Frequently Asked Questions About the United States National CAD Standard® (NCS)

Please Note: Questions in blue type are specific to version 3.1.


  1. What is the current version of the NCS?

    The current version of the United States National CAD Standard®, is Version 5 published in May 2011.
  2. What is in the standard?

    The web based online document includes:
    1. NCS Foreword and Administration; AIA CAD Layer Guidelines; Uniform Drawing System; Plotting Guidelines and NCS Appendixes.
    2. Excel Files: AIA CAD Layer Guidelines; UDS Terms and Abbreviations, Schedules, Regulatory Information; and Plotting Guidelines' tables, downloadable from the online document.
    3. DWG Files: UDS Symbols, downloadable from the online document.
  3. Will the NCS come with updates (like a subscription) or do you have to buy new releases each time a new one is published?

    The NCS does not come with updates. Each revision of the standard is evaluated in term of its scope. A minor revision will be issued as an addendum at an update price. A major revision requiring republishing the full document will be sold as a new document at a new full price.

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Price / Discounts / Licenses

  1. Can the standard be installed on multiple computers so that members of a firm have it readily available for reference at their desks?

    A Site license of the NCS 5.0 may be installed on up to 10 computers in a single office location.
  2. What is the licensing for the National CAD Standards? Do we need to buy a copy for each person, office or can we purchase one license for the entire company?

    A site license allows you to access the NCS from up to 10 computers in a single office location.

    An NCS Enterprise license allows companies to access the NCS from more than 10 computers from a single office location or from multiple offices with the same office domain name.
  3. What is the price of the NCS?

    The list price of a single license of NCS Version 5 is $410. The AIA, CSI and NIBS member discount price is $290.
  4. Our firm currently owns a copy of version 2.0 of the NCS. Is there an upgrade price for getting the latest 5.0 version of NCS?

    There is NO upgrade price for migrating from 2.0, 3.0, 3.1 or 4.0 to the latest 5.0 version of the NCS.
  5. Are there discounts for bulk orders?

    Bulk orders of 3-10 licenses are covered by a flat Site license fee. Bulk orders of 11+ licenses are covered by a flat Enterprise license fee.
  6. I am an instructor of Drafting Design and Technology and interested in purchasing the "United States National CAD Standards" package as a resource and instructional tool for my classroom. How do I order a copy for my drafting design class?

    Academic institutions can purchase the NCS at the academic rate of $200. The academic rate is available to any educational institution or vocational school. A Site license of the NCS 5 at the academic rate of $520 may be accessed by up to 10 computers in a single classroom.

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  1. How do I participate in the update of the NCS?

    To participate in the development of the standard please join the National CAD Standard Project Committee (NCSPC). A committee membership application form can be filled out and submitted online. There is no cost to join the NCSPC other than possessing a current copy of the NCS.

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Adoption / Implementation

  1. When did the Air Force adopt the National CAD Standard?

    The CADD/GIS Technology Center was one of the signatories of a 1997 "MOU that formed the basis of a cooperative, collaborative relationship for the development of the NCS" (
  2. I am looking to implement the National CAD Standard to bring some semblance of order to our drawings and file management. Could you tell me how the NCS is implemented into AutoCAD?

    If you are considering implementing the NCS, you might want to take a look at some helpful NCS implementation tips on our website.

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  1. How have you addressed the growing use of BIM software in our field as it pertains to layering? I was wondering if you have an example of what works, how it works and if it will work (inter-office, multiple offices) across many hands.

    There are quite a few very good examples of BIM for design and specifically architecture. The most notable are probably the winners of this years AIA TAP BIM awards which were summarized by Lachmi Khemlani:

    2006 2nd Annual BIM Awards, Part 1
    2006 2nd Annual BIM Awards, Part 2

    There are significant differences in approach between CAD and BIM. CAD is based on traditional drawing and really is simply automating that process, while BIM is focused on objects and providing varying levels of information associated with those objects. It is anticipated that there will be some discussion of the relationships between BIM and CAD in both the new version of the NCS and the National BIM Standard. In essence CAD is a set of reports off a building information model. As long as we use paper to build from we will need CAD. Layers are really an organizational structure primarily related to drawings and do not have any importance in BIM. We are mindful however that there will be a lot of practitioners that will be using a CAD approach for many years to come. As indicated a BIM is a grouping of objects identifying their relationships with other objects. A floor plan for example is simply a slice through all the objects represented in that particular view.

