Natural wall options for a renovation?

Hi All,
What are some good materials or wall systems that are natural and would work for an existing house?

I'm looking at possibly buying an old abandoned house. It will need some serious renovations and since I will probably have it down to the studs... I figured it would be good to put some natural materials back up. What are my options?

Maybe things like...
wood clapboard siding?
wood boards?
wood shingles?
lathe and plaster?
plaster with an overhang?
hempcrete?

Looking for options for inside or outside.


I'm not sure cob or logs would be good for a retrofit?

I just did lathe and plaster on a conventionally framed and insulated wall and really like it. Ripping lathes was kind of a pain but the plaster came out great. I've heard that you apply and earthen/lime plaster but never tried it myself.

I also like wood shiplap for both interior and exterior but you're right that a good roof overhang is key any natural finish.

If you are going to be doing any long rip cuts for lathes, do yourself an IMMENSE time and labor saving favor and get a cordless track saw, with track saw guides,  track saw guide rail clamps, and a track saw guide square.

Add a big piece of sacrificial foam  to cut it on, kneeling on the ground, and you'll be cutting ten lathes a minute, all uniform, and with no heavy lifting and a minimal  danger of kickback like from long rips in a table saw.

Obviously, the longer the lathes you can cut, the better. I recently cut two 1/8 inch wide six foot long pieces of flooring with my track saw to finish a room.  

It's not a cheap tool with all the accessories, but it works a lot better/faster/cleaner  than a circular saw with a guide and it totally chumps the table saw in terms of effort and ability to do it right there.

Get whatever brand you already  have the batteries for, all the cordless track saws are pretty good- as long as they have a riving knife.  

Those long rip cuts drain hard on batteries, so if you don't have batteries with 5 or 6 amp hours, get one.

Jeff

something i have been thinking about lately is the feasibility of retrofitting old interior walls with light clay straw.
of course in a new build its a different matter because you are starting from scratch, but when dealing with an old house already built, what is built and the way it works may not be immediately apparent...if you could just replace old walls with light clay straw.

sorry i have more questions than answers, but something to think on.
as far as i have gotten in my thinking is there may be a weight issue, but as long you have a sound foundation, interior walls should not be load bearing etc...i think the weight would be ok in most situations, if you would be inclined to it. to me it seems like very similar to lathe and plaster only cheaper and easier, more insulation and sound proofing....although maybe even more time consuming.
i suppose you would have to like the look and feel of earthy plaster walls though, and there are some small issues like its hard to hang pictures or put up shelving etc into a fully plastered wall..as well as where the wires/pipes/etc that may need to go through the walls, but there are ways around these things, like putting in a pipe to carry wires, or attaching wood pieces to places where you may want to hang something up, so it can be attached to the wood, like say shelving or hanging a picture.

edit to attach some links, in case you arent familiar - some random google recs
- https://www.greenbuildermedia.com/blog/the-advantages-and-appropriate-use-of-light-straw-clay

https://www.youtube.com/watch?v=FfbML5qHpu4&ab_channel=RoadrunnerFlats

How's the roof of the house? What material, and will it need renovation as well? How much roof overhang will you have?

I've got my head full of cordwood walls at the moment, since that's what we're planning for our cabin, so far no direct experience, though. But they sure are pretty...

The roof is currently shingles and will need to be replaced. Not much of an overhang, but thought about adding more of an overhang regardless of the siding option.

If it's not a monolithic wall.. I'm a little stuck on the inside. Pine boards everywhere is a simple choice... but that is a lot of wood... I like wood, but I'm just not sure I want that look in every room of the house. I'm really trying to avoid sheetrock if I can. So that tends to bring me back to some kind of plaster or boards.

leila hamaya wrote:something i have been thinking about lately is the feasibility of retrofitting old interior walls with light clay straw.
of course in a new build its a different matter because you are starting from scratch, but when dealing with an old house already built, what is built and the way it works may not be immediately apparent...if you could just replace old walls with light clay straw.

