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The main purpose of construction drawings (also called plans, blueprints, or working drawings)  is to show what is to be built, while the specifications focus on the materials, installation techniques, and quality standards. However, the distinction is not clear cut.  Most designers put basic construction information in the drawings and use the specs to elaborate on materials, techniques, and standards to be met. Others pack their drawings with written notes that cover a many of the issues commonly contained in the specs.  In some cases, you’ll find the same information in both places. If there is a conflict between the specs and drawing, the specs generally override the plans, at least legally.

Scale Drawings. Nearly all construction drawings are drawn to scale. The large blueprints or “working drawings” used on the job site are typically drawn at a scale of  ¼” per foot. Drawings of the whole house, or small details, may be at a different scale. At a scale of ¼” per foot, a line 1 in. long equals 4 ft., a line 4 in. long equals 16 ft., and so on. A special architectural scale ruler (photo below) makes it very easy to read dimensions on construction drawings – or to create your own scale drawings.

Architectural symbols. Over many years, a set of standard architectural symbols  has developed for construction drawings so that anyone familiar with the building trades can understand their meaning. Different designers and draftsperson  have small variations in their style of drawing, but usually their meaning is clear to anyone familiar with construction drawings. When an designer or tradesman looks at a set of drawings, every little line, arrow, squiggle, and symbol has significance. Together they provide a detailed guide to how the building goes together and what it will look like.


A complete set of house plans usually contains floor plans, elevations, sections and “details” that together form a detailed picture of the entire house. There is often a separate page for each major trade, including a site plan, floor plans, foundation plan, electrical plan, plumbing plan, and framing plan. In general, each drawing is either an elevation, plan, or section view, as described below:

Exterior elevations:These are the sides of the building viewed looking straight at them (see below). These can be a little deceptive, since everything appears as a single, flat plane, with  no clues as to depth. So, for example, a sloped roof viewed from the side looks like a flat vertical rectangle – not what you would actually see in a 3D world. Two walls or objects, offset by 10 ft. appear in the same plane.  Exterior elevations give you a pretty good idea of what the house will look like on each side, but 3D perspective drawings provide a much more realistic view.

construction drawings, blueprints

Exterior elevation from a set of working drawings. Click to enlarge.









Sample architectural floor plan

Small-scale floor plan from a stock plan book. Click to enlarge.

Floor plans:These are views looking straight down at the floor, showing precisely dimensioned rooms, closets, kitchens and baths, and the locations of doors, windows, stairs, and other interior elements (at left).






Insulated wood frame wall

Wall sections cut through the building, showing foundation, framing, and insulation details. Click to enlarge.

Sections: These drawings show what you would see if you cut a slice through the building, revealing the inside of walls, floors, foundations, and other elements. Most common are elevation sections, cut vertically through the walls and floors. Sections are especially useful for carpenters trying to see how the framing and other elements fit together (at left).










Sample of architectural section detail

Section detail of deck attachment to house. Click to enlarge.

Details: These are drawings of specific elements where the designer wants to provide more detailed information than can be seen in the larger drawings of the entire house. A larger scale may be used. Details are often section drawings of the foundation, exterior walls, windows, stairs, framing, or other construction elements. Where section drawings are cut through is usually indicated on the floor plans with an arrow and letter label matching the elevation drawing (at left).





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  1. Deborah Haylett says:

    Plumbing Details in Blueprints?

    Hello. Can you advise on what level of detail full construction plans should have for building regulations. Specifically we would have expected details on drainage — guttering and soil waste pipes to be on the plans. Should they be?

    • buildingadvisor says:

      The level of detail in architectural plan varies, depending on the project and local regulations. All plans include the location of plumbing fixtures, but in general, do not include the location of plumbing lines (supply, drains, and vents). These are usually worked out between the plumber and general contractor to work within the framing plan and comply with local codes.

      If required by local authorities, an architect can provide a mechanical plan showing the location of equipment, ductwork, and plumbing, but this is usually not required for residential projects.

      A good designer takes mechanical issues into account in an effort to reduce plumbing and hvac costs, but this is usually secondary to other design issues such as a good floor plan. In a remodel with tricky mechanical issues, the design might include recommended locations for ductwork, plumbing drops, or other mechanical systems.

      Also, If there is a septic system, the septic plan will typically show the elevation and location of the main building drain.

      Small details like rain gutters may appear on a section drawing, but without much detail unless there is are special drainage conditions that require more detail – such as a drywell or tie-in to storm sewers. More details on issues like gutters may appear in the written specifications.

      In some cases, you won’t know exactly what level of detail is required until you submit the plans for a building permit. During “plan check” the local building department may ask for additional details on some aspects of the plan. They have a lot of discretion and sometimes seem to make up the rules as they go.

  2. Katherine says:

    Should Plan Fit the Site?

    Hi. When drawing up a concept plan, should it be a workable plan that fits on the site? Should the site be inspected for the boundary lines to determine the layout of the building? Thanks

    • buildingadvisor says:

      You should absolutely develop a plan that fits on the site from the outset – taking into account views, sunlight and solar orientation, slope, road frontage, privacy and whatever else is important to you about the site. For example, it’s nice to locate the kitchen with some eastern exposure for morning light and to avoid the overuse of west-facing glass which can overheat a room on summer afternoons.

