As soon as I mentioned a detail I learned here…
the highly rated contractor from Wellman Iowa got defensive. Apparently, he had never heard of a capillary break on the footings before the stem wall. But the conversation became so tense over our first phone conversation, I had to pour a drink afterwards. And then I called a recommended women who I assumed was an engineer that draws blueprints, and she had never heard of it either. She thought I was talking about the expansion joint placed between a slab and wall. I wanted to say, “that’s not the purpose of an expansion joint.” but there’s another bridge burnt.
I’m concerned about burning bridges with the limited number of contractors in my remote Iowa County area, to the point where I won’t be able to complete my project without calling one of you guys’ in. Don’t get me wrong, there are many highly skilled and educated folks on these pages, but what good is the advice when contractors don’t want to deviate from the method they have always done?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
It's your money therefore you are in charge! Contractors work for you,
they are not the final authority!
However, you have to be certain - if you overrule their advice you and
only you will do the suffering if anything goes wrong. This little bit
of philosophy needs to be clearly understood by both parties before
contractual agreement - It very seldom is!
I wish I had a sense of what was important, and what wasn't as this capillary break might not be. Do I really need R60 ceiling? Do I really need liquid applied WRB's? Because all you see in Iowa County is house wraps. House wraps that Risinger says should be illegal.
That's a detail I have also had trouble getting implemented. As long as the interior of the foundation walls are insulated with foil-faced polyiso, or have a membrane vapor retarder, and something at the top of the wall, I'm ok with skipping it. My current spec is: "If schedule allows, provide capillary break between footing and concrete wall." And I list a couple of options.
Residential concrete contractors are rarely at the forefront of building science, in my experience. It can be pretty hard to build a house without them, so compromises are made. A concern they have relayed several times is that they want the joint to be concrete-to-concrete so the wall won't slip on the footing. I tell them that's why I spec a keyway and/or vertical rebar. And a cold joint doesn't provide much lateral strength anyway.
Two days ago I had an excavator quit a job before starting because I wouldn't change my conditioned crawlspace into a conventional, vented crawlspace. The concrete contractor was actually fine with my detail. Though he balked at my rebar schedule, which I had intentionally over-designed so I scaled it back and everyone is happy. (We found another excavator quickly, and after a bad experience, I do go above code-minimum for rebar.)
“…which I had intentionally over-designed so I scaled it back and everyone is happy…”
I learned this from a senior engineer. On some of the component drawings, he would intentionally put in overly stringent tolerances or requirements. During the drawing review with the vendor, these would inevitably draw attention, and the engineer would debate for a bit and then concede. The vendor would take more ownership of the design and manufacture because they felt involved, and my engineer would preserve the key design requirements. He called these overly stringent tolerances “bitch deflectors”. I’ve never forgotten that term.
Haha, that is a great term! To be clear, I don't intentionally over-design; I had drawn what I would like to see but we compromised between there and code minimum. If I were savvier I might do it intentionally, though.
Many/most contractors are reluctant to do things they aren't familiar with because no one wants to be the guinea pig on new stuff. Remember that if something fails, the contractor will get blamed, and they don't want to be in that situation.
The purpose of that capillary break is to limit moisture migration up into the foundation wall from the footing. There are other ways to deal with that problem. You can, in the case of a poured concrete wall, mix in Xypex with the concrete to make the concrete essentially water proof. Aside from the mixing in of the Xypex, everything else is done normally in this case. Another option is to go with Michael's recommendation of an interior side vapor barrier (which can be rigid foam). If you go that route, I would use something more robust than sill seal under the mudsill on top of the foundation wall. I'd probably use a strip of EPDM roofing membrane in this case, which will give you a very long-term robust vapor barrier up where it's most important. I'd be surprised if your contractors have a problem with that simple step.
Bill
Ive never heard of Xypex. I wonder what the best way to approach my concrete contractor would be? Mention the advantage that it can replace the need for exterior water proofing and under slab poly saving him time and labor? Thanks
I sort of feel like, "who am I to tell you how to do your job?" It's essentially like throwing sand in the gears of a smooth running gear box. And I can't, or rather don't want to afford to teach workers how to perform a new technique.
I myself installed typar under the vinyl siding on my town home. But now it sounds like house wraps might be the next synthetic stucco fiasco.
I'm tempted to build old school and live with higher energy bills. liquid applied WRB's are just as expensive as great paints, so why not install clap board over furring strips and paint the house every 10 years? Sorry for the rant, but it's frustrating for someone who has OCD. Information overload.. It was so much easier when I didn't know things.
It's entirely possible for you to learn newer/better techniques than your contractor is familiar with. Learn the why behind what you want to do, then explain things to the contractors. Be professional about it, and know what you're talking about and it should be OK.
Bill
My builder friend Steven Demetrick has what I think is a smart policy. He only builds Passive Houses or very close to Passive House performance. But he doesn't want his subcontractors to do anything they aren't already familiar with, so he designs and arranges things so his crew takes care of anything atypical. His does ask for things like a separate hole for each wire that penetrates the building envelope, but if I recall correctly, he'll even drill the holes if that's an issue at all. In a case like this, if he wanted a capillary break, he would install it himself. I have had at least one owner-builder do just that.
. His does ask for things like a separate hole for each wire that penetrates the building envelope,
whats that do?
It allows you to seal each hole so it's airtight. To achieve Passive House-level airtightness in a smaller home, the total area of air leaks can't exceed roughly the size of a business card. Or maybe it's an index card, I forget. Either way, every little hole adds up. You can't fully air-seal a bundle of wires going through a single hole.
