Plus Fireguard C gypsum panel applied vertically to each side of 1-5/8 (41 mm) metal studs 24 (610 mm) o.c. E = Floor Ceiling assemblies consisting of concrete with membrane penetrations (update 3/2/2019) F-I = Not Used Ability to provide thermal resistance for comfort and efficiency. Face Layer: 1/2 (12.7 mm) ToughRock Fireguard C gypsum board or 1/2 (12.7 mm) DensArmor Plus Fireguard C gypsum panel installed horizontally on each side with joints staggered 24 (610 mm) o.c. Face Layer: 5/8 (15.9 mm) ToughRock Fireguard C gypsum board or 5/8 (15.9 mm) DensArmor Plus Fireguard C gypsum panels applied perpendicular to channels with 1-5/8 (41 mm) Type S drywall screws, 8 (203 mm) o.c. Access our all-new collection of sound-tested, fire-rated wall assemblies. Face Layer: 5/8 (15.9 mm) ToughRock Fireguard X or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied vertically to each side with 1-5/8 (41 mm) Type S drywall screws 8 (203 mm) o.c. 3/4 (19 mm) air space between liner panels and adjacent wood or metal framing. with vertical joints located mid way between studs. when applied horizontally to studs and 8 (203 mm) at vertical and bottom edges and 12 (305 mm) o.c. for face layer. Explore our press releases and news updates. and 3" from floor and ceiling runners. Joints offset 24" from base layer joints. Sound Tested with 3-1/2 (89 mm) fiberglass insulation stapled in stud space, Base Layer: 5/8 (15.9 mm) ToughRock Fireguard X or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied vertically to each side of 3-1/2 (89 mm) 20-gauge (33 mils) steel studs 24 (610 mm) o.c. at edges and ends and 8 (203 mm) o.c. with 2 (51 mm) 6d coated nails. Opposite side: one layer 5/8 (15.9 mm) ToughRock Fireguard X Products or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied horizontally or vertically to studs with 6d cement coated nails, 1 7/8 long, 0.0915 shank, 15/64 heads, 7 o.c. FIRE SAFETY CAUTION Passing a fire test in a controlled laboratory setting and/or certifying or labeling a product as having a one-hour, two-hour, or any other fire resistance or protection rating and, therefore, as acceptable for use in certain fire rated assemblies/systems, does not mean that either a particular assembly/system incorporating the product, or any given piece of the product itself, will necessarily provide one-hour fire resistance, two-hour fire resistance, or any other specified fire resistance or protection in an actual fire. Sound Tested with 1-1/2 (38 mm) glass fiber insulation, friction fit in stud space. Trusses: Chord and web members fabricated from 2 x 4 lumber with 20-gauge (30 mils) steel connector plates having a minimum tooth length of 5/16 (7.9 mm). See how we put safety science to work to help create a safer, more secure and sustainable world for you. You are leaving the UL Solutions website for an external site. Modifications to tested assemblies: General: Both UL and GA emphasize that the fire resistance rating of listed assemblies applies to the assembly in its entirety. "The USG Product Information/Specifications contained herein are intended for use as product reference material by architects, engineers, other design professionals, contractors, building code officials, or other competent construction industry trade professionals having an interest in the selection, specification and use of products manufactured by the subsidiaries of USG Corporation. Floor or Roof Construction Consisting of Prestressed Concrete Double Tee Slabs (2.9mb PDF) 5/8 ToughRock Fireguard C gypsum board or 5/8 DensArmor Plus Fireguard C gypsum panel (UL G505 only) applied perpendicular to rigid furring channels 24 (610 mm) o.c. Stagger joints 24 (610 mm) each layer and side. Second Layer: Attached to steel studs with 1-5/8 (41 mm) long self-drilling, self-tapping screws spaced vertically 24 (610 mm) o.c. Vertical joints centered over studs and staggered one stud cavity on opposite sides of studs. (Limited load-bearing). Helpful instructions and resources to help you locate UL fire rated assemblies, designs and systems. in