Straw in the Wall: Using light straw clay (slip straw) as interior wall fill

[@maxwellwoodhouse2908]

This is such a good wholesome family friendly video ! I mean it’s like third from the bottom from the light straw clay insulation search but still I am surprised more families don’t do this ! Dirt and grass is all we need folk! I’m super excited to work with light clay straw… love from Oregon ❤️ heh

[@MiltonMudburn]

Thank you for your kind words. We dug the clay we use out of the ground when we excavated for a root cellar. It's possible to get clay from construction sites, because many times they have extra to get rid of. You can also buy clay through some artist supply places -- I bought some white kaolin clay in 50 pound bags for the finish coat of plaster in the house.

[@lyria8469]

Good Job! Straw is just great for sooooo many things. Mud + Straw = one of nature's great combinations so useful in so many ways.

[@MiltonMudburn]

This building technique (and other ones using straw and clay) have been used for centuries, even in the UK. I don't know what the fire regulations in the UK are, but once the walls are plastered, they are quite resistant to fire, perhaps more so than conventional walls. That doesn't change how regulations work, I know. I am glad that I don't have to submit to irrelevant regulatory oversight where I'm building.

[@charlesmartin7347]

I couldn't press subscribe quick enough you Sir earned a big ol Texas dammit boy. That's smart and you made me smart. Thanks for sharing your knowledge. Blessings and more Blessings to you and your Family 🤗👌

[@kerriemortimer8243]

Hi!!! Cant find any info. Do you think i need a vopor barrier between straw and exterior sidding??? Using this insulation for a tiny home and doing plaster inside but standard sheeting outside . Help!! 😬ty

[@MiltonMudburn]

@@kerriemortimer8243 I wouldn't want a vapor barrier immediately against the infill. It would probably be okay with an OSB sheathing and then standard vapor barrier & siding. The concern is moisture that migrates through the wall from the inside. If it hits an impermeable barrier, it will be stuck in the wall, and wet straw will deteriorate and mold. I would be more comfortable with OSB, an air gap, then vapor barrier & siding (an air gap can be achieved with vertical or horizontal furring strips).

[@MiltonMudburn]

I'm glad you appreciated it. If you wanna come over sometime to play in the mud and put it on the walls, let me know!

[@MilesRoseProductions]

This is a very informative and well presented video on slip straw infill, though I have to ask, what is the R value of slip straw? Would more densely packed slip straw make for better insulation? How does this method compare with more conventional insulation, like dense packed cellulose? Would this method of insulation be suitable for infilling the exterior walls of a house in Michigan, where we get pretty extreme winters? Thanks again for the great video.

[@PatientenO.T.]

Can you pack it into an old house as insulation between the wood beams? I always wonder if it dries okay with the one side never getting air to it.

[@Goldifarms]

So helpful and inspiring! Will be doing this at Goldifarms real soon!!

[@MiltonMudburn]

We used slip straw in the interior walls, all of which were 3.5 inches. Twelve inches for exterior walls is a common thickness, though. The rule of thumb seems to be an R-value of 1.7 per inch of thickness (assuming consistency of mix and packing). That would be an R-value of 12-13 for an 8 inch wall. Although the plaster used wouldn't affect the R-value significantly, the air tightness and thermal mass it provides would affect how well the home could be heated and cooled.

[@christinebaker3293]

Great video, thanks! Going to use slip straw in the north walls instead of adobe for more insulation and your video is really helpful.

[@MiltonMudburn]

+Christine Baker I'm glad you found it helpful.

[@MiltonMudburn]

Our plaster mix consists of clay-rich dirt that we dug out of the ground, sand, chopped straw, and water. The ration we use is 2.5 buckets of sand, 1.5 buckets of clay (these are five-gallon buckets), and about 1.5 gallons of chopped straw. We add enough water to achieve a desired consistency. You have to adjust your mix to fit your clay-rich dirt -- it's not all the same. So, there is some experimentation to figure it out.