I like to use the example of solid vs stranded wire to explain this point. It's very difficult to properly air seal a bundle of cables, because there are all the small interstitial air spaces between the individual members of the bundle. Stranded wire is larger in diameter than solid wire because of this: solid wire has the same amount of copper as the same gauge stranded wire, but the stranded wire is larger diameter because of the small air spaces between the individual strands that take up additional space.
The only way to really seal a bundle of cables is to use a flowable sealant and make sure it gets between everything, but in practice it's very difficult to actually do that. Seperate cable penetrations for each cable help to ensure reliable air seals on each cable.
Bill
mikeolder,
A capillary break there is still a rare detail and I wouldn’t sweat not using one. As Michael Maines said, it’s beneficial but not essential.
"But now it sounds like house wraps might be the next synthetic stucco fiasco.”
Can you expand on why you think that?
I watched a Matt Risinger youtube vid where he shows sheathing damage caused by water infiltration behind the house wrap, and he went as far as to say he thinks it should be banned. Ive also read siding guys say that after removing 15 tear old vinyl siding, the wrap was falling apart. Guessing the UV rays through the vinyl made the wrap deteriorate? Matt has since transitioned to liquid applied WRB's. But at $2 a square foot and a unproven track record, I question why not just paint the house. I'm planning stained pine board and batten over furring strips, but am unclear what I will use behind, or even if I need anything behind to protect sheathing. The board and batten wouldnt allow UV rays from entering so maybe tyvek might survive. Maybe tar paper would be a better choice and construction adhesive for the sheathing.
Mikeolder,
Matt Risinger often gets things wrong. Apart from showcasing new products, I would be careful relying on his advice for anything important.
Don't use construction adhesive for wall sheathing. It performs poorly with sudden loading like seismic. If you need more shear strength use a more aggressive fastener schedule.
https://www.youtube.com/watch?v=PHEOQaPRnC8
Mike,
I think you've missed some pretty important points - and I take back my criticism of Matt Risinger's advice in this video now you have posted it. As he says:
- The damage stemmed from bad detailing. The lack of roof overhang at a corner, and inadequate sill-flashing at the windows. Neither of which are the fault of the WRB.
- Matt isn't condemning all house-wraps. His comments are specific to woven generic lumberyard ones. I agree with him entirely. No one with any experience would use them. I have no idea why they are allowed to be sold. That has absolutely no relevance to the performance of other well known brands like Tyvek or Typar.
Why not just paint the house instead of using a WRB? Because using a a WRB is mandated by code. It's required because it fulfills a completely different function than the cladding, whether it is painted or not.
I have been involved with hundreds of home renovations and I can't recall a single time where Tyvek or Typar were responsible for causing damage. Damage is usually caused by faulty flashing techniques, particularly where a roof meets a sidewall and at windows, in my experience. It can appear as though the WRB (aka housewrap) is the cause because that's the closest material, but the real cause is that the rate of wetting exceeded the rate of drying.
Are you able to perform any of these tasks yourself? Rolling on fluid-applied WRB can be easy. You don't have to have a heavy-duty spray rig unless you want an excuse to buy a nice one.
Yes, I was thinking that. I'm retired now, but seems like I'm busier than ever trying to rehab the crumby mobile home on the property. I put a roof on it solo down to the rafters, but it was the most challenging thing I've ever done physically and mentally.
I think the challenge is to know which details really matter. That is not an easy judgement call.
For me, on a foundation. The important bits:
-compacted gravel bed under the slab
-poly under slab
-weeping tile beside the footing not on top of it
-exterior waterproofing with drainage mat
Capillary break is a good idea but if you get too much pushback, I would not worry about it. Most production builds don't have a it and survive just fine.
As for the bit about house wraps, that is nonsense. There are 100 year old houses out there with nothing but tar paper and has held up fine. Synthetic stuff is much more durable. The micro perforated stuff can have water issues, so I would stick to better house wrap brands.
More important than WRB type is getting all your flashing details right. That is again one of those that require some judgement on which details are a must.
About the one place you want fluid applied is with some of EIFS systems. Those have their own proprietary details and usually include a fluid applied WRB.
The "housewrap" on my house is a single layer of 145-year-old newspaper under original cedar clapboard siding. (It wasn't meant to be a WRB, just to stop the wind from ripping through the house).
What I've seen during selective demo/remodel work looks good as new, other than some yellowing from age. It helps that my house is currently 17 ACH50 (...I know, I'm working on it), so things tend to dry out very quickly. But the real saving grace has been that the old timers who detailed the thing took the "think like a drop of water" thing to heart and took care to trim everything so water moves down and out - I don't think they used a piece of metal anywhere, just painted wood installed at a slope for "flashing." They nailed the most important details, and anything beyond that hasn't mattered much after a century and a half.
My 1830 house, and the 1820 house I grew up in, have birch bark for a wind barrier! The also carefully bent it over windows so I think it had a bit of WRB function as well.
Regular paper usually degrades over time and falls apart. I'm amazed you have 145 year old newspaper still holding together! I'd probably be distracted trying to read all the interesting stories that are now about historic events :-)
More modern housewrap materials are more reliable over time. Even tar paper often gets brittle and degrades over time. Many have experience dealing with old Kraft faced insulation where the kraft paper facing has become very, very brittle and crumbles almost when you look at it wrong.
Bill