Joe Vaughn

Yes tape and mud joints, screws, and around electrical boxes.

And unless you have blue type sheetrock for veneers, i would definitely prime with wheat paste and sand for thin veneers or alis. For plaster thicker than a thin veneer, I'd prime with wheat paste, sand, horse and a little fiber.

Spray the drywall first for suction, bond, and to prevent drying out too quickly.  Plaster when the primer has tacked up a bit. If the prime is drying out mist it. Don't overwork the plaster off the wall. Better to let it bond well first. Then lightly rewet and rework if needed after the bulk hardened.

If it's bagged veneer (American clay, etc.), follow the instructions,  as they often have additional binders mixed in.

I prefer wallpaper wheatpaste, over diy wheat paste, especially on drywall veneer. Mix well and hydrate thoroughly in a cheap blender before mixing in your plaster.

For a thin veneer I'd  mix in some WP in there too.

Test inconspicuous areas like closets first to see how your clay plaster ratios play out as a drywall veneer.

If your client wants LED lighting for their new construction of a 1600 ft2 residence, this installation should empower their financial investment in building a new home, not jeopardize it.


This means that the electrical work should:

1) Be legally permitted and inspected. In most localities, a homeowner may pull a homeowner permit and perform the work themselves. But the homeowner is not here asking these questions themselves. Without permitted and inspected work, client would be hard pressed to have a mortgage, insurance, certificate of occupancy, or resell the house.

2) Should enhance their investment and not jeopardize it. It is standard and expected in the said client's NY State real estate market, for homes to be equipped with lighting (or lighting branch circuits) wired with 120V AC. LED lighting fed with AC power is the norm in new construction, many good UL listed options exist affordably on the market. Even if the client wants LV DC wiring powering their fixtures (hey it's their house, their money), and there are non-lighting branch circuits being wired in AC, then I suggest to include a full AC lighting installation, so that their investment is not trashed. The added cost of some 14ga when the wire is already being strung is not much. Nothing more wasteful than tearing out drywall on a perfectly good house--or investing (burning) huge sums of money on constructing a new house, while killing one's potential resale with a few tightwad quirks.
If I was to bid on buying a house that only had LV lighting wiring in place, that would provide me great leveraging on the asking price. There is a place for LV DC wiring, including lighting, but I don't see advantages using it in a new residence these days with abundant cheap AC LED fixtures and bulbs, including even low budget off grid electrical systems.

The general contractor should hire a liscenced and insured electrical contractor for this new construction. If you are a general contractor, unliscenced employee/worker, or some type of subcontractor, then don't touch your clients electrical installation. It will cost your client less to have it installed professionally, safely, and legally from the beginning. No reason to accidentally burn down a structure just to try to save a buck. There is a reason it takes a decade of trade experience and a hard test before someone can become an master electrical contractor. Likewise, your client can hire a professional lighting designer, or architect or electrical engineer if they wish.

M.A.: go for the inch minus and don't pick out the inch. Try grabbing a few buckets of that inch,x9 fill a bag, sew it closed with some wire, tamp it solid and cut the bag off. You'll see that it's all locked into place. I've removed enough to know the larger stuff is what you want.
You could always look for a screen at scrap yards, landscape yards, etc. Pretty handy for plaster too. But best to get it already screened. You could ask your supplier of they have a 3/4 screen, but I get a lot of inch in my 3/4.

William: you're correct, the fines block out the insulating voids.

Billboard tarps off Craigslist or ask around. Cheap, big, grommets, durable.
Anything else is too expensive for large size, or easily destroyed by UV or winds.

1. Yes, it'll be plenty strong enough, just lay it tight, plumb, running bond, leave some wall between openings or carry with decent framing if you slam openings together, etc. That's a tiny roof on thick round walls. I much prefer 3/4" aggregate for serious structural scoria bag. I use 1/4" scoria for lightweight concretes. Try to find a bigger size if you can. If not, you'll be fine at your size and roof type. And make sure they screen the fines out!
I suggest Considering making it bigger than 12' diameter. If you are gonna go through the steps of foundation, bag, plaster, roof, plumbing, wiring, doors, etc, a few more foot diameter ain't much more work and it's much more enjoyable. I know you're going tiny, but my original 25' interior diameter scoria bag dome just keeps getting additions on all sides...

2. R value--i think that's a joke of a rating for Owen Corning to validate their fiberglass in a perfect lab conditions. But wind doesn't blow through 16" of scoria bag, nor does humidity degrade it's thermal performance. Temperature doesn't change it's performance like foams. And it is hard to improperly insulate the scoria bags.
I think scoria bag performs comparably with strawbale laid on edge, although the scoria has a lower R, it has a mass enhanced insulative value. Yes ideal to separate and outsulate in exterior wall/roof systems, but it works great (kinda like ICF works great). Not looking to argue this with anyone who hasn't lived in one, they never get it... I'm in a colder climate and proud of it's thermal performance.
Your build is small, it'll take nothing to heat. Some passive solar and a small stove of sorts. I prefer wood stove and operable windows. Small cheap round buildings is where scoria bags shine in my opinion.

3. Challenges.. 25' interior diameter dome is rather challenging. The other 4 scoria bag projects were straight forward. Youre round, but if others are reading, corners on straight walls can experience slump if not planned for. Don't get delivery via belly dump. I love plastering, I do some stucco side jobs I enjoy it so much. Most prefer to drywall just because.. Just know that. Have fun. I really like scoria bags (and strawbale, and brick/blocks and ferrocement and rammed earth with a tractor). Earthbags are more work, and tires or hand cob are much more work. Scoria bags hit the sweet spot with cost, speed, ease, insulation--if locally available. The only other suggestion is rammed earth with a tractor and straight walls since you are building so small with a shed roof, if you're find a pocket of right dirt.
4. Haven't noticed any mice in walls or bags. Just detail it well.