[@kerriemortimer8243]

Hi!!!!! Help cant find any info about using this as an insulation for a post and beam tiny home. Should i have a vapor barrier between straw and out side wood sheeting??? 😬

[@FidelKastrat]

very good video. thank you very much. I think this is the best natural building method

[@MiltonMudburn]

The chance of fire is very limited -- I would be much more concerned with empty-cavity walls. The clay slip the straw was coated with deters fire. Also, the straw is packed in the wall, limiting the amount of oxygen available for combustion (kind of like burning a phone book). Additionally, it is sealed in the wall with 1/2" of plaster on both sides. It's not a fire-friendly environment.

[@ESLinsider]

Cool. I want to try it. How does it work?

[@stephaniefritchley9022]

Hi, I have just found your incredibly informative video. Thank you so much for sharing your expertise. I wonder if you could answer a question please? I want to convert an existing outbuilding into a studio so the exterior walls are already there (concrete and terracotta blocks sadly, but at least that’s one cost I won’t have) but I need to insulate these walls and was hoping to be able to use this method. I think the technique itself would obviously work but are there any problems likely to arise when one side of the wall is made of the materials described above? Also, did I notice full bales used as an exterior wall (under the window)? If so, how did you hold them in place? The building currently has an open front which I need to fill in. Many thanks.

[@terril2643]

This is very good information. Is there any mold issues? Thank you

[@MiltonMudburn]

The only mold issues I've experienced happened during the drying time when drying conditions were not ideal. When weather is too cool or too damp/humid, the mixture does not dry well, providing the opportunity & time for mold to potentially grow. You can kill or retard the mold growth with white distilled vinegar, but the best thing is just for everything to get thoroughly dry.

[@RVBadlands2015]

Do you have a video plastering though walls.

[@hennalisa454]

Do you mean you would use this for interior walls but not for exterior walls? If not for exterior walls, what would you use for exterior? I live in a humid climate in SE USA. Thanks!

[@matthewleestudio9327]

Super helpful video to get a sense of this type of work. I'm thinking of insulating exterior walls of my storage shed this way, am in the deep South of USA. Hoping it will be okay in an exterior wall. Currently the walls have OSB type panelling that looks like siding on the outside. It's only 10' x 12', so should go fairly quickly. I'm not sure where I will find dirt in the city.... Thanks again.

[@MiltonMudburn]

If the straw in-fill is kept dry, it should work fine. Water/moisture is the main threat to it. If you can't find clay locally available, you can order a 50 pound bag from a pottery supply business.

[@simonmasters3295]

So, as a ball park estimate, comparing costs of drywall (plasterboard as we say in UK) and SlipStraw, given the studwork is identical and the final finish plaster coats might be a bit thicker on the Slipstraw. DRYWALL: 2 x drywall panels £5 each, 2 x 25mm insulation £20 each plus cost of cutting, fixing and fittings say 1 hour but that would be working fast (perhaps less if 1 x drywall panel and 1 x drywall and insulation integrated panel (9.5mm + 40mm cost £20 on eBay) So drywall overall cost including fittings £40 - £75 per 2.8m2, i.e. £15 to £25+ per metre of wall in "straight run" conditions. SLIPSTRAW: I would estimate you use roughly, one small bale per 8' x 4' (2400 x 1200mm) panel (cost £5 delivered in UK and it takes about 30 minutes (say £10 of labour cost) to fill once wetted. I can't see very much slip being used (allow £3?), so if the mixing of slip and straw also takes 30 minutes that's a total cost, including labour, of around £28 per 2.8 m2 panel. Let's say £10 per square metre in "best" situations. The straw could be much cheaper - this "straw infill" method would allow for large round or square bales to be the delivery approach - easier to keep on site until required, and the round ones can be rolled fairly easily right up to the work. To my mind the material cost appears to be significantly lower for the SlipStraw approach and most of the total cost is labour which, if you are paying yourself is generally a big advantage. The straw+clay have a much lower ("delivery only") energy cost and the embedded carbon sequestration is relevant in an eco-build.. I can also see how you might use 3/4" ply ro create rounded cornices and alcoves. Finally, as this delightful viideo points out, "my boys" doesn't always refer to the employed workforce!