    BIM may not necessarily be appropriate for all facilities. If the owner is not interested in having facility information for future facility management or is not willing to make the process changes necessary to maintain the information then they will be just as happy with the 2D floor plans. A lot of spec building will fall into this category. However we are finding that designers are doing BIMs just to make things go together more smoothly. One significant benefit is the integration of design and the tools available to do conflict analysis. In reality in CAD there is no machine readable link between the different types of drawings, specs and cost and conflict analysis must be done by hand. A lot of RFI's and change orders are born from failures in that process. There are quite a few examples now of facilities that have had no RFI's or change orders, although the bulk of properly coordinated BIMs have only seen significant reductions in the numbers.

    A BIM really provides us an opportunity to design and analyze a facility virtually prior to physically building it so we don't need to wait till the building is being built to find conflicts between beams and pipes and ducts. We can also do a better job of energy analysis. Cost engineering will also benefit. There are demonstrated benefits in both the design phase as well as the construction phase, however the real benefits will be realized over the life of the facility in operations and sustainment. This was identified in a NIST study several years ago that identified $15.8B lost annually due to lack of interoperability.

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CAD Layering

  1. We were wondering if you already have layer naming conventions for swimming pools and associated equipment. When I look at the list on page CLG-5 it looks like we would use "X" Other Disciplines. Thus, would our layer name look like this (i.e. X-Pool- and X-Equi…)?

    Depending on what you are supplying we could see entertaining an amendment to the NCS to move POOL from minor status to major status but for now derivatives of the following are allowed:


  2. Are there layer names already established to use for Title Block and Border?



  3. Our firm specializes in Entertainment Design. In some cases our designs fall under the heading of architecture while in other circumstances our designs fall under an electrical heading. Could we use discipline designator "X" or user defined discipline designator "XJ", to define our layers?

    Furthermore after the first hyphen, we then have difficulties with the major group designators. Our work could be classified under one of the following seven major groups: architectural/theatrical lighting, audio, video, control, theatrical rigging, special effects, and utility circuits. We did not find categories for video, rigging and special effects in the current Layer guidelines. If we blocked out the major group headings, the two minor groups' headings would not leave enough space for the proper designation of systems. Given the above limitations how should we implement the Standard?

    You are correct you should be using "X" as a discipline designator. If you think that there should be a new discipline added you could submit it as a ballot proposal.

    In looking at what you need for Major groups I would suggest that you submit a ballot item for the ones you need with explanations as well. I have looked through what we have and agree we are lacking in your industry needs. You bring a unique requirement to the NCS that no one else has asked for yet.
  4. The Major Group field definitions are not to be changed from what is set by the NCS Layer module. In the NCS Layer module the description are just simple ones. When going thru the list of Major Group/Disciplines I have come across a couple with the same layer name but with different descriptions:
    1. Under Survey/mapping the layer name PROP - is for Property boundary but the Civil Layer name PROP - is for Property. Are these the same?
    2. Under General the layer name PLAN - is for Key plan (floor plan) and SITE - is also for Key plan (site plan). Which one is correct? The Survey/mapping layer name SITE - is for Site features, the Landscape Layer name SITE - is for Site improvements. That's three different descriptions for SITE, which one is correct?
    3. Under Survey/Mapping the layer name:
    PROP - is for Property boundary;
    PVMT - is for Property boundary; pavement;
    PVMT-ASPH - is for Property boundary: asphalt surface;
    PVMT-CONC - is for Property boundary: concrete surface;
    PVMT-GRVL - is also for Property boundary: gravel surface;
    Shouldn't PVMT be Pavement?
    Under the Civil layer name CTRL - if for Control points but the Electrical layer name CRTL - is for Control system. Which one is correct?
    4. Under the Survey/Mapping layer list & the Civil Works layer list the name FUEL - is for Fuel gas but in the Mechanical layer list the name FUEL - is for Fuel systems. Which one is correct? Also, Gas is not the only fuel! (v3.1)

    1. PROP = Property - Yes we are working on making all of the definitions the same in the next release.
    2. SITE = Site; PLAN = Key Plan - Still looking at the definitions.
    3. PROP = Property - Property Boundary was a typo all of the definitions should and will read like this in the next release. CTRL = Control - It originated with survey control points and some electrical folks switched the meaning around. I have to look again but I think we may have clarified this in one of the ballot items for NCS4. If not it will remain one of many dual definition items we need to fix in the future.
    4. NGAS = Natural gas; FUEL = this represents fuel for your cars. We kept it generic for everything but natural gas. There is a ballot item to remove civil works from the NCS so this will go away.
  5. The Civil discipline has layers C-TINN, C-TINN-BNDY, C-TINN-FALT, C-TINN-VIEW and C-TINN-VOID. I cannot find them in the Survey discipline. Should I make a V-TINN set of layers?

