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Construction details

Posted by jrldh (My Page) on
Sat, Oct 29, 11 at 19:51

So today I was checking out a new development in Dallas from a mid-range production builder with average prices ~450k for ~2500sf homes with brick facade on 1/6 acre lots.

There were a few construction details that I found a bit disappointing and I was wondering if this is typical for semi-custom new home construction in this price range.

* studs: load bearing walls were 2x6 studs spaced 24". Each stud was made out of what looked like ~2 ft long scrap lumber spliced and glued together. Is it normal that builders use heavily stitched lumber instead of whole pieces?

* shear walls: The outer walls had no plywood whatsoever. Shear was taken care of by styrofoam sheathing. I'm surprised that this is sturdy enough.

* water: All PEX but installed like copper (daisy chained fixtures - not home-run). I thought PEX is usually home run to a manifold because it's cheap and easy to do. The homes that I saw today had PEX that ran in loops connecting each fixture in two long single loops for hot and cold with branches. PEX was Teed off with plastic T's inside walls (eventually hidden). I'm surprised that this is code compliant. My plumbing inspector was very adamant that no fittings must be in the wall...

* DWV: All pipes were cast in the concrete slab without any sleeves. I thought that code requires 2 nominal sizes larger sleeve so that concrete expansion/contraction due to temperature doesn't eventually damage the PVC. I noticed that a lot with local construction?!

Are construction details like that typical?


Follow-Up Postings:

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RE: Construction details

2x6 studs spaced 24"

Shear was taken care of by styrofoam sheathing

This is all quite impressive to me as an illustration of advanced framing which saves energy and lumber. The research on these techniques was developed by a collaboration between HUD and the National Association of Home Builders Research Foundation. Shear loads can be handled with corner bracing or, as I have done on my engineer's advice, with bucking at midpoint. Incidentally, 2x6s are an upgrade that is not typically required by Code, but which provides greater depth for higher R Value insulation.

As for the "stitched together" 2x6s. These are likely Timberstrand LSL, which costs 2-4 times the cost of traditional pine studs while providing absolutely true straight walls. They're usually recommended only in rooms of visual importance, such as high foyers or double height rooms where a wavy wall would be most annoying.

It's a shame that these thoughtful green improvements are looked on as somehow cutting corners.

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When I've seen PEX used here, it is has only been done in the "homerun" configuration. Slabs are virtually unheard of where I build, so I can't comment.


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RE: Construction details

No they are not laminated strand lumber studs like the premium Timberland product. They are finger jointed studs and from a quick "research" (not claiming to be an expert) it looks like it's a way to recycle scrap pieces and market them as "straighter" studs. With the disclaimer not to get them wet because the joint may fail. And they must only be used vertically because the joint would break in a joist application.

I find the advanced framing techniques to be advanced tornado fodder. They look like they'd transform a traditional F1 into an F4.

Not that I have a hat in that game given that my house is a concrete house and has no wood studs at all (not even interior)... Just thought that stick built houses nowadays would be a bit more substantial and was wondering if this is typical of framing in the year 2011.


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RE: Construction details

FJ studs must meet the same standards as sawn lumber with the caveats as mentioned: in compression and with limited water exposure. However, some FJ is indeed approved for horizontal use.

Advanced framing may not be suitable for all wind conditions. But aside from speciality buildings, it is not practicable to build all homes to resist F4-F5 storms which pack sustained winds as high as 261+ mph.

Testing has demonstrated that impact resistance in windstorms is even better with advanced than traditional framing.

An experienced builder in high-wind conditions suggests that advanced framing, combined with some special techniques, can offer superior performance.

As expected, steel reinforced poured concrete homes offer the greatest impact protection in tornado force winds--if you ignore windows.

Here is a link that might be useful: Advanced Framing Information Sheet


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RE: Construction details

I have never seen DWV plumbing in floor slabs sleeved. In poured walls, yes, without fail.
Studs are always vertical members. (I wanted to add, "dear" but resisted the urge!)
I can't tell you without detailed photos whether or not the shear is adequate.
There's that old saying "Fools and children should not see things when half-done".
I didn't make that one up, it became an adage for good reason.
Casey


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RE: Construction details

Thanks, but I didn't ask for "smart" sayings, honey.

You wouldn't know the reason for the sleeve exception in slabs, would you? That would add some useful info but that's probably above your level of knowledge.


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RE: Construction details

I would actually argue (with exception of the pex) the framing method for this house is better than your typical cheap 2x4 walls. There is actually about the same amount of BF of lumber in an OVE framed house as there is in a subpar 2x4 framed house. The builder had increased energy efficiency in mind when doing so. You did not mention, but I assume shear was picked up with either corner sheathing or diagonal bracing, both methods are code acceptable. Foam sheathing is not a shear resistant assembly. While my details for advanced framed walls still include sheathing with the foam (ZIP sheathing to increase air tightness), there is nothing cheap about the construction...just different...and.....better when compared to 2x4 framing (from an energy stand point). I still prefer the sheathing mainly for infiltration reasons, but it does add some slight resistance to wind puncture. Obviously not as good as an ICF home, but in our climate zone, the advanced framed/exterior foam house, sealed properly, will out perform ICF any day of the week. Our parts also have basements, so full ICF rarely sees any payoff.
Advanced framing is sill fairly new to our framers, and exterior foam sheathing is very new as well. However they are all very open to it, and are working very well along side myself and eager to learn "new" methods (there is nothing new about OVE and foam sheathing, however).


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RE: Construction details

Any DWV or supply line though concrete is supposed to be sleeved.

Direction (walls vs floor) does not matter.


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