Earth Plaster and some questions

[Beavers]

I've always planed on using pine boards for the ceiling in my house, but haven't really decided what to use on the walls.

I'm giving earth plaster a try.  I put some lath up on one wall to do a small test patch.  If I screw it up or don't like it shouldn't take much to tear it out.


I didn't use a trowel, just smeared it on the wall with my hands.  I though I had it mixed up pretty good, but discovered I had a bunch of marble sized balls of clay in the mix.  I'm going to try soaking the clay in a bucket of water overnight before I mix the next batch.  Hopefully the clay won't ball up as bad.

Not sure how thick the first coat is supposed to applied, it ended up about a 1/4" thick.  






Here is a shot of the backside of the wall.  Do I have enough "squish through" or whatever the technical term is?  





The exterior walls are standard 2x4 construction with fiberglass batt insulation, and then covered with a layer of 1" foam board insulation.
Can I add furring strips and then lath over the foam board?  I wouldn't think I would have to worry about moisture getting into the insulation doing it that way.  





Any other tips or thoughts from anyone who has done this before would be greatly appreciated!    

[MikeT]

Is this the American Clay product?  We used that on our house and really liked it.  Of course it was only one wall and essentially as an accent wall.  I can't comment on the lath.  All I can say is we liked the workability of the product and the textured appearance when it dried.  We also liked that with an imperfection (that we didn't like), we just added water and went over it again.

[Beavers]

Is this the American Clay product? 

My soil has a ton of clay in it, sucks to dig in, but should work great for earth plaster.  I just mixed in sand and water to make this batch of plaster. 


Glad to hear you like how yours turned out.  What did you end up using for a finish on the wall?

[MikeT]

We just added some color mixture to the clay/plaster and let it dry.

[glenn kangiser]

You might add straw and sand if you get too much cracking, Beavers.  Looks like you got the sand I see.

Lime helps too- makes it sticky.  You can add Henry's 107 to help bind and waterproof it it you like - around 5 to 7%

I did some with wire stucco netting about 6 years ago - still good.  Wood lath is more authentic.  Looks like you are doing good.  Please update us as you progress.

I think your furring strips and lath would work fine.

[Ernest T. Bass]

Perhaps you've already thought of this, but I'll share my personal experience w/ earth plaster and baseboards... Unless you plan of troweling the walls perfectly flat, which is nearly impossible, you may want to attach a "sub" baseboard at the bottom of the wall before you plaster. Something like a 3/4 x 2, so that you can run run your trowel against it and make the wall perfectly straight and flush down there...

Looks good so far! We added some chopped straw to our scratch coat, though. Makes the wall a lot tougher.. We have yet to break through a wall, and we've had some good impacts!

[glenn kangiser]

Tossing your little brother around again, Andrew? 

A family version of midget hurling?

[speedfunk]

Looks good beavers!!  we to are going to use some earth plasters.  The american clay is VERY expensive... Good job on doing it your self.  You bring up a good point being that if is doesn't work quite right it's not hard to remove. 

Look forward to the progress of the walls..
peace
Jef

[Ernest T. Bass]

Tossing your little brother around again, Andrew? 

Nah, he throws himself around... You can't keep the little archeologist strapped down for two minutes...

[Beavers]

Thanks guys.

If the test wall turns out good, I'm going to have to use something other than wood lath...big $$$ to do the whole place with that.  They make plastic stucco netting too don't they?  Think that would work, or would the metal stuff be better?

Every earth plaster recipe I can across called for adding something different to the basic mix...manure, wheat paste, borax, ect.  I figure I don't know enough about it to know what to add and what not to, so I just did the most basic mix.  If my test patch cracks up bad, I'll redo it and try adding some straw to the mix. 


Thanks for the tip on the baseboards Ernest.  Do you do the same thing around windows and doors, or is there another trick to that?

Speedfunk,
Are you going to be plastering right over your concrete blocks? 

[Ernest T. Bass]

We were kind of unconventional with our interior doors and window trim.. We made the jambs extra deep so that they protrude about an inch beyond the plaster, into the room. The plaster is just troweled up to the edges of the jambs... The best way to do that would be to put a groove around the jambs so that the plaster has something to key into, or some wire lath stapled around to make the wood-to-plaster connection..

Our mix was pretty basic.. We used manure for a finer texture in the finish layers. Borax is a good idea to reduce mold growth. We had several walls that molded quite badly, and even had grass growing out of the plaster from the wheat straw. Once everything dries out it's all fine though. You just have to accept the sarcastic comments from your neighbors for a couple weeks. Think lots of ventilation; keep the air moving..

[Don_P]

You've described plaster "grounds", they were also used around windows and doors back in the days of true plaster .
Plaster was just earth building in its' time. The bricks were also often made on site. There were 2 lime kilns nearby that burned and crushed the rock. Slaking often occurred in a pit in the front yard. Lime mixed with water and spread will over time absorb CO2 and return to calcium carbonate, limestone.