I think light clay straw(LCS) in interior walls is a great idea. LCS is great for sound deadening. Downside with a retrofit if you might have to adjust your electric boxes. In conventional home boxes are mounted 1/2" or so proud of the studs to accommodate for the thickness of the drywall. So, you would have remount each electrical box flush with the studs and then use a mud ring to fur it out to the depth of the the plaster. Also, you need a mechanical key to the stud bay to "grab" the LCS. I typical fasten a 1 x 2 running lengthwise on each side of the stud.  

Magnesium Oxide panels are a natural alternative to drywall/sheetrock. They are made from magnesium sulfate and do not contain fly ash, formaldehyde, crystalline silica, or toxins.

I've seen this installed in a house, and it looked nice. I hope to use this on a future build.

MagOx panels are mold-resistant, fire-resistant, and do not provide a food source for termites, carpenter ants, or other wood boring insects.

It comes in a variety of thickness. It adds an insulating factor for sound and temperatures.

It can be used indoors or outdoors.

Here's the website, if you'd like to learn more: https://www.magpanelmgo.com

Good on you Matt for thinking about making an older building better!  Most of us who use more natural building materials to make energy efficient buildings have focused on new construction, but there's a much larger opportunity in renovation and remodel work in the U.S.  Housing stock in our country is "replaced" at the glacially slow pace of between 1% and 2% each year.  If we're to make all of our buildings more energy efficient as quickly as possible we can't wait 100 years for all of the existing stock to be replaced--we need to make older buildings better, and we could do it with more natural building materials.

I think using light-straw-clay for insulation in your exterior walls isn't a great idea.  At 12" thick LSC has a resistance to heat flow of only R-21, which may not be adequate for your location.  Apart from being quite heavy (15 lbs. to 20 lbs. per cubic foot), a 12" wall thickness would require a second sill plate interior of the existing one, which places much of that weight over flooring that may not be supported by either a thickened slab or floor joist.  If you're working over a basement or crawl space you may be able to remedy that.  In any case, assuming the existing building's walls are made with 2x4 or 2x6 studs, you'd be losing some interior floor space to thicker walls.  Just filling the existing 2x stud bays with LSC gets you to less than 1/3 or 1/2 of R-21.  

Although not completely "natural," you might consider hemp wool, sheep's wool, or cotton batt insulation. They are all comparable to fiberglass and rockwool (R-3 to R-4 per inch of thickness) but made with much more natural and lower embodied energy fibers treated to resist burning.  All are available in batt form as cavity insulation like rockwool or fiberglass.
 
To bump your wall insulation consider these three options:  

(1) a Larsen wall truss attached (cantilevered) to the exterior walls that functions like a sweater, wrapping the building's body in an additional layer of insulation. This gives you two separate but attached insulated stud walls. Use the hemp wool, cotton, or sheep wool insulation in the stud bays and sheath with siding appropriate to your area. You may need to remount windows and doors into the new exterior wall plane or fuss with exterior sills, reveals, and soffits so the windows and doors are inset into the exterior wall surface--it's a cool look and reduces wind washing (heat loss from air movement against the window surface).

(2) a wood fiber board wrap of the entire building. Many building codes in cold climates now require an R-21 + 5 wall insulation achieved by standard 2x6 wall cavities filled with fiberglass or similar, sheathed with plywood or OSB, then covered with 1" of rigid foam board (R-5 per inch).  A more natural alternative to the foam is wood fiber board like Gutex.  Though it's considerably thicker at 2 1/2", wood fiber panels are still vapor open so moisture can move out of the wall assembly towards the exterior.  Insulating wood fiber panels are very common in Europe and have been available in the U.S. for the last decade or so, but can be hard to find locally.  Similar challenges and benefits as mentioned above when it comes to remounting the windows/doors or dealing with exterior window reveals, sills, soffits, etc.

(3) an offset stud wall to the interior of the existing wall.  Leave the windows and doors as they are mounted on the exterior sheathing (assuming you're not going to replace them) and add an interior sill plate and top plate to the inside of the existing one, place 2x studs offset from existing.  Move electrical boxes to the new interior walls (may need to change box locations and heights as you'll be limited by how the slack in the original cables running to the boxes, and as mentioned above, adjust the box depth for whatever interior finish you're planning to use.  Note that there are adjustable depth electric boxes, but they cost more than regular boxes.  Fill both stud wall bays with whatever mostly-natural batt insulation you like. The offset eliminates thermal bridging, and the extra insulation thickness can double the wall's R-value. But the cost is reduced interior space and some fussing with the new, deeper interior sills, soffits and reveals for windows and doors. Assuming your exterior sheathing (plywood or OSB) is in good shape, use whatever exterior siding is appropriate to your area.  

