All About Larsen Trusses

A detailed history of John Larsen's system for building thick superinsulated walls



Larsen trusses are non-structural
These lightweight trusses are tacked onto the sheathing after a house is framed and sheathed. In most cases, conventional 2x4 studs hold up the roof load, and the 2x4s are sheathed with plywood or OSB. The Larsen trusses get installed late in the construction schedule, after the roof is on.

A Larsen truss is a type of wall truss used to build a thick wall — thick enough to provide room for above-average amounts of insulation. It was developed in 1981 by John Larsen, a builder in Edmonton, Alberta.

In honor of the 30th anniversary of the Larsen truss, the time has come for a definitive article on the invention. This report includes an interview with the inventor of the Larsen truss, a history of its use, and a discussion of its advantages and disadvantages.

Defining a Larsen truss
A Larsen truss is usually site-built. Because the truss is not required to bear any roof load, its components are light. The original Larsen truss consisted of two parallel 2x2s connected by small rectangular gussets of 3/8-inch-thick plywood. The gussets measured 6½" x 8¼" each and were spaced 24 inches apart. A completed Larsen truss looked like a ladder with rectangular plywood rungs.

Although early Larsen trusses were 8¼ inches deep, they can be built to a variety of depths. Many builders have made 12-inch-deep Larsen trusses.

Larsen trusses are designed to be attached to the exterior surface of the wall sheathing of a new home. In most cases, these homes were framed with conventional 2×4 or 2×6 studs. Larsen trusses can also be used in retrofit work, in which case they are installed on top of the existing siding.

Many builders confuse Larsen trusses with wall trusses. If a truss is designed to bear the roof load, it is not a Larsen truss; it's a wall truss. For example, some builders create double-stud walls with the inner studs bearing the roof load. They may connect the two rows of studs with gussets in order to allow the outer studs to cantilever off the foundation. Such trusses are properly called wall trusses, not Larsen trusses.

I've worked on a few su

Quote from: K-Dog on Sep 09, 2023, 08:58 PMAll About Larsen Trusses

A detailed history of John Larsen's system for building thick superinsulated walls



Larsen trusses are non-structural
These lightweight trusses are tacked onto the sheathing after a house is framed and sheathed. In most cases, conventional 2x4 studs hold up the roof load, and the 2x4s are sheathed with plywood or OSB. The Larsen trusses get installed late in the construction schedule, after the roof is on.

A Larsen truss is a type of wall truss used to build a thick wall — thick enough to provide room for above-average amounts of insulation. It was developed in 1981 by John Larsen, a builder in Edmonton, Alberta.

In honor of the 30th anniversary of the Larsen truss, the time has come for a definitive article on the invention. This report includes an interview with the inventor of the Larsen truss, a history of its use, and a discussion of its advantages and disadvantages.

Defining a Larsen truss
A Larsen truss is usually site-built. Because the truss is not required to bear any roof load, its components are light. The original Larsen truss consisted of two parallel 2x2s connected by small rectangular gussets of 3/8-inch-thick plywood. The gussets measured 6½" x 8¼" each and were spaced 24 inches apart. A completed Larsen truss looked like a ladder with rectangular plywood rungs.

Although early Larsen trusses were 8¼ inches deep, they can be built to a variety of depths. Many builders have made 12-inch-deep Larsen trusses.

Larsen trusses are designed to be attached to the exterior surface of the wall sheathing of a new home. In most cases, these homes were framed with conventional 2×4 or 2×6 studs. Larsen trusses can also be used in retrofit work, in which case they are installed on top of the existing siding.

Many builders confuse Larsen trusses with wall trusses. If a truss is designed to bear the roof load, it is not a Larsen truss; it's a wall truss. For example, some builders create double-stud walls with the inner studs bearing the roof load. They may connect the two rows of studs with gussets in order to allow the outer studs to cantilever off the foundation. Such trusses are properly called wall trusses, not Larsen trusses.

I've worked on a few super insulated shells and done at time of construction they are great. My only issue with the system shown above is as a retrofit to the outside it grows square footage and forces you to refinish the outside; the most expensive part. I've been a part of two reframing from the inside projects. The outside finishes stayed intact we gutted the inside. Cellulose in a hollow core for one then a new frame and spray foam. The second was stripped of drywall, reinsulated and a steel stud wall installed one inch off the existing and insulated. Both turned out pretty good. I was a part of it not in charge so could not say how they have worked out.

Quote from: 18hammers on Sep 09, 2023, 08:28 PMActually a method of doubling a existing homes insulation exists, it is called a Larsen Truss. Can be built into new construction or because it is non load bearing added to older homes. I speak of it because I have it. My home has 1 foot thick walls, I can't remember now as it was over 30 years ago but somewhere around R32-R36 insulation. I also insulated all interior walls to R12 both upstairs and down.

sounds like a great space

Quote from: 18hammers on Nov 25, 2023, 08:38 PMDiesel fuel is something like 1.50 a liter  but back in 2020 when everything shut down due to covid the price at that time dropped to 75 cents a liter, I put away 6 barrels of the stuff so I am drawing down my reserve a bit.

Back in the old days, and in many places of the L48, wood stoves seem to be a quite nice alternative to burning liquid fuels. Grew up with them, used them later in life, heating substantially more than just 200 sq. feet, is wood burning not allowed in your area or something?

