I have seen trusses for high pitched roofs. Their big problem is transportation because they are so tall. The ones I have seen used were made in two parts to keep them under the maximum height for vehicles. The first part spans the building, and the second part fits on top to create the peak.
My aunts lived in one built around 1880's near Utica, NY and it still survives but a lot of this has to do with normal maintenance. I can't say how many are still around but I would say even a well built one won't be around without normal maintenance. I suppose even back then you had good and bad construction tho I'm no expert on this era of home building.
Oh, I've seen them, but they're rare. Yes, I've seen manufactured houses that basically do the same thing; hinge the peak over to make the maximum height (or hinge both roof sides and lift the center into place).
The building supply company delivers almost anything on a flatbed with a small built-in crane. On my house, and others in the neighborhood, the crane put the on the ground and the three men that did the rest of the framing put those in place as well.
About sixty feet of two-by-four. Since I can carry two ten-footers, I don't see any reason to doubt that three can put one up. On the other hand, I always wondered why they didn't wait and have them delivered after the walls were up. Crane could set them on top and the crew would only have to stand them up.
Tony, I haven't read too much in this thread yet but what do you mean by caps? Do you mean essentially the top and bottom flanges? If so, I agree with you. These flanges are made to take tension and compression while the web is for shear forces.
As the OP, my question was about Trusses, not floor joists, or Web joists. I'd consider trusses, but no way would I use those joists that are particle board with a 2x3 on the top and bottom. I'm not sure what they are called, but I'll avoid them. Particle board is just not real sturdy, and if the toilet overflows, what happens to those things when they get wet.
Web joists are another matter. I have seen them used in commercial buildings. They look sturdy, but in a house, they would consume a lot of space, so a standard 8 foot wall, would end up being 10 feet.
However, this is not part of my original question about roof trusses.
Not only that.The ones I saw completed the roof on the ground including laying the shingles, the vents, furnace chimney and whatever else you see on a roof. No heavy shingles to carry, no dangerous falling off the roof or climbing up and down a ladder. Once completed a crane comes around and lifts the whole finished roof onto the house where they fasten it.
One more observation I missed. Once the roof was on the workers could finish the rest of the house sheltered from rain and snow. I live in Edmonton Alberta.
never seen it done that way, and wouldn't want to on anything more than a small cottage.
2x4 rafters are only 3-1/2" tall. With the code required 1" air gap above the insulation, that only leaves 2-1/2" for insulation. Even the best polyurethane foam board maxes out around R8 per inch, or R20 total in a 2x4 rafter bay.
Most parts of the US require at least R38. One exception is vaulted ceilings with no attic space, which use R30.
You would need at least 2x6 rafters to accomodate R30 insulation using foam, though you might need larger rafters depending on the span.
I used 12" R38 fiberglass batts for the trussed section of our house, and
9-1/2" R30 fiberglass batts (in 2x12 rafters) for the vaulted sections of our house.Anthony Watson Mountain Software
On Friday 04 January 2013 15:11 HerHusband wrote in alt.home.repair:
Only if they are planed. Mine are sawn and as near to 4x2" as you can get.
Are you not allowed to go under the rafters with another layer of PIR? Here it is considered desireable to do so as it reduces cold bridging through the timbers.
Our house is 40'x40', which includes a 6'x24' front porch.
The trussed section of our house is 16 feet wide, allowing for a 15 foot wide space in the living room and master suite (subtracting for the 2x6 walls). There is an interior bearing wall that runs the length of the house to support the inside end of the trusses.
My photos and time lapse video can explain it better:
Most building materials are 4' wide (plywood, sheetrock, etc.).
If you design your building on 4' increments, you will have less cutting to do, and less waste overall. That saves you time and money. You'll also end up with evenly spaced stud bays, which saves time when you install insulation.
Instead of 23'x30' I would go with 24'x28'. That just happens to be the same size as our garage:
We built our house in 2003/2004, with no real prior experience. I designed in lots of bearing support so there were no major point loads. I used 2x10 floor joists (most spans are 12', except for the 15' spans in our living room and master suite).
I used 2x12 rafters for the vaulted ceilings, mostly to accomodate the required insulation.
Not counting our front porch, our house is only 1456 square feet. But the vaulted ceilings, open spaces, and avoidance of hallways makes it feel much larger. We love it!
Anthony Watson Mountain Software
I'm not sure what the original poster means by "caps". I would assume he means the upper and lower flanges on truss joists. These usually have a thick flange at the top and bottom (where most of the stresses are), and a thin plywood web in between. Basically a wood I-beam.
If there are no flanges, he may be looking at LVL's (Laminated Veneer Lumber). These are usually the same thickness as standard dimensional lumber. For example, an LVL joist might be 1-1/2" thick, compared to the
3/4" web on a truss joist.LVL's are common for building beams and headers, but would work great for joists too if the price were right. LVL's are straighter, stronger, and more stable than standard lumber.
Anthony Watson Mountain Software
Which would not be code compliant in North America. Structural lumber MUST be graded and stamped - you can NOT build with self cut or ungraded contract cut lumber, without having it all graded AND engineered.
Engineered PLYWOOD would likely be LVL beams - which can have lglued up cores (think fingerjoint) with basically thin plywood skins, or be oriented grain ply.
You read it right. In aircraft building parlance they are "spar caps" on a spar, and "web caps" on a rib
Asd well as being able to be made from young growth or scrap wood - making them much more efficient use of natural resources.
On 1/4/2013 1:58 PM, snipped-for-privacy@snyder.on.ca wrote: ...
...
Nonsense.
In the _far_ north, maybe, but certainly not at all universal in US.
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Sure is in Canada. - and I'm farther SOUTH than a large portion of Americans.
You need engineering in Florida ... even for a shed.
Not to mention, unless they are just monsterously big, they can be set by hand. They set 11 thirty footers with no machinery right in front of my eyes in less than 30 minutes. Four guys.
The trusses on my addition are 29' and we set them without a crane. (literally 2 men and a boy)
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