Straw Bale What They Don't Tell You!!

So we built a straw bale building about 10yrs ago (as practice) followed by a straw bale house. All permitted etc non load bearing yada yada. There’s a lot I know now that I wish I knew then and somethings that have changed drastically (like price associated with farming practices).

Bugs and mice - I gorged on straw bale books videos all info I could find before building. All the books talk about how glorious straw is...bugs don’t eat it, mice don’t eat it, it doesn’t burn, great insulation etc. Well most of that is true...bugs and mice don’t eat straw but they love to live in it!!! Mice are a constant problem they eat holes right through the plaster and it’s not like tire going to beat off the most labor intensive wall finish on the planet to get to them. So your left with only trapping options while mice are chewing up and pooping in your walls!!! Is this different than a “normal” house? We’ve had more mice in our Strawbale house than anywhere we’ve ever lived. Now BUGS all manner of bugs make homes in our house the good bad and ugly. Bumble bees being the most visibly destructive I’m going to try to include a picture. Yellow Jackets being the most dangerous (we had 6 best in our walls last year which you can’t get too and all normal options aren’t effective). The annoying silver fish, moths etc (we could get over those)

Price - When we built our house straw was abundant and $2 a bale when bought in bulk. I’m a plumbing contractor who buys straw frequently the last few years it’s been around $6 a bale which when combined with all the other downsides doesn’t make it a viable building material to me unless you don’t value your time at all...because you will spend mountains of time plastering. It’s by far the most labor intensive building method I’ve ever used I can only imagine cob being worse.

Resale - All my kids will be out of the house soon and we’ve considered selling...well forget that unless you’re going to owner finance. Banks won’t loan money on them to you or anyone else. Appraisers don’t know what to do with them. So now I’m stuck with the biggest investment of my life in money and time and I can’t get my investment back out of it. Renting isn’t a good option because you have to me conscience of things in a straw bale house that doesn’t matter in regular house and renters don’t care about those things.

Insulation - Our house is tight with all insulated windows etc and my power bill in summer for ac and heating load is as much or more than anywhere I’ve ever lived in conventional housing. We burned about 12 cords of wood a year in a mild North Carolina winter. If you think you’ll heat your house with a candle or cool it with a fan you can forget that.  

Thanks for posting this.  I think for alternative housing to be taken seriously and to expand, it's important that people are realistic about the drawbacks as well as the advantages.  I appreciate you posting your experience.

Second that, thanks for posting.


Would love some more details; what sort of plaster are the bees/insects getting through?

If you were to do it again, do you have any ideas about addressing these problems?

What is your roof/ceiling insulation like?

So sorry to hear this David, that's terrible news; it sucks to have such an emotional, time-consuming, and financial investment not pan out.  

Maybe there's something we can do to help you diagnose/remediate this issue, or at least help others to avoid the pitfall traps you've identified? (and I'm sorry if any of these questions are patronizing - they are not meant to be)

If you'd like, please tell us about:

Your ext. and/or int. plaster recipe?

Did you account for house orientation, prevailing winds, window placement, shade trees/structures, etc for passive cooling/heating during design/construction?

What is your roof material and insulation? Foundation type?

Thank you for sharing your experience here, and I hope we can help!

Oops, I was posting same time as you, Dillon - sorry for the duplicate questions!

Have you figured out how the mice got in ?  Detailing is so important.  We have amazing rats here,  I have them under control at this point so out of the main ( standard stock frame)  house but I sometimes get them in the ( standard stock frame) garage that has an ill-fitting door.    The back wall of the garage is light straw clay with thin earthen plaster with a lime wash, this is part of my retrofit studio.  They never try and chew on it.  They don't know there is straw behind it or a nice warm studio or food and the lime washed plaster is of no interest to them.  Now I could see them making quite a mess if they somehow got into the ceiling of the studio and there was a crack showing the straw in our walls.  

