Advanced Wood Framing 3

[bigmig]

Has anyone heard of Advanced Wood Framing? I was talking to an architect about it and just recently read a publication at

http://www.builditgreen.org/attachments/wysiwyg/3/Advanced-Framing.pdf

Has anyone ran into specific problems with this type of construction such as stud capacity issues etc.?

 

[ztengguy]

To me it looks like a way to build a cheaper house. single studs at rough openings, rim joists transfering point loads, header hangers instead of jack studs.

Seems the brunt it going to be on the engineer. Checking that there are enough nails to transfer point loads, checking every opening for bending, etc.

I will stick with a custom framed house...if it uses 5 or 10% more studs, I will sleep better at night.

 

[XR250]

I am not a big fan of it. Much less redundancy than traditional framing. Single top plates have less horizontal spanning capability (wind blowing on the wall, ceiling joists running parallel to the wall) Also, single top plates have less ability to keep a tree from crashing thru the house. Lot of other details that have to be considered that won't get done in the field. I am not a big fan of 24" O.C. anything anyway. The roof sheathing sags eventually and the floor sheathing feels soft and deflects under the weight of partition walls.
For a big vinyl box tract house that is selling at some price point is one thing, but not on a custom house.
For that matter, I am not a big fan of I-joists and floor trusses either. Seen too many problems with those in the field.
Dimensional lumber and steel beams or properly sized LVL's is all I commonly spec.


I won't design with advanced framing (I wrote an article about it in Fine Homebuilding a few years back)
Think of it this way - the more wood you put in the house, the more carbon you are sequestering :>

 

[a7x1984]

I think it is silly. An engineer can currently design the framing of an averaged-sized conventionally-framed single family home (seismic hazard A) in 8 to 12 hours (drafting included). As zten mentions: checking every nail, etc. means a ton more time for the engineer. There is a reason the IRC and IBC has fastener tables for conventional connections.

On a side note, do custom home mortgages cover design fees? If they do not this would add to upfront costs for the owner.

In Russia building design you!

 

[bigmig]

I did a cost analysis using the above mentioned article for a 2800 sq. foot house and found that Advanced Frame method was something like $28000 more, primarily because a true (or pure) green building is constructed out of engineered lumber, which is 172% of conventional lumber in my area.

After you go through the payback period, it would take 180 years to see your orginal investment returned.

My general impression after visiting a couple architects during a job marketing campaign this week is that they are very, very high on themselves and form and care very little about function or economy. They will easily justify spending $10,000 upfront to save eight dollars a month on a heat bill in the name of "going green" and saving a tree somewhere.

When I walk into their offices, which are very beautiful and well lit, I notice that the handle on the door is custom, unique and totally impractical....(I nearly twist my wrist trying to open it), or the seat and table I'm sitting on puts me too close to the guys face etc. As least it looks cool on their website.

 

[a7x1984]

bigmig: Funny you mention saving a tree. If the lumber comes from the northern hemisphere it is coming from foresting practices that are growing trees much faster than those that are being harvested. That mean's 2 wood studs verses 1 stud is already green enough!

In Russia building design you!

 

[msquared48]

And the lumber structural stress ratings in these faster growing trees are nowhere near the old growth values, or the second, or the third... So. we have to use more lumber to resist the same loads. How is that saving trees?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[XR250]

@bigmig

How is using engineered lumber greener than conventional lumber?
All those glues and manufacturing processes cannot possibly be greener than dimensional lumber.
I can see once you get up into the 2x12 range, it takes a really big tree to make the member, but other than that, i don't see it.

@Mike

Do we have any old growth timber left? So we are pretty much stuck with fast growing, weak and un-stiff members anyway.

 

[TomDOT]

@ ExcelEngineering

There was a project some years ago to start pulling OLD old growth timbers out of the Great Lakes and other North American waterways. These waterways were used for timber transport 100+ years ago. Apparently about 10% of the virgin timber was dense enough/waterlogged enough to sink, and was preserved on lake/riverbottom.