[@MiltonMudburn]

That's an interesting analysis -- I've never calculated the costs per square meter when using slip straw. I've done both drywall/plasterboard walls and slip straw walls, and both require a fair amount of labor. One item that I don't see in your calculations is the cost of the sand and clay for the plaster to be put on the walls to finish them (and the labor if being paid). If all materials had to be purchased (we used a lot of clay dug from the ground on the building site -- only the finish coat clay was purchased), the slip straw approach may be the more expensive of the two, but it will have less embodied energy in the materials and will be more environmentally friendly.

[@simonmasters3295]

Hello Milton - Love your work! Watching Slide Show Part 1 and Part 2 now. Respect on the framing detail! I am glad you liked my cost analysis, sorry to focus on costs in the context of your "debt free" approach. . So I assumed the finishing coats would be about "about equal in cost" in both cases, but you saying drywall will have a much lower skim thickness and therefore cost I believe? I am in the UK and have Ash that I planted - with which I hope start building a hybrid advanced frame - roundwood home. Like you I am trying approach my project from a "near debt-free" approach. In your experience is a lot of "trial and error" involved in getting the slip and render mixtures right when using non-manufactured sands and clays?

[@MiltonMudburn]

Getting the mixtures right does involve some experimentation, whether with site-based materials or ones that you buy. Nothing extreme -- just try different ratios and compare the outcomes. Generally, drywall is finished with joint compound over the seams and screw heads which is sanded smooth before painting. The plaster applied to the slip straw actually takes the place of the drywall -- it's the skin of the wall. It isn't as durable as drywall, in my experience, but it is natural and has an organic feel/look to it. Finishing it to drywall smoothness and flatness hasn't been worth the effort in my work. In fact, we're at the painting (natural clay-based paint) phase in our project, and the first coat includes silica sand to give the walls some texture which covers up imperfections and trowel marks that weren't buffed out completely. For me, I think drywall would have cost more, although the time investment would have been less. I also would not have had the insulation in interior walls. I didn't pack the walls with slip straw for the purpose of insulation but in order to provide a base for the plaster. It's also possible to plaster directly on top of drywall -- I considered doing this, and did do it in a couple small areas. Focusing on costs is important for doing a project debt-free, more so than for building with debt -- you have to pay for what you're doing when you're doing it or before. If you're willing and able to provide the labor, you can do a lot of things. The most important part is to believe you can and to be willing to try things out in order to figure out how it will work. Too many people aren't adventurous enough, I think. We're on track to finally finish enough to move in this spring. I'll be putting together another slide show video to go with parts 1 & 2. Thanks for you comments!

[@simonmasters3295]

MiltonMudburn Love your help man!

[@bartolomeugusmao4445]

Does anyone have any idea about how much clay is needed to slip a cubic meter, or any other volume?

[@TwoTrees777]

Hi milton awesome video can u tell me will this keep me as warm as using SB for my exterior walls? I want to build on my land but in Northern WI and it gets pretty cold up there winter sub zero temps

[@MiltonMudburn]

The R-value for straw walls increases with the thickness of the walls. Straw bales are 18" thick, nearly 5 times thicker than a 2x4 wall packed with slip straw. So, there is no way for a thinner wall to insulate like a thicker straw bale wall. I don't know how slip straw as insulation compares to other forms of insulation.

[@TwoTrees777]

@@MiltonMudburn thanks so much

[@williamhunt5325]

What is the dry time before plastering or cobbing?

[@RVBadlands2015]

Going to do this with our strawbale walls.

[@ESLinsider]

How long did you wait to take off the bottom form?

[@MiltonMudburn]

I took off the form as soon as I finished packing in the form above it. You can "slip" two sets of forms up the wall that way.

[@ESLinsider]

@@MiltonMudburn That's cool. Curious how much this stuff weighs. Considering it for inside a step van. The walls would only be an inch or 2 thick. Wondering how it would work. Exterior walls are made of aluminum and then there are aluminum ribs so it seems like I can do something similar to what you did in the video. R value seems low though for only a wall that's going to be an inch and a half thick. Would get better r value with that poly stuff but I don't like it. Hemp and wool look pretty good too but expensive. I like the idea of making something. Just don't know if it would offer much insulation in this case.