Did your mice get in by chewing thru your walls or via an opening for plumbing or wiring ?  Did they get into the ceiling or crawl space and then find the walls ?  I just wonder if it is due to the bale walls or if it was the kind of detailing that could let them into any house.  It definitely would be harder to open the walls compared to drywall that you can take off.  But, even with drywall, we don't take the walls apart to get the rats.  I had rats in the ceilings and walls in the main house here when I first moved in and they rip apart fiberglass insulation and drywall to make their nests, but they cannot eat it, just as you mice cannot eat the straw, so they have to leave for food and water.  Trap or bait and kill them all and seal up how they got in - in my case it was the crawl space under the house and plumbing openings

Just retread you say they have chewed thru plaster, to get in or to get out of the walls or maybe it is too hard to tell ?  I am just trying to help you fix the issue.  I would kill the.  Crawl thru every spot I could and adress all cracks and openings and junctions nail on tight wire mesh, spray foam plumbing penetrations and if I thought they were chewing thru my exterior plaster -  I would add to it with a lime plaster layer

Is this a normal thing for all strawbale homes? I was thinking of doing a hybrid of cob and strawbale.

Diane Maldonado wrote:Is this a normal thing for all strawbale homes? I was thinking of doing a hybrid of cob and strawbale.

I have never heard of this complaint before.  But we can all learn from this and get better at keeping it from happening as well as improve this families situation

It’s been many years since I did any plastering but if I remember correctly the earthen plaster exterior is mostly sand, a little clay (just enough to bind but not crack, straw of course, and I think a small amount it type s cement but I can’t remember why we added that to the recipe. The ration was probably 5-3-1 but that’s a guess at this point. The interior plaster is gypsum and and sand (literally Sheetrock mud and sand which I’m sure some of you don’t like but it’s durable affordable and went on faster and better than anything else we tried and we were just ready to be done with it). We built the house completely by ourselves I paid no one to do anything...which is not always a good choice by the way. I’ve got places which I’ll take picture of where mice have made holes just right out the side of the building with no Rhime or reason why it’s there (yes it came from inside the wall to outside.  
The house is oriented about 15 degrees off direct southern exposure to the front of the house. Dug into a hole that knocks most of the wind off of it (we considered an earth ship originally but could get by code enforcement. Shaded in summer. Shed roof design with spray foam insulation made from soybean oil Sprayed to meet r -30 requirements, black epdm roof painted white. It’s on a 6” insulated slab with raidiant floor heating that heated by a wood boiler with rocket stove for back up...rocket stove are another rant for later. I’ve built several based on what I learned here. I still have one but I tore out my rocket mass heater last year...I’ll take a restyles old wood stove any day. Oh the house is two story which tripled labor I can’t tell you how many hundreds of 40lb buckets of plaster we pulled up scaffolding with ropes. I am glad I did it when I was younger.

I have yet to hear a good reason as to why it is preferable to build out of straw bale than, say, rammed earth.

As I understand dewpoint and how heat is transferred through different media, the best option in a temperate climate is to insulate on both sides of the structure. For my money, that means nice, thick rammed earth walls with insulation inside and out, preferably an insulation that is dense and inedible, and sealed overtop with a waterproof earthen plaster.

Nothing for vermin of any kind to eat, no space in which they can nest, and a sandstone-like mass around two feet thick to burrow through to get inside; easier to find other accomodation.

-CK

I'm sorry to hear you've had this bad experience.

Can you remember how thickly you did the earthen plaster on the outside?

A while ago I was looking into building a strawbale house with a strawbale building company. They build a lot of strawbale houses and use around 5cm/2 inches of cob as the render/plaster. I wonder if this extra thickness stops animals from nesting in the bales?

Ok, you said the mice ate the hole thru the plaster from the inside, so from the inside of the wall ?  Yes, I have seen this with rats they will chew thru anything to get out.  The real issue is how they got into the wall in the first place.  Do you think it is probable that they got in the way they would in any other type of building ? This would mean via an opening into the wall for plumbing or electric or from where the wall meets the under floor or over the ceiling areas of the structure ? How are these areas detailed ?

Chris Kott wrote:I have yet to hear a good reason as to why it is preferable to build out of straw bale than, say, rammed earth.