Found a website for you:

http://www.timelesstimber.com/

 

[ztengguy]

I would bet my savings on that you cannot build a advanced framed house cheaper and easier than a regular time tested way. Contractor using ladder clips at corners for drywall...CRACK. Its just not worth the headache. I dont see it being cheaper. Architects dream this shit up to get their name on something.

 

[Archie264]

Whenever you see the word "green" in the construction industry be careful. It's a code word for those trying to cheat the laws of physics for the pursuit of a political agenda. It's one thing for them to design toilets that take six flushes to accomplish their task but it's quite another to design buildings that are structurally inadequate. I don't know if that's the case here, but I'm just throwing that out there as something to be on guard against.

(Please note that the foregoing is not a political commentary but is, rather, a technical comment that's relevant to the posted topic. Yes, it contains a snide jab but it is one that is, unfortunately, relevant to all of us working in our discipline.)

 

[manstrom]

I think the details are created with good intentions, but some are far from practical.

A lot of the green/earthcraft/LEED details seem to some from the world of academia, not the field. Many of the concepts do not work with structure or typical framing concepts.

For example, I have yet to see a practical way to insulate the exterior of an concrete foundation.

 

[bigmig]

@Excelengineering, the way it is explained in the "green journal" is that engineered lumber is composed of mulched saplings.
Here is the excerpt:

Structural engineered wood products are composites made with smaller wood pieces
(veneers, chips, particles, strands, etc) and adhesives. They are generally made with
smaller, younger trees and can utilize small parts that would otherwise be unusable,reducing demand on older trees.

Hence they see engineered lumber as green.

The "green" way, while completely impractical and uneconomical, is a big deal where I live. The guy who introduced me to this concept
is so busy he is hiring architects in a time of economic depression. It reminds me of the Emporer's New Cloths bed time story I read my
4 year old. Everyone building it has no clue why they are doing it, but the Architect claims it is the bees knees.

 

[Ron]

It's a code word for those trying to cheat the laws of physics for the pursuit of a political agenda.

PERFECT! LPS to you.

 

[focuseng]

Don't forget that engineered lumber is stronger and more stable than dimensional lumber. Thus I can do more with less. I can use a 9.5" LVL instead of 2-2x12. The 9.5" lvl came from smaller "waste" trees. Yeah it has "glue" but so does my kids lunch bag and the clothes I wear.

"green" is a marketing term in my experience. There is no such thing as a 5,000 sf "Green" house. It is all relative. It is well intentioned but like anything, once it turns into a market it becomes a game for dealers/manufacturers/etc to grab in an attempt to have/retain market share. I use the methods and materials I use because it 1) can be engineered properly, 2) has builder acceptance, 3)proven to be satisfactory in actual performance. If I can use one shoulder stud that is what I specify. If I need two then that is what I specify rather than the prescriptive code tables. I am an engineer after all -it's what I do. "an engineer is someone who can do with one, what any idiot can do with two". I do not subscribe to cheaping everything out. It has to work and be defensible in all respects. Using only one top plate on walls is not very defensible without a complete engineering analysis of the lateral loading on every component and connection. If something doesn't get installed properly then potentially catastrophic. Remember that Light Frame construction traditional techniques work because there is so much redundancy. When the redundancy is reduced it is now more at risk and requiring everything to be detailed and engineered out. We all know that the prescriptive design standards cannot be 100% duplicated in an engineered design. Yet houses still stand up. We do what we can to ensure this remains true.

and more...
Now if one top plate is removed, how tall is the wall? We just added extra labor and waste to the project because now the wall is a custom height and all the drywall is the wrong modular size from a standard pre-cut stud... this is minor but I can keep going! Structure is just one aspect.

With that said, if you really delve into it conventional wood framing is really not too bad in the spectrum of environmentally friendly structural materials. Of course that depends on who you ask. Trying to squeeze so many bd-ft of sustainably harvested lumber out of a house is a tiny drop in the bucket and cannot compare to other "green" practices such as alternative energy sources and better insulation. The carbon footprint of the lumber compared to the lifespan of energy use on the home is nothing! anyone who says otherwise is selling something. How much carbon was used to manufacture and ship that $5k Stainless steel refrigerator the client wanted? Compare to taking out one top plate?