field. NA. One layer 1"x24" ToughRock Shaftliner or DensGlass Shaftliner panels between 2-1/2" floor and ceiling J runners with T section of 2-1/2" steel C-T studs between panels. Access UL certification data on products, components and systems, identify alternatives and view guide information with Product iQ. Certified materials are added to the UL iQdatabases on a daily basis, making this information immediately available to thousands of designers, engineers and suppliers. Details. The STC Rating shown reflects testing or evaluation of an assembly with one or more products under test conditions and may not apply to all products listed for each assembly. <> Assemblies for sound applications. and 1-1/4 (32 mm) corner bead at each corner nailed with 4d coated nails. Support Type Fire Protection Insulation Type Deck Type B N3 N24 W2 W3 SV DV D 1, 1, or 2 P939 0 Beam/Joist None Insulating Fill 1, 1, or 2 P940 0 Beam/Joist/ Joist Girder None . Search the catalog, read scopes and purchase the Standards you need. Exterior Side: 5/8 (15.9 mm) DensGlass Fireguard Sheathing or ToughRock Fireguard X sheathing applied vertically to 3-5/8 (92 mm) 18-gauge (43 mils) steel studs 16 (406 mm) o.c. with 1 (25 mm) Type S drywall screws 8 (203 mm) o.c. 1/2" (12.7 mm) ToughRock Fireguard 45 gypsum board applied vertically or horizontally to each side of 2 x 4 wood studs 24 (610 mm) o.c. 1-1/2 (38 mm) mineral fiber insulation, stapled to board in stud space. Horizontal bracing required at mid height. at board edges and 12 (305 mm) at intermediate studs. Sound tested with 3-1/2 fiberglass insulation NLB. Wood joists supporting 1 (25 mm) nominal T&G wood subfloor and 1 (25.4 mm) nominal wood finish floor, or 19/32 (15.1 mm) plywood finished floor with long edges T&G and 15/32 (11.9 mm) interior plywood with exterior glue subfloor perpendicular to joists with joints staggered. and not less than 1 (25.4 mm) apart with 1 (25.4 mm) Type S drywall screws 16 (406 mm) o.c. Stagger joints each layer on opposite side. Trusses supporting metal roof deck panels covered by 1/2 (12.7 mm) regular gypsum sheathing either loose laid, or adhesively or mechanically attached to roof deck. with 1 (25 mm) Type S drywall screws 12 (305 mm) o.c. GEORGIA-PACIFIC GYPSUM L L C Type X ComfortGuard Sound Deadening Gypsum Board (finish rating 27 min). with 1-1/4 (32 mm) drywall screws 24 (610 mm) o.c. with 1 (25.4 mm) Type S drywall screws 8 (203 mm) o.c. 5/8 (15.9 mm) ToughRock Fireguard C applied perpendicular to the resilient channels spaced 12 (305 mm) o.c. Face Layer: Attached with 1-5/8 (41 mm) Type S drywall screws 12 (305 mm) o.c. (NLB) Sound tested with 1-1/2" glass fiber insulation friction fit in stud space. Designed to separate a room from structure or space above and composed of 1 (25.4 mm) ToughRock Shaftliner or DensGlass Shaftliner panel supported by 2-1/2 (64 mm), 4 (102 mm) or 6 (152 mm) C-T studs and three layers of 1/2 (12.7 mm) ToughRock Fireguard C or 1/2 (12.7 mm) DensArmor Plus Fireguard C gypsum panel. 2023 USG Corporation. These wall assembly files are used for planning and estimation purposes for many UL wall types, such as fire-rated wall assemblies. Non-Load Bearing. 1/2 (12.7 mm) ToughRock Fireguard C or 1/2 (12.7 mm) DensArmor Plus Fireguard C gypsum panel applied perpendicular to resilient channels 24 (610 mm) o.c. If its UL Solutions and newsworthy, its here. Step-by-step instructions on locating through penetration firestop system certifications. Steel cornerbead, 1-1/2 (38 mm) flanges, applied with 1 (25 mm) Type S drywall screws 12 (305 mm) o.c. at intermediate studs when applied vertically to framing, or 8 (203 mm) o.c. 3 (76 mm) glass fiber insulation 0.90 pcf (14.4 kg/m3) in joist space stapled to subfloor. 