I'm building a new basement wall that goes perpendicular to my heating ducts. This will be about 20 feet long, so I have 2 questions. first, getting a 20 foot piece of 2x4 is not easy so can I use 2 10 foot pieces for the top and botton plate and somehow join them to make a 20 foot top and bottom plate ?

Second question, I have another section of wall that I need to build parallel to the joists. I've seen pics of blocking where you cut a 2x4 and nail it in between the joists then nail a top plate to that blocking. So my question is must the blocking go between the joists, or can I make the blocking board 3 inches longer and nail it on the joists (instead of in between them).

i think the easiest way to do this would be to build the wall in two 10ft sections. build one lift it up level it of and nail it home, then build the second section and nail it to the 1st then level the other end off and nail it up. building it in 2 smaller sections will not only make it easier to get the lumber into the basement, but will also make building and putting up the wall a one person job (but it will be much easier with an extra set of hands). make sure that the bottom plate is presure treated 2x4 if it is on a concrete basement floor, and i would staple a sill seal to the bottom of the pt 2x4s also.

as for the wall running parallel with the floor joists you can put the blocking on the underside of the floor joists, but what ae you planning on doing with the ceiling? if you plan on sheetrocking the ceiling those blocks will now be in your way. being this is a basement you probably wont want to sheetrock the ceiling. if you want to finish the ceiling i would use a drop ceiling system. the advantage to that is you can remove pannels if you ever want to add change or need to repair any electric plumbing or hvac items.

Thanks for your thoughts ! I like the idea of 2 walls, so is there anything unique to connect 2 walls going in the same direction to strenghten the top and bottom plates, ie an extra blocker or anything recommended ? I assume with the walls ending in 2x4, but nail then togheter? Also I was going to have a door at one end of the wall so may go with walls of lenght 8,8, 3 foot door, last 1 foot wall.

I planning a suspended ceiling and I have about a foot of room, so connected to the botton of the joists makes things much easier since I wont need to worry about a 1/2 water pipe and some 12/2 running by.

PS want is a sill seal ?

sill seal is a foam that comes in rolls precut to the width of a 2x4 or 2x6 what ever that u staple to the bottom of the pt, you should be able to find it in the building materials section of home depot.

i would still do the walls in 2 ten ft sections, with the dor framed into the one wall, the less sections you build the wall in the straighter it will be, which will be important especially at the door way.

when you nail the 2 end 2x4s together on your 2 wall sections that should be more then enough to make the wall solid. and make sure you secure the bottom plate to the floor, if it is a cement floor use tapcon screws or masonary nails.

in the ceiling for the wall running parallel with the flor joists i would put the blocking in flush with the bottom of the joists rather then nailed to the bottom, it will look better like a pro did it, but if it isnt easily possible its your house so do what u want.

mrr magna 111 gave you some good advise. But the corners should made different than he stated I would make first one(wall) with either a pocket: studs 2x4 (turned stud or blocks spaced T- M -B 4x2, 2x4 or stud, spacers (top middle bottom), stud. what I do in the corners is add a extra block to the finished corners bottoms for my base mouldings Also don't forget that the door openijng should have jack studs and header and made larger than the door size Example: 30"wide X 6'6"heigh should have rough opening 32"wide x6'8"heigh for levelingand pluming door also don't forget the door swing left or right. You should take a ride by a construction site and look at the corners and the door opings if you are confussed by what I'm sending you if anyone is on the site they would most likely show you and answer your questions. good luck with your project Dave A.

I would really suggest that you stay away from conventional framing and drywall as much as possible. Even if your basement is very dry, Basements sill have very high humidity. Which causes mold, and musty smells. There are a number of new products out there you can use. Like, The Total Basement Solution, Owens Coring, Champion. All these companies have great new products. But if you much use drywall and studs your vapor barrier should go against the wall to protect the studs. This is not necessary to keep the studs dry it is more to keep the walls from wicking humidity into the basement. I also suggest that you get a ventilation system for basements. You can check out our website to see what we use. All though we don’t service your area it will give you an ideal of what you should have. www.thebasementguys.com