I like the interior lath and plaster option because it gives you a distributed interior thermal mass--more material to absorb and release heat so you have a more stable interior temperature.  Clay plasters are probably the easiest to work with, and with baseboards installed through the house (and chair rails in the dining area) can be very durable.  In any case, clay plasters are very easy to repair.  Note that the weight of a 1" thick plastered wall is around 15 lbs. per square foot (1/2" sheetrock weighs  a lot less at 1.6 lbs. per square foot!).  If you have a crawlspace or basement you may need to reinforce the floor under the new interior wall so it can support the extra weight.

Eves. Some years ago Fine Homebuilding magazine published an article that described construction features that helped ensure building longevity--sufficient roof overhangs was at or near the top of the list.  The roof overhangs on all of the strawbale or LSC projects I worked on here in S. Oregon and N. California had roof overhangs of at least 2'.  I think you can afford to go with less if the exterior siding system you use has a proper rainscreen (air gap between the sheathing and the siding).

Jim
Many Hands Builders

I'll add that blown-in cellulose is also an excellent nearly-natural choice for wall cavity insulation.  Like the other mostly-natural insulations--cotton, wool, hemp wool and blown-in chopped straw (which is currently available only in Europe), cellulose is treated to resist decomposition and flame spread.  It has a very low embodied energy (which means that not much energy was used to create it) and makes use of a waste product (newsprint and other waste paper).  It also offers outstanding insulation comparable to the batt insulations listed here, and also helps to resist air movement between interior and exterior wall surfaces.  

I have applied an interior wood lath and clay plaster over blown-in cellulose on several projects--the combination offers outstanding insulation and distributed thermal mass.

Jim
Many Hands Builders

I appreciate all the responses, and I have been able to do some deep diving into plaster options, which seems like the most likely option for a renovation like this.

Now, I am trying to figure out, the outside. The roof is a gambrel roof, which does not lend itself to extending the eaves... which means a plaster finish is probably not a good idea. And I am learning about the benefits of having a rainscreen behind the siding.

If I were to do some sort of wooden clapboard siding, a normal rainscreen created by strapping is simple. But if I wanted to use cedar shingles (which is what is on there currently), the only rainscreen I can find is a plastic mesh that is stapled up. Slicker Classic Rainscreen specifically. It looks like it would do the function just fine... but if I am trying to minimize plastic in the renovation, I wonder if there are any other options?

Does anyone know of a natural option for a rainscreen with shingles? Or maybe a natural wall does not need a rainscreen as much as a modern style wall?

There are plenty of houses in my part of the world that don't have a rain screen inside the wooden siding, or if they do it's paper based rather than plastic. I personally think plastic in the wall will do more harm than good, since it prevents the wall from breathing. If you have an impermeable barrier, all the moisture that gets into the wall will stay there, and might create mold problems. I think breathability is key.

If you do want a rain screen inside the wooden siding, but don't want plastic, you could use birch bark. (I feel like I'm recommending birch bark for everything lately, but it is an awesome material!) It's in separate sheets, rather than a continuous layer, so the wall retains breathability, and if the sheets overlap somewhat they will still stop any water that might be pushed through the siding by the wind.

For the siding itself, you might paint it with something pine tar based to improve its weather resistance.

In the UK building membranes are often felted synthetics - breathable but water resistant. So you can have waterproof plastic and breathable....

To avoid a plastic barrier then overlapping layers to shed the water might be enough, depending on your wind/rain characteristics. In my old house (in the UK West Midlands) we didn't even have paper under small clay tiles on the roof and had no issues except for a fine mist in 'really wet and windy' conditions. Here on Skye we have sarking (like floorboards on the roof) waterproof membrane and much larger tiles that overlap by 2/3 and the water still gets in!