As I understand dewpoint and how heat is transferred through different media, the best option in a temperate climate is to insulate on both sides of the structure. For my money, that means nice, thick rammed earth walls with insulation inside and out, preferably an insulation that is dense and inedible, and sealed overtop with a waterproof earthen plaster.

Nothing for vermin of any kind to eat, no space in which they can nest, and a sandstone-like mass around two feet thick to burrow through to get inside; easier to find other accomodation.

-CK

To me the appeal is that the strawbale is reasonably insulative. It's uncommon amongt the common, DIY-friendly green methodologies in that regard. Light-clay straw/chip, hempcrete are other options...

Rammed earth in your example is not really replacing the strawbale; the unspecified dense inedible insulation is!

Interested in more discussion(another place?) of the pros/cons of insulation on inside of walls... the upsides that I am aware of don't really seem worth it to me..

Once I got rid of mice I had no problem. I have exposed straw right now and still no mice problem. I did have problems at first. The sooner you can get it plastered the better. My problem has been birds. I’m slowly getting a hardware cloth under the plaster, but till then. I live with sparrows and starlings. My buddy had a kestrel living in his strawbale house.
I knew about the loan thing. I remember reading about it when I was first considering this, but I have less than $20,000.00 and no mortgage. After the 2008 crash I would have lost my home if I had a mortgage. The only two other people I know manage to sell their strawbale homes for a substantial profit, just need to find an enlightened buyer.

I am with Dustin on this, something is dramaticly wrong.
Was lime used in the plaster, because cement should never be used, it creates moisture problems.
Lime helps make the wall unpalatable to mice, ETC along with sharp sand
Explanation about mice and strawbale

Is the plaster 50mm thick

Is the ceiling actually insulated

In Australia, I have never heard of a bank not financing a strawbale house

Chris Kott wrote:I have yet to hear a good reason as to why it is preferable to build out of straw bale than, say, rammed earth.

As I understand dewpoint and how heat is transferred through different media, the best option in a temperate climate is to insulate on both sides of the structure. For my money, that means nice, thick rammed earth walls with insulation inside and out, preferably an insulation that is dense and inedible, and sealed overtop with a waterproof earthen plaster.

Nothing for vermin of any kind to eat, no space in which they can nest, and a sandstone-like mass around two feet thick to burrow through to get inside; easier to find other accomodation.

I agree! I'm writing this as I sit in my rammed earth home, and until last year I lived in a campus of rammed earth and adobe brick buildings for 25 years. We have a climate with winters about as cold as northern New England. Two-foot thick rammed earth walls have proved to be both insulating and thermal mass. In our high desert environment, with passive solar design, it is just about enough. At the school it was a little colder indoors than I would have liked during Jan and Feb, and in my new house this past winter I used a little portable electric heater in the evenings in Jan and Feb. Other houses here are running their wood-stoves from October to March or April.

To be honest mice have been known to dig a tunnel through our rammed earth walls, but they don't seem to nest in there, or love it, or proliferate. Our tailoring-waste insulated ceilings, now, were another mouse heaven. But a friend of mine helped dismantle a year-old straw-bale wall in the US, and found the whole interior hollowed out by happy nesting mice.

The rodent problem is most probably from the scent of soybean oil in the foam. Anything made or derived from natural food byproducts will attract vermin of all kinds indefinitely. I know this because I own several foreign cars with engine wiring   made from vegetable oils and every year, no matter the precautions, the wires are chewed, wile the Ford truck has never had a chewed wire.

Chris Kott wrote:I have yet to hear a good reason as to why it is preferable to build out of straw bale than, say, rammed earth.

As I understand dewpoint and how heat is transferred through different media, the best option in a temperate climate is to insulate on both sides of the structure. For my money, that means nice, thick rammed earth walls with insulation inside and out, preferably an insulation that is dense and inedible, and sealed overtop with a waterproof earthen plaster.

Nothing for vermin of any kind to eat, no space in which they can nest, and a sandstone-like mass around two feet thick to burrow through to get inside; easier to find other accomodation.

-CK

I would like to try rammed earth, but still have my heart set on strawbale first (if I can).