There is one story that by royal decree the fireplace in peasants cottages could not be built narrower than 2 bricks, this resulted in 16" firewood being common. In the winter as a peasant was feeding the fire any nice straight grained chunks were split by the fireside into plaster lath to finish the inside of their homes. Made sense to stud up the walls on 16" centers.

[glenn kangiser]

They make stucco lath that is chicken wire over building paper - already attached and ready to use.  It works well - rough guess about $70 for a 3'x 100' roll.  There is also light expanded metal sheets for stucco that will work.  

I can cut tons of them fast on my sawmill but that doesn't help you.  Cutting them (wood lath)with a skill saw or table saw is a bit slow but works.  The Native Americans used limbs - twigs - reeds etc.

[Beavers]

Thanks Andrew,

I really appreciate all the first hand knowledge!  Did it work ok just butting the plaster up to the jambs or does it pull away at the edges?

I was planning on letting the first little patch of plaster cure before I did any more work, but I just couldn't help myself.  I ended up plastering the rest of the wall today, it's just too much fun playing with mud. 

I think I've got to bottle this stuff...all this playing with mud, and my hands are the softest they have ever been!    Seems like I could get big bucks for that kind of moisturizer! 

I did add a little Borax to the mix today.  I figure even with keeping the windows open, it might be nice to have a little extra protection from mold while it dries.

Don_P,

Thanks for the history lesson...interesting stuff.  Is that really why we ended up with 16 oc studs? 



Glenn,

I'm not sure if it's a technique thing or what, but I've had a hell of time getting the mud to stick to the lath.  It sticks like crazy to my hands, but not as good to the wall.  Do you think the lime would help that?  And where do you get lime?

author=glenn kangiser link=topic=8606.msg111725#msg111725 date=1268617954]
I can cut tons of them fast on my sawmill but that doesn't help you.  Cutting them (wood lath)with a skill saw or table saw is a bit slow but works.  The Native Americans used limbs - twigs - reeds etc.

Thanks for the idea!

I've got a whole pile of weathered 2x4's sitting around that I used for forms with the concrete piers.  Might as well get started on ripping them down.
Can't be any worse than ripping 1x12 cedar into 1/4" strips for canoe building. 

[glenn kangiser]

You can get hydrated lime at a lumber yard in the cement product area.  It is powdered and is used in mortar mixes for bricks etc.  There are a couple types but I didn't worry about it too much as I didn't have a choice.  Dump it into a barrel of water and let it soak - it keeps there forever - there has been thousand year old lime found in Italy I think it was - still good and as I recall it was somehow still wet.  I keep it in a 55 gallon drum - just keep excess water over it band a lid over it.

The water can be used to prime earth plaster areas - wet the wood etc.  Just add more to cover the lime - You could get started with a few bags - then dip out a shovel full or so per batch.  Wetting the wood will likely make the plaster stick better - damp - not dripping.  Lime will help also.  Henry's 107 in exterior applications is also real sticky.  The smell goes away soon.

http://www.papercrete.com/

Likely you will find lime info there also.

Some lime info and experience here.   http://www.papercrete.com/sept02.html

Free book download or read on line - check out chapter 8 for lime plaster recipes then just adapt the ideas to your mud plaster with lime added.  In general just studying this stuff gives you ideas for your experimentation.  Straw can substitute for hair or you could use fibermesh when down to wanting to get a finer finish. I like the coarse earth plaster with sand and straw - it is a cool look.

http://books.google.com/books?id=XH06AAAAMAAJ&printsec=frontcover&dq=lime&ei=nrOdS-DaKI3ilQTCze3iCQ&cd=20#v=onepage&q=&f=false

Unlike the old lump lime the hydrated lime can be used immediately but it works better if you store it as paste in a barrel as I mentioned.

Use rubber gloves with the lime to keep from getting burns - and keep it out of your eyes.

Cutting down both sides of each strawbale string or wire before cutting them, with a sharp chainsaw will give you shorter straw for easier plaster work.

Mud plaster likes to stick better to damp mud plaster anyway.  Too dry and you have to coat it with slip clay to get it to stick - also don't smooth the coats too well before the final coat - it sticks better.

[glenn kangiser]

More old lime info - many free downloads


http://books.google.com/books?as_q=lime&num=100&btnG=Google%20Search&as_epq=&as_oq=&as_eq=&as_brr=1&as_pt=ALLTYPES&lr=&as_vt=&as_auth=&as_pub=&as_sub=&as_drrb_is=b&as_minm_is=1&as_miny_is=1800&as_maxm_is=1&as_maxy_is=1950&as_isbn=&as_issn=

[Beavers]

Thanks Glenn, a ton of good info there.

I read through most of the 1915 book that you linked...learned a lot.
There are actually some limestone quarries in the area, would be cool to get some limestone and do the whole process on my own.  One of these days when I have more time to play.

If I understand it correct, the clay and lime both do the same basic job when mixed with sand for plaster?  The lime would make a stronger more durable product, and when added to an earth plaster, strengthens it, and might even reduce cracking?  