Tile hung houses can be very attractive and they don't need to cover all the wall.

(source)

tile hung house in Surrey

(source)

oast house with decorative tiles in Kent

I've always liked much of English architecture. That is a beautiful building.

Just to clarify for people who do not spend way too much time reading and watching about building science... like the OP of this thread... :)

A house wrap is a thin water resistant, sometimes "breathable" membrane installed directly behind the cladding (or siding) of the house.

A rain screen creates a ventilated space behind the cladding, providing a place for water to go and to provide better drying (and presumable longer life) of the siding. I like the idea of a rain screen... but how to create that gap with a bunch of small shingles is a challenge. See the picture below for a roll of the mesh that would probably work. I don't want perfection to be the enemy of good... so maybe this exception wouldn't be too bad :)

Nancy Reading wrote:In the UK building membranes are often felted synthetics - breathable but water resistant. So you can have waterproof plastic and breathable....

To avoid a plastic barrier then overlapping layers to shed the water might be enough, depending on your wind/rain characteristics. In my old house (in the UK West Midlands) we didn't even have paper under small clay tiles on the roof and had no issues except for a fine mist in 'really wet and windy' conditions. Here on Skye we have sarking (like floorboards on the roof) waterproof membrane and much larger tiles that overlap by 2/3 and the water still gets in!

Ok, that makes sense. Now that I think about it, I think I've seen that kind of material used on some new-built houses here, I just didn't realize it was for waterproofing. I'm a bit curious as to how a felted material doesn't absorb any moisture? Some chemical wizardry to make it extremely hydrophobic maybe? Or are the spaces between the fibers just so tiny that liquid water doesn't get in due to surface tension?

I guess my (poorly stated) point was that there have to be ways to build entirely without plastic, no matter which climate one is in, since synthetic materials like that haven't been in use all that long, and people obviously built houses before that point. Though some climates (like yours, Nancy) will present more challenges than others I suppose! (On a side note, have some variation of turf houses been used in Scotland? The Icelandic ones are well known, and Iceland also has an oceanic and windy climate...)

I think it is tiny gaps meaning that water can't get through but water vapour, and other gases, can.

I think turf as a building material probably deserves a thread of it's own! I found this article from the Scotsman which is fascinatingly tantalising. I could certainly see a temporary house being built from turf, but I don't know how durable it is likely to be.

Matt McSpadden wrote:

Now, I am trying to figure out, the outside. The roof is a gambrel roof, which does not lend itself to extending the eaves... which means a plaster finish is probably not a good idea. And I am learning about the benefits of having a rainscreen behind the siding.

If I were to do some sort of wooden clapboard siding, a normal rainscreen created by strapping is simple. But if I wanted to use cedar shingles (which is what is on there currently), the only rainscreen I can find is a plastic mesh that is stapled up. Slicker Classic Rainscreen specifically. It looks like it would do the function just fine... but if I am trying to minimize plastic in the renovation, I wonder if there are any other options?

Does anyone know of a natural option for a rainscreen with shingles? Or maybe a natural wall does not need a rainscreen as much as a modern style wall?

It's pretty labor intensive but you could do a lime plaster base coat, attach furring strips over that and then put on on your shingles/siding. The shingles/siding protects the lime plaster from the worst of the wind driven moisture and any moisture that makes it behind the shingles/siding will be shed by the lime plaster.

Melissa James wrote:Magnesium Oxide panels are a natural alternative to drywall/sheetrock. They are made from magnesium sulfate and do not contain fly ash, formaldehyde, crystalline silica, or toxins.

I've seen this installed in a house, and it looked nice. I hope to use this on a future build.

MagOx panels are mold-resistant, fire-resistant, and do not provide a food source for termites, carpenter ants, or other wood boring insects.

It comes in a variety of thickness. It adds an insulating factor for sound and temperatures.

It can be used indoors or outdoors.

