sam congrats on your project - we just finished 1/2 of our basement - I did research on soundproofing - and found a host of information - I ended up applying Roxul (brand name) which is a mineral wool used for firestopping & soundproofing btwn the joists - it now comes in batts similiar to the pink stuff Next applied MLV (mass loaded vinyl) 1/8" thick HEAVY stuff and difficult to work with overhead (see pic) THEN used grid system & Acoustical tiles - Not an easy application Depends what you are isolating - ?Foot fall on wood floors above - that is probably the most difficult - I still hear foot fall We did it now for kiddies - isolate the noise - later perhaps a real home theatre layers of sheetrock - of varying thickness is another proven soundproofer - homosote (basically what these ceiling tiles are) is another - Try over on the remodeling forum - you'll find threads there and also on home theatre type acoustical forums It does get confusing & adds $$$ up - any conduit for sound must be properly treated or you will continue w/same prob. I put a wood exterior door from finish/utility side of basement w/a sweep on the bottom walls btwn the 2 sides may need to have some application as well good luck Here is a link that might be useful: audioholics

Hi illinigirl, The standard insulation used under basement floors is rigid insulation (XPS -- extruded polystrene). It comes in 2 inch thick often blue pieces of styrofoam. Dow manufacturers it among others. It is not spray foam. We used it in our build -- we are in southern Canada. The labour to lay the rigid insulation sheets was not high. The guys had to dig away a bit more gravel so the basement ceiling level was not compromised. They used the red tuck tape to attach the sheets to each other. This allowed the concrete flat workers to pour the floor with wheel barrow loads. I am not sure yet what a difference it will make as we are partway through our build. We have hydronic in-floor heat that was just turned on for the basement level. The floor is wonderfully warm (mostly due to the in-floor coils). We were required by code to place the rigid insulation because of our planned in-floor heat. Otherwise, I understand, the heat from the coils would not just heat upwards and instead would have been wasted heating underground? We did place the rigid insulation around the perimeter of our our unheated garage. I will go and step on the parts of the garage floor that have the insulation vs the parts that don't to see if I can detect a big difference and report back. Our architect spec'd for this rigid insulation under the basement slab. At the time, we had not planned for the in-floor heat. In other words, he felt it was a good practice even without in floor. The rigid insulation sheets are not cheap. We paid $25.00 a sheet (each one is 2 feet by 8 feet). We are in Canada where everything seems pricier. You can calculate the area needing coverage and see how much your builder is charging for labour vs material to help you decide if the price is reasonable. Don't forget the tack tape is also not cheap. Best of luck. Carol

Thanks annz, good info. Due to the fact that my workshop is in the basement, I definitely want to go unvented in the basement / crawl IOT prevent the high local humidity from turning my equipment to rust. Without insulation in the ceiling now, humidity levels down there are reasonably controlled by the air movement between the basement and the conditioned first floor. Should I decide to insulate the basement / crawl ceiling however, the issue then becomes how do I control the humidity level down there in an unvented application without having to go through the pain of insulating the basement walls that are covered in mechanicals. Also, in the summer, how do I prevent condensation between the warm air in the basement and the cool floor above it? Finally, there is the issue of comfort while working in the basement which is third in my prioritization of issues because the weather here is just not that extreme. The house will be cooled in the summer by central AC with the air handler in the basement. The house will be heated in the winter by a hydronic system (boiler in the basement with emitter combination of radiant floor and cast iron.) Is there an HVAC strategy that would allow me to do an unvented basement / crawl with rigid foam insulation on as much of the exterior walls as I can reasonably get to. Plus, insulation in the basement / crawl ceiling (plus sealing all penetrations) to keep the first floor warm? The idea would be that in the summer with the AC running, put a return and supply duct down there large enough to remove moist air as well as reduce the temperature differential enough to prevent condensation between the basement and first floor. In the winter, I'd have a cast iron radiator down there to provide some level of comfort on the coldest days, but really don't forsee high humidity levels in Winter. Anyone with thoughts? What am I missing? Best regards, Scott

Sue, I've heard folks tell that it helps to insulate under the floor. But what about insulating down the basement walls to a few feet under grade? That wouldn't take a lot more insulation, and you'd have some more comfortable space in the basement. In summer, I often turn on the furnace fan late in the afternoon when things get rather hot, here north of the southernmost Great Lake (Erie). That blows some rather cool basement air up into the house. We find that in that semi-cool basement in summer the warm air moving down there from outside tends to deposit some moisture and goods made of iron tend to rust. Some papers, etc. tend to mould and there is some on the walls of a finished basement room. Several years ago our local utility added a timer to our water heater that made it run at 2:00 a.m., when there was low demand for power (with an over-ride button that one could push in case of shortage). Plus they added an insulating blanket. When another jurisdiction took over that project, they removed the timers when they made service calls, plus the insulation, when they installed a replacement heater. At least, they were going to, but I told them to leave that blanket right there - which they didn't mind doing. Hope you can make arrangments that keep you and yours as snug as a bug in a rug (or should that be, " ... as snug as bugs in rugs"?). ole joyful P.S. I guess the number of bugs isn't a big deal for you who, like I, live alone. o j