>>Not sure how you can have adjustable shelves in particle board- (is that a possibility?) Not only do I have 19 yr old particleboard kitchen cabs in perfect shape (Kraftmaid frameless Euro6 line), I've owned painted particleboard bookcases for over 30 years, lugging them around from place to place. And yes, the KM cabs are completely adjustable with pins, no problem. There IS a difference in quality to look for. 3/4" is not as good as 1" (you can see some of the thinner particleboard cubes below show some bowing, although at 19 yrs in the same configuration they have yet to fall apart). And high-density is a lot better than low-density. Here's a photo of a mix of 3/4" and 1" bookcases and cubes. Notice the 2-shelf unit on the bottom LH, of 1" board? One of the oldest ones I have, it has been loaded with those extraordinarily heavy art and coffeetable books for thirty years. If you stacked up all the books that are on one shelf there, it's 30" high and I'll bet no person here would be able to lift them all at once. BTW, ignore the tilt in some of the vertical stacked cubes - we used L-brackets to bolt each individual piece to the wall for earthquake proofing, so it tilted some of the cubes forward as we worked upwards. Also, these are only half of the bookcases; we have 8 full-height teak-veneered particleboard bookcases in other rooms, also heavily loaded, and all over 20 yrs old. I can assure you, having moved these books and bookcases around several intracity relocations, each one of those bookshelves is holding much more weight than is being held on my fully-loaded, 75-lb capacity rollout KM pantry shelves in the kitchen. Lousy quality particleboard will bend under the weight of a few folded sweaters - I can attest to that, I've owned some of it (and had to throw it out). OTOH, lousy quality plywood is just as bad. We also own the "solid wood" Home Depot Masterbath bathroom cabs - what crappy plywood it is! 1/2" ply so flimsy, I was surprised it managed to support the weight of the double sink countertop without crashing to the floor. You'd better believe I'd never stand on the Masterbath cabs - but I have stood on the KM cabs without any problems, and at 230 lbs. I'm not exactly lightweight. The point made about the quality of interior veneers is an excellent one, and far too often overlooked. The interior veneer used by KM in 1989 is far superior to what they use now. I put dishes away wet and even had a six-month slow leak in our sink cab that did no damage outside of a quarter-sized bubble raised in the veneer, no substrate damage. There is an additional cost to using particleboard that should be noted - you should never go over 30" wide without a - I don't know the right woodworking term - front vertical support slat? - to help prevent the shelves from bowing. Plywood can go 36-48" in width, depending upon board thickness and weight capacity desired. Therefore, you should use more, slightly narrow cabs in particleboard, than you can use in plywood. That is the ONLY advantage of plywood, IMHO, coming from someone who has put frameless particleboard boxes through a lot more heavy use than most people ever manage. Being able to use fewer, larger cabs can sometimes save enough $$ to be worth the upgrade cost, for those who prefer plywood anyway. Plywood cabs are lighter and easier to DIY. Installers hate particleboard because it takes 2-3 people to do the install and it's a lot more heavy work. But either material IF of good quality, will be able to last so long you'll get tired of it before you'll see it disintegrate.

Update: The GC tore out all the dry wall in the old part of the house. There was mold already growing so they sprayed the walls with...something, I don't know what. They're also going to replace all the wood flooring that can't be fixed. And as an added bonus we were able to put up insulation in the old part of the house, which had fallen by the wayside with all the other cost overruns. So all in all I think it will be O.K. Thanks for all the great advice, this site/forum is the best!

Thank you for your resoponses. Yes, something appears amis. This roofer got good ratings in Washington Checkbook too! Replacing plywood is something a roofer should be able to do. Its difficult to examine the roof from the inside. Its a Cape Cod style house, and the majority of the wood was replaced on the portion of the roof that has on the inside only a stud cavity and then drywall for the upstairs rooms. There is insulation in the stud cavity and I think it DOES NOT have a vapor barrier, and I think that is why the wood degraded over the years. I may be able to go behind the knee wall upstairs and view from the inside one of the pieces of plywood that is lifting. I do not think this is a moisture issue, because I noticed it within days of the roof being installed. Also, about 12 years ago the roof was replaced (by the previous owner) and some plywood sheets were replaced. Those replaced sheets are still in great shape and are not lifting a bit. --Nate

I have a drywalled porch ceiling. 1968 house. Something happened to cause the fasteners to fail; a roof leak or termite damage are the first things that come to mind, speaking from experience. Have you tried screwing a new drywall screw along the joist? If the joists are badly damaged, it won't hold. Again, speaking from experience with hidden termite damage. I'm not saying your house has termite damage, tho. ETA: I look at your pictures and it looks like a moisture issue as GN Builders said. Try screwing a new drywall screw near one of the nails to see if it will hold.