Hi everybody ;D, first post, but long-time reader of this site. Last month I bought the Big Enchilada plans and hope to build soon on lots in town. Which do you think would be the best way to go; a concrete slab or standard foundation and why?
Well, around here in NM a concrete slab is considered a standard foundation. ;D Back home a standard foundation was an excavated basement with poured concrete walls. And I have friends in a small UT town where the standard seems to be a perimeter foundation that provides a crawlspace under a wood joist floor. So that depends on what "standard" you are comparing to. Don't mean to be a smartass but standard does mean different things in different parts of the country.
I have serious reservations about using slabs. One has to be careful about insulation when a slab is used ... not impossible to do, just has to be planned. In my area, termites have a feast on wood framing so close to the earth ... so I would only use a slab if the walls are to be masonry. I would prefer not to have long runs of sewer or other services under the slab ... more planning required!
Certainly, as a newbie to the building game and with reasonably basic plans, doing a perimiter foundation was a lot more forgiving. No need to decide on e.g. exactly where drains go right at the beginning. And reasonably easy to run wires and pipes - just drop them into the crawl space and head to wherever you want from there. That being said, next time I'd make sure there's a non-load-bearing 2x6 interior plumbing wall in the bathroom, which would make it even easier.
Having done a slab for the garage and perimiter foundation for the house, the perimiter was less stressful. I still can't quite picture doing a 20x30 slab myself, even though I did a 10x20 and it turned out fine. And doing the perimiter wall with speed blocks (filled with rebar and grout) was pretty straightforward - I'd be happy to do it again (although I'd probably avoid doing it in the peak of Summer if I did more block laying).
All of the framing end of a wooden floor close to grade level is pretty straightforward and good practice for higher up when things get a littled harder.
Thanks for all the replies. My idea of a standard foundation in this instance would be concrete footing with cement block wall, which sounds like it might be the best option. Although I do like the idea of the slab to eliminate steps, termites are plentiful here. I am also considering a full or partial basement if it won't raise the cost too much.
Quote from: Joseph Cabot on September 23, 2010, 06:43:27 PM
Thanks for all the replies. My idea of a standard foundation in this instance would be concrete footing with cement block wall, which sounds like it might be the best option. Although I do like the idea of the slab to eliminate steps, termites are plentiful here. I am also considering a full or partial basement if it won't raise the cost too much.
We did a 4ft crawl space, which was the max. without requiring engineering as a retaining wall in CA. This isn't too unpleasent to work in and can be used for storage if desperate (we use it for storing outdoor stuff druing the 5 months of snow here). This was 3 extra courses of blocks @ about 80 blocks/course and $2/block, so maybe $500 in blocks, perhaps the same again in concrete grout/rebar and one or two extra hours of excavation. So perhaps $1200 more than the minimum required to get down to the frost line and up away from the dirt. This is all rural CA prices, which it seems are pretty much as expensive as you get outside of Alaska and Hawaii.
Having lived in a slab home for the last 30 years, I hope to never live on a slab again! The unyielding concrete is hard on your back and feet. Professional dancers won't dance on a concrete stage; they always have a wood floor suspended over it. You can build a slab to be warm, but if not right, it will be cold much of the time. Your plumbing often runs under the slab, which means if you want to move something, or have to fix a pipe, it's concrete saw and jackhammer time. And of course, anything you drop will break. I like the very slight give of a wood floor, and the ability to get under to fix or change things.
Here in FL, everything is concrete block on a monolithic slab. The one advantage (besides cost) is that it's great if you want tiled floors.
The extra storage space of a crawl space or basement would be worth a lot. If a person had a basement built, I guess it could have an open staircase and be used as more living space. It would be good for a mechanical room and possibly a bedroom, if you had a couple windows for egress.
In cold or wet climates the houses that tend to last the longest have a perimeter concrete foundation and the house is raised up perhaps 3' or so above grade. This allows for moisture and insect protection, a usable crawlspace, or in colder climates where frost depth pushes footings lower, a basement. The trouble with small houses doing this is that the full sized stair needed to use these multi-levels can eat up a lot of the usable floor area. In the 14x24 cottage a code stair will use 17% of each floor.
That's why the Builder's cottage is a one story building with a small loft accessed with a ladder stair.
Maybe not practical these days, but most of my relative's homes in Upstate NY had basements with no interior access although most had a dumbwaiter. These were farmhouses with a cistern, root cellar, coal-fired convection heating system and grandpa's workshop. By the time that was all crammed in there only and exterior stair with a bulkhead door would fit. Granted, these were homes that predated modern indoor plumbing...
The teacher who runs the Building Construction Department at my local community college (Eastern Maine) told me once that slabs (and other basementless types of foundations) are getting to be more popular up here. This is because, in his words "all the good land has already been developed". I think what he was getting at was the fact that basements aren't practical where water is a problem. Maine is the second "wettest" state in the country. At my primary residence, the water table is only about 4' below the surface during the wet season. Anyway, he was the one who convinced me to go with a FPSF slab with radiant heat for my Victoria's.
I had real reservations about the plumbing being below the slab with no access. One thing I did was run 3/4" pex for all my hot/cold supply lines (home-run style). Then I ran 1/2" pex through it. This way, if there is ever a problem, the 1/2" could just slide out and be replaced. Also the 3/4" protects the 1/2" from abrasion where the lines pass through the slab surface.
if you are thinking resale at all, a crawl or foundation is more popular than a slab.... at least in my neck of the woods.