Your thoughts on my basement plans

[CurlyDave]

I think that is a great decision. Sure, it is possible, but it is not easy and there are much better ways to do it.

 

[dfkrug]

Eddie, my complete house HVAC supply ducts are PVC under slab. Return in attic. That's how it's cooled and heated for less with a 2.5 ton unit that's 32 years old and that's why my basement is inset 5' on one side of the house and 3' on the opposite side. That's how ducts and water supply gets to that other end of the house.

Interesting. In my house, I installed galvanized rectangular ducts under the slab, before the pour. I used
conventional ducts, wrapped them in 1" rigid EPS foamboard, then covered them in 1/2" concrete backer-board.
The backer-boards were to keep the ducts from getting crushed by the slab jockeys during the pour. I
considered round PVC pipes, but to get the same volume, I would have to dig deeper, and insulating them would
be harder.

Before I did this, I asked some HVAC contractors how they would install heating ducts under a slab. I got
only blank looks.

 

[Deere Dude]

I woke up this morning with the realization that I really don't want a basement, and I was overthinking this whole thing, making it a lot more complicated then I needed to. My reasoning for the basement was protection from tornadoes. Since I'm digging a hole in the ground, I might as well make it as big as the room that is going to be above it. There is no reason for a tornado shelter to be 16x16 feet. Once I got to thinking of how big it needed to be, and that while we where in it, we where going to be wide away and not doing anything until the threat had passed, I got to thinking that I could have everything i wanted by just building an above ground shelter in the corner of my garage. This now removes a huge weight off of my shoulders and allows me to move forward with what I really want to do, build my great room!!!

Thank you, I really do appreciate all the great advice and humoring me while trying to figure out how to build something that I now realize, I no longer want. If I would have just listened to my own words when I said that I never plan on going down there once it's built, I would have realized that I really don't have any need or desire to have a basement. As for storing stuff, I am already in the process of creating a canning/processing room that is 12x24 that will hold everything we plan to can or pickle.

Kind of like post #14. Ours is 8'OD but just enough room for some bunk beds, a chair and some snacks.

 

[EddieWalker]

Interesting. In my house, I installed galvanized rectangular ducts under the slab, before the pour. I used
conventional ducts, wrapped them in 1" rigid EPS foamboard, then covered them in 1/2" concrete backer-board.
The backer-boards were to keep the ducts from getting crushed by the slab jockeys during the pour. I
considered round PVC pipes, but to get the same volume, I would have to dig deeper, and insulating them would
be harder.

Before I did this, I asked some HVAC contractors how they would install heating ducts under a slab. I got
only blank looks.

Just curious why would you want to insulate a duct that is buried in the ground under the slab? I'm thinking that Schedule 40 PVC will be strong enough to support any weight that is over it during the pour, and once the concrete cures, it wont matter. I'm still thinking on what size to get. The sticker shock of the pipe will hurt, but it's better then using a window unit.

 

[westcliffe01]

Dirt is a good conductor. The only thing better is water.... Even a 1/2" of rigid foam will act as a break to keep the heat or cool in the duct and not be heating or cooling the great outdoors. Condensation may be a second issue you want to avoid.

 

[jk96]

Eddie I'm looking forward to your great room build. Can't wait to see what you come up with. Maybe I missed it but do you have a timeline on this yet?

 

[dfkrug]

Just curious why would you want to insulate a duct that is buried in the ground under the slab? I'm thinking that Schedule 40 PVC will be strong enough to support any weight that is over it during the pour, and once the concrete cures, it wont matter. I'm still thinking on what size to get. The sticker shock of the pipe will hurt, but it's better then using a window unit.

WESTCLIFF has got it right. I would lose a lot of heat into the ground if I did not insulate.
Cooling would not be a great issue, however.

PVC pipes are plenty strong, but insulating them is not easy, esp if you want crush-proof
insulation. Also note that you would have to go deeper for equivalent volume to conventional
ducts.

Note that 14"x3" galvanized steel ducts, the kind you use for stud cavities, are quire inexpensive, too.
They have much greater cross-sectional area than a 6" pipe.

 

[dfkrug]

Just curious why would you want to insulate a duct that is buried in the ground under the slab? I'm thinking that Schedule 40 PVC will be strong enough to support any weight that is over it during the pour, and once the concrete cures, it wont matter. I'm still thinking on what size to get. The sticker shock of the pipe will hurt, but it's better then using a window unit.

WESTCLIFF has got it right. I would lose a lot of heat into the ground if I did not insulate.
Cooling would not be a great issue, however.

PVC pipes are plenty strong, but insulating them is not easy, esp if you want crush-proof
insulation. Also note that you would have to go deeper for equivalent volume to conventional
ducts.

Note that 14"x3" galvanized steel ducts, the kind you use for stud cavities, are quire inexpensive, too.
They have much greater cross-sectional area than a 6" pipe.

 

[EddieWalker]

We are doing a total remodel on the exterior that will include a new back porch and adding on the canning/processing room. I am in the early stages of converting the 10x10 shop door into a 16x7 standard garage roll up door with an opener. Down the road I will build a much bigger, butter workshop and my current attached workshop will become a place where Karen can park every night and we can unload her car out of the weather when she buys groceries. I am working on plans for the above ground storm shelter that will go into the corner of the garage, out of the way, but easy to get to in case we have to.

Once all that gets done to a certain level, I will start on the dirt work and get the pad poured for the new great room. If all goes well, that should happen this spring once the rains stop and the soil is firm enough to get cement trucks into position.

On the AC duct under the slab, there will only be cold air going through it. 100 % of our heat is from our wood stove. So no hot air will ever go through the duct under the house. I would prefer a solid pipe without any insulation around it for strength. I think insulation would leave voids under there.

 

[BitChin1]

Eddie check into your annual ground temps for the depth you would install the pipe. What you want to avoid is any condensation forming in the pipe that might sit there for extended periods and allow mold to get going which will then be spread into your room when you turn it back on in late spring

Google "earth tubes" to get more info on what folks use and potential issues and how to avoid them.