Concrete-free slab and footings in Iowa
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Hello folks.. I asked a similar question with no replies so lets try again..
I know most of the talk here is to promote “comfort”.. But are there any hippy penny pincher types left in the crowd?
If so, lets talk about cheap living.. Not saying comfort and efficiency arent important, but “pretty good” construction probably gives the most $ return or break-even, especially when attention to air sealing is emphasized. Does it really save money reducing your energy bill from $75 to $25 when spending $20K to do so?
Anyway, what Id like to also consider is property taxes, and how to reduce them without sacrificing allot of comfort.. My county, who doesn’t enforce a building code, drops the value of the structure greatly when it doesn’t have a permanent foundation.. Thus why my old leaky existing mobile home taxes are 1/10th of the taxes of a home on a foundation.. My thoughts are to build separate modular “rooms” no larger than 12×16 with 10″x10″ timer foundation frames, under a large open air polebarn roof. And build them directly on top of gravel but at least 10′ from the edge of the open air roof. Yes this complicates the mechanicals, increases the amount of exposed wall square footage and requires a exterior door on every room because you would have to walk outside to go from the bedroom to the kitchen.. But if your the type who can get over that one con, there’s allot of savings potential on taxes, and also utilities since its all new construction.. Plus, you reduced the amount of concrete used..
My question is about building a few 12×16 rooms on gravel. My location is on top of a hill so all rain water will run far away. So realistically, the only moisture to contact the bottom of the “rooms” will be vapor from underneath since the room is 10′ from the roof eave..
Does this sound doable? Because I could save hundreds, and maybe thousands a year on taxes by building “temporary” structures that never leave the property..
Thanks!
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Replies
Mike,
I'm not going to comment on the code, or tax implications, just the practical question you asked.
There is something intriguing about what you are suggesting, and with some thought you could end up with a really interesting place to live.
Detaching the roof frees you up to create a small village of rooms only worrying about internal moisture drive, not bulk water wetting from above. Because they will be relatively small, and not connected, you should be able to easily support them on clear compacted gravel. If they shift a small amount, who cares? Just make sure your utility connections have some flexibility.
I don't think you need to keep them 10 ft from the perimeter of the main roof, just far en0ugh that wind-blown rain can't get at the top of the rooms.
Spend some time thinking of how the rooms create outdoor courtyards, and the relationship between them. What you end up with could be very architecturally intriguing.
https://www.dezeen.com/2020/05/22/richardavidarchitekti-tops-czech-home-with-a-greenhouse/
https://www.dwell.com/article/four-friends-joined-forces-to-realize-this-idyllic-forest-retreat-outside-toronto-ba860998/6133519170781622272
I don't know if this count as a permanent foundation in your area but my answer for the search for cheaper construction was helical piles. Not only for price reasons but also because of the fragility of the site I used TechnoMetalPost piles.
https://www.technometalpost.com
The whole 800 sf footprint 2 story house sits on 14 metal piles. I spent a day and a half with a Bobcat levelling the ground under the house and the piles went in less than 3 days into the rock/clay ground. The cost was fraction of the cost of concrete piles, not to mention a real slab or crawlspace foundation.
In addition there was absolute minimal site disturbance.
That's very cool. What are the biggest downsides? Insulation? Critters getting under your house?
Thanks everyone.. My area had a power outage and I'm just getting back to normal..
I still keep coming back to this open air roof idea.. I'm glad a few of you folks are also intrigued.
The green house is cool.. But in reality, permacolumn.com is probably the product I would choose and build a pole barn with no walls.. I like the contemporaneity look of a flat roof and need a soffit on the bottom side to prevent nesting. So which truss should I consider? Wooden engineered flat roof truss placed every 24" and hung on a bunch of beams of some sort? I'm wanting at least 40x80 roof.
Thanks
A couple of concerns:
- it can be dark in the middle under a 40x 80 roof
- wind force for a free standing roof this big
- because of the span you need support in the middle if you don't want expensive stucture
- going outside to get from one part of the hose to the other sounds fun in SoCal but in Iowa?
Here are a couple of pics how we built our house. The footprint is 43x21. No stuctural steel and we used exactly zero concrete in the whole construction.
What pier system are you using?
https://www.technometalpost.com/
Yes there are plenty of disadvantages and challenge's I'd face building a village of 16x20 cabins under a 40x80 open air roof. Not clear span.. Advantages would be the upfront money savings of no concrete, and long term savings of over 50% reduction of property taxes. Plus I could do allot of the work myself slowly since there's a existing mobile home. Or be the GC.
A low pitch roof is probably impractical so maybe a 4:12 lean to..
There was a grand design episode where they built pavilions under a big tent:
https://www.lifestyle.com.au/property/grand-designs-australia-a-16m-tent-in-the-rainforest.aspx
You can find the video on dailymotion.
The tent turned out to be very expensive.
You would think you could build a nice timber frame structure for well shy of $1.6 million.
This discussion reminds me of this project in California.
http://www.jetsongreen.com/2009/06/desert-modern-rimrock-ranch-house.html
Greg,
i've always liked that project. it makes sense to me to separate the roof from the house in very hot climates - and I think something similar would work here in the PNW, where if you deal with the rain, the climate is mild enough that outdoor covered areas work year round.
My largest concern would be the composition of the soil. This would be difficult to pull off on expansive clay soils.
BTW..I'm 90 percent certain that wooden piles would fall into the category of permanent foundation.