I'm very grateful for this thread and the information in it (including the post I quoted).

Edit: After finishing the thread, I would still like to build something out of strawbale, but it looks like rammed earth might be better.

I came very close to doing a diy strawbale dwelling.  But over the years when I was researching it, I constantly had in the back of my mind memories from my younger days working on farms where mice and rats drove farmers crazy.  The rodents would tunnel through stacked bales of hay, leaving droppings and tunnel openings everywhere.  And they lived in the ground, too.  By the time winter snows melted, we would find holes everywhere- into the clay soil underground, and through every bale of hay up to the second layer.  Barn cats could not possibly handle the number of mice and rats.  And the mice and rats are not as shy of humans as many believe.  They would run right in front of me as if they owned the place.  Putting down poison did little except to just give you a lot of dead rodents in addition to the ones running around and living in the straw and hay and underground.  And did I mention the droppings?  Literally everywhere, including in the grain.  The rats were so big they would startle the sheep at night.  The only reason that I came close to doing a strawbale house in recent years was due to reading advice about how to prevent the infestations.  Sometimes, however, the authors giving the advice would end their articles with a one-sentence caveat that warned of no guarantee.  Sometimes they did not.  This is my opinion today about strawbale homes: all you will get is many more mice and rats than you would otherwise have in conventional structures.  I do not care about the fact that the tunnels may not compromise structural integrity- though I do not believe that either for the long term life of the house; no one wants to live with the rodents, no one wants to see them as much as you will see them, and eventually the increased population of rodents that you attracted with the bales will invade your home.  It is almost common sense.  I am sorry for the ones who have invested in such dwellings.  The plaster coatings, the cementitious coatings, etc., etc. Forget it.  The money you would have to put into building with straw that might help stave off the rodents is not worth it.  Maybe the very rich can do it.  But not the average diy'er.

Just curious, why couldn't you just wrap the first 3 feet in hardware cloth? Would they chew through galvanized steel wire? I know it would add some cost and effort, but it seems relatively simple.

Hay and straw are two very different things. Hay contains seeds for rodents to eat, straw doesn't. My sister used to keep horses, and if I recall right, she'd get rodents in the hay and the feedbins, but not in the straw bales. Not that I can claim any knowledge of actual straw bale housing, though I'm interested in possibly building  with strawbale one day. We currently have a big rodent problem in our stick-built shed. They're chewing through thick plastic storage containers to get at the bird feed.

Jane, I am sure that, given the choice between hay and straw, the mice and rats would go to the hay.  But I am not surprised to read of people seeing mice in the straw bales.  After all, there are no hay bales around and the mice are looking for shelter.  I am in northern Maine.  I have seen the mice in both hay and straw and mulch bales.  I went for two years without seeing mice and rats in my new sheep house.  Now they are all over the place.  So, sooner or later, they get to it.  I am amazed that more people who have built straw bale homes have not reported mice.  My guess is that they are simply unaware of them.  The mice chew through the plaster coatings, making a rather small hole.  You might not notice it if you are not looking.  It is very low to the ground. And I also suppose locale plays a part.  Here in the North Maine Woods, the mice are numerous.  Put up bales of most anything, and they will eventually find it.  And the rats.  I catch them going underground.  But they tunnel through the first layer of bales on their way.  Speak to farmers in the north, and they will tell you that mice and rats will get to bales eventually.  All bales.  No matter what is baled.  Sure, you can lay concrete slabs, and protect the straw- but only with much time, effort, and money spent.  It can be done.  In my opinion, it is not worth it for the average diy'er.  

Benjamin, sure, if you put enough wire, etc., you might hold them off.   For me, the added cost of hardware cloth and its installation was a deal-breaker.  I was looking at straw bales for their insulation value and inexpensive cost for a cold climate dwelling.  The cost has become too high for me and I suspect for the average diy'er.  At $6 a bale, plus the concrete and hardware cloth that only might solve the issue, I gave up the idea.

Good point, Alden. The rodents I've encountered all had plenty of other things to have eat and nest in before they had to make do with strawbales.