    Yes, you can use any Discipline with any major and with any minor as long as it is a logical combination.
  6. My company will always be a "Z" Discipline I would like to see a Major Group list created for what the contractor is going to supply. My thoughts are that the types of materials a contractor supplies can be broken down to:
    METL - Misc Metals or Metal Work; WOOD - Misc Wood Work; GLASS - Misc Glass; CONC - Misc Concrete Work; ELEC - Misc Electrical Work; PLAS - Misc Plastics; FURN - Misc Furniture or Furnishings; EQPM - Misc Equipment; STON - Misc Stone Work.
    NCS v3.1 page CLG-8 states: The Drawing View field codes are specialized codes for layers that are organized primarily by drawing type, rather than by major building system. The field codes DETL, ELEV, and SECT may also be used as Minor Group field codes to modify a major building system. Or in this case the "major building system" would equal the contractor's area of expertise, followed by any View fields (or any other current group) as the Minor Group, and any Minor group modifiers that apply. What would you see as the strengths and weaknesses of expanding the "Contractor" discipline in order to be divided down to "Contractor by Material Type" for lack of a better term? (v3.1)

    "Contractor/Shop drawing layer list" this is a grey area in the Layer list. We combined the UDS Discipline designators with the AIA layer discipline designators and in some case one may not ever use the other.

    Let me explain. We no longer support the idea of "contractor of record" for layer naming. The world as we know it is moving toward BIM or Building Information Modeling. At the end of the project all of the files, layers, etc. become "The Building" or whatever. The "Building" doesn't care 5 years from now when someone is looking for spare parts for their casework hardware who originally added it to the drawing. They will be looking for a Q-CASE-HRDW* layer for information. "Z-" is just not required. My suggestion is use all of the discipline codes for what the items represent and use "Z-" for file naming.

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Drawing Set Organization

  1. a) We have traditionally put stair sections with the Building Sections. Please explain logic behind suggesting that stair sections be put in the 400 series of drawings instead of the 300 series. b) We have traditionally created a separate sheet(s) that includes all of the elevator information (plans, elevations, sections, details) and placed them at the end of our drawings. Do you believe the best location for this type of sheet the 400 series, or another series?

    The NCSPC recognized that combining stair plans and sections on the same sheet (as well as elevator plans and sections) was common practice in many workplaces throughout the industry that provides benefits to drawing users by allowing both views to be seen together. Sections of stairs and elevators can still be located on Sheet Type Designator 3- series sheets if there is no compelling reason to locate them on the Sheet Type Designator 4-series sheets.

    The Sheet Type Designator 4-series sheet provides an excellent opportunity for you to group the elevator information together.
  2. Re: page UDS-01.13: Please give an example of what you mean by 'sections that are not details' that would be placed in the 400 series of drawings.

    This is one of the most frequently asked questions we get. One of the best examples I can provide is an enlarged toilet room. According to the UDS Drafting Conventions Module, auditoriums, kitchens, and laboratories are examples of rooms that usually require large-scale views; stairwells, elevator shafts, and mechanical and electrical rooms are also examples of plans referenced to the enlarged plan. This wording, combined with the examples of large scale views on pages UDS-04.68–04.71, implies that sheet type designator 4 sheets are for individual areas drawn at larger scale. The Common Scale table on page UDS-04.12 indicates that enlarged plans should be drawn at 1/2" = 1'-0
  3. We have a partial building section that includes the top floor of the building with a bulkhead and has been drawn in ½" scale, as opposed to the other building sections drawn in ¼" scale. Would this section be placed in the 300 series or 400 series of drawings? Is this what you mean by a 'section that is not a detail'?

    Unfortunately, there is quite a bit of grey area with regard to what is a detail and what is not. We usually locate all of our building sections on the Sheet Type Designator 3-series sheets. Your example of a "partial" building section sounds more like something that belongs on the 3-series sheets to me and that is where I recommend locating it.