I'm not aware of any projects doing this, but I think that it is an awesome combination. The closed cell spray foam blowing agents being used in the last few years (solstice and similar) have a much much lower footprint. By grabbing a complete air and vapor barrier on the exterior, and seamlessly insulating the exterior of all that mass, that house, properly designed and built, should have a tiny heating/cooling load for a very long time. Stucco over spray foam over Adobe is very popular and successful in northern NM. Stucco over SPF would keep all insect, UV, fire away from the  SPF. In your climate, I'd just keep the inside as your breathing side. If you can afford it, it'd be awesome. I do know of exterior rigid foam over EB.

Joseph Lofthouse wrote:The foundation of a building should be the strongest thing in the building, instead of the weakest. Doesn't seem prudent to build a stone building on a plastic/clay/sand foundation.

I bet 99% of stone buildings were over lots of clay/sand. All but those over bedrock.

If he excavated Adobe to pour a concrete foundation, there will still be Adobe underneath his concrete. His proposed grade beam over the earthbag wall is a good jumbo foundation, not chincy....

Many unreinforced stone masonry buildings succumb. So do reinforced concrete. So do earthen. So do framed. A well built earthbag foundation, wall or roof is nothing to sneeze at. Especially comparatively.

People do masonry over wood, everyday, everywhere. I think they are nuts, but it is done. Different expansion rates and wetting tolerances and elasticities. That doesn't seem prudent.


If moisture is dealt with appropriately, a good rammed earth wall can carry way more weight than he's taking about.

nick bramlett wrote: I'm 45 minutes outside of atl ga. Humid and hot. 50 inches rain/year. Sandy clay soil. Plaster inside, no plaster outside, just a couples sheets of polypropylene sheeting and the back filled with same sandy clay. Bags would also be filled with sandy clay. Single heavy duty 18x30 bags. Thinking of making earthbag section a 12x16ft oval meeting up with 12x16 oval stone which squares up to 12x16 rectangle as it nears roof.

Nick, hey I forgot to check back on your forum post. My building experience is not in your climate. But I believe a few things with regard to your climate:
1. Insulation needs to be on the outside of your basement mass walls/floor to prevent dew point and moisture from condensing there. I believe this is a big reason for many moldy earthen projects above grade and basement funk.
2. Grading
3. Drainage
4. Backfilling basement with clean aggregate, appropriately sized. Not backfilling with clay.
Is your clay expansive, does it crack it slabs and basements and block crawlers in your area?
5. Mechanical ventilation or drying in basement.

Should all be pretty standard in your area.

6. I still stand by ICF basement under your stone hut. Hey it's 12x16. 14 block per course if you cut and glue your corners. I could have stacked them in the time that I spent typing this out. When it's all done, that is just a drop in the bucket

7. Hey I love good mass in a house. I also appreciate exterior insulation. If your dead set in single wythe stone exposed on both sides, then some diy icf downstairs might be welcomed for a number of reasons.

8. Your water table sounds like it could rise in a heavy rain. then again, I don't know your topography or drainage plan. Maybe I just see too many areas flooding in the news recently.

It could work, I stand by it. And I have high levels of acceptability. Depends on lots of site and construction details. I could bang it out and sleep soundly down there till the day I die. But considering all this talk of diy squinching an oval footprint into a a rectangle, already using concrete in your grade beam, high humidity, rainy clay area, high water table, clay backfill, guess work, I'd suggest you to just pour icf, I would without a thought if I was out your way. Then deck over that and be happy. Backfill and grade correctly. That icf won't cost much; over it's lifespan, it's footprint is justifiable, moreso than a slab. But I'm of the 'concrete for walls and roofs rather than floors' mindset. That's my free advice from a nut builder hanging around this forum. And I love earthbag, don't get me wrong.

To me, an earthbag basement is like an earthbag dome, awesome is the correct setting. Many materials can be used awesomely and correctly, but materials are also often used in situations when better options exist for that particular set of conditions, a trade off typically due to cost, time, availability, labor, ideology...

Or if you really want to have an earthbag basement, then have a good mix, , good high site, good drainage plan, and good backfill, and be prepared if you need mechanical ventilation or dehumidification.

If the basement is too daunting, rubble trench that clay and grade beam, and don't look back.

I like Glen's point about moist sub grade earthbags creeping under load over time. Aside from flood, I think if you have that kind of moisture, you would have serious mold issues already. I also think his honkin grade beam would not produce much creep. Plaster cracking due to wall creep settling don't really seem like an issue in eb, sb, re, Adobe, or tire construction. I haven't seen any. Not like drywall cracking, etc... Wood moves way more, though that's more a hygro-thermal deal. Plaster cracking in these wall methods is typically from lack of shear, or lack of reinforcement around windows/doors. Or bad mixes, attachment, cure, freeze thaw, weathering, etc. Plaster cracks in settling earthen walls would be apparent. Never saw any in the pueblos. Heck, the adobes under lake Mead look good still.

It could work.
If it were me, I'd consider climate, soil composition, moisture, topography, access to suitable earthbag fill, and the loads that it carries ( eg. 12" thick single wythe stone masonry, one story tall, etc). We're you thinking about plastering the exterior side of the EB, backfilling with drainage stone, or adding a membrane?
I'm not an engineer but have a good working relationship with EB. If you want free structural and construction advice, then what are your structural conditions, anticipated basement uses, priorities, resources?

(depending on reasonable soil conditions, I'd be comfortable doing what you propose, with regular 50lb bags, however there are larger sizes... If soil conditions, climate, no termites, swayed me, I'd also be just as happy with icf for the basement which depending on your stone wall thickness, could be only 5-7 times the concrete as your 12"x18" bond beam...)