2x4 Floor Support?

Hey Guys, I have done a few thousand inspections and I believe this is the first time I have seen this type of support under a house (see Photo). House was built in 2011 and instead of piers or even 6x6’s on footings it is 2x4 walls between joists and uneven footings. Are any of you familiar with this building type and do you believe it is correctly done?
Thanks for your any input.

That is a bad image.
Do you have another?

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Thanks Roy. Sorry about that, these should be much clearer.

Looks like it was designed that way with PT 2x6 sill and anchor bolts @ 4’ OC.
Piss poor job with the vapor barrier though.

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Agreed Marcel. Thx.

I agree with the master. :smiley:

The better question is why this knee-wall design over other more traditional methods :face_with_monocle:

Nothing wrong with that design… but side note, it looks to me like that PVC drain line either has a negative slope on it, or that long bend san-t is installed in the wrong direction.

2x4 how tall are the 2×4 wall stud in the photo? What part of the country are you in? Earthquake design required?
The bottom plate sitting on concrete must be pressure treated wood, and the vertical studs within 6" of soil must be as well.
Supply piping in unheated spaces requires insulation to prevent freezing, and should be supported at intervals depending on the type of pipe.
Is this a vented crawl space or an enclosed basement?

What kind of foundation? Shallow footings or is it built on piles? Just curious…

The footing or grade beam under this knee wall looks like it was added later. Maybe the joists were found to be under sized and this was required for the span.

Wow, the plumber must have used up all his band iron on this job (Not legal in NY)

are you referring to the steel hanger strap used to hang PVC pipe? can you cite NY code that prohibits its use, thank you.

Very common. A lot better than in my mother’s house.

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I have a crawlspace question since we are in a crawlspace here. I have a rental house, it has a crawlspace and it is insulated between the joists. The insulation is sagging and dropping throughout the crawlspace. Could I line under the joist with Tyvek to hold the insulation up in place with out creating a mold issue, since Tyvek is breathable?

Tyvek will most likely not meet the fire spread requirements if left exposed. I believe there is also a heat/fire warning on the Tyvek coveralls most of us wear (in crawl spaces). I tried to google the data and didn’t have much luck without spending time searching the DuPont .pdf data sheets, however It was talked about here: http://www.inspectionnews.net/home_inspection/building-interior-home-inspection-and-commercial-inspection/21995-exposed-housewap-tyvek-interior-surfaces.html

When we were in the insulation trade we either used twine, wire or what is known as wire insulation anchors, (we called them “lightning rods”) they are lengths of rigid wire that are pointy on the ends and you place them between the joists about every 2 feet. the lengths will very depending on spacing of the joists and also if framing lumber vs. TJI.

Well I was looking at using this duct strap that is roughly 2” wide and I can just staple to the joists but I would have to run about every 16” and it just seems it would take me forever to do just to hold the insulation up cause it is so flimsy. I am not to thrilled about ripping it all out and installing fresh.

Perfectly acceptable method of midspan support. I’m surprised you have not seen this before.


Which one, the strapping? yes used it myself supporting flex duct, but with this insulation being aged and having no stiffness to it anymore running a row every 16“ seeams like a lot of work in the crawlspace. I was considering using Tyvek because it is breathable and covering the underside of the crawlspace floor joists completely. What are your thoughts on using Tyvek to hold up the insulation?

Insulation netting. Or metal insulation hangers …They are easy to install.


Ronald, if that is the source… FYI, you’re looking at code check author’s interpretation of the standards found in third party sources at best. The author has an issue with direct contact of the metal straps, it does not claim they are prohibited. The actual code does not prohibit their use or even mention direct contact issue. In fact, I see them used & approved in NY all the time. Talk to your AHJ before you start calling them out :slight_smile:

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