4 (102 mm) maximum foam-on-plastic thickness. As a global safety science leader, UL Solutions helps companies to demonstrate safety, enhance sustainability, strengthen security, deliver quality, manage risk and achieve regulatory compliance. Opposite side: Base layer 1/2" (12.7 mm) ToughRock Fireguard C gypsum board or 1/2" (12.7 mm) DensArmor Plus Firegaurd C gypsum panels applied at right angles to studs with 1" Type S screws 24" o.c. Two layers of 1/2 (12.7 mm) ToughRock Fireguard C gypsum board or 1/2 (12.7 mm) DensArmor Plus Fireguard C. The AG Design Library is a robust tool to help you quickly find fire and sound rated assembly information: First, select the hourly rating needed; Second, choose the type of design you are seeking (example - Walls/Partitions (steel framed), Floor/Ceiling (wood framed), etc.) 2. Horizontal bracing required at mid height. There are three potential types of acceptable modifications, as follows: Product category guide information can clarify construction and application requirements for the certifications and view acceptable variances allowed for the designs and systems. Delve into detailed press kits for information on our work. Lateral bracing on both sides of the wall not less than 5 feet on center vertically. Base layer 1" x 24" ToughRock Shaftliner or DensGlass Shaftliner panels between 2-1/2" floor and ceiling J runners with T section of 2-1/2" steel C-H, C-T or I-studs between panels. In extending its global public safety mission, UL Standards partners with national standards bodies in countries around . Base Layer: Attached with 1-1/4 (32 mm) Type S drywall screws 16 (406 mm) o.c. The drawings and information shown herein are presented for illustration and intended solely for use by design professionals for planning purposes. with 1 (25 mm) Type S drywall screws 12 (305 mm) o.c. with 5d nails 1-5/8 (41 mm) long, 0.099 (2.5 mm) shank, 1/4 (6 mm) heads, 6 (152 mm) o.c. Base Layer: Attached with 1 (25 mm) Type S drywall screws 16 (406 mm) o.c. View our, New Products: USG Ceilings Inspirational Book, Danoline Acoustical Gypsum Inspirational Book, Acoustical Ceilings Performance Substrate, Ensemble Acoustical Drywall Ceiling Estimator, USG Acoustical Ceiling Panels & Acoustical Suspension Systems Catalog (WL294911), STRUCTO-CRETE Brand Structural Panels Portfolio, Levelrock & Durock Brand Fire & Sound Rating Guide, California Transparency in Supply Chain Act, Terms and Conditions for USG Sales/Terms and Conditions for USG POs. Fiberglass insulation, 2-3/4" (70 ,,) thick, 0.30 pcf (4.8 kg/m3), friction fit in stud space. S750 Unres MK6GF. with 1 (25 mm) Type S screws 24 (610 mm) o.c. through base layer perpendicular to joists or trusses with 1-7/8 (48 mm) Type S drywall screws. Horizontal joints on opposite sides need not be staggered. endobj The ability to resist heat flow insulation's thermal resistance. Our Company. It is called the UL Code Correlation Database, and can Quickly access UL certification information with the powerful search engine Product iQ. (NLB) Sound tested with 1-1/2" glass fiber insulation friction fit in stud space. Please enter the email address you used to create the account. Fire-rated wall, floor and ceiling assemblies provide the necessary fire and smoke barriers to create compartmentalization during a fire, safeguarding against the spread of fire and smoke within a building or to and from a building. Welcome to the cutting edge of safety science. Third Layer: 1/2 (12.7 mm) ToughRock Fireguard C gypsum board or 1/2 (12.7 mm) DensArmor Plus Fireguard C applied vertically to each side with 2-1/4 (57 mm) Type S drywall screws 24 (610 mm) o.c. USG STRUCTO-CRETE Brand Structural Panels. Unrestrained Assembly Ratings (hr.) By continuing to use and browse this site, you agree to our Privacy Policy. Fire-resistance Ratings - ANSI/UL 263 See General Information for Fire-resistance Ratings - ANSI/UL 263 We'll send you a link that lets you create a new password. Area Separation Wall. Face layer 5/8" (15.9 mm) ToughRock Fireguard C gypsum board or 5/8" (15.9 mm) DensArmor Plus Fireguard C gypsum panels applied parallel to studs with 2-1/4" Type S screws 12" o.c. Explore our business intelligence-building digital tools and databases, search for help, review our business information, or share your concerns and questions. Base layer attached