    The Drafting Conventions Module clearly indicates that building sections should be located on the 3-series sheets (UDS-04). Other than the examples for stairs and elevators discussed earlier, there are probably very few instances where wall sections would appear on the 4-series sheets.
  4. The NCS isn't explicit about where "Basement levels" should be placed. We are planning to put them after the floor plans, numbering them sequentially down from the ground level. For example, first basement (B1) A-106, 2nd basement (B2) A-107, etc. Is this correct?

    The Drawing Set Organization module does not require specific assignment of sheet sequence numbers because there are too many possibilities to develop a single standard that would accommodate all conditions. Therefore, the numerals used are user-defined (anything except 00).
  5. We notice that the roof plan is after the ceiling plans? Why wouldn't it be after the floor plans?

    The purpose of the sheet numbering examples in Appendix B of the Drawing Set Organization Module is to provide users with guidelines for the order of sheets within each discipline, and within each series of sheet type designators. It's fair to say that determining the order for some of the sheets was arbitrary (if we had put the roof plan ahead of the reflected ceiling plan, someone would have surely questioned that, too). There are always arguments—some would say that interior plans should come ahead of exterior plans—but then why are exterior elevations (A-201) ahead of interior elevations (A-202)? If you are compelled to put the roof plan first, do so.
  6. I'm looking to develop a standard for revision (specifically Addenda) drawings in our firm and am unclear, based on the standard, how to proceed. (v3.1)

    There are clear formats in the NCS for the symbols, sheet sizes, title blocks, sheet identification, etc., that could be used for revised sheets—but HOW those formats are used can vary somewhat depending on each user's specific needs.

    For example, some clients may only require addendum changes to be identified and the issue block to be updated (without any changes to the sheet identification). This could be accomplished by only using the revision indicator symbol/revision cloud and issue block.

    In some cases, supplemental drawings are issued as part of an addendum that illustrate a revised portion of a specific sheet—and the NCS provides some examples of these conditions such as those in Figure 02.15, and in the table in UDS-01.
  7. Given the consecutive numbering of drawings in the A-1xx, as you move from floor plans to ceiling plans, etc., if one wanted to insert a new sheet in the middle of the sequence (say our building added a storey), does it then require re-numbering all subsequent sheets?

    You can avoid renumbering sheets if a new sheet needs to be inserted by using a user-defined designator Such as A-103A. This is an extreme example, but it would save renumbering the sheets.

    Be aware that you can also skip numbers if you anticipate this happening when you set up your sheet numbering system. For example, you could number your sheets as follows:

    A-110 First Floor Plan
    A-115 First Floor Reflected Ceiling Plan
    A-120 Second Floor Plan
    A-125 Second Floor Reflected Ceiling Plan
    A-150 Roof Plan

    With this numbering scheme you could insert a sheet later without having to renumber anything else. For example, if you decide to add a story, the new list of sheets would appear as follows:

    A-110 First Floor Plan
    A-115 First Floor Reflected Ceiling Plan
    A-120 Second Floor Plan
    A-125 Second Floor Reflected Ceiling Plan
    A-130 Third Floor Plan
    A-135 Third Floor Reflected Ceiling Plan
    A-150 Roof Plan
  8. Our company does a lot of Restoration and we were hoping to change over to the NCS. We may have to use a modified version of the NCS because we don't see a place for our Restoration section in your layering system or Drawing Set Organization. Could you tell me where we should be looking to put our Restoration layers and sheets?

    There are no specific layer names or discipline designators with the term "restoration" in them. However, if there are compelling reasons to provide specific identification of restoration work than there are many options available.

    For example, many of the disciplines include a Level 2 discipline designator for demolition (the Architectural discipline includes AD; the Interiors discipline includes ID). Many disciplines also includes user-defined Level 2 discipline designators that could be assigned to restoration (Architectural includes AJ and AK; Interiors includes IJ and IK).

    If it is necessary to assign a Level 1 discipline designator to restoration, use "X". The X discipline designator is used for "other disciplines" (refer to page UDS-01.11). Restoration sheets (X-sheets) would then be located toward the end of the drawing set after Electrical, Telecommunications, and Resource sheets. It would be advisable to verify this option is acceptable to clients requiring NCS compliancy prior to creating their CAD drawings.

