12-24-2009, 10:48 AM
yellowlynn Wrote:I was on a mission trip to Jackson, Ohio to build a church. We used 5 1/2 TON of nails. The reason? state codes required 70 nails, repeat, 70 nails at all truss joints with 1/2" plywood gussets. Pound 35 in from one side, turn it over, crimp the nails and put in 35 from the other side. Then turn it over and crimp those nails. It sure splintered the plywood, but the state inspector said those were the best trusses he'd seen (????????) . I think the trusses were about a 40 or 50" span. We had no nail guns, all by hand. Talk about sore arms!!!!
Lynn
Wow! You'd think that with that many nails through it, there'd be little wood left, leaving a weak spot in the truss.
When I built my house, I discovered that the architect who did the blueprint probably had little or no training in engineering, as he had a pair of 2"x10" joists spanning the kitchen ceiling at the point where the upstairs outside wall needed to be located. In addition to supporting that wall, those two joists were to have the upstairs floor joists hung from them (running at right angles), in addition to supporting the load of the upstairs roof. Equally ridiculous was the fact that the joists were to be 24' long!
Surprisingly, the local building department approved the plans. I caught the oversight before construction began and went to the lumberyard that was supplying the materials, mainly to see if their truss department could design a "wall" truss, which I estimated would need to be a full 8' high, that would do the job. Looking at the blueprint, the engineer agreed that it would be feasible, but that it wouldn't need to be so deep. Once I had the ground floor framed, I called them to come down to take measurements for the truss, which they did. I was surprised (as were they, I'd guess) that the required truss would be comprised of three identical trusses, each 8' high and 24' long and built-up from 2"x6"s, shipped as three assembled units, and to be installed separately, then joined together. Set out in the accompanying paperwork were the specs: two rows of 5 1/2" spiral nails, spaced 6" apart, and applied from both sides (staggered), with the ends clinched-over. This was to be done on all members - top and bottom chords and all crossmembers. I managed to get all three trusses in place singlehandedly, but either standing on a ladder or dangling from the truss itself, it was tough work hammering all those nails in place, especially since I'm not particularly comfortable even standing on a chair to change a light bulb.
Gary, I think that part of the reason that screws aren't normally considered for this type of construction is the cost and the installation time. Most home builders aren't especially concerned with quality (despite their ads to the contrary) but they are concerned with getting done as cheaply as possible and on to the next project. Luckily for them, most homeowners know little of proper construction techniques (and many building inspectors can't be bothered to check thoroughly, either), so everything that's built gets bought regardless of whether it's well-built or not.
As for the screws, good-quality ones are still available (you get what you pay for, though). I also discovered that ringed flooring nails will, over time, work loose enough that their heads will protrude - I'm guessing that this is at least partially due to the wood drying out over time, plus the flexing of the floor itself. I discovered this when we replaced some wall-to-wall carpet with hardwood - luckily, I reset all of the displaced nails, then doubled-up on them with flooring screws before the hardwood was installed.
Wayne