More foundation fun - straw bale garden room on clay

[Nick Thomas]

4 hours ago, saveasteading said:

On the hollow blocks. Upright will be much better. If not too much hassle or cost, can you fill them with gravel?. I couldn't prove any improvement but it would add some stability, especially at any weak points ( which these blocks sometimes have), and would increase the bearing surface if the timber, spreading the load.

 

Definitely on filling them with gravel, it's actually where I started ^^.

 

 

The one difference will be some packing tape placed before the fill.

 

Half the pier are these 140s, the other half are 215s, so I just have to remove some gravel from the ones currently using 140s to get the level back. Maybe tomorrow.

 

Today I picked up a mitre saw and processed the timber that made up the old deck, cutting off rotten ends and generally tidying up and stacking stuff neatly. Far more fun than it had any right to be. Got a fair bit of 2x4, and ~7M² of decking boards that would otherwise have been thrown - the saw was £100, and I've salvaged maybe £150 worth of timber with it already.

 

[SteamyTea]

Fill them with soil and grass seed, then it will be a self sustain wall.

Add a bit of bamboo and you can incorporate the structural elements.

Got to be better than hazel twigs.

Edited September 24, 2023 by SteamyTea

[Nick Thomas]

Eh, it's coppiced lumber so they're boughs, not twigs. It's optional, though - best thought of as training wheels for straw bale newbies. Helps to hold the wall in place until compression, and doesn't have a significant role thereafter (although it does help a bit against lateral loads, you don't benefit from that unless you've got a long exposed run. In practice you've got door and window posts along those too, most of the time, which will do a lot more).

 

In low-humidity places they often use rebar for the bottom set of spikes - more for convenience than strength. Can't get away with that in a humid climate. Bamboo can be used; it's about the same price, but somewhat harder to source locally at ~38mm diameter. None of it's structural though.

[Nick Thomas]

OK, finally got around to calculating some wind loads. The question for me was whether wind pushing against the side of the garden room might cause the whole thing to roll away, off into the sunset.

 

Assuming I'm doing it right, it all seems pretty simple. Call it 4 tonnes of structure sat on top of the gravel. Coefficient of friction for a concrete block sat on wet gravel is apparently 0.4: https://www.eng-tips.com/viewthread.cfm?qid=379441

 

> The CalTrans Falsework manual (4-5.09) allows mu=0.6 for concrete anchor blocks on dry gravel (or 0.4 for wet gravel).

 

Mass * gravity * CoF = 15.68kN. 100mph winds against 10sqm of wall exerts a force of 12kN, so even in those conditions it should stay put. In reality, the gravel surface should generally be dry, the winds will never get up to those levels, the concrete blocks will be bedded into the gravel, it's braced on three sides, etc, etc. So I figure there's no need to anchor it to the ground (e.g. by shoving a post through the concrete block and down into the gravel).

 

Progress elsewhere - I've figured out the 15° cuts on the mitre saw to get 105° angles on the baseplate. That's allowed me to locate the final two foundation holes; I've dug one out, got the other one halfway. Will finish those off, level, then screw all the timber into place next time. Illness and weather have conspired to make it hard to get much done recently :/.

[Gus Potter]

21 hours ago, Nick Thomas said:

OK, finally got around to calculating some wind loads. The question for me was whether wind pushing against the side of the garden room might cause the whole thing to roll away, off into the sunset.

 

Assuming I'm doing it right, it all seems pretty simple.

Well done having a go at this. Unfortunately it's not a simple task...

 

I can see you have had a go at calculating the sliding resistance. Call this the global behavior of the structure.  I have not looked at you calcs in depth but you are missing two vital things, the first is factors of safety, second and fundamentally when the wind hits the side of the building some goes round the sides and some over the roof. But there is already wind over the top of the roof so you need to squeeze this extra air into the envelope around the building. This increases the air velocity and particularly a flat roof starts to act like an aircraft wing and the roof lifts up. The uplift forces are large so you need to deduct this from the self weight of the structure. Now normally the sliding check is fine and not the critical check as say masonry structures are heavy.. bales less so.

 

The structure could also hold together and overturn.. roll like a ball. My gut feeling is that even with a bale building this will probably not be the critical check.

 

What I think will be the critical check it to make sure that the columns you are forming on the front elevation are able to carry the wind loads as individual elements. Around the sides of the door and at the corners you could get very big uplift forces.. unless you make the roof very stiff. In other words I think that even on a windy day the front wall will start to skew sideways (you also need to transfer what are called shear loads and the bales I don't think will do this well).. then you won't be able to open the doors... take this as an early warning you have got it wrong.

 

To sum up the above.

 

Wind loading is complex, there is a lot to it and the knock on effects are significant.

