When a geotech report refers to “below-grade walls” I think it’s talking about foundation walls and basement walls. (Right?)
The report recommends a perimeter drain system “wherever possible to minimize the possibility of hydrostatic loading on below-grade walls.” The architect thinks that only means basement walls. I think it means basement walls and foundation walls.
Do others have opinions?
It’s any vertical surface below grade.
While the architect may only want to waterproof below grade walls with occupied space inside, you still need to relieve hydrostatic pressure. You also need to prevent your foundations from being washed away over time.
Besides, the first law of waterproofing is “If the water isn’t there, it can’t leak.” Get rid of the water. It may be necessary for life, but it can be a real nuisance.
See www.DHMO.org for more information.
A foundation (stem) wall is supported on both sides by the surrounding soil (unless a crawl space is provided), whereas a basement wall is essentially a retaining wall with a soil load on one side only. Therefore, on the soil-retaining side, basement walls are subject to hydrostatic pressure if groundwater is present–thus, a perimeter drain ssytem would be necessary.
It can also mean retaining walls too.
I have specified perimeter drain systems at site (retaining)walls on a number of projects.
I’ve also had to dampproof/waterproof some of these same walls.
I hate geotech reports. Why can’t they all conform to some basic format? Instead, each ome is totally different, making it difficult to determine which portions need to be inseted into the specs.
Why not simply ask the Geotech Engineer as to what was meant?
I believe you will find that the concern has to do with walls that retain soil.
As suggested ask the Geotechnical Engineer who should ultimately be asked to review the relevant specification sections.
Who is writing the earthwork and grading specifications.
Thanks, Bob and Mark!
I’m not doing earthwork and grading specs.
Civil is under a separate contract, and I presume that they are. I know, I shouldn’t assume anything…
I agree with Ron about the definition. However, it is usually up to the structural engineer to interpret the geotech report and advise the architect on how to proceed.
Don’t count on it!
When I was doing specs for the architectural firm, I ended up writing the Earthwork and Grading specs. The structural and civil engineers didn’t want any part of it, but did review them for me. Since the Geotech was usually hired by the client, I would always run my specs by them to confirm that what I had was okay.
Practice varies but is rapidly becoming more consistent that structural and civil will not touch the earthwork or subsurface drainage sections
As for those that do write these sections, consider that the reason structural will not is that they do not consider themselves soils engineers. So in taking on this task, do you consider yourself a soils engineer?
What we do is require that the Owner’s geotechnical consultant edit the sections. We have our own master specification so they are marking it up, make it job specific and making it their own product.
They all initially balk at this as it is not in their fee, they never propose doing this. So, the Owner has to include this into their scope of services.
How adamant are we about this being done by them? 100%. We have had projects issued to the contractor with no earthwork section included. General it is no later than a few addenda down the line - but we are not going to assume the responsibility of becoming soils engineers.
Yeah, I’ve been over and over this with this architect-client, although not this specific project manager at the architecture firm. I don’t think their projects ever get earthwork spec sections. I sure don’t do them.
I now include this under “Assumptions” in my fee/services proposals:
“The Civil Engineer, Structural Engineer, or Landscape Architect will prepare specifications for sitework, earthwork including site preparation for construction of the building, subdrainage (such as perimeter foundation drain), and exterior site improvements, including asphalt paving, concrete paving and sidewalks, chainlink fences and gates, site furnishings, plantings, etc. The Specifications Consultant can send formatted, unedited, sections to these consultants for them to complete in Word format, convert to PDFs, and return for incorporation into the Project Manual. The expectation is that these consultants will stamp and seal these documents, not the Architect.”
But this project was before I started doing that in my proposals.
But its still not the normal scope of work for you. We actually only require them to mark them up, they send back markups and we edit them here. Though I am internal, not an independent, our own proposals to clients does not include anything about that either, never has. But we always require the geotech to do this.
Oh, I’m not writing any civil, earthwork, or subdrainage sections, ever.
I can’t stop thinking about this, even though it was last week that I mentioned to the architect that I noticed that, although the perimeter foundation drains shown on the architectural said “Re: Plumbing,” the drains weren’t shown on the plumbing engineering drawings. The architect told me that he verified with plumbing (!) that they don’t need the perimeter foundation drain. I wrote back “I think the geotechnical report recommends a perimeter drain at the foundation walls. See page 9 of the geotech report. If youre considering eliminating this, you might want to confirm with geotech, and also see whether structural designed those foundation walls based on having a perimeter drain.” and he wrote back “I dont see anything in the report about needing it and all the boring were dry.” and I’m just trying to make sure I’m not crazy, since the geotech report says “It is recommended that perimeter drain system be used wherever possible to minimize the possibility of hydrostatic loading on below-grade walls.”
I don’t think the architect plans to check with geotech. I’m just trying to see what might happen down the road with this one.
document, document, document your correspondence with this architect.
Yeah - I should do some printing. Thanks, Lynn.
The fact that the borings were dry is irrelevant. The water can come from rain and surface runoff.
Liz;
I have a sign in my office: Not responsible for advice not taken. Occasionally, when I am feeling snarky during a discussion I point at it. When I am especially upset I read it as part of the discussion. Perhaps that is why some claim I am not a team player: if someone wants to shoot themselves in the foot (or worse) I see no reason to approve their actions.
As long as you document your advice and the responses you received you should be OK in the long run. Of course if the building has water problems your advice will be forgotten and you could (will?) be pulled into any dispute. Your records will be invaluable then.
Is your relationship with the architect solid enough to justify an email such as: As you are aware, the elimination of the perimeter foundation drainage is contrary to the recommendations of the geotechnical engineers report. Elimination of the perimeter drainage could result in water damage to the building and foundations. I strongly recommend that you review the elimination of the perimeter foundation drainage with the geotechnical engineer.
I wasn’t suggesting that the structural engineer write the earthwork specifications. I agree, that would not be typical. I was suggesting that the structural engineer could determine whether the hydrostatic load on the foundation walls was sufficient that a footing drain was required.
That is somewhat separate issue from whether the presence of this water may create other issues in regards to moisture. Addition of a foundation drain is quite a bit cheaper (especially if it is a question of whether it should be extended to cover areas not initially considered) than remedial work to solve a water intrusion problem.
Yeah, I’ve gotten dragged down into the “is is plumbing or is it civil” before, too. Got pushed into calling it plumbing on at least one project because the plumbing inspector “claimed” it because it was withing ten feet of the building. I think he was wrong.
Clearly, as you all realize, lots of discussion with all parties is needed to avoid problems. It still amazes me that there are architects out there who don’t seem to have a very comprehensive view of the design process. Not that they should do it one way or another, but they need to steer clear of the shoals by being sure everyone is clear. Often they don’t.
I’ve heard that “10 foot rule” before. It’s a plumbing “thing” if it’s within 10 feet (or sometimes 5 feet) and it’s a civil “thing” when it’s beyond that perimeter.
It’s a matter of agreeing on something and whoever is in charge making sure that all is covered by someone. Seems rather simple to me - planning and scheduling, delegating responsibility. Abdicating that responsibility will lead to problems somewhere out there…
The five foot rule: Pipes are ten feet long. The last length of building sewer pipe ends up outside the building, so five feet is a convention (half the length in, half the length out) for where the interface between inside and outside occurs. I don’t think anyone ever puts a tape measure on it to make sure it is exactly 60 inches.
Just a guess. A plumber told me that on a muddy jobsite once years ago - I’ve never verified that is the real origin, but it makes sense, doesn’t it?