Once mixed into the plaster does the lime loose any of it's kick, or do you still need to wear gloves when handling it?

Is there any rule of thumb as to how dry the first coat has to be before you apply the next coat?  Thanks for the tip on smoothing too much, I've been trying to get it as smooth as possible.  Still trying to sell the Mrs. on the whole idea, so I was trying to get it looking as nice as possible.  

Thanks for all the help!  I've been able to find a lot of earth plaster stuff with Google, but nothing really gets in depth on the topic. 

[Ernest T. Bass]

We tried to apply the next coat before the first had completely dried out, but we often moistened the walls with water before recoating--make sure you leave the sub layer good and rough for a better connection. I think the wheat paste is supposed to make things more sticky.. We used it often.

I do remember having a little trouble getting the first layer to stick to the lath at times... You end up getting a lot of mud on the floor.. A good scraping motion (and not worrying too much about uniformity) and some chopped straw might help there. We chopped our straw in a garden chipper/shredder, but Glenn's method or a lawn mower with a bag might also work.

We never added any lime to the plaster mix itself, but we did use it in our paint. We're still not real happy with the water-proofness of the paints we made, so we plan on doing some more experimenting with lime..

No, our plaster isn't pulling away from the jambs, but it just would have been stronger with the key grooves, especially if we didn't have much fiber in the mix. Actually, quite a few of our doors were installed after the plastering. We had just left the plaster edges rough around the framed openings. We still need to mix up some more mud and do some detail plastering around a few jambs, but it would be good to do that right before we re-paint for color uniformity.

Here's a lot of really good info on earthen plasters:
http://www.thelaststraw.org/bonus-articles/earthplaster.html

[glenn kangiser]

That is pretty much it.  Plain plaster was used in the old houses then sheetrock came along.  Gypsum mud sandwitched in paper to make a commercial mud wall to sell to the consumers who pay lots of money for it.  OK - so it is a lot easier but who wants easy.  We are tough and gluttons for punishment....

Lime improves the qualities of almost any earth plaster or lots of other earth building projects.

I also would like to burn limestone rocks for plaster and make bricks out of the local soil as they did in the gold mining days.

Even the mud will suck all of the oil out of your hands and make them dry but the lime can possibly burn them even in the mud.

[Beavers]

Thanks Andrew, and Glenn, I really appreciate all the help!  

I got a bag of lime today, going to try adding it to the finish coats of plaster.  
The book that Glenn posted shows the "Lime Cycle"...pretty cool stuff...the lime starts as limestone, is burned to make lime, is mixed with water to make mortar/plaster, and then when dried returns to the original carbonate form as it started...limestone.   I like it, dig up a rock, burn it, soak it in some water, mix it with earth, then smear it on your wall, and it returns to rock.

I've been adding buckets of clay and water to a large tub to try and dissolve the clay, and get rid of the chunks.  Discovered after reading some of the links that I made clay slip.  I was thinking of painting the slip onto the lath to make the plaster stick better.  Think it would help or not?

Thanks for the link to The Last Straw Andrew.  There is a lot of good info there.
Cool thing is they are based out of Lincoln, Nebraska...only 45 minutes from my house.  Also found out some of the first straw bale houses in the US were built in Nebraska.
I always thought that Nebraska was a bunch of conservative type folks who never tried anything new.  Guess I was wrong.  

[Ernest T. Bass]

Glad you enjoyed the link.. I've read through it several times and would probably learn more if I did it again. Can't tell you about priming lath with clay slip... Couldn't hurt to try; you're all covered in mud by now anyway, right?

[glenn kangiser]

The lath should be damp according to something read.  Slip couldn't hurt.

http://www.strawbale.com/making-your-own-hydraulic-lime-on-the-cheap

Interesting article and discussion.  Hydraulic lime takes a set a bit more like portland cement.  I also read about 10 days between coats with normal lime on the below site I think.

http://www.stastier.com/

[Beavers]

Turns out you really do need straw in the scratch coat. 

As the plaster has dried some it's developed big cracks, and is pulling away from the wall at the cracks.  I peeled it off today before it hardened too much.

Going to give it another try.  Should be more successful this time now that I know a little more about earth plaster.  I kinda jumped into this project without doing all the research first.  Oh well gotta learn the hard way sometimes!

[Ernest T. Bass]

I kinda jumped into this project without doing all the research first.  Oh well gotta learn the hard way sometimes!

That's right! Too many times I'm afraid to start a project for lack of a clear image in my head of the finished product, or uncertainty of the process I wanted to use, etc. Much better to jump in and get your hands dirty, make mistakes and fix them, rather than hesitate to do anything at all..

[Sassy]

We tried different "recipes" - some worked really good & others didn't.  When you can use your own clay & not spend $$$$ on some company's product, it's worth experimenting to see what's the best combination.   You have to be much more careful for walls that will be exposed to the elements outside or for floors that get a lot of traffic.  We had fun doing it