brickeyee Your point about RH of winter air seems well taken. What was missing from the Carson Dunlop explanation, I think, is that attic air in a home is often more humid than air outside the attic due to leakage from the conditioned to unconditioned space. Here's how another P.E. describes truss uplift: "A problem that can occur with this system causes cracks in wallboard over time. In recent years, attic insulation usage has increased, which ends up covering the bottom chord of the truss. This tends to keep the bottom chords warm and dry while the top chords absorb moisture and expand. The top cord expansion causes the top chords to lift, pulling up the bottom chord as shown in Figure 1, hence the term truss uplift. " Charles C. Roberts, Jr., Ph. D., P.E. My untrained guess would be that the lengthwise shrinkage of grain does not relate to the length of the wood but to which portion of the tree the wood was cut from. Here's a longer explanation: "Truss uplift is caused by wood's natural response to moisture exposure. This response occurs when humidity changes differentially in two areas (an attic floor and attic ceiling, for example). A truss's top chords expand as their moisture content increases. Problems resulting from truss uplift are most common with flat-bottomed trusses in homes during winter when a truss's bottom chords, often covered by insulation, are kept warm and dry while its top chords are exposed to moisture from condensation. During winter months, warm, humid air emanates from buildings' interior use and occupants. The uplift movement occurs because, as the truss's upper components resize themselves under the differential moisture conditions, internal tensile stress occurs in the truss's web members, which then pulls up the bottom chords (and the attached ceiling drywall), resulting in a separation along the wall-to-ceiling juncture of the drywall. To put this into perspective, consider a truss with top chords made of two members, each measuring 30 feet in length. The total movement anticipated from winter swelling caused by the truss's moisture content increasing is a 0.72-inch expansion per side, or a 1-inch total rise of ridge above the bottom chords. And once a crack forms inside a home, additional moisture generated by occupants and their activities can escape into the attic, travel to the cold attic ceiling surface, condense on the truss's top chords and cause further truss uplift. " Lucas J. Hamilton manager of building science applications, CertainTeed Corp.'s Insulation Group For interest, I will forward this thread with a request for comments to Carson Dunlop. lzerarc As I said, different places, different practices. I've changed only reluctantly. Seeing those spindly stuck-together 2x2s gives me a visceral reaction and I have to rationalize using roof trusses. However, my engineer says they're much better done now than ever and with wall lengths less than 50 feet uplift is rare. None of this applies to warm climate homes.

I don't really buy any of the excuses that the framer is trying to sell you on. Trusses are transported on special trailers. Most truss builders use machine graded lumber rather than visual graded. A crane with a experienced operator and a knowledgeable crew on the ground can have the roof on in a day, two max while the framer will more than likely take a week or better (depending on weather) to stick build. Will the walls be 2x4 on 16" centers or 2x6 on 16" or 24" centers? If the walls are on 16" centers I would have it stick built with the rafters lined up with the studs. If 24", then I would go trusses and have them lined up with the studs. Keeping them lined up will provide better structural integrity.

OP here. My roof is in great shape so I won't be replacing it any time soon plus it has some interesting curves to it so adding rigid foam and sleepers over the roof deck might be more trouble than its worth. See pic: I do have the gable vents and the giant vent over the porch so I think ventilation in the front part of the attic (the shorter knee wall in the original picture) is ok. I think what I've decided to do is to add soffit vents on the back of the house (where there are no intake vents). Then I'll install a foil radiant barrier on the bottom of the roof deck in all of the accessible attic areas. I will pull down the wood paneling stuff, add rigid foam between the studs in the knee wall as well as the roof rafters, and install sheetrock over it all. Its all 2x6 so I should be able to get 4 inches of foam (R20 or so) in there while still leaving a 2 inch gap for air flow under the roof. I found a guy on craigslist selling 4 inch closed cell foam at 75c per sqft. I've also thought about being cheap and just using fiberglass batts (r16) with baffles on the roof deck instead of foam. That would cost r4 but save quite a bit of money. So long as I make sure I've got a good air seal with the sheetrock and plenty of ventilation, after that, its all down to r value right? I've also essentially given up on the thought of spray foam on the roof deck. That would cost in the neighborhood of 5k plus the cost of ripping off and reinstalling the sheetrock.

Kristin, foundation design for a ranch house is not different from a foundation for a 2 story house. If additional support required for an existing beam, i.e shorten the span, etc you talking about adding additional support to break up a beam span, which is not a big deal. Also, keep in mind the older homes foundations carried allot more weight in the old days in comparison to modern construction. You had plaster walls, you had exterior wall cavities filled with brick, you had a slate roof's, cast iron tubs, etc. So foundation shouldn't be an issue. Speaking of foundation, I was vacationing in Spain and we visited Sagrada Família built by a famous Architect Antoni Gaudi, lots of it was still under construction (I was there 4 years ago) the construction started in 1882, so I was walking around the old part of the Church and I checked out the new part of the Church and being a builder first thing you look at structural components and the old foundation didn't have a single crack in it in comparison to the new foundation and columns on top of it which already had noticeable cracks in it. So don't think that if this is an old house the foundation cannot carry another story, 100's of additions going up on top of existing homes and 98% of the time foundation is never an issue. P.S As Architects go I don't know what you mean by "architect pricing is in line with our market" if you mean if houses sell the Architectural fee goes up, everyone is trying to do that around here also, I can get an Architect to do the plan for a $1 PSF and get one who will charge $10 SF for the same plan... Nothing new in that, as a matter a fact I was looking at the plans for an addition where people spent a bundle, and not only the addition was over-designed the layout made no sense. I re-drew the layout and they got another Architect to sign off on all the changes, not only they saved on construction, they end up with a much better layout. In many cases, guys who charge $1 per SF will come up with a better design and will draw the plan with a Homeowner in mind, of course, if it's a complicated structure involving engineering, huge spans, etc the cost will go up. But when you dealing with a simple addition going over existing walls, etc you shouldn't be faced with huge costs and anyone in business know that... Just look in here, how many screw-up plan layouts we see on Houzz every day and people pay a good penny for some of them and still look for someone else to make the changes.