Architects, God bless them. Can you imagine how dull this world would be without them? We would all be still living in primitive mud huts. They are artists with a vision. But sometimes after the design is formulated in the mind of an architect and the process of creating a building plan is set in motion, problems occur.
Being an architect is also a "management" position. They are responsible for not only drawing the plans for their building but seeing that it gets built properly, within budget, to government standards, and usually within a decent time frame. They must coordinate between engineers to make sure that all of the elements of their design are functional, that the plumbing, electrical, HVAC and structural are combined to properly express this vision of their artwork. Unfortunately with todays hustle and bustle and tight design schedules, this management process sometimes breaks down. Conflicts arise between what is desired and what is put down on paper as a building blueprint. Often these conflicts slip through the cracks and make it to the field disguised as a "complete set of plans".
When I first get a set of building plans from an architect there is a ritual I go through. No it doesn't involve incense or candles. It involves a lot of painstaking, detailed and often boring work. My goal? To find the flaws in this work of art and make it perfect. I know, it sounds a little ambitious and even egotistic. But after years of reviewing building plans I know that the perfect set of construction blueprints only exists "after" the building is complete. It is called an "as-built". So my intention is to go through the plans with a critical eye, find as many flaws as possible and try to fix them before they are created in concrete or wood or glass or steel. This is where my value lies, this is how I save money for my customer, this is the true beginning of "The Construction Process"...
First I recommend a complete numerical check. Add up all dimensions and cross check with overall lengths. Once the floor plan reaches "dimensional clarity", all things add up, I go vertical, checking the architectural elevations and resulting dimensions. This is almost a Zen-like experience. "The Quest for Dimensional Clarity". With todays CAD programs the dimensioning on a set of building plans is a lot better than it used to be. But it still is worth while to do the math. A good construction calculator helps. As I plug in a string of dimensions for an overall dimension I put a little red check by each measurement so I know it has been included. If a "bust" occurs I re-check my math until the problem is found. Once the problem is found and it is a "major flaw" I contact the Architect and work out a solution. If the problem is "minor" I generally work it out in the field.
The first comparative phase I go through after the dimensional groundwork is over, or at least over for the time being,is to begin the Architectural to Structural comparison. In basic buildings this can be a simple procedure of dimension analysis, horizontal and vertical. However, in larger more complicated facilities with multiple stories and unique configurations care must be taken by the plan reviewer when comparing the architectural and the structural.
First of all, the foundation is compared to floor plan dimensions. I make sure that structural walls are where they are supposed to be. Make sure that all wall thicknesses are compatible between formats.
Once I am satisfied with the foundation plan I then move to the elevation and cross sectional work. I look for support beams and how they fall into the architectural design. If the ceiling in the architecturals changes elevations in a soffit, does the steel end where it is supposed to? Are the beam bottom elevations compatible to architectural design? Are all support walls accounted for? It is not unusual or uncommon for engineers to overlook some integral design element. Perhaps the architect wasn't sure either and left a cross section out in hopes that the engineer would provide the necessary details. Who knows? The fact is, do not take anything for granted because all is not as it seems.
I end this phase by making sure all of the vertical support for the roof system is in sync with what the architect has designed. Do all of the elevations shown in the architecturals work with the structurals and vice versa? Oftentimes I find that they both are wrong. The architect sees it done one way, the engineer provides the structural detail to back that design up and it is illogical or incorrect. At this point I make a drawing as to how it should be shown and some notes to make my case. My purpose is to make this building, buildable. If something appears to be illogical, chances are pretty good that it is.
Keep in mind the three dimensional picture. Visualize where the structural framework or skeleton fits within the finished building.
Now things start getting a little tricky. You now have to add the brain, heart, lungs and other functions to this skeleton. I usually start with the heating/air conditioning system. It occupies the most concealed space of all the systems.
The HVAC "heating, ventilation, air conditioning" is the lungs of a building. How the building breathes. This network of ducts takes up the bulkier portion of the trade infrastructure in a framework. Be real careful here. Just looking at a duct size shown on a drawing isn't going to cut it. For one thing, most ductwork is insulated somehow. It is either wrapped with or contains insulation. So, for example, if a 20"x20" duct is shown and it is supposed to have 2" of insulation around it, this duct is now 24" x 24"..A big difference when dealing with areas where every inch counts.