Here's the website, if you'd like to learn more: https://www.magpanelmgo.com

i do think this is a great suggestion.

yeah this may be my answer, i am looking for similar solutions as the op, trying to re do some walls.
its what i have been leaning towards and researching it for a while. seems like its mostly being produced in china, though. i had picked out some suppliers on alibaba B2B site...
idk i am not quite ready to commit, but now tariffs ! idk. i may wait it out, i cant rush myself to try to buy right now, this month before the end of the de minimis.
then again maybe i do rush myself into a vague estimation of how much board i might need and try to order in the next month. even if itsjust i want some samples, i am feeling sure i can find a use for it if i go all in on getting it now and figuring it out later.

some of the things i like about it - its simple, can use for inside/ outside, floor ceiling or walls. its super versatile.
to us who are more sticklers for earth friendly, it may not be the purest material, it does involve some industrialized weirdness, but then again much less than that of some other materials, besides being less toxic than many common materials. the fireproof, no mold, breathable, all of these aspects and more make it attractive too. the price isnt that bad, at least as far as what limited sources i have been able to dig up, its maybe a bit more than plywood while being far superior, around the same as something like hardieboard, another thing i have been thinking on, or other "backer board" cement board.

they make lots of interesting finishes for it, although i have been leaning towards more of the raw type, and then do some finishing myself, using it like hardie board, or backer. as far as i have been able to figure out (research and methods is lacking, or i am not finding the best specific how to info) BUT i believe you can plaster it directly, use a gypsum/lime plaster - base coat and a lime plaster right over that, maybe some PVA or other "adhesive" before base coat.
even with the extreme added tax, it still might be my answer.
i guess the OP was looking for the really really natural -- eg clay, mud cob, etc
but i definitely think its worth exploring.

some sources i found, are all chinese companies.
this one stood out to me and i may place some small ish order see whats what and what i can do with it -- https://www.alibaba.com/product-detail/A1-Grade-Fireproof-MgO-Board-Chloride_1600490450654.html
they have their own website and seem pretty solid -- https://www.zcmgo.com/product_list.html

theres so so many different types, theres all the laminated types meant to be used as is, i am mostly interested in the more raw types, or those with insulation in the mix --
like perlite-- https://www.alibaba.com/product-detail/24mm-Mgo-Perlite-Board-Manufacturer-Heat_1600878765749.html
eps-- https://www.alibaba.com/product-detail/Soundproofing-Eps-Mgo-Sip-Sandwich-Panels_1600504324318.html
raw -- https://www.alibaba.com/product-detail/Premium-Strong-MGO-Fireproof-Flooring-Board_1600994895448.html
floor - and use this for outside/exterior/ and /or walls? seems like -- https://www.alibaba.com/product-detail/Fireproof-Mgo-Floor-Magnesium-Oxide-Wall_62220840022.html

but then they also make the thinner instant wall types, with like faux wood look, or all sorts of funky decorative wall types. --
https://www.alibaba.com/product-detail/HPL-Magnesium-Oxide-SIP-Panels-Fireproof_10000014446772.html

if theres anyone who knows good suppliers or has any links for how tos or other info, maybe post it up. not to hijack OPs thread, but i do think MgO ( or MgsO) board is a good suggestion for the want to build with more ecologically friendly stuff - crowd. going to keep looking up info, maybe should search here on permies, although i think i did early in my exploring MgO panels and what you can do with them and didnt find that much info. yet, or maybe i do my own experiments, where i have a high tolerance for failure. i'm sure i've spent a few hundred bucks on worse ideas before =P

even with a lack of info, with some experience with plastering and clay, i feel like i could tackle this MgO board then plaster project a whole lot easier than plaster and lathe. i also like that it could be a good exterior material.

on the topic of rainscreen, one thing that is totally free is - air. idk if that helps, with something already built you may have some limitations. but its something to keep in mind. an empty space can qualify as kind of rainscreen...

leila hamaya wrote:on the topic of rainscreen, one thing that is totally free is - air. idk if that helps, with something already built you may have some limitations. but its something to keep in mind. an empty space can qualify as kind of rainscreen...

Absolutely. The Rainscreen creates an air space to allow the siding to dry faster.

However, when you are using lots of little pieces like shingles... it makes it harder to create that airspace, than with something big and long like clapboard or vinyl siding.

