THE MUD HOME
  • Home
  • Building
    • Earthbag
    • Living Roofs
    • Gravel Foundations
    • Off-grid how to >
      • Off-Grid Prep Course
    • Earth Plaster
    • Mud as Mortar
    • Wattle and Daub
    • Lime; Hydrated, Hydraulic, and Putty
    • Mud Building Blog
  • Books
    • Dirt Witch
    • Mud Ball
    • Mud Mountain The Book
    • An Earthbag House in 7 Days?
  • About
    • Contact
  • Learn Mud
    • Courses
    • Mud Building PDF Package
    • Other Projects
  • Earth Whispering
    • Join the Earth Whispering Exploration
    • MUD MOUNTAIN

Considering going off-Grid?

Sign up for the mini course

When to Use Clay? And When to Use Lime?

9/12/2019

2 Comments

 
As you probably know, I’ve renovated two tiny stone huts this summer. They began the year as abandoned, poop-filled, caves. Now? Aha... The transformations were surprisingly inexpensive too, because a) I did all the work myself, and b) I'm predominantly using two very inexpensive materials: clay and lime. But can you use either in any situation? And why did I choose lime in some places, and clay in others? 
Picture
Before.
Picture
After.
As far as the cost goes, both are inexpensive. Earthen plaster is almost free to make. The only cost is the sand, which is about 4 euros for a 25kg bag. Lime costs marginally more (6 euros for a 25kg bag, and that goes a long, long way). Both have other pros and cons. Having worked with the two extensively now, in both hot, dry Turkey and cool, wet northern Spain, I’ve learned when to use which, and why.
Picture
Earth plaster window frame.
When to use lime
 If you have a lot of damp to mitigate, mould issues, or some burrowing termite-type trouble, then lime is unbeatable. Even the resourceful, genius of mice teeth hesitate before lime render. Lime is potentially harder than clay plaster, but interestingly, it’s not necessarily stronger.
 
Lime also works better (in my opinion) if you have a pre-existing stone structure and need to refill the mortar. It’s hard to get a decent earth plaster mixture in and out of a mortar gun.
 
Lime Pros:
1. Lime can handle plenty of damp.
2. It’s an insecticide. Lime deters termites and fire ants.
3. It’s a fantastic fungicide.
4. If you have damp issues, lime is the way.
 
Lime Cons:
1. Not as easy to sculpt (though you can etch it into shape).
2. It’s caustic, so less of a joy to use than clay (but still much nicer than Portland cement).
3. Lime isn’t hugely load-bearing (I wouldn’t make a supporting wall out of limecrete, for example).
Picture
Lime render.
When to use clay
 Clay plaster is much, much better for sculpting. It has a wonderful elastic quality that holds its shape beautifully, and once dry is ridiculously tough. I had one heck of a job bashing down a bit of my cob spice rack, for example. (Video) Earthen plasters are also wonderful to work with. Everyone feels happy when they build with mud.
 
Earthen plasters feel warmer too, and although earth is not an insulator, it's still better than Portland cement or stone (Cob has an R value of around 0.5 per inch compared to 0.08 for poured concrete). If you make your plaster very straw-heavy, that R value can increase. Yes, I know half the natural building world will disagree with me, because they are all obsessed with the fact that earth has thermal mass. But in my experience, it ain’t quite that simple. I’m not the only one who has noticed that earth-plastered walls are way warmer than stone or concrete ones. especially in the damp. Mud is magic.
 
Clay Pros:
1. Lovely to work with.
2 Cob has structural strength.
3. Clay plasters are warmer to the hand, eye, and soul.
 
Clay Cons:
1. Clay doesn’t love the damp, and can sometimes go mouldy.
2. Clay and earthen plasters usually take longer to dry out than lime in wet climates (though some have had the opposite experience).
3. Clay expands and contracts when it gets wet or dry, which can cause issues.
Picture
So what did I do in my huts then?
1. My bedroom hut is semi-submerged in the ground. In fact, one side is built out of the rock of the land itself! I could see there would be damp in one corner, so I used lime render and lime paints in those areas.
2. I used clay plaster on all the other areas because it felt warmer. I used clay plaster for sculpting sills and shelves, inlaying mirrors, and embedding windows.
3. I used limecrete on one floor because again, the flagstones were directly on the ground and prone to damp.
4. I used lime mortar between the stones, but earthen mortar to build a wall from scratch.
Picture
Lime and clay performing together.
So there you have it. We live in an adversarial world where things are idiotically pitted against one another. But it’s not lime versus clay. As with most things in life, the two actually perform beautifully when they’re doing a cha-cha.

Remember lime is caustic

Lime is a natural substance, but it is caustic and can burn. Make sure you are protected properly before using it. Read the health and safety guide to find out more.
How to Use Lime Safely

Links

My flagship digital earth plaster course
http://www.themudhome.com/earthplastercourse
The Mud Home Amazing World of Lime Course
https://the-mud-home-courses.teachable.com/p/the-all-about-lime-course

Do you enjoy The Mud Home?
If you find these articles inspiring or useful please consider joining us on Patreon. Your support pays for the running of this website, my virtual help, and my sustenance. A big thank you to all The Mud Sustainers, and everyone chipping in and keeping these posts and articles coming.
Join us on Patreon
2 Comments
Peter den Hond
30/5/2022 01:08:26 pm

Thanks for detailing that out for us.

