I’ve never seen a single wall top plate before, but I’ve seen very few if any 2x6 framed walls. The way I read the IRC the top plate should be doubled (no matter what the dimension) unless there is hardware provided. This house had no special hardware.
What are your thoughts? Under what conditions would this be allowed? Any framers out there?
I recall reading somewhere that if they align (studs & floor joists/trusses) its now acceptable. Sorry but I don’t remember the source.
Some info on benefit and not at link below:
http://www.builderonline.com/framing-and-lumber/single-or-double-top-plate-diminishing-returns.aspx
It’ll fly in certain instances:
http://www.sbcmag.info/article/2012/single-top-plate-wood-stud-wall
The 2012 International Residential Code (IRC) allows for the use of a single top plate in a wood stud wall if the design meets specific requirements. IRC Section R602.3.2 outlines the top plate requirements, and then the exception lists the qualifications for using a single top plate. The 2012 IRC Commentary further explains the requirements for a single top plate in Figure R602.3.2 (see Figure R602.3.2).
To summarize, in order to use a single top plate per the IRC’s prescriptive requirements:
• Plate must be tied at the joints, corners and intersecting walls.
• Minimum 3" x 6" x 0.036" galvanized steel plate must be fastened to each wall or segment by six 8d nails.
• Trusses, rafters or joists must be centered over the studs with a tolerance of not more than 1".
The minimum connector and fastener schedule, along with the 1" tolerance, provide the strength needed to transfer loads from member to member when less wood is used in the wall. When trusses are used on a project, the stud spacing can be increased to 24" o.c., which removes more lumber, improves energy efficiency and still allows a continuous load path.
Excellent
http://www.buildingscience.com/documents/published-articles/pa-future-of-framing
Dr. Joe and the BS folks have been talking about this and other wood/energy saving ideas for years
Advanced framing. Post a link on it a couple of years ago.
Well, I guess it was only a few months ago. 
Exactly what I did not see.
Good read thanks!
One more reference source for advanced framing. Reinforces the need for ties at the locations mentioned, joints, corners and intersecting walls.
http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/26449.pdf
I recently inspected a home where the builder used single plates…this method of framing has been around for a long time however certain criteria is required for it to be approved. The main problem you have is the joints not being properly fastened with approved plating and/or the number of fasteners required per plating.
Joe,
Every home I have inspected in Mecklenburg County that utilizes this type of framing the building inspectors have failed to find improper or missing ties/plates. I recently wrote one up where I went back 3 times and every time the building inspector and builder kept missing single wall plates that were not properly joined.
Currently the homeowner is actively engaged in suing the builder over this and many other issues the builder and building officials failed to address. An engineer was called in and he too found the same issues plus improper truss repairs as well as designs.
The other issue that you some times find, which is often outside of the building codes, is the 24 inch spacing often used for single plate framing; depending on the exterior veneer used the panels will often warp which translates to the exterior veneer…especially with stucco…this often is deemed cosmetic however homeowners do not view it the same way…and rightly so.
When such framing is utilized it is best to use a minimum of 5/8 - 3/4 inch sheathing
to prevent same; also blocking is required at all edges of the exterior panels in order to meet the fastening requirements at the edges of the sheathing.
Hope this helps…
Jeff
Using single top pates is generally a money-saving practice and on interior, non-bearing walls, not a big deal. Especially with a conventionally-framed roof, single top plates can be nailed to ceiling joists and they won’t go anywhere.
With truss roofs- interior, non-bearing walls are not supposed to be in direct contact with truss bottom chords, so the top plate corner connections between intersecting walls become more important.
Realistically, it’s hard to imagine any real problem stemming from using one top plate only. I’ve never seen one. But I consider it a red flag that corners are being cut in order to save money and that I should keep my eyes open for other methods that do compromise structural integrity.
Single top plates indicate a carpenter with limited knowledge, limited pride in his work, or a poor economy that forces him to squeeze what he can out of each job.
Still seems cheap and less safe somehow if those trusses manage to slide over and tempt fate for any reason.
Just one more place for it to mess up.
Makes me think of a house of cards.
Wouldn’t want to be the poor stiff hanging the s/rock. The ceiling s/rock will cover 5/8 of an inch leaving less than an inch to catch the nails or screws…
Single top plates and other labour and materials saving techniques were were combined in the 1980’s (or maybe before) to give the OVE (Optimum Value Engineering) framing system. As well as being a money saver, it improved the energy efficiency of dwelling by having more insulation and less low R value wood in the exterior walls. Other techniques were the 2 stud exterior corner, eliminating lintels (headers) over windows/doors in non-load bearing walls, and single studs along side load bearing windows and doors.