For me, the cost and availability will surely be the key issues deciding whether to use strawbale or not. I don't have land yet, so it's all hypothetical till I know what is locally available at a reasonable price and without an embodied energy cost that will make me cringe. If I do choose strawbale, I'll be learning all I can about detailing to prevent these problems.

Jane, I decided that a cordwood structure was for me.  The softwoods are readily available here in northern Maine, and the insulation value is amazing.  I have yet to see or hear of any rodent or insect issue with cordwood construction.  That is not to say there are zero insect issues.  Wasps might be an issue.  But any issues with cordwood, in my case- cedar, are much more easily dealt with than with strawbale.  Especially if you buy a piece of land, the wood is free.  Straw was free in the old days.  Not anymore.  Now it is a commodity.  And it is getting harder and harder to find.  I am in the process of two building projects.  One, a small cordwood cottage and the other is a not-so-tiny home constructed of stacked cedar.  I am of the belief that, in a northern climate, stacking softwood is the way to go.  It is inexpensive.  It can be done by two older adults.  And it does not entail the concerns that strawbales bring.

Sounds good! Cordwood is high on my list of possiblilities, as it's likely to be one of the most accessible building materials. Do you have a thread with pics of your build?

Jane, both builds will be documented right here on Permies.  But site work will only begin in the spring after the snows are gone.

Jane Mulberry wrote:Hay contains seeds for rodents to eat, straw doesn't.

The rodents might not be eating the straw much, but they might be building condos in it, and coming into your home to eat other stuff. We used tailoring waste and/or crumpled paper for insulation in some ceilings, and wow, the mice love living in there! Rodent heaven! They come down and eat other stuff.

I can imagine the tailoring waste would be a mouse's ideal nest!

Thank you! Posts and comments like these are so helpful. Learning what doesn't work is one of the most important parts of learning what does.

Did the same issues happen with straw-clay? I'm hoping to move to rural Bulgaria. the tradtional houses are stone, mudbrick, and wattle and daub, with straw-clay used for insulating floors and ceilings.
I haven't stayed in one of the older homes that still used straw-clay, only renovated ones that have been redone using modern materials- lots of concrete render and floors unfortunately.

Could be the traditional homes are rodent heaven, too.

Jane, straw-clay sounds better to me than straw bale.  And if they are doing something for hundreds of years, my guess is that it works in that area.  Betcha that a local farmer could tell you!

I own a strawbale home that I bought in Quebec and have the same problems. Bought the home and land for very cheap because the seller could not sell the house because banks asked for 25% down deposit because of the strawwalls. The house has a lot of bugs and mice and feels drafty all the time it does not retain heat well you have to always have the woodstove going if its below -10Cof my neighbours have strawbale homes and have similar issues. Im curreny re'insulating fron the interior on the 2x4 walls with 1 1/2 inch rockwool comfortboard and 2x3 strapping
And re doing the whole interior. Next summer.im going to re-do the exterior walls one at a time and reinsulate, sheat and re-install the wood siding. My neighbours was one of the pioneers of strawbale in our region and even he is in the
Process pf re-insulating his home conventionally. Straw simply does not do well longterm it seems in our harsh climate with very cold winters and high humidity in the summer.

Briefly, last summer, I had the opportunity to get hold of cheap straw. I checked into building a small storage building.  I couldn't get it to make sense $$$/ labor wise. Now, I am talking about an unheated 12 x 20 building. No matter what i would have to frame it and roof it.  To me, the labor going into the walls was going to be a pain.

Chris Kott wrote:I have yet to hear a good reason as to why it is preferable to build out of straw bale than, say, rammed earth.

As I understand dewpoint and how heat is transferred through different media, the best option in a temperate climate is to insulate on both sides of the structure. For my money, that means nice, thick rammed earth walls with insulation inside and out, preferably an insulation that is dense and inedible, and sealed overtop with a waterproof earthen plaster.

Nothing for vermin of any kind to eat, no space in which they can nest, and a sandstone-like mass around two feet thick to burrow through to get inside; easier to find other accomodation.

