Basement Wall Height ?

[Mudball]

I met with a builder today and he said that if it was his house (concrete block on footer) then he would just build 8' high wall and set the roof trusses right on top of the interior walls for support.
I have google searched several pages and cant find an answer to have 8' or 10' high walls.
If I go with 8' walls and the trusses are supported from the interior walls then don't I need thicker concrete below those supporting walls (aprox. 4" to 5" thick slab) ?
What he said makes sense and would be cheaper...I think. I mean the duct work, water, and electrical is all going to be run through and laying on the trusses anyway.
So why would I need a 10' high block wall ?
Please explain to me any pros/cons.
I'm going to call him back tomorrow morning and tell him he has the job but I'm going to have to know my correct block wall height ( 8' or 10') before they start.
Thanks

[JRR]

Of course it depends on your intended usage of this area ... is it to be "living space" or "storage and utility"?   Are the wall heights that you are pondering measured from excavated ground level ... or from top of footing?

You may need to do a quick "elevation" sketch of the building, and account for every dimension.  Do you intend to place gravel on the earth?  How thick?  Insulation?  Tile in a grout bed?    ... It all adds up.
Will the joists (trusses) be exposed or will you have a ceiling installed?   Whatever you put below the joists, I think there should be 7' minimum vertical clearance down to the finished floor.   If a code is involved, you may need more.

On the other hand, if you make the height excessive, it may come back to haunt you when you try to lay in a stairwell ... if there is to be a fixed stairwell.

Its all about trade-offs!

[Mudball]

Thanks JRR.
This will be a one level with slab floor.
It will be living space.
We would like to have inside finished wall height of approximately 8' high for ceiling fans.
The trusses wouldn't be exposed. There would be a ceiling installed.
There will be gravel fill on the ground and he said that he can pour the footer and it can be filled with gravel so that when the slab is poured then from there to the top of the wall will be very close to 8'.

So why would I need a 10' high block wall ?
Are people building an extra 2' space specifically for ductwork ect...?
Is this necessary and/or more expensive for our building type ?

[DavidLeBlanc]

There's a guy having a house built on the Woodenboat forum I hang out on - with daily pictorials! House is going up fast!

He's had 9' walls put up for his basement so that he'll have a finished ceiling at 8', leaving 1' or so for ducting and plumbing runs. I think that's on top of the slab.

If you want to see the pics, go to  http://www.woodenboat-ubb.com/ubb/ultimatebb.php?ubb=forum;f=5
 and look for threads named: Home Building PhotoJournal (6/17/05)  (dates differ, of course and some have fallen off the front page).

[Mudball]

Thanks David.
Thats a nice looking house. I'm afraid that its nothing like what we're building.
I'm starting to learn that some basement walls are 10' high for support beams and floor joists, ductwork, ect...because they will have an upper level.
Our house will be a walk out basement with a roof.
I'm wondering if the ductwork, pipes, and electrical was in the trusses and the trusses are being helped with support by the interior walls then will I need special trusses and/or will I need thicker concrete in the slab just below those support walls ?
Thanks

[JRR]

Mudball
I agree with you .... the argument for 10' , for your purposes, eludes me.

You might consider a "13 block high" wall ... that would give you an extra 8"( if my math is correct)  for a hanging ceiling or whatelse .  

[Daddymem]

My boss put 10' walls in his basement for two reasons.
1.  He has a pool table in it and the extra clearance prevents chalk marks on the hanging ceiling.
2.  He has a wood shop in there and it is waaay easier moving long pieces of wood around with that extra room.

Just a couple reasons one may want the extra height...

[JRR]

... and I forget to add:

I think your planned ceiling height may be a little too "snug" to be using a ceiling fan.   Ceiling fans are great for stirring air in "tall" rooms, but you will not have any stagnation problem that a guarded pedestal fan will not handle ....... and be safer and more flexible.

[JeffnTN]

Partly because of the slope of my site, but also for the extra height for the workshop area, I did 10' walls in my basement.

http://pg.photos.yahoo.com/ph/tnmtnbiker39/album?.dir=3b77&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos

[Mudball]

Thank you all for the input.
It looks as if for our application that it would be better and more economical to go with the 8' walls since there will be ample room for ductwork ect...
Thanks