How does the ductwork get throughout the building? Most of the time it attaches to the underside of the bar joists or trusses in commercial applications. Sometimes it fits up inside or between joists etc. At this point we need to go back to our structurals and architecturals. Be very conscious of elevation changes. If the building steps from one height to the other, has the mechanical engineer taken that into consideration? These kinds of things go back to the Architect and how well they communicate to the mechanical engineer and how well they cross check the engineers work when it comes back through as a finished drawing.
We check the ceiling height of a given room. Then we refer to the structurals and determine, exactly, what the bottom of our roof or second floor structure is. Now we subtract our ceiling elevation from the "BOJ, bottom of joist" and see if there is room for the ductwork.
Duct that penetrates a "fire wall" has "fire damper" at this location. This fire damper takes up room also. Make sure that any concrete,steel or masonry beams in these walls allow for the added room a damper takes up. These dampers also need to be accessible so either a crawlspace condition has to exist or an access panel built into the ceiling or a grid ceiling with removable panels allows access.
Plenums: Not all "return air" is "ducted". Oftentimes the ceiling cavity or a soffit area is used to convey return air to the HVAC air handler. In a plenum situation you will still need fire dampers at firewalls so even if there is no return ductwork you will need to make sure that the return air can get from point A to point B without obstruction.
I have run into plenum problems when there are conflicting design elements. One such instance is when sound walls or barriers are added between conference rooms etc. Often the architect forgets that the return air still needs to get out of these rooms. If sound is an issue there can be a short run of duct work between rooms "transfer duct" to allow the return air access to the adjoining plenum. Sometimes instead of using the plenum between rooms, the doors are undercut to allow the return air to be sucked out of the room via under the door. This is shown on the plan generally as a U with an arrow and a number like 1" showing that that door needs to be Undercut one inch.
In todays commercial building market with computer servers and wireless networks we face more challenges than ever before making sure the electrical infrastructure is workable. Oftentimes the biggest challenge is in the underground phase. I have seen electrical trenches eight feet wide and six feet deep filled to the brim with conduit. This can be a challenge to accomodate when other trades, especially plumbing come into play.
Electrical engineers can oftentimes be somewhat misleading in their drawings. Not that it is a deliberate act on their part as much as naivete in some instances. For example: When you look at an electrical drawing you might see one dashed line indicating a trunk line going from point A to point B. This line might have a number assigned to it, or several numbers assigned to it.
It is imperitive for the building superintendent to read the legends that correspond with those numbers. That one dashed line very well represents multiple conduits. In some cases five or six four inch, eight three inch, ten two inch..you get my point.
Never take an underground electrical run for granted. Some electrical engineer when drawing these things are merely showing where they want to end up without considering how you really need to get there.
Depending on the plumbing layout of the building you may need to reconsider the routing of the electrical. Or best case scenario the depth of the electrical trench involved. Try to do a cross sectional drawing of all the conduits bundled together to determine the actual space involved. Then determine where your plumbing and electrical will be crossing each other.
If your crossing involves a sewer lateral you need to trace that lateral to its beginning and estimate the fall from that point to the area of conflict. This will determine who goes first, so to speak.
Say your sewer lateral is three hundred feet long at an 1/8" per foot fall. That lateral has dropped in elevation over three feet. If you have a bank of electrical conduit three feet thick then your electrical trench needs to be at least six feet deep to get under the sewer lateral.
The same goes for structural. Look at all footing sizes and elevations in the areas where the electrical crosses. You might need to step a footing down to get the pipe over it. Or you might need to run the pipe before the footing so that the footing can go over the pipe. Big column pads can pose problems when overlooked by the Electrical engineer. Jogging pipe around a large column footing can be fun if not picked up early enough in the layout process. Do not run large banks of pipes under these concentrated loads if at all possible.
When all is good and the pipes are in the ground. Make sure that they are bedded properly in the dirt. This means no large sharp rocks in the backfill. It also means that the air space between conduits needs to be filled. Sand is the best filler for this type of work. I like to see sand washed into the conduit trench. In other words the electrical sub, when backfilling, will dump sand on top of the pipe bank and then using a hose wash the sand over around and between pipes. Let the water percolate out and repeat the process untill you have a nice solid bank of pipe. Then backfill over that in six inch lifts, each lift compacted with a plate compactor. Just compacting your lifts will not fill the voids in large pipe banks. Eventually the soil around these unfilled areas will sift into the gaps between the pipes and create a void under your concrete slab.
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