At the risk of sounding like a curmudgeon, I say "Advanced Wood Framing" in this use of the term is a Gimmick and not worth it. Why stop there? We should all be living in caves or grass huts really...

Sorry. This kinda got me going.

______________
MAP

 

[ClemsonGrad]

Before "green" became a buzzword, advanced framing was for energy savings. My experience was in Washington state. Early on advanced framing was 2 x 4 studs on 24" centers rather than 16" because the continuous wood stud contributed to heat loss. Advanced framing also meant a special corner condition so studs could accommodate more insulation. Advanced framing also meant special split headers with a strip of insulation between them. It didn't add much cost to a building, but the heat loss was greatly reduced.
I used to use a program called Wattsun to do energy calculations for construction document plans submittals.

Another form of framing became the double envelope house which was much more expensive as it was two walls with a thermal barrier between them.


Larry

 

[XR250]

@Focus Eng.
Yes, a 9 1/4" LVL is stronger than (2)2x12, but not stiffer - so it is only useful where strength controls. It is also over three times as expensive per foot than a 2x12 (at least around here). I use dimensional lumber where appropriate and LVL or other engineered lumber where appropriate as well.
FWIW, if an LVL is installed wet, it WILL sag - something traditional lumber will not do.

I agree with most that the energy code and structural engineering are at odds with alot of details.
My current favorite stupid detail is a system DOW is pushing on Architects for metal studs asemblies. Basically, brick veneer over 2" polyiso board installed directly on the metal studs. No exterior gyp sheathing used to properly brace the stud flanges. Also, one less barrier for moisture penetration.
Unfortunately, the building owners will be paying for this down the road.

 

[msquared48]

Excel:

Rergarding your previous question - yes we do, a lot in the older turn-of-the-century structures we deal with all the time 1900 to 1930, and some trees still standing, but protected, like in the Olympic Rainforest of Washington State. Remember the Spotted Owl controversy that shut down the logging industry on the Olympic Peninsula a few years ago - most of that logging was old growth material.

It is around, but protected for the most part.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[amorrison]

There was a "new house" fire in my city a couple of months ago. Seems the firefighters were concerned about the floor joists failing due to the glue heating up and "melting".

Seems "green thinking" fails when faced with "red heat".

Might be interesting to see a picture of a floor joist that has been heated became distorted due to loading and then cooled to become "permanently reshaped".

 

[CANPRO]

I think them reporting a savings of $2400 for a 2000 sq ft home is kind of funny because the increase in labour costs will be at least that much (not to mention if anything goes wrong within the small margin of error they have left - say goodbye to savings). And I question where these estimates come from as well...I get the feeling that they compare the worst case of the traditional framing methods with the best case of the new. Refer to their "Standard Framing vs Advanced Framing Cross Section" figure...I have a decent amount of experience framing residential homes and have been involved in the engineering side for a few years now and I can honestly say I've never seen a corner built like the one in their top left detail. 3 studs nailed together and one perpendicular? I've always built the corners similar to the bottom left, except the 2x4 turned sides for the siding is moved down to fasten the drywall so you don't need a drywall clip and the siding gets nailed on the 1.5" side of the other stud. Same with the T-joint...only time we used "U" shaped builtup 2x4 is with 2 interior walls.

Speaking of interior walls...they say you can go up to 28" c/c with 2x4 studs on the flat?? Holy crap...not in my house. Call me picky but I like to be able to lean on my walls and not feel them move. And what does the top plate look like for a wall all framed with studs on the flat?

Back to the price issue...another thing they fail to report on is the life expentancy of the structure. If both framing methods last 50 years then the upfront savings of $2400 is almost not worth mentioning, but I have the feeling that the traditional framing methods will better stand the test of time and overall be a better investment. Either way...not a huge selling point for them.

They made some good points....like picking dimensions in intervals of 24" to reduce waste. In other areas it seems that they're out to lunch.

This article kind of read like an infomercial to me...the ones where they show a person trying to get along without the product and are apparently useless without it, then they get the product and life is finally worth living.