I am going to build a new house ranch style. Could you please give me the pros and cons of a crawl space and a slab.
Thanks CoachB
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Hmm, right off the top:
Slab cons
harder surface under linoleum/tile, even under carpet (i think my last apartment -- slab over -- was a contrib factor to my plantar facititis) Painful if you've ever had it.
never perfectly level, I've seen larger slabs (commercial), out (low) 2" in the center of a 100' floor.
Crawlspace pros
Access to all utilities - accessible under-house sewer cleanouts, water, etc
Can locate some devices in crawlspace (around here, HWH and heatpump)
2-3' above grade, more protection from storm flooding (been there in apartment)
termite protection - 2-3' masonry to climb before getting to sheild & wood
insulation
access to underfloor for adding circuits, phones, speakers, etc in future
if I remember right from my college years, it's a good place for the grow lights ;)
PLUS, the right and opportunity to argue vent vs. no-vent here on Breaktime
---
PB (can you tell I'm partial to crawlspaces?)
Thanks for your reply, you mentioned a lot of things that I didn't think of. especially uneven slab.
Coach B
The only good thing I can say about slabs is that you have no floor squeaks.
Other than that the crawl gets it hands down.
Thanks for your reply from most all the replys the crawl space has it. Notchman had a good idea of pouring a rat slab. Thanks again Bax
Trying to think of it the other way.... I've had both slabs and crawls. Slab is cheaper to build, but harder to remodel and repair. No worries about weight on a slab, you could park a truck in the living room. Slab would be easier for wheelchair access. The subfloor in a slab never squeaks, but you can install wood wrong and get it to squeak.
Think about the view from your windows. Do you prefer to be down in the shrubbery, or elevated 2-3 feet above grade?
-- J.S.
"Think about the view from your windows. Do you prefer to be down in the shrubbery, or elevated 2-3 feet above grade?"
That is exactly one of the reasons that mine is on a slab. My yard slopes down to the lake.
You can always remove the shrubs.
Bill Thanks for your comments, I think I am going to go with the crawl space with the rat slab. Thanks Coach
John Thanks for your reply, As you can see the slab seems to be the way to go. My windows are going to come down to about 24 inches from the floor. The crawl space we give me more height Thanks Coach
But if you are planning radiant floor heating, than a slab is defintely cheaper than pouring gypcrete on a wooden floor over the crawlspace.
With slab, you do have to carefully select floor coverings for high-use areas. Walking through the hallway doesn't matter, but standing/working in the kitchen does. You'd think carpet would soften up anything, but the added bounce of wooden floors does help the arches.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
This is a very interesting discussion.
My wife and I are planning a two storey house in the Ottawa, Canada area (cold winters, reasonably hot but short summers) and are considering slab for the first floor to provide radiant floor heating and level wheelchair entry from the attached garage.
We also want radiant floor heating on the second floor. Does anyone have experience with thin (1-1/2") suspended slab 'regular' concrete on the second floor? Gypcrete is available but must be covered with a flooring that essentially insulates the slab and eliminates any direct solar heat gain/storage. We like the concrete stains such as those offered by Kemiko.
Any comments or suggestions?
Thanks.
Another consideration is period and style. Slab on grade may be cheaper now, but prior to the post-WWII building boom, it was virtually unknown. Before then, foundations were dug by hand, and concrete was generally site-mixed by hand. Leveling the site for a slab by hand wasn't cost effective. Cement mixer trucks came into use in the 1930's, and right after the war, earth moving equipment became cost effective for residential construction, especially large tracts.
So, slab would be an odd choice for a two story Victorian or Spanish colonial revival. But it's appropriate for a sprawling low ranch or modern.
-- J.S.
I agree with probozo that the crawl space is usually the way to go. I would especially rather have a wood floor in any area in which I planned to spend lots of time on my feet (Kitchen!). That said, if you hire a flatword contractor to pour you a floor and it's more than about 1/4 to 1/2 inch off from lowest to highest elevation, IMHO don't pay him full price. Rare for a home to have a slab nearly as big as the one probozo mentioned.
The crawl space also makes radon gas abatement much easier if that's a consideration. Radon is the second most common reason for lung cancer in the US.
Plusses of slab: Depending on the area that you're building in, such as lower Arizona, you might save quite a few dollars by having a slab floor. You may save lots of money on future heating and cooling bills by orienting the biggest window area to the south, calculating the roof overhang to provide both summer shade and winter sun, and having an exposed (or covered with tile or stone) concrete floor directly in the area that the winter sun will shine on. You can benefit from this low tech method regardless of whether you were planning a "solar house" or not. If you live in an area of heavy winter overcast, although it's much less, you still save in the long run. Also, IMHO the durability of the installation of tile or stone over an adequately reinforced poured floor will be more than on any other surface.
It doesn't matter how fast you get there, it just matters that you go in the right direction.
Thanks for your reply. I think I am going to try and go the way of the crawl space with the rat slab. I sure do appreciate you getting back to me, I have a lot more questons. Thanks Coach
If you live in an area where radon gas could be a problem be sure to include a plan for mitigation. It's the second leading cause of lung cancer in the US.It doesn't matter how fast you get there, it just matters that you go in the right direction.
>> It's the second leading cause of lung cancer in the US.
Can you point me to a study or studies that draw this conclusion? I went Googling for it yesterday and all I could find were second and third hand reports.
The last thing I read on radon, and this has been some years ago, said there was no correlation or even a negative correlation between residential radon exposure and lung cancer.
I'll make a note and check when I get back to my office. (We're having major snow, FINALLY!) I think it is the EPA (maybe State of CO) pamphlet that real estate brokers give to clients who ask about it. It doesn't matter how fast you get there, it just matters that you go in the right direction.
For information about Radon:
US EPA, Region 8, Denver, CO, 800-227-8917 or 303-312-6031
I'm referring to two booklets:
Consumer's Guide to Radon Reduction 402-K92-003
AND
Home Buyer's and Seller's Guide to Radon 402-R93-003
The inside cover of my copy of Consumer's Guide... states that radon is the second leading cause of lung cancer.
Just something else to learn about!It doesn't matter how fast you get there, it just matters that you go in the right direction.
Thank you kindly.
I prefer crawlspaces, but in the last couple of houses I've built, we've poured a "rat slab," which is just a 2" or 3" slab of concrete over the the entire house footprint. Pour it with the footings, just like doing a monlithic slab, then do the stemwall. The advantage is that you have a clean, dry space, easily kept inaccessable to unwanted critters and easy to navigate on a mechanics creeper.
The cost to add this feature is about a push with doing the traditional thing with plastic and pea gravel...doesn't take that much concrete.
And the accessability to your mechanicals and utilities is a real plus. Codes require lighted crawlspace now, so they can actually be functional and not the horrible places they've been known to be in the past.
I have a guest house which was actually built to house a quadraplegic relative, who eventually passed away. We poured a slab to bear the weight and wear and tear of his motorized wheelchair, but that floor is pretty unforgiving and hard on the feet. It served well for its original purpose, but eventually, I hope to put down sleepers and a wood floor.
Notchman, Great idea of the rat slab I was going to put down the pea gravel and plastic. I believe that I will still use the plastic on the wall. The March issue of Fine Homebuilding has a good article on treating a crawl space. My next question that I am going to post is block vs poured concrete for the footers. Thanks again Coach
If you live in a cold climate, ventilating, insulating and heating a crawl space can be a pain. A hybrid is a possibility. Several years ago I designed a house that was to serve initially as a vacation home and ultimately as a retirement home. I wanted to be able to keep pipes from freezing without the cost of heating the whole house. The concept that I came ultimately came up with was two slabs connected by a separately (electrically) heated 'utility corridor", that had a crawl space under it. All plumbing was in, above or backed onto the the crawl space and/or utility corridor (which also housed the fireplace, etc.).
I am a fan of slabs -- but they are unforgiving of poor design or execution. A good air/vapour barrier should keep out radon gas. They are great for radient heat and ceramic tile. If you are concerned about the lack of 'give' under foot, install a good carpet and underlay.
The only advantage to a slab is low cost. You will regret it if you use one, especially the wear & tear on your feet (slabs are HARD!!)
Over the past several years, 22 skunks at my friend's house liked the crawlspace too!
I'm a fan of raised floors and crawl spaces. If you ever want to change, repair or modify the house you have access to all rooms. Throw on an attic and rewiring or replumbing is much easier.
One other point is that the extra 18-24" of freeboard makes life on a flood plain a bit more manageable. On the down side wheelchair access is complicated by the extra height.