    For layer naming remember that any major group can be used with any discipline; any minor group can be used with any major group; and user-defined minor groups are permitted. An example of some potential restoration-related layer names could be as follows:

    X-FLOR-D (Restoration, floor elements, existing to demolish)

    AD-WALL (Architectural demolition, wall elements)

    X-CLNG-E (Restoration, ceiling elements, existing to remain)

    IK-DOOR (Interiors restoration, door elements)
  9. I represent a company who specializes in precast building components such floor/roof decking, cladding/bearing walls, columns, beams, stair risers/landings. In certain circumstances our products can account for 95% of the framing elements. With modular and precast building designs become a greater segment of the construction market has there been any thought on adding this as a Discipline Designator?

    Unlike MasterFormat, which provides unique identifiers for specific construction materials and processes, it would not be impracticable for the NCS to follow that example for a variety of reasons.

    First and foremost is that the NCS establishes discipline designators according to very general categories of subject matter. This methodology is very flexible because it allows many different materials and processes to be grouped together within the same discipline. It also allows the same material or process (such as modular/pre-fabrication) to be used in different disciplines, depending upon the application.

    Instead of assigning a new discipline designator, you might want to consider establishing new CAD layer data fields that are specific to your industry. This approach has been used before, and it can provide identifiers that are unique to a specific industry.
  10. Is there a standard for numbering smaller format supplemental drawings such as 8.5"x11" drawings or 11"x17" drawings that change a portion of full size drawing? (v3.1)

    In a situation where only a portion of a drawing is being reissued a supplemental drawing that includes the first revision to a floor plan on sheet A-102 would be identified as Supplemental Drawing A-102-R1.
  11. When an intermediate "view" file is used to compile multiple model files for annotation purposes, how do you recommend naming these view files? (I am specifically referring to the differentiation Autodesk Architectural Desktop makes between "constructs", "views", and "sheets".)

    The NCS addresses names for model files in UDS Module-01 and includes a table with examples of model file types with characters that can be used to define the type of model. These characters are the third and fourth characters in the file name and are user-defined. Therefore, a model file name for an architectural ceiling plan could be identified as simply as, A-CP.dwg; and a model file name for an architectural roof plan could be identified as A-RP.dwg.

    Model file names can also include optional, user-defined characters to help further identify the model file. These include four alpha-numeric characters after the third and fourth characters; and/or additional characters before the third and fourth characters. Model file names using this approach could include the following:

    Model file names with optional fifth through eighth characters:* (Room 101 reflected ceiling plan)* (Building 1001 Roof Plan)
    Model file names with optional prefix characters**:
    Room 101 Reflected Ceiling Plan Model File*
    Building 1001 Roof Plan Model File*
    *The three characters after the required decimal point (xxx) are defined by the CAD software and represent file extensions such as .dgn, .dwg, .dwf, and .dxf.
    **The use of prefix characters may conflict with software operating systems that do not allow more than 8.3 characters.

    Please note that the NCS is universal to all CAD software systems. Therefore when a model file name will be associated with proprietary functions of a specific system, we recommend including the optional, user-defined characters as may be needed to identify the type of file required.
  12. Resource could take on several meanings.

    Resource sheets typically include important information about existing conditions or new construction that is related to the work. Resource sheets are often not part of the contract documents. Typical examples may include equipment furnished by others, soil boring locations, site conditions surveys, and photos of existing conditions.

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Discipline Designators

  1. We currently use the discipline designators of "AS" for Architectural/Structural stairs and I notice that you use it for something else. If I can't use "AS", where else I could put my Architectural/Structural stairs. It saves us a lot of money if we can combine the Architectural and Structural information on one set of documents.

    There are various options for discipline designators that can be used to identify sheets containing information from two disciplines. However, please be aware that the NCS does not require sheets of this type to be identified with level 2 discipline designators. In the architectural/structural example referenced, when the information on the sheet is predominantly architectural use A (architectural) or AE (architectural elements); if the information is predominantly structural use S (structural) or SB (structural substructure).

    Note: Some jurisdictions do not allow dual professional seals on the same drawing; in these types of situations combining information from different disciplines may not be a viable option.

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Sheet Identification

  1. NCS states that the first sheet number for Architectural floor plans would be A-101. We could not find a provision using 'Level 1' numbering for a Basement plan not at the first floor level.

    In some instances, NCS sheet identification can be established to replicate the floor name within each discipline. An example of this approach would establish sheets A-102, M-102, and E-102 as the second floor plan for each of the various disciplines. This option is up to the user; however, when plans of basements and mezzanines are required, this type of sheet identification will need to be modified.