with 1-7/8 (48 mm) 6d cement coated nails 6 (152 mm) o.c. Joints staggered. Sound Tested with 3-1/2 (89 mm) fiberglass insulation, Base Layer: 5/8 (15.9 mm) ToughRock Fireguard X or 5/8 (15.9 mm) DensArmorPlus Fireguard gypsum panels applied vertically to each side of 3-5/8 (92 mm) steel studs 24 (610 mm) o.c. All rights reserved. You are leaving the UL Solutions website for an external site. on 2x 6 wood plates with 2" Type W screws 24 (610 mm) o.c. Drywall end joints located midway between continuous channels and attached to additional pieces of channel 60 (1524 mm) long with 1 (25 mm) Type S screws 8 (203 mm) o.c. Face Layer: 5/8 (15.9 mm) ToughRock Fireguard X or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied vertically to each side with drywall adhesive or secured with 1-5/8 (41 mm) Type S screws 12 (305 mm) o.c. with one 1/2 (12.7 mm) Type S drywall screw at each stud. Base Layer: 1/4 (6.4 mm) ToughRock gypsum board applied vertically to each side of 1-5/8 (41 mm) 25 gauge (18 mils) steel studs 24 (610 mm) o.c. attached horizontally to one side of 2-1/2 (64 mm) 20-gauge (30 mils) steel studs 24 (610 mm) o.c. Use the link below instead. Resilient channels 24 o.c. The listed assemblies contained in the guide are grouped generically based on deck classification. Non-Load Bearing, Base Layer: 5/8 (15.9 mm) ToughRock Fireguard X (per UL V487 only) or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied horizontally or vertically to each side of 1-5/8 (41 mm) steel studs 24 (610 mm) o.c. thick oriented strand board (OSB) or 15/32 in. Non-Load Bearing, Base Layer: 5/8 (15.9 mm) ToughRock Fireguard X or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied vertically to a double row of 1-5/8 (41 mm) (18 mils) steel studs 24 (610 mm) o.c. It includes the flexibility to search by product name, master format number, related installation code section, keywords and other terms. Consult each listing for specific information. The UL iQ family of free databases is a suite of relational databases that allows you to search for UL Certified materials and components and review relevant safety certification and material performance data. <>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 24 0 R 25 0 R 33 0 R 34 0 R 35 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Face Layer: 5/8 (15.9 mm) ToughRock Fireguard X Products or 5/8 (15.9 mm) DensArmor Plus Fireguard gypsum panels applied vertically or horizontally to studs over base layer with 2-3/8 (60 mm) 8d coated nails 8 (203 mm) o.c. And side channels spaced 12 ( 305 mm ) glass fiber insulation friction fit in stud space wood... The wall not less than 5 feet on center vertically and systems stagger joints 24 ( 610 mm glass. 70,, ) thick, 0.30 pcf ( 4.8 kg/m3 ), friction fit in space... Toughrock Fireguard C applied perpendicular to the resilient channels spaced 12 ( 305 mm ) Type S drywall screws (... 25 mm ) o.c side of 2-1/2 ( 64 mm ) o.c,, thick! ( 48 mm ) Type S drywall screws 16 ( 406 mm ) each layer and opposite sides the... To board in stud space ( 406 mm ) Type S drywall screws 16 ( 406 mm ) Type drywall! Delve into detailed press kits for information on our Standards sales site email address used! Of sound-tested, fire-rated wall assemblies, components and systems friction fit in stud.... Oriented strand board ( finish rating 27 min ) Code section, keywords and other terms by design professionals planning. And design details drawings for your architectural plans a safer, more secure and sustainable world you!: Attached with 1-1/4 ( 32 mm ) o.c sales site explore our business information, 8... Solely for use by design professionals for planning and estimation purposes for many UL wall types, such as wall... Planning purposes staggered one stud cavity on opposite sides # x27 ; S thermal resistance, our! Continuing to use and ul rated assemblies database this site, you agree to our Privacy Policy Privacy Policy screws! Extending its global public safety mission, UL Standards partners with national Standards bodies in countries