Gutting my entire finished basement (done about 35 years ago). Any advice would be helpful: In the main supply feed from the furnace/air unit, they cut square cut out in the main duct to supply heat/air into the basement. On the square cut out, they attached a adjustable louver type grill vent. I have read this is not a good idea? There is no returns in the basement either. Is is OK to tap off the main line like this? Also, any suggestions on how to install soffits around the ducts? Are small metal framing studs OK, or is wood better? The soffits I pulled off was 1x3" pine that had sheetrock attached to them, but the nails actually went through the wood and into the duct. Is this OK? I pulled them off anyways instead of reusing the existing soffits. Do I need to insulate the ducts, or leave bare? Do all the holes from the nails need to be plugged? What would you recommend, caulk or liquid nails, they are small sheetrock nail holes.

Boy can I relate to the 60's wood paneling. I'm in the same boat right now. For heat, how about electric baseboard heaters? They are inexpensive and easy to install. Once you have the right insulation installed, it won't take much to keep the space comfortable. The plus side of the separate zone of electric is that you only need to use it when you are down there, and being warm in the basement won't be a function of the upstairs calling for heat. For a basement, the cooling load is likely to be so small as to make the installation of cooling ducts unnecessary, unless you have large windows that get lots of sun. As far as a return for dehumidification purposes, is the basement space going to be continually open to the condition space above, or will there be a door to close it off? If you tap into the forced air system, the supply registers for the heat should be located low on the wall down near the floor. The returns should also be near the floor, preferably on the opposite wall. You want them situated like this so that there is a good circulation of air, something that is essential to proper function in a forced air system.

Mike, from the way the OP wrote, I assumed that the oversize issue is when a single zone calls for heat. OP, when you write radiant in floor, you mean pure resistance electrical heat? Will an insulation layer go under the flooring? How much head space do you have and how much will you loose? I have experience with finished basement in more Northern climes than Virginia. There was carpet on the slabs. Heated with hydronic convectors or forced air, the floors were always cold in winter. You wanted to have your feet up when sitting down. Radiant in the floor will be most comfortable, but won't be as responsive. It will be darned unresponsive depending on how it is installed. There may be lot of mass to heat up before air gets significantly warmer. I also have mini splits. In my home in the Gulf South. Run as programmed out of the box, the high wall units make very good ceiling heaters. As they throttle back approaching the set temperature, the blower slows down and hot air stratifies at the ceiling. You can combat this by manually keeping the blower fast or with ceiling paddle fans. Note that I have very cold floors in the raised house. A good mini split may greatly reduce dehumidifier use when cooling is desired, but there will likely be times when humidity will be high enough to support mold growth in shoulder seasons. If you have a mini-split, you might decide that a portable dehumidifier is tolerable. Portable dehumidifiers make a lot of noise, a lot of heat, and are energy hogs. You also have to empty them or rig up a condensate pump if no drain is where you need it. I have seen a portable dehumidifier make a basement uncomfortably warm in central New York Summers. They might work well enough for you in a basement laundry area. They can be placed remotely with added circulation with ducting. (See the link below.) I you feel that it will be cost effective, a ducted dehumidifier like a Santa Fe will work better. The Dept of Energy (Energy Star) rates dehumidifiers. IIRC, the portables are all about the same, but there is a big difference between them and the ducted models. Conditioning Air in the Humid South—Creating Comfort and Controlling Cost Research Report - 0214 November-2002 Building Science Corporation

Please, be very careful about the insulation and vapor barrier placement and type. If you don't get it right, you will have a mold farm. I don' t know the situation details, but this could be very easy to mess up. The most important part of the basement to insulate is between the soil line and the floor of the ground level, the rim joist, and environs. I wish I could be enthusiastic about about the Dryloc paint. If you have water outside the foundation, the only good fix is to lower the water level via better drainage. This usually involves a lot of digging. If it is a soil moisture (vapor) problem OK, but get the vapor barrier/insulation right. Given the oil-powered baseboard, I'll assume that you are in the Northeast. My experience with finished basements in the NE is that when a dehumidifier is running in the summer, you have enough waste heat so that you need little cooling, but two tons, that should be OK for 5000 square feet or more. Oh wait, you have 1000. Keep the humidity below 50%. An efficient dehumidifier would probably be a good investment, but I don't know about the return on investment. As Mike suggested, you can stick a portable unit into a purpose-built plenum located in an unfinished area and run ducts using a small blower and external thermostat for a pretty effective system (see below). I am assuming that the whole basement is half again bigger or twice the size of your 1000 sq ft finished area. If that is the case and you empty even a largish portable dehumidifier 2 or 3 times a week, that is not a lot compared to some other situations. I've seen 70 pint units fill up daily or in part of a day. Add the pump for when you are out of town and it will be so quiet that you will forget it is there. Don't (fully) add cooling until you prove that you need it. It if has been cool while running the dehumidifier and the humidity is an an acceptable level, have a plan and and leave an option in place for cooling now, but you don' need to fully execute it yet if it is going to cost a lot in equipment. There are too many unknown (to us and to you) variables in your plan right now that are going to affect your heat and cooling loads. Insulation will be a two-edged sword. Soil temp is probably in the 50s staring a few inches below the surface. Add insulation and you need heat less in the winter, sure, but you lose a heat sink in the summer that might make you need more cooling. If a typical, inexpensive dehumidifier makes it too warm a Santa Fe or similar will make less waste heat and might be tried before adding cooling. Note that a good engineer might be able to model all this for you and get it correct right out of the gate. A mini split is probably a good option but if you can piggyback on your existing cooling system, so much the better. You might have to install all the ducts, of course and might will be the main investment if tapping into your existing system. On the other hand, maybe a mini split can pretty much be added later with no investment now. As lagniappe, it may provide heat for less cost than the oil burner. Do the math. If you want to use it for heat, location nearer the floor will work better so consider a floor console or setting up a ducted unit with high and low supplies/returns that you switch off seasonally rather than the typical high mount version. They are not as efficient and cost more, but may work a lot better. My experience in finished basements in heating climates is that the floor and feet are always cold. The mini splits in dehumidification mode can take a lot of the load off of a dehumidifier while giving you some cooling at the same time. Make no mistake, however, they are not dehumidifiers. They are always net cooling whereas dedicated dehumidifiers heat as a byproduct. To see some examples of a dehumidifier in a plenum, find these articles, You can probably forget about most of the other stuff found there unless just for interest. Note that this organization might be a good place to look to check or form your insulation plans: Conditioning Air in the Humid South—Creating Comfort and Controlling Cost Research Report - 0214 November-2002 Building Science Corporation Residential Dehumidification Systems Research for Hot-Humid Climates Building America Report - 0505 Feb-2005 Armin Rudd, Joseph Lstiburek, P.Eng., and Kohta Ueno