GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Knowing Some Building Science and Working With a General Contractor

stuartd | Posted in General Questions on

I may be in the same situation as many customers who have had a house built for them, and have enough building science information, and lack of real world experience, to make the customer-builder relationship dicey. I have read the benefits, and techniques for sealing between Zip sheathing and a concrete foundation have been discussed extensively over the years, whether using tape of various manufacturers, or liquid flashing, or both.

My many-decade experienced builder is happy to do whatever I would like, tape, or liquid flash, and further, to use acoustic sealant in addition to the sill sealer, but he suggests it is overkill and a waste of money. I explained that I am not a builder, and my knowledge comes from GBA, and various YouTubers, who explain and show this is the best practices method.

On the other hand, I do not want to cause a problem down road, such that the builder would not take responsibility, since it was the customer (me), who suggested and showed him how to do it.

If you’ve read this far, I’ll also mention he thinks a 5 degree beveled window sill is a waste, but again, he will do it.


GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. kbentley57 | | #1


    You need to be very honest with yourself and the builder here. Either you're able to specify what you want, and get it, or not. The builder will do what you ask, just make it easy on him by saying it up front - "Hey, I know this isn't your normal thing, and I realize it's going to take a little longer and cost a little more. I'm OK with that, and if you're OK with that, and willing to accommodate my requests, we'll get along great!" Otherwise, he'll do it his way, and you wont be happy. It's not confrontational, it's just a business request, and you need to treat it as such.

    1. Danan_S | | #13

      I second this. I was in a similar position, and luckily found a general contractor who always prefers to build high performance if a client will do it. It was hard to find that contractor, though, especially in my market when they have more work than they can handle at this time.

      Customers should be able to ask for the highest performance that makes sense for their climate zone and budget from all the building professionals they employ, from architects to designers to builders, so that things like good moisture control, air sealing, and ventilation become table stakes rather than nice-to-haves. After all, customers' stated preferences are the strongest signal any product or service provider can get, even more than regulations (although those are important, too).

      "Overkill" should be an description reserved for truly extraneous things like pot-filler-faucets, steam showers, and jacuzzis.

  2. Expert Member


    Luckily there is no circumstance where air-sealing the concrete to the sheathing could cause a problem, so you are safe requesting that even if he disagrees - and yes it is one of the most critical junctions to seal if you want a tight house.

    I'm no doubt in the minority on this, but I'm not certain sloping the sills is that important. All the damage I've seen on the sills and lower jambs of windows has been from prolonged, persistent dampness, not water intrusion of a volume that would drain. If the window and opening are properly flashed, that should always be the case - and the solution is a sill-pan. The amount of water that will accumulate on it should dissipate and not require a slope to drain it. If enough water gets down to the pan that it needs draining, something has gone badly wrong, and a bit of a slope won't help much.

    1. AC200 | | #8


      "I'm no doubt in the minority on this, but I'm not certain sloping the sills is that important. "

      I'm going back and forth and this. I agree that if windows are caulked at the flanges on top and sides, taped and then flashing on the top, it would indeed take a major failure for any water to accumulate at the sill. On the other hand it shouldn't be that hard to do with cutting a 5 deg bevel in the cripple studs. Key word being "shouldn't". With the labor shortages and crews, I think it would be very challenging to have this communicated and done by every crew member if they don't normally do it. I mean, I think I will be happy if I can get them to check crowns in the studs and align them.

      I'm tempted to to just ask the framers to do it and not sweat it too much if they miss some or many openings.

      1. creativedestruction | | #10

        It's easier to nail on split cedar undercourse shingles to achieve the slope than to rip the rough sill. Requiring a table saw for rough framing slows things down unnecessarily.

        1. AC200 | | #14

          To clarify, I don't think ripping the sill is a good idea. Framers can cut the cripple studs at 85 or 95 degrees to create the slope. If not, I would use cedar lap siding tacked to the sill before shingles. The shingles create too many joints for the taped sill pan.

  3. jwolfe1 | | #3

    Just seal the zip to concrete yourself?

    1. Expert Member
      MALCOLM TAYLOR | | #6


      Once you have a contract with a builder, you have to be pretty careful about going on site and performing work without discussing it first.

  4. Expert Member
    ARMANDO COBO | | #4

    This is a question that got personal. As a custom designer, who’s been in this business for 37 years, I’ve always felt my primary job is to advise my clients to the best of my abilities. The older, more educated and wiser I’ve gotten, it has allowed me to draw the line (pun intended) on designing high-performing houses exclusively.
    To be effective, I educate my clients. I show PowerPoints, share PDFs of any article about high-performing houses, forward links to webinars, etc. My clients know upfront what is negotiable and what is not. It does makes it easier that if they hire me, they already know what and how I work.
    With that in mind, all my clients are on board with a sealed house (≤1ACH50) and ≤HERS 45, without renewables, and a well-designed and install HVAC system. Open flame fireplaces are a red line, but I recommend not to install gas ranges, and most of the time it works, yet I have a few clients that went from the 48”-72” gas stoves to 36” induction with a two gas burner and the required make-up air. I call that a win.
    I feel that as long as all wants and wishes are discussed and agreed upfront before you sign on the dotted line, any custom designer or builder should make sure your wishes are carried out. After all, I tell all my clients, with 100% certainty I will NOT help them with their house payment, so let’s make sure we agree with the style, products, systems and methods before they hire me.