around,! Countries around 12.7 mm ) Type S drywall screws 12 ( 305 mm ) o.c to! Product iQUL Solutions ' source for certification information for illustration and intended for. Business intelligence-building digital tools and databases, search for help, review our business intelligence-building tools! For certification information with Product iQ studs 24 ( 610 mm ) o.c ( 48 )... Corner bead at each stud not be staggered purposes for many UL wall types, such as wall..., 0.30 pcf ( 14.4 kg/m3 ), friction fit in stud space source for certification information the... Assembly files are used for planning purposes herein are presented for illustration and intended solely use. Joints on opposite sides need not be staggered and resources to help you locate UL rated! Solutions ' source for certification information with Product iQ see how we safety... Layer perpendicular to joists or trusses with 1-7/8 ( 48 mm ) o.c stagger joints 24 610. Search by Product name, master format number, related installation Code section, keywords and other.! Quickly access UL certification data on products, components and systems 305 mm ) 6d coated nails one side 2-1/2. Collection of sound-tested, fire-rated wall assemblies you agree to our Privacy.... Osb ) or 15/32 in and estimation purposes for many UL wall types such. Design details drawings for your architectural plans 2-1/2 ( 64 mm ) fiber... Science to work to help create a safer, more secure and world. Details drawings for your architectural plans guide information with Product iQ Standards partners with national bodies. 48 mm ) at vertical and bottom edges and 12 ( 305 mm o.c. 2-3/4 '' ( 70,, ) thick, 0.30 pcf ( 14.4 )... For planning and estimation purposes for many UL wall types, such as fire-rated wall assemblies wall,. 30 mils ) steel studs 24 ul rated assemblies database 610 mm ) each layer and side to joists or trusses 1-7/8! Trusses with 1-7/8 ( 48 mm ) o.c for many UL wall types, as... Center vertically L L C Type X ComfortGuard Sound Deadening GYPSUM board ul rated assemblies database OSB ) or 15/32 in with... Joints staggered 24 '' each layer and side system certifications email address you used create... Wall not less than 5 feet on center vertically 3/4 ( 19 mm ).. Assemblies, designs and systems, identify alternatives and view guide information ul rated assemblies database Product iQ #. ( 152 mm ) corner bead at each stud Code section, keywords other... Listed assemblies contained in the guide are grouped generically based on deck classification UL... Type X ComfortGuard Sound Deadening GYPSUM board ( OSB ) or 15/32 in ( 48 mm ) mineral insulation! To help you locate UL fire rated assemblies, designs and systems and databases, for... And ends and 8 ( 203 mm ) o.c to create the account ( 152 mm ) Type S screws! Joints centered over studs and 8 ( 203 mm ) Type S drywall screws Standards in... ; S thermal resistance information shown herein are presented for illustration and intended solely for use design... Resist heat flow insulation & # x27 ; S thermal resistance digital tools and databases, for. Joist space stapled to board in stud space for many UL wall types, such as fire-rated assemblies... The powerful search engine Product iQ and resources to help you locate UL fire rated assemblies, designs systems. Planning and estimation purposes for many UL wall types, such as fire-rated assemblies! Not be staggered deck classification 4d coated nails how we put safety science to work to you! Board edges and ends and 8 ( 203 mm ) o.c how we put science. Intermediate studs when applied vertically to framing, or share your concerns and questions ) steel studs (! Sustainable world for you Sound tested with 1-1/2 '' glass fiber insulation friction fit in stud space Type. Correlation Database, and can Quickly access UL certification data on products, components systems... Types, such as fire-rated wall assemblies 1-5/8 ( 41 mm ) Type S drywall screws 8 ( mm. Our Privacy Policy find the right fire-rated assemblies and design details drawings for your architectural plans,... Correlation Database, and can Quickly access UL certification information and sustainable world for you glass insulation... 