    One approach that can be used for drawings sets containing basements and mezzanines is the user-defined designators. An example of sheets identified in this manner would be the following:
    A-101-B Basement Floor Plan
    A-101 First Floor Plan
    A-101-M Mezzanine Floor Plan
    A-102 Second Floor Plan
    A-103 Third Floor Plan

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Sheet Organization

  1. May we use a tighter grid (more drawing modules) within the drawing area than shown in your samples? We are having trouble laying out enough interior elevations on a sheet. Or may we use a tighter grid on some sheets than others?

    UDS Module-02 states that module sizes are user-defined and they can be sized as needed to meet user requirements. It also states that modules need to remain the same size throughout the drawing set.

    If the required module size in your drawing set is larger than you need for interior elevations, consider using the multiple view interior elevation indicator symbol because it allows up to four interior elevations (views A, B, C, and D) to be placed within the same drawing block.

    FYI: The requirement to allow user-defined module sizes in the UDS was suggested by an interior designer for that very purpose.
  2. Typically in the A-1xx section, the NCS system aligns the floor plans with the drawing number (i.e. 1st floor is 101, 2nd floor is 102, etc.), but there are also other Plan and Horizontal Views information that are put in the 100's in various places. For instance, G(or GI)-101 is listed as Location and Area Maps. Then G-102 is Code Summary Fire Exiting and Separation (which I come to interpret as Life Safety plans since it is in the Plan designator, not the notes designator), so the first floor, no longer aligning the floor number with the drawing number. Is the number alignment on between floor number and sheet number a happy coincidence, or is that a goal of the system?

    The sheet sequence numbers are user-defined.
  3. What about a large floor plan that we divide into 2 or 4 sheets, for example. Would these be placed as detail sheets in Section 4? Or in Section 1?

    According to the Drafting Conventions Module, auditoriums, kitchens, and laboratories are examples of rooms that usually require large-scale views; stairwells, toilet rooms, elevator shafts, and mechanical and electrical rooms are also examples of plans referenced to the enlarged plan. This wording, combined with the examples of large scale views, implies that sheet type designator 4 sheets are for individual areas drawn at larger scale. The Common Scale table indicates that enlarged plans should be drawn at 1/2" = 1'-0".

    When an overall floor plan is too large and needs to be separated into areas, the areas can be drawn on sheet type designator 1 series sheets, and be located after an overall floor plan, with a key plan on each sheet as follows:

    A-101 Comprehensive Floor Plan (1/16" = 1'-0")
    A-102 Floor Plan - Area A (1/8" or 1/4" = 1'-0")
    A-103 Floor Plan - Area B (ect.)

    The plans for the areas do not need to follow a comprehensive floor plan—they can appear by themselves, with a key plan on each sheet. Reference each plan using the match line indicator symbol UDS-06.

    Note: The use of sheet type designator 1 series for these conditions is also implied in Figure 04.13. Having said all this, and depending upon your situation, if there is a compelling reason for you to locate the larger scale plans on sheet type designator 4-series sheets, do so.
  4. We do a lot of multi-family residential, hotels, etc. Similar to the divided floor plans above, would these best be placed in Section 4 or as part of Section 1?

    For unit plans such as those that would appear in an apartment complex, hotel, etc., I would use sheet type designator 4 series sheets for the larger scale plans. However, you could use sheet type designator 1 series sheets depending upon your situation.
  5. When placing a drawing block on the sheet grid, must the insertion point be exactly where the grid boundary lines intersect or can it be anywhere within that particular grid area? How should details in detail boxes be placed?

    have been indicated that way, the lower left hand corner of a drawing block does not need to be located at the lower left hand corner of a drawing module. It is very common for a drawing block to encroach into a portion of an adjacent drawing module.
  6. Nowhere in your document do you define the difference between a "drawing" and a "sheet". I have a problem with the word "sheet" when referring to a drawing. I started drafting in 1963 and I have always created drawings not sheets. Every tab page in your document is labeled as "Uniform Drawing System (UDS)" (CSI's designation). For example, under the tab "Drawing Set Organization" you discuss a drawing set content comprising Procurement "Drawings", Contract "Drawings", Resource "Drawings", Addenda "Drawings", and Modification "Drawings" then you go on to talk about "Sheet" Identification and "Sheet" Types.

    This document, in my opinion, is full of contradictions as to what is a "drawing" and what is a "sheet". Everywhere the word "sheet" is used the word "drawing" could be used instead. Please explain.

