Drafting Standards for Concrete Pits
Drafting Standards for Concrete Pits
(OP)
I have a peer that swears that all pits, tanks, clarifiers, etc., have and should be dimensioned fully in every view.
I've always gone by the standard drafting rule of dimensioning something once only to avoid mistakes and aid in checking. For example, for a concrete box pit, you would show the out-to-out dimensions and wall thicknesses in plan, but show only the depth and base thickness in section. Similarly, in steel design, the plan members and plan dimensions are only shown on the plans, the column members and heights are shown on the elevations (but plan dimensions are not repeated).
What say you guys?
I've always gone by the standard drafting rule of dimensioning something once only to avoid mistakes and aid in checking. For example, for a concrete box pit, you would show the out-to-out dimensions and wall thicknesses in plan, but show only the depth and base thickness in section. Similarly, in steel design, the plan members and plan dimensions are only shown on the plans, the column members and heights are shown on the elevations (but plan dimensions are not repeated).
What say you guys?
-5^2 = -25 ![]()
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RE: Drafting Standards for Concrete Pits
The way I usually explain this to people is that for a given feature 'X', I want there to be exactly one controlling drawing whenever possible. If I dimension that feature in other drawings that I intend to control other features but not 'X', it is now not clear to the fabricator/contractor/installer/engineer who has to interpret my drawing set in 10 years which drawing should be used to control what.
The other side effect that if a change is made, I only have to correct 1 sheet instead of 2 or 10 or 100.
RE: Drafting Standards for Concrete Pits
I may not say every view must show every dimension, but generally, I agree with your peer.
The minimalist dimensioning practice you refer to as a standard drafting rule hasn't always been so standard. Avoiding dimensions is more a defense mechanism than a drafting rule. As budgets have decreased and finger-pointing has increased, it has come about to aid the design team by preventing conflicting dimensions from showing up in the drawings - understood. And I will admit that when amendments, addendums, etc are issued, fewer sheets need to be re-issued when fewer sheets have a changed dimension - great. However, for the following reasons, I don't let a potential conflict prevent me from showing dimensions:
* We owe the client a set of drawings that can be easily interpreted. The drawings should be useful - they should not be a puzzle to be solved each time they are opened.
* Each time someone looks at an undimensioned view (happens hundreds of times throughout design, redesign, shop drawing production, construction administration) and needs a dimension, they have to find it or worse, derive it --> multiple chances for error. Compute the dimensions in the relative calm of the office, use your cad software to help, and show them. Remember a contractor's error in computing a dimension often becomes the design team's problem as you help bail him out of his predicament. As a team player, you're not likely to be remunerated for your effort.
* Showing dimensions in multiple views helps the reader identify components of the structure among the views; e.g. the interior wall I see in plan is the same wall I see in section. Helps everyone.
* Showing dimensions in multiple views allows for coordination among the disciplines. Helps other design team members, not as familiar with your structural drawings, see at a glance if there may be a size/fit/clearance problem with their equipment, etc.
* Showing dimensions in multiple views aids in quick check of the design. If I see a given span length with given reinforcing steel, I can make a quick judgment regarding the reasonableness of the design. Without the span length, height, or other critical dimension, I can't do spot checks, over-the-shoulder checks. Spot checks, while not a replacement for a formal checking process, have prevented a lot of problems over the years.
* You need the dimensions readily available for easily comparing calculations with drawings during the QC process. A dimension (e.g. wall thickness or span) that is not readily available, may go unchecked, or the component may may go unchecked.
* When your office is QCing the documents, the only way you know if a dimension is missing, is to go on a scouting trip through all the sheets to see if it might be shown somewhere else, or worse, might be derivable from dimensions shown somewhere else. You might as well use this time up front to just show the dimensions.
* Shop drawings are not created from just one view, not just the view on which dimensions are shown. Being able to go view to view without recreating dimensions aids the Contractor's detailer greatly. Don't be a jerk, help the man out.
It's not a drafting sin, nor a bad business decision, to show the same dimension in multiple views. In fact, in the long run, it's a good idea.
RE: Drafting Standards for Concrete Pits
Abundance does not mean superfluous or unnecessary
RE: Drafting Standards for Concrete Pits
* We owe the client a set of drawings that can be easily interpreted. The drawings should be useful - they should not be a puzzle to be solved each time they are opened.
* Each time someone looks at an undimensioned view (happens hundreds of times throughout design, redesign, shop drawing production, construction administration) and needs a dimension, they have to find it or worse, derive it --> multiple chances for error. Compute the dimensions in the relative calm of the office, use your cad software to help, and show them. Remember a contractor's error in computing a dimension often becomes the design team's problem as you help bail him out of his predicament. As a team player, you're not likely to be remunerated for your effort.
* Showing dimensions in multiple views helps the reader identify components of the structure among the views; e.g. the interior wall I see in plan is the same wall I see in section. Helps everyone.
* Showing dimensions in multiple views allows for coordination among the disciplines. Helps other design team members, not as familiar with your structural drawings, see at a glance if there may be a size/fit/clearance problem with their equipment, etc.
* Showing dimensions in multiple views aids in quick check of the design. If I see a given span length with given reinforcing steel, I can make a quick judgment regarding the reasonableness of the design. Without the span length, height, or other critical dimension, I can't do spot checks, over-the-shoulder checks. Spot checks, while not a replacement for a formal checking process, have prevented a lot of problems over the years.
* You need the dimensions readily available for easily comparing calculations with drawings during the QC process. A dimension (e.g. wall thickness or span) that is not readily available, may go unchecked, or the component may may go unchecked.
* When your office is QCing the documents, the only way you know if a dimension is missing, is to go on a scouting trip through all the sheets to see if it might be shown somewhere else, or worse, might be derivable from dimensions shown somewhere else. You might as well use this time up front to just show the dimensions.
* Shop drawings are not created from just one view, not just the view on which dimensions are shown. Being able to go view to view without recreating dimensions aids the Contractor's detailer greatly. Don't be a jerk, help the man out.
It's not a drafting sin, nor a bad business decision, to show the same dimension in multiple views.
In fact, in the long run, it's a good idea.
The motto here should be "fit for purpose." It should be no more or no less than what is required to get the point across. Drawings are strictly a communication tool and a concise, well organized set beats a bloated, over-dimensioned set every day.
-5^2 = -25
http://www.eng-tips.com/supportus.cfm
RE: Drafting Standards for Concrete Pits
Well said.
RE: Drafting Standards for Concrete Pits
RE: Drafting Standards for Concrete Pits
The benefits have been: things are much easier, more efficient, clearer, sets are more concise, and less error-prone when we avoid over-dimensioning. Yes, there's a bit more page-flipping, but if the drawings are assembled correctly, there should not be a question/overlap, and there should be a single point to go to for every dimension/elevation. If the set is poorly detailed, however, that is a different story (i.e.: common sense inclusion of gridlines, property lines, notes such as "see plan" coordinating to a 'real' plan dimension, etc. are critical to help this idea).
RE: Drafting Standards for Concrete Pits
RE: Drafting Standards for Concrete Pits
"It is imperative Cunth doesn't get his hands on those codes."
RE: Drafting Standards for Concrete Pits
-5^2 = -25
http://www.eng-tips.com/supportus.cfm