      You can do a lot of this work yourself if you have a good design sense, but will probably need to bring in a professional designer or architect at some point to turn your ideas into a buildable plan.

      Also be aware of well and septic locations, setbacks, height restrictions and other zoning regulations that might impact your design. On many smaller sites, there is often only one place where you can locate a house. If you design a house without taking all these issues into consideration, you can end up wasting a lot of time and money. If you are not sure about local zoning regulations, visit your local (town, city, county) zoning department and meet with a zoning official. Most likely, they will be happy to meet with you and offer some guidance.

      If you know the approximate location of the boundaries, then that is probably enough to do a conceptual house plan. Often you can find the boundary markers with a little investigation. Otherwise a survey is a good idea. If a recent survey has been done, the records may be available through the town zoning office or county registry of deeds. The town might require you do a survey anyway when you apply for your permits to make sure that your house and septic system are located within the required setbacks.

      Best of luck with your new home!

      See also: Site Planning Basics     Siting a House

  3. Resolving Conflicts in Plans

    Can someone please tell me what should take precedence: a typical section detail or the notes?

    Scenario: Foundation drawing states two different types of reinforcement for the same foundation, one being on the notes and the other being on the typical section detail. One would ‘assume’ that a typical detail is less site specific than the notes… Thanks

    • buildingadvisor says:

      Good question, and a tricky one.

      There is no widely accepted principle for how to solve these contradictions. Many AIA contracts state that the contractor should submit any such conflicts to the project architect for interpretation.

      It’s best if the issue of conflicts in the plans is addressed in the contract’s “general conditions”.

      Some contracts state that one or the other (plans, specifications, written dimensions vs. scale drawings) takes precedence in the event of a conflict. Some contracts state that the document that requires the greater (more expensive) work will prevail. The contractor might be inclined to choose the least expensive interpretation.

      Many contracts do not address this issue so it must be resolved by negotiation or, in the worse cases, litigation. Assuming the project is not yet built, it’s best to have the designer resolve the conflict before proceeding. While your assumption may make a lot of sense, not everyone would agree.

      In my experience, misunderstandings based on assumptions and poor communication are biggest cause of construction disputes. It’s never a good idea make assumptions on a construction project. Always get it in writing and make sure everyone is on the same page before proceeding.

      As the old saying goes, ASSUME stands for “You make an ass out of you and me.”

      • Typical Loads for Foundation Plan

        We have a similar question. On our Foundation Plan, there are some statements about “typical roof” and “typical floor”. Will these be taken as “required” by the city inspector? Or will they take it as a general guideline? Thank you!

        • buildingadvisor says:

          These notes probably refer to the typical roof and floor loads (live load and dead load) that need to be supported by the foundation.

          Standard roof loads and floor loads are specified in the building code depending on the building use and climate (snow loads on roofs). They are calculated by the square footage of floor and roof area.

          Unless there is something unusual in your plans that requires an engineer’s stamp, the city inspector will assume standard loading, which has a large safety factory built in. The loading will determine the foundation details such as wall thickness, footing size, and steel reinforcement required.

          If you’re still unsure, ask the architect, contractor, or whoever supplied the foundation plan that you are using.

  4. donald Allen says:

    How Many Plan Sets Required?

    How many sets of drawings are needed in designing and building a house?

    • buildingadvisor says:

      The number of plan sets required depends on a number of factors. For example, is there a bank involved? An insurance company? Is it a complex plan that needs special approvals, engineering or consulting work, etc.? Also, you may need more plan sets in California than a small town in the Midwest, where life and building permits are simpler.

      That said, eight sets is pretty typical – four for the contractor and subs, two for permitting, one for the mortgage lender, and one for good luck. FYI: I just applied for a “special permit” for a small non-conforming addition in a small town, and the Zoning Board of Appeals required 13 sets of plans (just elevations and floorplans), but since I drew them, I did not have to pay extra for the additional plan sets.

      Best of luck with your new home!

  5. Where To Find Code Information

    I have a question about the understanding of construction drawings. Where should I look for information building codes, and especially about reinforcement?

    • buildingadvisor says:

      Professionally prepared construction drawings should be in compliance with local codes, but it’s no guarantee. Getting a building permit based on the drawings and specs is also not a guarantee of code compliance. Many larger towns and cities have a formal “plan review” process to inspect building plans for code compliance. Periodic inspections during construction also help ensure that the building complies with code. However, at the end of the day, it’s the owner’s legal responsibility that construction be up to code. Some of that responsibility can be contractually shared with with the architect/designer and contractor, depending on the specific contract language and state law.

      As for structural reinforcement — of concrete work, walls, roofs, etc., this should be clearly specified on the plans and it’s the sort of thing that would typically get picked up during plan check. If there’s anything unusual structurally, the building department might required an engineer’s stamp on the plan. If you’re not sure about a structural detail, for example, the size of a major support beam, it’s always a good idea to run it by a local structural engineer. The fee for an hour of the time is worth the peace of mind.



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