    The term, "drawing" has historically been used for two different meanings—i.e., "sheet" and "a graphic appearing on a sheet." As stated in the UDS Introduction, "as a delivery media, the document sheet is the hardcopy representation of information presented on a vellum or mylar "original" or "tracing"; in an electronic media sense, the document sheet is the screen window;" A drawing is the, "graphic and pictorial portions of the documents showing the design, location and dimensions of the project, generally including plans, elevations, sections, details, schedules and diagrams."

    Since the terms "drawings" and "sheets" can also have the same meaning, the NCS uses the term, "sheet" to help differentiate one meaning from the other whenever it is needed to help clarify intent. For example, it is easier to differentiate concepts such as, "drawings set organization, sheet organization, and drawing block organization" as opposed to, "drawing set organization, drawing organization, and drawing block organization." There are other examples that demonstrate the need to distinguish the different meanings (i.e., drawing (block) identification vs. sheet identification; drawing type vs. sheet type; etc.).

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Drafting Conventions

  1. What line types should be the standard for duct, equipment etc.

    The use of lines is addressed in the UDS Drafting Conventions Module. In general, most of the lines you are asking about are visible object lines which are usually drawn at 0.35 mm; Hidden object lines are usually drawn at 0.25 mm.

    There are also a number of symbols in the UDS Symbols Module which identify certain line types and line widths for some of the mechanical symbols. The NCS does not require that a certain line width be used for every object, every time, because scale and type of view do have an impact on line width. For example, if a detail indicates a duct in a section view, a wider line such as 0.50 mm could be appropriate for the profile of the duct. Instead, the NCS dictates that only one of eight line widths can be used for all lines: 0.18 mm, 0.25mm, 0.35 mm, 0.50 mm, 0.70 mm, 1.00 mm, 1.40 mm, and 2.00 mm.

    The NCS also provides for use of half-tone lines, as identified in the table included in the Tri-Service Plotting Guidelines component of the standard.
  2. We are having a disagreement between offices about the standard text width promulgated by the NCS. Could you expand on the intent of the table in UDS Module-04?

    The table of common line types in the Drafting Conventions Module (UDS-04) identifies four line widths that can be used for text:
    0.25 mm (thin); 0.35 mm (medium); 0.50 mm (wide); and 0.70 (extra wide). The table identifies each of these line widths to a range of text heights as follows:

    3/32" - 3/8" text: 0.25 mm
    5/32" - 3/8" text: 0.35 mm
    7/32" - 3/8" text: 0.50 mm
    1/2" - 1" text: 0.70 mm

    The overlap that occurs to allow three pen widths to be used for text heights between 3/32" - 3/8" is intentional in order to provide users more flexibility depending upon their specific application. This situation is similar to many other requirements in the NCS that provides options: each user needs to decide which of the NCS-compliant alternatives best meets their needs.
  3. UDS Modules-04 and 07 indicate that 2.4 mm is the metric equivalent of 3/32". Many symbol definitions in Module-06 indicate that 2.5 mm is the metric equivalent of 3/32". Why the difference? Which is correct?

    The error occurred because of the different methods to convert 3/32" into millimeters. The federal government makes a distinction between "hard" and "soft" conversions to the metric system. A soft conversion is a direct mathematical conversion from a U.S. measurement to its metric equivalent e.g., from 180 pounds to 81.65 kilograms. A hard conversion is the creation of a rounded, rationalized number that is easy to work with and easy to remember. Unfortunately, the hard conversion was used for some of the text heights in Module-06. The soft conversion was used everywhere else.

    A soft conversion of 3/32" equals 2.3812 mm, or 2.4 mm. A "hard" conversion of 3/32" equals 2.5 mm. As you have pointed out, the soft conversion (2.4 mm) is used throughout the UDS except for Module-06.

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  1. The NCS does not address sizing for a large number of standard symbols. For instance: What are line lengths and distance between the lines for an electrical normally-open contact? Where can I find these standard symbol properties?

    The Symbols module contains many graphics that originated from the Department of Defense. When they were provided for inclusion in the symbols module, there were no properties associated with them other than a title.

    The CADD/GIS Technology Center has maintained symbols in both MicroStation and AutoCAD format for users of the A/E/C CADD Standard. It can be said that it is not an easy task to do. Concerning sizes of symbols, we have decided to size symbols based on the size they should be when plotted. There has never been a definite source to refer to when determining sizes. It's been mainly based on the most appropriate size the symbol should be when plotted. This only applies to general symbols not parametric symbols.