For those that are in areas where 2x6"/R20 walls are popular, the average R value of the wall can be as low as 17.2 to 18 due to the amount of framing in the wall. It can be as much as 20% in some walls; all low R value, expensive wood (1.25 R/inch) versus insulation (R 3.5 +). And more wood means more labour!
http://www.buildingscience.com/documents/insights/bsi-030-advanced-framing
http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/26449.pdf
Finally Brian.
You start talking normally again…….HI or Brian…
Happy you are here. No joke.
Please excuse any jocularity. You are truly a good sport.
Energy saving design in the eighties were groundbreaking. Energy the focus but not many builders had the capability of erecting housing properly IMO.
I can see the 2/6" 24 "centers wall stud and there relationship to engineering but Kenton point hits home.
Engineering to the extreme limit as expressed in the thread is improper. We know builders will cut corners.
When you cut corners on this style of structural wood frame building you are asking for trouble.IMO
All the best Brian.
Joe,
I would prefer double wall top plate but this single plate seems to do the trick. As long as there is not a ton of snow on the roof like we can get here in Quebec!
My crib work days go far back Joe. Beer was still cold and the women warm.
Doubled sill plates are all I can remember and still see them using doubled sill plates on homes today.
Marc. It is not so much for dead load as it is for live loading.
yes snow is live loading but in the states and along waterfronts and open fields wind shear is amplified.
One 2/4 does not allow the manufactured hurricane plates or straps enough anchorage if my mind is working right.
like to get together and talk HI you know my number.
HI only please.
Hope you has fun in Ontario.
A single plate will not hold a truss or rafter in place when hurricane winds are loading a wall/eave or when seismic tremors are live loading the structure altogether.
I could be wrong.
I will look it up again.
Just my 2 cents.
Single plate are a call out.
I have called out 2 this year. Its a bear to crawl in an attic to the eave but when you have to, you have to. I must get photos.
PS: Mark and Joe.
The first home last year had the roof re-engineered but the builders used one 2/6" plate and walls had 2/6" with 24 centers.Doubled on loading areas.
The mechanical casement windows on the second floor jammed in the pockets. Once you got the out of the frame pocket they opened and closed with ease until the were returned into the framing pocket.
All the handles where off on all the windows on the second floor. It caught my eye. The main floor windows, all the same by the way worked great.
That sent me into the attic with a hypotheses. Loading and sill plate for one.
Agree with HI! I have a long PDF on Optimum Value Engineering and feel that new homes should be built with minimal waste. One of those wastes is 16 OC. The energy lose is also recognized as there are more points of bridging.
when we discuss waste they why use metal studs. It cost more money to make a steel stud they to plant a tree and harvest it in the same country.
Engineering tall building is shifting to wood. building as tall as 20 to 30 stories. Sorry I lost the material in April.
Wood and 2/6 with 24"OC is fine.
As for Thermal bridging. Materials at certain intersections can address bridging IMO. The same idea as window frames. A composite of mixed materials that block conductivity bridging.
What say you billy Nye the science guy if you are listening.
here is a decision and the top and bottom sill plate.
IRC 602.3.2
It is dependant upon the material used.
A single top plate is allowed under the International Residential Code (IRC), but it is an uncommon
construction practice. Standard practice for exterior and interior wall framing is to use a double top plate to.
The single top plates must be adequately tied at joints, corners, and intersecting walls by at least a*** 3-inch x 6-inch***, 0.036 inch-thick galvanized steel plate that is nailed to each wall or wall segment by six 8d nails on each wall segment. Rafters or joists bearing on a single top plate must be within ***1 inch of center over the studs below. ***
The top plate may be omitted over lintels that are similarly tied to adjacent wall sections with steel plates
I am sorry. I was using 2/4" constriction as my memory served me.
I have never built 24OC and using 2/6" material.
Sorry Joe.
I hope I did not confuse the issue.
Engineering and energy efficiency in buildings is understood.
Thermal bridging in materials is now being understood after decades of information.
That being said Kevin; I still see homes built without adequate insulation in the foundation, walls and attic space. I do not see thermal bridging in framing as being a key concern as of yet.
Once stiffer building practices take effect I can see a new approach to energy efficiency in new homes. But for now You still have a stockpile of older homes on the planet.
JMO.
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