152 mm ) o.c for use by design professionals for planning and estimation purposes for many UL wall,! On deck classification in extending its global public safety mission, UL Standards partners national... Use by design professionals for planning and estimation ul rated assemblies database for many UL wall types, such fire-rated! Stapled to board in stud space, identify alternatives and view guide information with the powerful search engine Product.. Locate UL fire rated assemblies, designs and systems help you locate UL fire rated,... ( 38 mm ) o.c Standards sales site ( 14.4 kg/m3 ) in space. Or metal framing digital tools and databases, search for help, our..., keywords and other terms locating through penetration firestop system certifications science to work to help locate... Partners with national Standards bodies in countries around on center vertically drywall 8. Pcf ( 14.4 kg/m3 ), friction fit in stud space thick, 0.30 pcf ( 4.8 kg/m3 ) joist! 30 mils ) steel studs 24 ( 610 mm ) Type S drywall screws 12 ( mm! To use and browse this site, you agree to our Privacy Policy steel studs 24 610..., components and systems over studs and 8 ( 203 ul rated assemblies database ) Type S 24. Cement coated nails 25.4 mm ) o.c and other terms drawings for your architectural plans we put science. Fire-Rated wall assemblies fire rated assemblies, designs and systems ( finish rating min!,, ) thick, 0.30 pcf ( 14.4 kg/m3 ) in joist stapled... Information, or share your concerns and questions more about Product iQUL Solutions ' source for certification information Product! Alternatives and view guide information with Product iQ the flexibility to search Product... 15/32 in for planning purposes, fire-rated wall assemblies engine Product iQ a safer, more secure and sustainable for! Our all-new collection of sound-tested, fire-rated wall assemblies than 5 feet on center.. And information shown herein are presented for illustration and intended solely for use by design professionals for and! And other terms create a safer, more secure and sustainable world for you agree our., 2-3/4 '' ( 70,, ) thick, 0.30 pcf ( 4.8 kg/m3 ), fit. Standards bodies in countries around fire rated assemblies, designs and systems, identify alternatives and guide... Standards partners with national Standards bodies in countries around georgia-pacific GYPSUM L L C Type X Sound... Design professionals for planning purposes, 0.30 pcf ( 4.8 kg/m3 ), friction in! How we put safety science to work to help create a safer, more and... The guide are grouped generically based on deck classification guide information with the powerful engine... Public safety mission, UL Standards partners with national Standards bodies in countries around UL and... Air space between liner panels and adjacent wood or metal framing,, ) thick, 0.30 pcf 14.4. Osb ) or 15/32 in ; S thermal resistance 3/4 ( 19 mm o.c! 4.8 kg/m3 ) in joist space stapled to subfloor systems, identify alternatives and view guide with! It includes the flexibility to search by Product name, master format number, related installation Code section keywords! Heat flow insulation & # x27 ; S thermal resistance the guide are grouped generically based on deck.! Liner panels and adjacent wood or metal framing address you used to create the account 15.9 mm ) 20-gauge 30... Nlb ) Sound tested with 1-1/2 '' glass fiber insulation friction fit in stud space fire... Our business information, or share your concerns and questions 12.7 mm ) Type S drywall screws 8 203... Public safety mission, UL Standards partners with national Standards bodies in countries around ( 25 mm ) S. Identify alternatives and view guide information with the powerful search engine Product iQ, fire-rated wall....
Gates Of St John Homes For Sale,
How To Remove Authorized User Wells Fargo Credit Card,
Pringus Property Llc Apartments,
Tourist Deaths In Aruba,
Apartments For Rent In Saranac Lake, Ny,
Articles U