    Until more definitive properties are available, users will need to interpret how to draw undefined symbol properties from the graphic provided (bear in mind that some of the symbols are scale dependent and others are not). Layers need to be assigned in accordance with the CAD Layer Guidelines, and pen widths and colors need to comply with the Plotting Guidelines.

    Are there any standard symbols for the geotechnical discipline such as environmental symbols & materials testing symbols? We do have layer standards, but not symbols. I see a few generic earthwork symbols in the NCS, but none specific to this question. Do we have plans to add geotechnical symbols to the NCS, or if not, what would we recognize as a standard?

    As you have discovered, the NCS includes a few symbols that can be used by the geotechnical (B) discipline. These include symbols such as the boring indicator and many of the earthwork symbols. There is no other standard recognized for symbols other than those in the UDS Symbols Module. However, The CADD GIS Technology Center (CGTC) does intend to submit more symbols for the geotechnical discipline (and other disciplines) during the next NCS Revision Cycle. Their symbols can be downloaded now from their detail library.
  2. I am looking for a standard that may detail what symbol is specific for NOTES on drawings i.e. TRIANGLE/ HEXAGON CIRCLE… It seems that any symbol may be used for notes or REVISION indicator i.e. triangles… Also is there a symbol that may denote "CRITICAL Feature" on a drawing… such as a form feature or dimension…typically this information is verbally transmitted to vendor to produce the item… but the critical dimension / feature maybe lost in subsequent productions of the item

    Keynotes on drawings can be provided using the sheet keynote symbol or the reference keynote symbol. The sheet keynote symbol is a hexagon and it is the only symbol allowed. The reference keynote symbol is the root of the specification section number and a user-defined suffix.

    A revision on a drawing is indicated with a revision indicator symbol consisting of a cloud and a delta symbol.

    There is no symbol for a critical notation or dimension since each notation and dimension indicated on a construction drawing is considered critical.

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Ordering the NCS

  1. We own the NCS V4 – is there an upgrade price to V5?

    No, there is not a discounted price for an upgrade from V4 to V5.
  2. Our company, organization or institution does not authorize us to use a credit card. Could you send us an invoice?

    No, the National Institute of Building Sciences does not invoice for sales of the NCS V5 licenses. Visit the Institute Store to purchase a license and select the payment option of 'Check/Money Order' at the checkout. You can print the confirmation page or email as your invoice.
  3. We have placed an order for the NCS V5 and selected to pay by check. Why have we not received our code yet?

    When the Institutes receives and processes your check, you will be sent a receipt with your access code.
  4. We purchased a Single or Site License and would like to upgrade to a license that allows more users. What is the additional cost?

    You only pay the difference between the two licenses. Please contact Dominique Fernandez at for more information.
  5. We ordered the NCS V5 but did not receive our copy. When can we expect it?

    The NCS is an online web based document and is available 24/7 by logging in through the NCS web site at We do not distribute hard copies or CDs of the standard. To view screen shots of the online document, visit the NCS V5 Content page.

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Access to the NCS

  1. We have a Site or Enterprise License – how do our employees access the site?

    Each employee can use the same access code to create an account as long as they have the same domain in their email address as was registered with the NCS license at purchase.
  2. Our current NCS license is listed under an employee who is no longer with the company. Can you please remove the name of the former employee?

    Yes, please contact Dominique Fernandez at and provide the name of the company, the name of the employee to be removed, and your contact information.
  3. Our firm merged with another company and our email address has changed. How do we change our authorized domain name registered with the license?

    Please contact Dominique Fernandez at and provide the name of the company and email domain registered with the license, and the new email domain.
  4. I ordered a Student License but cannot create an account with my email address. Is there a problem with the license?

    Check the email address you are using to create an account. If you purchased a NCS V5 Student License, you can only create an account with an email address ending in .edu.
  5. When a new version of the standard is released, will we maintain online access to V5?

    Yes, the current website for V5 will remain online even when the next version is released.

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Printing the NCS

  1. How do I print the whole document?

    You cannot print the entire NCS with one link but you can print each module by visiting the Table of Contents for that module and clicking the 'Print Entire Module' link at the top of the page. Warning: The NCS includes hundreds of cross links. If you print the document you will loose the ability to quickly locate cross references within the NCS.

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