There is no question that you will see a benefit from having the attic sealed with spray foam... the question is it worth the cost? From a study: FSEC-CR-1220-00 http://www.fsec.ucf.edu/en/publications/html/FSEC-CR-1220-00-es/ "Roof and attic thermal performance exert a powerful influence on cooling energy use in Florida homes. Unshaded residential roofs are heated by solar radiation causing high afternoon attic air temperatures. The large influence on cooling is due to increased ceiling heat transfer as well as heat gains to the duct systems which are typically located in the attic space (Figure E-1)." My summary: Sealed attic construction as promoted by spray-foam installers is not as big a benefit in primarily cooling climates as they promote. If you start with black asphalt shingles, switching to white asphalt will save 4% the spray foam sealed attic will save 9%. White metal, however can save 20-23%! So do you need a new roof? The selection there can surpass any savings you would get from a sealed attic. Of course, if your ducts are leaking, having them sealed would be smart as well, no matter which path you take. Andy Here is a link that might be useful: Comparative Evaluation of the Impact of Roofing Systems on Residential Cooling Energy Demand in Florida

love this forum that you can do a little diy advising! ok the mold in the supply boxes and on the grills probably isn't from the duct takeoffs @ the plenum. it takes a long time for mold to travel that far..and if there isn't moisture & food source it won't spread to that area. it isn't always mold..sometimes it is just dust. so mold/dust buildup at the ducts @ plenum is lack of proper air seal. mold in supply boxes & on grills is lack of proper air seal at the cut in the sheetrock ceiling where supply grill is attached to the box. nine times out of ten..you can solve the issue by sealing supply boxes to sheetrock. see attached picture. hardcast brand #1402 mastic tape is used to seal supply box to sheetrock. this tape is 3" wide. I split the 3" into 1 1/2" lengths. stick to sheetrock and fold into supply box. as the tape adheres to many surfaces you need to be careful to keep it within the area covered by the supply grill. once it sticks to the sheetrock..you'll lose paper if you try to move it. surfaces have to be clean & dry for tape to adhere. and once in place you'll want to press it in place as it is somewhat pressure sensitive. the tape is strong enough to keep the box tight to attic floor on the attic side when installing the supply grill. wash the dust off the grills, wipe inside the supply box & into the duct. reinstall the supply grill. oh and when you remove the supply grills..take a sharpie and mark what direction they faced (throw to window..dirveway side whatever note you need to put them back in same position) this way you'll put them back as they were. I've tried several other brands of mastic tape. hardcast 1402 is the best. the others are 2" width and mastic is thinner, resulting in less strength and useful life. why would I chose spray foam for my floors? I've sealed floors several ways, foam is the easiest albeit more costly, once prep work is done. there isn't enough room to physically install foam sheathing to the bottom of the floor joists. I'll seal any big holes..like under tub then do 3" foam. I've looked at froth packs like tiger foam..but having worked with so many foam companies locally, will just have them do my floor when they are in my area. the software is pricy. we lease it yearly. once upon a time we bought the cd..but too many people abused it. so now it is a download & upgrades to original install. a lot of mastic isn't always an indication of a good seal. it doesn't take a lot if you put it in the actual leaks. you can feel around the duct take offs on the plenum while unit is running and feel some of the leakage. also checking plenum connections to the equipment at the same time. I use mastic tape to connect plenums (after screwing them in place) much easier to seal under the plenum to equipment with tape than painting mastic upside down.

If the concrete used for the wall has a low water-cement ratio (highly preferred for strength and crack reduction), almost all of the mix water should be consumed during the hydration process. Any remaining water (normally 2 but 5% if saturated) will be trapped in the tiny capillaries of the concrete. Typically the moisture content of the concrete will be far less than wood (10 to 17%) so it should be possible for wood to be placed against the concrete wall. The larger concern is if the the relative humidity of the air after the forms are stripped is high and the concrete is exposed to rain. Wet curing would be an issue for slabs but it would not be used for walls. The walls should be protected from rain, the base of the footing protected by a vapor retarder and the exterior surface should be waterproofed and insulated before backfilling. The advantage of insulating the interior face of the concrete wall is that it covers the portion of the wall that is above grade. It also seal the wall but that could be accomplished with other less expensive spray applied materials. The musty smell in a new concrete basement is usually due to condensation on the interior face of an uninsulated foundation wall and poor basement ventilation rather than from moisture in the concrete. Spray plastic foam must be covered with a "thermal barrier" which can usually consist of drywall or a sprayed intumescent coating.

hrv for cold climates erv for hot humid climates. it matters what your location is. adding fresh air or make up air is easy. how much to add, is the question. was a blower door test performed on the house? what were the air changes per hour? using the blower door numbers, & volume of the house, ach is calculated. once amount of air required is determined then you make choices of how to do it. La. for instance is hot humid climate. an energy recovery ventilator will cost you approx $1200 installed. but a better choice is a whole house dehumidifier with fresh air intake. for a few hundred more. there are other methods of adding fresh air like barometric dampers etc. some work very well. you'd do best to find out how tight the house is. and go from there. best of luck