Great little device to take the work out of splitting wood for yoour Doomstead heating needs.



https://shoes.libiyi.com/me/new/Libiyi/wood-splitter-drill-bit/view4079?cep=f14kR1-dUF9CZmxvLLN7KEIYHlBnxPeYDJauhxyVVkO794eV3u7uj_Vh_U90UqRdhMZ76NTGuJ2qvnR5h_LY3wTZv2S01Q_wgpQwnuW_b7DHJ_C-Dr1BH1_K7yOEvfMAmiMOA71nX3Gf8Y-roDdH20KrWbAbZhNtI0tMOWME5_Fbj32wKvqsAK10rFXA-4GEF4Xrh8RBuNU2wDeqbOEERwryxS532_PipX6VEueXZjOE4WMBmHd_rFPXQVHoc3cJn73rgP2idJesLA8eLBWbnX93tvHeTqxJWN0RwJ7Z9pG9Di3QQWtW3vRp8leq3ZlNdyiNtLAkrpdZrzs1-tqiDL8GLbbTsGToWayljNOUKr4zRCMlysXTHEFq7nN4OA-Lu6W6fcXfCIu5BedBJMJgSNCGpsQQMcLpSyaK28YWGu7UgjICC_7aWYHzg4tGQjlW_LG4x3QyWcdCF0ASQRHFrsHh1OVFyBiwtGcFOvMQI-hVEmT4MExHuslCMsCclYaGUAWvlT3aYOG9VH0uV3g64e-xx8-QFXf3Q7PUTjahbtb3bQGSx1Gca8AGf9IcX2KBQhZ-xRVj55BtnDwqUbucFVgzmGUbnQAsVpAEqHEH48VwPnDajPDWyNh5KMHYJeQTGE3QRsO_tvBzUi5o5sUFP1R9F8wur-o-oy-qESEylad6h4p1IZuKzUhvW-cu8ubHq7RmhoBLHkapVsC6IIbLv-731u9YA4S16GG5qKJPMtdR0wk8k4n9XRTis1I-jL1ecxII2QBpbGC14Y_PFMMvGyLCJy4C1OvojQGFNw14VgfmgGTlRPrm1egbSUJMiupOQ9H7SDZDfd8_8YToy4aLvL6aAlbvNNi5nH0HwDF3fpOVLqGeWCn825YRdhhl7SC_T1ub20LZRas7pcMFDwsPMA&lptoken=1704047506f28062149b&site=gannettcompany-timesrecordnews&site_id=1053404&title=Why+Your+Firewood+Needs+This+Drill+Bit%3F&platform=Desktop&campaign_id=26737863&campaign_item_id=3721005704&thumbnail=http%3A%2F%2Fcdn.taboola.com%2Flibtrc%2Fstatic%2Fthumbnails%2Fc9d76da2a723481337c09d2a2f5c22b0.jpg&campaign_name=PG00294_PC_20230810_AB&utm_campaign=PG00294_PC_20230810_AB&utm_medium=1053404&utm_medium=referral&click_id=GiDqGyIh-JRg5qvFaOg6YzDzvd4pmRIEm3RrhHmgFw2dWiCOrFwolvvs2qTlypwH&utm_source=taboola&tblci=GiDqGyIh-JRg5qvFaOg6YzDzvd4pmRIEm3RrhHmgFw2dWiCOrFwolvvs2qTlypwH#tblciGiDqGyIh-JRg5qvFaOg6YzDzvd4pmRIEm3RrhHmgFw2dWiCOrFwolvvs2qTlypwH

RE

Quote from: 18hammers on Dec 31, 2023, 06:58 PMJust returned from a trip, Edmontonish area up to lloydminister, into Saskatchewan and back today. No snow, brown grass everywhere. Stepped outside to let the dogs in and it is now raining outside. Crazy, just crazy. It looks like things are the same down south  http://www.smirkingchimp.com/thread/rivera-sun/108895/the-winter-without-snow-a-wake-up-call

How do the mountains look this time of year? Always thought Edmonton was an okay town, but flat, and Lloydminister the same and more rurally. I've seen the most beautiful northern lights there on a cold evening in January once, heading west out of Saskatchewan towards the real gems.Given a choice its the Rockys from the US border until it hits Fairbanks...and then you skip up to the Brooks Range and the beauty continues.

Quote from: 18hammers on Jan 01, 2024, 03:53 PMMountains are to far west for me to see. You might think Edmonton is flat but you don't know flat until you have driven across Saskatchewan.

From Weyburn to Saskatoon to Llyodminster headed to Edmonton. Lived there for a year. Ran off to the mountains every chance I got. Fort Nelson and from there on to Alaska a couple times.

Saskatchewan doesn't have all that much on Cheyenne to Chicago, except Canadians are nicer folks along the way. Golf courses, Chinese restaurants and Dairy Queens still a thing in every small town out that way?

QuoteAll in all this is the mildest winter I can remember.

Atmospheric CO2:

December 2023     421.86 ppm
December 2022     418.99 ppm

Annual change:  +0.68%

The mildest winter you can remember.  Do you have any idea of why that might be?

Quote from: K-Dog on Jan 25, 2024, 09:48 AMThe mildest winter you can remember.  Do you have any idea of why that might be?