  5. AC200 | | #5

    There seem to be a couple main parts to your question. What things you should you incorporate above code that you see here and on youtube videos. The second is how to find and work with a builder to discuss and determine what to incorporate that meets your needs as well as having the builder stand behind the work.

    IMO, there is not much that is recommended here in the articles that wouldn't improve your build. The key question you have to answer is do they provide enough benefit for your individual situation that warrants the cost. That will depend on your climate zone, local codes, property values, level of build and your personal preferences and budget. For my own build, I access the cost versus likelihood and consequences of failure and how much the "insurance" costs and is needed. Others have less clear value. For example, mesh rainscreens work, but I can't really see how the incremental benefits justify the relative large cost increase over strapping. Only thing I can offer is ask questions here and make your own judgement based on your circumstances.

    The second part is finding the right builder for you. And again I think this is personal; and not all one size fits all. There are really three models; fixed bid, cost plus percentage and cost plus fixed fee, I won't go through what I think the pros and cons of each are and my thoughts behind each unless someone wants to know. Just as important is chemistry and relationship with the builder. Ability to communicate, openness and a good relationship were very important in my selection process. I told all of them I would be looking to discuss and do things outside of their "standard" before we got very far. Hopefully you had the chance to do that as well.

  6. stuartd | | #7

    I appreciate all your helpful comments, and will continue to forge ahead with 'give and take' from my builder.

  7. dfvellone | | #9

    You said he's happy to do whatever you'd like, and he's just expressing his opinion that you save your money. Sounds like he's open to your wishes and willing to do what you want, so you probably shouldn't worry.
    Listen to your builder and certainly consider his advice, but it's your money and your home that's being built.

  8. russell1313 | | #11

    I will wade in - given I am currently building a home in Mid TN - and I am the general along with the plumbing, elec, and a lot more. In my area, just finding a good framing crew is tough. All the issues you bring up-and more - I end up taking care of myself. True, my build is not the GB poster child, but it will be a pretty good home..... I hesitate to think what a general contractor would charge me to do what I am doing, the building cost today are bad enough as it is, and finding contractors that actually answer the phone, give you a quote, and then show up, hah.
    I'm fortunate I'm competent to do what I am doing - good luck,

  9. huey_ce | | #12


    I skimmed the responses so far but did not see any that addressed a part of your post that jumped out at me:

    "On the other hand, I do not want to cause a problem down road, such that the builder would not take responsibility, since it was the customer (me), who suggested and showed him how to do it."

    From what I remember in my construction law class there are two types of specifications, open and closed.

    An open specification says "I want X or equal" and are often performance based. The contractor is free to chose a solution that meets the performance requirement. If the chosen solution doesn't work, the liability falls on the contractor as the professional that selected and installed the solution.

    A closed specification says "I want X" full stop. The contractor is given no choice, the owner made the choice. If the chose solution doesn't work then the liability is with the owner unless there is something faulty with the contractors work. If you tell the contractor to use "X" tape, and that tape doesn't work well, or has compatibility issues, then you own that mess. However, if the contractor didn't follow the installation instructions and tried to apply the tape to a dirty substrate then they own that mess.

    Rule of thumb, the more you direct your contractor, the more liability transfers from the contractor to you. Your contractor has less responsibility on your build than they would on another build where the only requirements were "I want a house that is this big and meets code, you figure it out."

  10. jberks | | #15

    a bit of real world though, I'll wager you're not going to take your contractor to court. Its a huge cost in time and money with probably no gain. and your contractor sound great, but if they're anything like the contractors I've seen, they'll just dissolve their company, and start a new one.

    It can get tough, when you start asking for different things, and then start calling back for warranty issues, as in the contractor will start balking at what is his responsibility to fix. I generally don't care about warranties anymore becaseu I know they probably won't show up, or if they do, not make good on the problem, as in do the bare minimum and leave more work/cost onto me than before.

    The fact that your contractor is agreeing to work with you on doing better practices or using better materials I think is great. perhaps some of the things that is getting questioned is more from a cost/benefit perspective. For example, the selection of 5/8" plywood with tyvek vs. zip sheathing (where I am in Toronto anyway) has a huge cost disparity, and based on the entire wall assembly might not provide much benefit. Where that money could be spent elsewhere which does provide a greater benefit.

    Basically this contractor probably has lots of experience buying and implementing things and knows the cost of materials. It's up to you to research and do a cost/benefit analysis before you start asking for said things. Or hire a consultant/designer that has their finger on the pulse of that.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |