I’m getting ready to send soil tests and drawings out to a foundation engineering firm. Since the foundation will likely cost at least 50 times what the engineering for it costs, I am seriously considering getting designs from two seperate firms and going with the one I like best.
I suspect that pointing the foundation engineers in the direction I want before they start the design is likely to result in an answer I like better at the end.
The foundation will be a slab on fill under the garage, and pier and beam under the house. One end of the house will be about 9 feet above grade. My expectation for this is a stepped footer, a stepped cement crawl space wall such that the top of the concrete is always at least 6 inches above final grade, and then cripple walls from there up to the floor of the house.
All this is based on what I have put togther from a book here and there, pictures off the internet, reading this forum, and no experience whatsoever. So, do the tall cripple walls make sense, or would it be cheaper or significantly better to have 9′ tall concrete crawl space walls?
Replies
Paul,
I have worked on homes that had 16' concrete walls and on 2' concrete with 24' framed walls. Steps all the way down a hillside either way .
Either concept is viable. Either way there will be some engineering involved because of the height of the walls.
I would try to get Plan "A" and Plan "B" from the engineers if they think either way would work given your site s conditions.
Preliminary plans that would allow for a preliminary estimate to be given on each option. If the numbers are hugely differant when the estimates come back then you at least know which would be cheaper to construct. If they come back close to each other you can get down to "brass tacks " on the design and costs.
There are I my mind several long term things to consider though.
Maintenance of the siding of a framed wall is one . You might save some construction cost immediatly with frame , but spend way more out over time maintaining that portion of the building. On the other hand, if in the future it becomes desirable to utilize the space in that crawl area for any purpose it would be much easier to do so if it were framed. (easier to add windows, doors etc.)
In my experience these areas often get overlooked for storage, funace rooms, hobby areas etc.
I wouldn't want to just state one way will be cheaper than the other without some checking into your local costs for material and labor on the options.
Thanks, at least I now have some confidence in my research.
The "siding" for the framed walls will be brick - which is about $5 a square foot in this part of the country.
There will be a full sized door into the crawl space, and the plan is for the water heater, water filters, air handler, and all the duct work to be in there, along with lots of storage space for the DW's gardening tools.
Brick will mean minimal maintenance , so there is that issue taken into account.
You are definitely on the right track . One thing I would say is that if you get into detailed comparisons of the two systems for cost purposes that you offer to pay whomever is doing the cost work up for their time. Leaves a much better taste in the mouth .
i would just like to add that since there are two perfectly acceptable ways to do this foundation, you may want to talk to some foundation contractors to see what they think, see if you can meet with the guys, and get a feel for who you would like to hire, and what their ideas on building it are.
i have done quite a bit of both structural framing and structural concrete, if it were my decision i would spec a hell for stout stepped foundation, and frame it up, but i am not an engineer, when i design something it is usually overbuilt. i feel confident of the staying power of an overbuilt step foundation, and i feel confident of a cost effective job with brick veneered wood framing on top.
my thinking on overbuilding foundations comes from years of retrofitting the foundations of major highway structures, its amazing how they were perfectly good so many years ago, but now if we just add a little more steel, concrete, and footprint it will be so much better. at the time of original construction it would have been much more cost effective than adding it after the fact.
now if you take that thinking all the way up with structural concrete to the bottom of the joists now you have really put a hurt on your budget. my recipe is strong stepped foundation and wood frame.
It is almost always cheaper to step your foundation. The down side is esthetics. Of course, if the concrete foundation is not going to have a brick veneer on it, that is not real attractive either. Part of this depends on how the house is sited - what can be seen from the road. If the whole house is brick veneer, it normally should be stepped for cost reasons.
To price out the 2 scenarios you need a price per sq foot for the concrete foundation walls, vs the cost of framing material, framing labor, and siding materials and labor. Here those pony walls are normally framed with 2x6 rather than 2x4.
I think that if I built a house with 9' tall free standing concrete walls on the back of the house (ie - no unbalanced fill on these 9' walls) I'd probably get "called on the carpet" by my boss.
If the crawl space is 9' tall, you should go ahead and put a "rat slab" down there for storage.
""I think that if I built a house with 9' tall free standing concrete walls on the back of the house (ie - no unbalanced fill on these 9' walls) I'd probably get "called on the carpet" by my boss."" Man , You must be a "flatlander". lol I have worked on sites that had enough slope, You walk in the front door, straight to the back of the house , say 40', and look down 30' to the ground.
Right - and the walls are stepped - that was my point...
Matt,
The top pic shows 8' form panels at the lowest point on the slope, yes the wall is stepped, without the steps the pour would have been 20' + tall on that site. The fill at the low side will only cover the footings. leaving 7-8' bare concrete wall. The cost increase to go over 8' tall CIP around here is dramatic so framing becomes cost effective above that height.
Very rarely have I had a site that stepping the footing/foundation was not cost effective.
I may be misunderstanding the phrase "unbalanced fill". Do you mean being able to see the tall expanse of concrete wall?
If so in some cases that is not an issue due to site considerations. The second pic shows a corner of a different building. I just posted it to show how steep some sites are here. That is a 10' "pony" wall on top of a (at the lower right of the pic) 6' CIP foundation. Makes for a 16' tall crawl space. Plumbers, HVAC, Electricians and Insulators were all doing their "Ground Floor" work off extension ladders.
Edited 2/11/2007 2:41 am ET by dovetail97128
We are agreeing - sometimes it just hard to have an actual conversation via this dang keyboard... :-)
When I said unbalanced fill, what I meant was that, if for example, a house foundation was say 9.5' tall, but had 6.5' of fill on the outside, and 6" of fill on the inside of the basement creating an "unbalanced fill" situation, then no - a stepped foundation would not be warranted.
You are right about something else - we enjoy pretty flat building sites. Since many building sites are still available with minimal topology, we tend to gravitate toward those. Right now I have a site with maybe a dozen or so lots with roughly a 8-12' difference between the curb height and the house pad which is 25' away. I've wined to my boss because I don't know how I'm gonna be able to build driveways to access the garages that have reasonable slopes. This kind of situation comes up more and more as the years go by as the land that was previously considered undesirable is now being developed as the population density in our little city grows.
As you know, it all comes down to money though... Here, in most cases it is not financially feasible to develop sites like you pictured unless it were a very desirable location like maybe lake side, etc.
Matt,
AHH, now I understand your point. I never heard the term before .
As for the flat sites, you are right, just takes money and a creative mindset.
Helps if the actual labor on site is a bit masochistic as well. ;-)
>> Helps if the actual labor on site is a bit masochistic as well. << Yea, those 40' tall pump jacks the siding guys use are a little scarry to anyone with a bit of good sense. :-)
If you are filling in the area under the garage there's a good chance the engineer might suggest a precast suspended slab to hold up the floor of the garage and forgo the fill altogether under that area. At least that's where precast slabs become most viable around here.
Beer was created so carpenters wouldn't rule the world.
You may notice a small difference on your mortgage each month depending on your choice, but more important,you will be reminded of it every time you look at your house. I'd base it almost entirely on looks.