[@kdixuebw7884bfb]

Very helpful thank you

[@flyingmojo5]

You mentioned the walls were 12 inches. We are thinking about building a slip straw home, but we're limited on square footage, so we would most likely have our walls about 8 inches. Would this drastically effect the R-value?

[@safetyfirstintexas]

1.7 r per inch of wall. compare to whats used in your area for fiberglass batting

[@jessicag630]

Does it not attract insects such as termites?

[@MiltonMudburn]

Before I built with straw, I had the same question, especially about termites. The straw attracts no more wee beasties than other building materials, and termites don't eat straw - it's not composed of the cellulose they like.

[@ceacewilliams8082]

I'm in the process of building a budget Man Cave out of pallets and was trying to find an alternative insulation. What exactly is the clay mixture? Could I simply pack the straw in the walls between the outside and inside panels?

[@michaelwest2608]

+Ceace Williams Did you end up using the slip straw? I also have a building made from pallets and need insulation. I am fixing to try it now.

[@ceacewilliams8082]

+Michael West Well, I have not made any more progress on my pallet shed. I am planning to move to another state, and I don't intend to put any more time and money into it since I can't take it with me. I was intending to use the straw technique. You should try it, and post a video of the results. I would be interested in knowing how it turns out.

[@duffdoesstuff]

Very nice tutorial. Thanks for the knowledge! I plan to use this method on a small cabin I want to built. I know we have clay in the soil here (ohio) but would this work with regular mud also? I know we have that lol.

[@safetyfirstintexas]

no. mud lacks the adhesive quality that clay has.

[@shawnphillips2556]

Almost all dirt contains clay. So you can definitely use your local dirt provided you go through the extra step of refining the clay. It is a very low labor process.

[@bigjuju4love]

Hi, Thanks for sharing this. How long do you let the mold in place before removing it?

[@MiltonMudburn]

you can remove the forms almost immediately. We removed the bottom ones once we had packed a set above and moved the lower ones above until we reached the top of the wall.

[@davedrewett2196]

I'm pretty sure just by coating the straw with the clay slip that work pretty good as a fire retardant.

[@MaxSafeheaD]

I can't imagine this kind of thing ever passing fire regulations here in the UK.

[@ATZ44122]

can you hang cabinets in this wall?

[@MiltonMudburn]

Yes. Cabinets should be anchored to the studs in the wall. The light-straw-clay infill does not affect the structural soundness of the wall adversely.

[@ATZ44122]

in straw bale walls I see that they put iside the wall some extra pieces of wood,but may be this walls of you are stronger because they are mixted with the clay....thank you

[@niallwildwoode7373]

Thankyou...beautiful job!

[@orchardbarntraditionalbuilding]

Very informative video, thank-you

[@viacheslavdenisenko6296]

Hello! Please, components of the solution

[@safetyfirstintexas]

clay and water as a slurry, poured on straw to coat the fibers

[@daythinkerdaythinker]

INGENIOUS

[@MaxSafeheaD]

Well there's up-sides and downsides to that. I think all techniques here in the UK need to be approved safe and that testing for new ideas takes money. Good for developers, bad for people like me who want to use crazy new techniques! ;oP With fire I'd be a little cautious. My main concern would be fire spreading inside the wall undetected like with sandwich panels - do get a smoke alarm althogh a recent concealed fire I attended had progressed well into the roof before it sounded any alarm.

[@markchilluffo9638]

👍👍

[@ChaseSaxtonofKy]

great video!!!! thanks for posting!!!!

[@bigjuju4love]

thank you very much

[@beachfiredude]

Great and educational tube!

[@soilbellefarm3210]

I love it!!!!!!!!!!!!! Thanks:))

[@voidvoid1463]

House would light so fast if a flame got in there

[@MiltonMudburn]

That's a silly notion. Packed straw sealed in place with clay and covered with over 1/2" of clay plaster on both sides will not burn easily. It would take a lot of effort to burn it.

[@voidisyinyangvoidisyinyang885]

@@MiltonMudburn that's funny someone has a similar tag as me? I built a Double Wattle clay slip straw hut - 12 foot walls. kzbin.info/www/bejne/eYa0g3mieZeIq7M