straw bale right on the dirt

I wonder if it might be an okay idea to build a large roof area over a patch of land that has ground sloping away in all directions - and then stack straw bales well within the roof line, right on the dirt. In the end, you would have a wrap-around-porch-sort-of-thing going on. Maybe ten feet on all sides. That would keep 95% of the moisture off of the bales.

What would be the down side to this idea?

We built a straw bale doghouse directly on the ground with a roof covering. The only disadavantage was settling of the bales over time.

I saw a great idea for dealing with straw bale construction for outbuildings in flood prone areas last time I was in California. It was a strawbale noise reduction wall near a main highway. Since flooding was a problem They just starting using the strawbales after laying a foundation made of gabions (see http://en.wikipedia.org/wiki/Gabion). This way flood water could just flow right under the wall leaving the strawbales high and dry. I saw this technique used at the Solar Living Center in Hopland.

At any rate, I would probably lift strawbales off the ground somehow as a matter of principle. Even on dry ground I suspect that moisture will wick up from time to time and your bales won't last quite as long...

BBC recently did a feature on a guy who built a strawbale house in the UK for 4,000 pounds. He did a simple stone foundation with a wood base laid across it.

Nice photo gallery here:
http://news.bbc.co.uk/2/hi/in_pictures/7279502.stm

Here's how his money was spent in building the house:
£600 supplies for volunteers
£500 sarking
£400 floorboards
£400 pond liner
£300 straw
£200 plumbing
£150 reclaimed joists
£150 plywood
£150 equipment hire
£150 glass
£100 quicklime
£100 wiring
£100 tarpaulin
£100 paint/varnish
£100 batteries
£100 fixings
£100 miscellaneous
£100 fuel for power tools
£70 water pump
£50 water heater
£50 stove chimney
£30 cooker

I believe you would also have greater problems with pests in your walls if you put the bales straight on the dirt.  Critters tunneling in and borrowing your insulation/walls if it was load bearing to make nests would be a hard problem to address.  It would probably be better to lay down some sort of footing.

Termites love straw bales sitting right on the ground.  On the other hand, after the building collapses and you turn the bales over, your chickens can have their favorite smorgasbord.

Sue

I think that by putting it right on the dirt, you are pretty open to the idea that it isn't going to last as long.  But there are things you can do to attempt to get it to last longer.

permaculture.dave wrote:
I saw a great idea for dealing with straw bale construction for outbuildings in flood prone areas last time I was in California. It was a strawbale noise reduction wall near a main highway. Since flooding was a problem They just starting using the strawbales after laying a foundation made of gabions (see http://en.wikipedia.org/wiki/Gabion). This way flood water could just flow right under the wall leaving the strawbales high and dry. I saw this technique used at the Solar Living Center in Hopland.

I had a similar idea for a privacy/sound wall in my yard that I flood irrigate. I was considering using salvaged chain link fence to contain river rock for the foundation.

Were the walls you speak of temporary or permanent? If permanent, what was used to cap the top of the bales?

Thanks.

I personally think that doing something as laying down flat stones on the ground befor building the straw bale structure would help extend the life of the lowest bales by a number of years. Building straw bales directly on the ground has been done befor though, here is something from a book called, Handy Farm Devices by Rolfe Cobleigh coppyright 1909.

Cheap Sheds of Straw
It would pay every farmer to put up in the pastures some kind of protection for his sheep, hogs and cattle. Where labor is scarce and hay and straw is plentiful and cheap, a condition which prevails in many large sections, straw sheds and barns are very profitable. Put up a framework of posts 8 feet high, 16 feet wide and as long as needed; 30 feet is a good length.

The posts are hewed evenly on two sides and set so that a bale of straw will fit snugly between them. They are cut off at a uniform height and a 2 x 6 spiked securely on top. Rafters are nailed to this and covered loosely with poles. Baled straw is used for the sides.

After the sides are up the roof is covered 2 feet deep with loose straw held in place with a few poles that are tied together in pairs and placed over the ridge. Several of these sheds have been built for five years and have not needed any attention.

Might not hurt too much as long as the walls are not load bearing. Use mud finish and just stack a new bail on top every ten years or so, as the wall settles. Assuming you are in a dry climate. I build a straw bale on some railroad ties that has stood for ten years. I wish I had just left them on the ground without the ties.

Might I suggest you wrap the bales to be used for ground contact in chicken wire and coat with reinforced fiberglass stucco.

Even if you only coated the tops and say 3-4 inches around the sides then flip them over for your bottom layer it would seal the bottoms from moisture as well as critters.

Once the base is in place then standard Cob, Rammed Earth or other options could be easily added to the wall finish. Stucco generally only has a work time of 2 hrs and can be applied by hand and smoothed if you dont have mason tools.

The recommended cure time is traditionally 72 Hrs for best results but it can be worked or placed after 24hrs without any issues.

Hope that helps a bit, not a real earthen mix but should do very well while you finish it properly.

i would not put straw bales on the ground without a vapor barrier even if it is roofed on high ground unless it has been roofed for a couple years and then there would be some ground moisture though minimal and a potential bug environment that would be eliminated with a vapor barrier

I agree Pahanna but much of the building of a straw bale structure depends a great deal on budget, temporary vs. sustainable and other mitigating factors. Based on the question format I can assume if your desire is to apply directly to a dirt surface that the plan is either temporary or budget constricted.

Both could be constructed with those constraints however again I agree with you a vapor barrier and or water proofing / resistant ground level is very important to stand up to moisture, mold and insects or rodents for the best long term results.

absolutely Mark, sometimes rocks are free and sometimes they arent, luckily my banker loaned enough money to buy a roll of 6mil poly so i didnt have to tape the plastic grocery bags together

I think it depends on whether you are going for quick and easy, or if you want it to last longer. If I were doing it I would probably put down flagstones under them. Or I might put flagstones under one or two walls and leave the other walls directly on the ground as a type of experiment.

If you aren't going to plaster over the straw, you can, but a few inches of gravel under the straw will make it last longer. Either way you need to understand it will not last very long. you really need a mortar of some kind on all sides of the straw. Straw works best if you treat it as one component of a composite material like fiberglass. Fiberglass is a mix of fibrous glass and a plastic resin. Straw is a fiber, you really need a masonry like product to complete the equation. If you don't make sure you block the water coming up from below, your bales will rot.