Earth plaster going moldy is new for me. Earth buildings in foggy Lima, Perú winters stay mold free in my observations.

But I can imagine that it's different with under ground stonework. There I can imagine that a living space heated with a wood stove can keep the lime dry enough to make life impossible for mould and fungus.

You als write: "4. I used lime mortar between the stones, but earthen mortar to build a wall from scratch." I guess that has to do with the ease of lime mortar application between existing stones. I also have good experiences with building stone walls with earth morter. Amazing how well it sticks! If you can keep it away from running water.

Reply
Atulya
7/6/2022 01:47:52 pm

Hello Peter, just saw this! Yes clay plasters can sometimes get mold when damp. I'll show mine in the next Patreon video and explain more about that.

Yes wood burners are the way for sure.

""I used lime mortar between the stones, but earthen mortar to build a wall from scratch." I guess that has to do with the ease of lime mortar application between existing stones. I also have good experiences with building stone walls with earth morter." Yes I also built some stone walls with earthen mortar here, and they're great. I meant repointing existing stone walls. It depends how picky you are about how neat you want your mortar, but clay mortars don't work well in mortar guns.

Reply



Leave a Reply.

    Many thanks to the Mud Sustainers supporting this site!

    List of Sustainers
    Picture
    Do you find The Mud Home valuable? Please consider supporting the blog on Patreon. For as little as $2 a month (not even a coffee where I'm from), you can join the club.
    BENEFITS FOR PATRONS INCLUDE:
    Email priority, private Facebook group, review copies of my books, sneak previews of courses and books, Q and As, priority for courses and more.

    Author

    Atulya K Bingham
    Natural builder and author of Mud Ball.


    Picture
    "Beautifully written and inspiring." The Owner Builder Magazine

    FREE!

    Picture
    If you want the step by step guide of how I built my house, sign up for the PDF.
    WHY NOT? IT'S FREE!

    Categories

    All
    Adobe
    Building Codes
    Building With Wood
    Cob
    Composting Toilets
    Earthbag
    Earthbag Mistakes
    Earth Plaster
    Foraging
    Hobbit House
    House Renovation
    Insulating Plaster
    Insulation
    Laying Earthbags Faster
    Limecrete Floor
    Lime Plaster Issues
    Natural Floors
    Natural Roof
    Off Grid
    Permaculture
    Roofing Options
    Stone Houses
    Straw Bale
    Sustainable Building
    Using Lime
    Wattle And Daub
    Yurt

    RSS Feed

    Picture
    Join the free Mud Home earth plaster mini course.

    Picture
    All the Mud Home How-to posts have been compiled into a PDF package with 75 articles and over 200 photos. You can still buy it now, and enjoy lifetime access to all the updates.
    PDF Contents

    My latest book is now out!
    Picture
    “Entranced! Be inspired by one who’s lived and breathed dirt.”
    Kim Fraser, Get Rugged
Disclaimer: All the content in The Mud Home website is provided for informational purposes only. The author undertakes no responsibility for any person or entity who chooses to use the information on this website. It is not intended to be a standard and should not substitute for the exercise of good engineering judgment by engineers. It is the user’s obligation to make sure that he/she uses the appropriate practices and consults the appropriate experts when building. It is the user's obligation to make sure they are following health and safety guidelines. The author is not responsible for any accidents, injuries or damages to persons or property incurred while using the information presented in this website.

Some blog articles refer to the use of lime. Please note, lime is caustic and can cause burns. Read The Mud Home guide to using lime safely here.

EARTHBAG BUILDING PDF
EARTH PLASTER GUIDE
BOOKS
Newsletter
About Atulya
Privacy Policy

SUPPORT

Picture
Picture
The Mud Home takes many hours a week to run, and costs a lot to sustain. If you find this site useful or inspiring, please consider supporting it so that it can continue.
Picture

Many thanks to all those who've already become Mud Sustainers.

The Mud Home  Copyright © 2013  Atulya Kerry Bingham
  • Home
  • Building
    • Earthbag
    • Living Roofs
    • Gravel Foundations
    • Off-grid how to >
      • Off-Grid Prep Course
    • Earth Plaster
    • Mud as Mortar
    • Wattle and Daub
    • Lime; Hydrated, Hydraulic, and Putty
    • Mud Building Blog
  • Books
    • Dirt Witch
    • Mud Ball
    • Mud Mountain The Book
    • An Earthbag House in 7 Days?
  • About
    • Contact
  • Learn Mud
    • Courses
    • Mud Building PDF Package
    • Other Projects
  • Earth Whispering
    • Join the Earth Whispering Exploration
    • MUD MOUNTAIN