Not holding an expert's opinion, as witnessed by our " house that Dr Seuss built" , I can at least advise you on what NOT to try.  

While helping a friend plaster his interior walls, I was struck by his creative solutions.  He started with roofing felt , 30 weight, stapled over the insulated studs, then super-stapled chicken wire over that. I helped plaster this using an Adobe style mix:   mostly clay-chopped straw-sand-horse manure. He added an ounce of Pabst beer to each bucket full.  We had limited success on the higher walls so he used papier mache above five feet. This  was a passable idea, i thought. . It had a rustic look after being painted.

Fast forward to the next month, when he heard absurd levels of chewing/scratching inside a wall.  Yes, he had created a world record Saltine cracker.....

well i have finally gotten some info, but not all of what i want to know.
theres a real lack of info on MgO, though. found a few things,  maybe post up some info here. perhaps if i really get to it myself i might make my own thread, if i do end up doing this MgO -- with lime plaster route.
not like i can give expert opinions on anything, but mostly because there seems to be a real noticeable lack of specifics online - and i think there should be more. perhaps there are members of this community on permies with a good deal more experience with specifically MgO, or at least with lime plaster walls.

one thing i really had to go through dozens and dozens of generic articles to finally get what i was seeking here -- is what kind of primer, is primer even really necessary, and is PVA just a totally unsuitable plaster primer for MgO board. one of the benefits of MgO is that its breathable, same with lime which is why they seem in my mind to be a nice matching pair.
it is as i thought, a bad idea though, being a polymer glue basically, to use PVA -- which would be the go to thing for say plastering a plasterboard or drywall "sheetrock" type wall.

so what goes on as primer, onto MgO, to get the plaster to stick, is it nothing? i still dont know that answer, if nothing is ok --its possible that nothing is needed. if i am going forward with this, or even if i instead use cement fibre board or some such -- can you straight plaster on that. of course after mudding and covering all nail holes, tape seams etc. ?
i think its possible, especially as MgO has a rough side, that to me seems like it would bond with a absecoat. like a basecoat gypsum/lime plaster...with a top coat of a lime plaster.

what i did finally get to is this, and a couple other quick references in passing that a mineral based primer would be better than PVA.so i have a bit of a list of something called beeck plaster primer, and vasari mineral primer, plus a few other brands which seem to be all in the UK or europe. but i still am wondering if nothing is ok, maybe even better, and i find no info on how different is MgO -- most references are for plastering drywall or plasterboard, or even cement board.
ah well...just spent a few days off and on looking for this...so heres some links.

https://cornishlime.co.uk/articles/primers-or-bonding-coats-key-things-to-consider-for-lime-plaster-applications/

https://cornishlime.co.uk/articles/working-with-various-backgrounds-for-lime-plaster-applications/

and this was an interesting site...with some good info in general on plasters and such, more from a perspective of people with sensitivites, which overlaps nicely with eco friendly, actually.
anywho this got me to think of this discussion, so perhaps theres some info or at least some ideas there for you.

some info -- https://www.mychemicalfreehouse.net/2014/01/natural-plasters-some-tips.html

she used a clay plaster over MgO boards, in a tiny house on wheels. thats interesting by itself, i dont think i would ever even think of any kind of plaster on a moveable structure.

and if you look around theres some good info and options and ideas for brainstorming there.

https://www.mychemicalfreehouse.net/2021/10/choosing-a-non-toxic-plaster.html

https://www.mychemicalfreehouse.net/2020/05/non-toxic-drywall-mud-and-wall-texture.html

https://www.mychemicalfreehouse.net/2024/04/zero-voc-insulation.html

Matt McSpadden wrote:
Now, I am trying to figure out, the outside. The roof is a gambrel roof, which does not lend itself to extending the eaves... which means a plaster finish is probably not a good idea. And I am learning about the benefits of having a rainscreen behind the siding.

You mentioned the roof needing to be redone, and you mentioned plaster on the sloped walls on the interior so that's conditioned living space. What about a "cool roof" or adding an entire second roof on top of the old, either framed/insulated/sheathed, or SIP panels? All of these would extend the eaves to varying degrees, and allow more insulation in the old roof system, or even add more to the outside.