-CK

Don't know whether or not you'll consider these "good reasons". Rammed Earth has thermal mass but no insulative value. Straw bale walls run about R30. So if you're in a cold climate, straw bale has that advantage.
When your site is pure sand and you would have to import tons of clay in order to build with rammed earth, suddenly strawbale looks a whole lot better.

You say "waterproof earthen plaster" as though that were a thing that is readily achieved on a whole building scale ;) It really is hard to make earthen plaster waterproof.

The OP never mentioned where they are located, which might help with addressing some of the issues they had. He does say they used an earthen plaster on the exterior, where it is commonly recommended to use a lime plaster, because it's significantly more durable. I'm really curious what the pressures are on the mice and insects that are pushing them to use the house walls rather than their natural habitations. This isn't a situation I've heard of with any other straw building. If it were a common issue, one thinks it would have come to light by now.

On the resale front - anyone doing any kind of outside the box natural building ought to be aware of these issues going into the process. Things that don't fit the "norms" are often difficult to sell on the market. All part of the package. As a person trained in residential real estate appraisal, I would be able to appraise a strawbale house. Getting comparable sales in your area would probably be difficult, so the appraisal would be on a building cost base rather than a comparable sale base. But it's entirely do-able. Finding a bank that will finance a strawbale house? Probably depends a fair bit on your region and how many there are. The further outside the "norm", the less likely the banks are to touch it.

Personally, resale isn't a consideration. I'm building my last home, selling it won't be my concern ;)

Thank you so much.

Today I heard sounds of something nesting inside the wall of my straw-bale house.

I know where it got in. There's a gap in the eaves at the top of one exterior wall where it meets the soffit.

So how best to proceed? How to get it/them out before I somehow seal it up? Want to avoid corpses in there, also don't want anything eating through to the outside.

Is there some polite way to lure them out without poison?
Or if it has to be poison, what kind?

And then, finally, probably too cold now to use lime plaster, so should I use something else for a temporary fix?

Would something like electrical putty be a really bad idea?

Thanks for your Heeeeellllppppp!

I know for bats you can put a flap on there so they can get out but not back in
that might work for birds too.

On problems with strawbale.
I don't like the idea of putting the posts inside the walls.
Having to cut, trim and stuff around the posts adds a lot to the work.
And they provide a huge thermal bridge,..
what's the R-value of a tree?

Of course adding a separate foundation for the posts is extra work.

I wonder how quickly some of those strawbale houses were built- owner-built places tend to have breaks in building, and the longer a wall sits half-finished the more time critters have to take up residence. Also if newer bales were used and they were not properly strapped down to compress the straw, then settling can occur over time and open up cracks in the outer finish coating. Bees (mason bees in particular) digging into a surface suggests the finish coat may have not been hard enough, I thought a lime plaster would prevent that? If a stem wall/foundation wasn't used then rodents could tunnel in the soil to get up under the wall and bypass a proper finish coat. But any type of stem wall of stone and mortar should stop that. I've seen a cob house with dry-stacked stem walls that have mouse problems as they will find that one gap which is just big enough to get in and they will expand their newly found dry spot. I've also seen unfinished cob garden walls riddled with holes from insects, but adjacent cob houses were fine as they had a proper finish coat.

Kris Ford wrote:Today I heard sounds of something nesting inside the wall of my straw-bale house.

I know where it got in. There's a gap in the eaves at the top of one exterior wall where it meets the soffit.

So how best to proceed? How to get it/them out before I somehow seal it up? Want to avoid corpses in there, also don't want anything eating through to the outside.

You could probably set up some bucket traps for the mice, give them some tasty peanut butter etc to lure them out. Unfortunately you could lure out mamma mouse and babies are left in the wall if she just had a litter. While a sad way for them to go, after you stop catching the rodents you can then properly pack in any gaps and seal the surface with a lime plaster. Even with my stick-framed house, it's a twice a year task to walk around the perimeter of the house looking for any damage to soffits and near the foundation where critters try to find a way in, I would expect any style house needs that regular maintenance/upkeep.