 

For me.. you have a limited life structure, not occupied all the time.. you could compare this to an open sided farm building in terms of sideways stability (your front elevation with windows / doors), a marquee or similar temporary structure. When we design these we take a more pragmatic view, settlements are less important. What we say is we need to stop two main things happening. The first is that it does not suddenly collapse (without warning) and second is it does collapse say in the wind that bits don't fly away and hit people first and then other buildings ect.

 

I think you really need to stop the front of the building moving sideways and will struggle with bales. One solution that springs to mind is to make the frame around the doors very stiff and strong so it resists the sideways forces. We do this when making big openings in the walls of buildings that are intended to hold things up and stop the building moving sideways. You door frame could be a portal (two columns and a top beam very well connected together) or a box frame, I think this may be best to look at first... the box frame You could make the structural door frame a feature to compliment your attractive design?

 

To get your head round how the sideways forces work make a portal or box model out of 3 or 4 members.. bits of wood. Hold it at the bottom and push it sideways and see what happens. Look carefully you'll get a downwards load at one side and an upwards load at the other... this uplift load is the dangerous one! This load needs to be resisted by tying down.

 

Encouragement!

 

I bet there are loads of folk that would love to be able to do what you're doing and can see you are making a great effort. If you can do this for 3 -4k materials folk will chew your arm off!

 

One way of really understanding this and how it will roughly behave is to get a cardboard box (or a few), cut holes in it to the scale of your windows / doors. Make a roof for it and pin / tape it with match sticks ( to represent your Hazel sticks) to the top of the box. Tape the thing to the dining table and start to push it sideways.. see what happens.

 

This can be great fun for both adults and kids.. before you test it to destruction observe it first or you'll use a lot of boxes! This might sound a bit daft but this is how we teach SE's!

 

Keep posting!

 

 

 

 

 

 

 

 

[SteamyTea]

32 minutes ago, Gus Potter said:

factors of safety

Think that is built in with a 100 MPH wind at ground level. 

32 minutes ago, Gus Potter said:

there is already wind over the top of the roof so you need to squeeze this extra air into the envelope around the building

Getting a bit technical, the energy in a moving fluid as it hits an area is proportional to the cube of the velocity.

So should not be too hard to do a rough calculation based on downward force and uplift.

Then add in some safety because, as you rightly say, the failure mode is important.

 

I tend to prefer a failure to be in very small parts, like a toughened windscreen. It can take quite a wallop before catastrophic failure, but after that, the main missile has lost a lot of energy, and the tiny bits of glass are so low energy that they are, in effect, intrinsically safe (maybe a few scratches).

Edited September 27, 2023 by SteamyTea

[SteamyTea]

Just had one of my long journey thoughts.

Why not use rope to tie the roof structure to the ground.

Even small dingy boats have quite large sails, the sheet (sailor boy talk for a sail rope) is quite thin. Could easily be thinner but it would cut into fingers.

When I went climbing I think the static lines were 6 or 8 mm. They could stop 80kg after a seconds fall without hardly stretching at all, thankfully.

[Gus Potter]

Hi @SteamyTea

 

The general equation we use in the design codes is below. The extract is from the BS wind code. The factor of 0.613 is related to the air density but it boils down to Newton.. Force = mass x velocity squared.

 

 

I know and agree that in most parts of the Uk 100 mph is not likely.. but we design on a 3 or 10 second wind gust speed depending on which commonly UK design code we use. It's these wind gusts that cause problems.

 

Looking at @jayc89's design I think there will be issues at a much lower wind speed. I'm sure that can all be dealt with no drama.. main thing for me is to do it so you understand where you need to improve and where you don't.. thus not waste money and time.

 

51 minutes ago, SteamyTea said:

I tend to prefer a failure to be in very small parts

 

Well you have nailed that. As SE's we call this disproportionate collapse. In other words we design so a small local failure won't result in the whole building falling down.

 

A good example of this is when we design steel reinforced concrete beams. We make sure that the beam will fail by the stretching of the steel (steel is streatchy stuff) reinforcement rather than a sudden explosive failure of the concrete  as it is compression. Doing this way means that folk inside will hear noises, see big cracks and think.. I need to leave the building. The same applies to the straw bale construction.

 

@jayc89 I think that you could build this and you could have big problems with the operation of the windows and doors. Now you can kill two birds with one stone. By making it safe you'll get the best service life out of it. I don't think you need to spend loads extra.. just understand what you need to do structurally and find off the shelf products that will do the job.

 

 

 

 

 

 

 

[jayc89]

10 minutes ago, Gus Potter said:

Hi @SteamyTea

 

The general equation we use in the design codes is below. The extract is from the BS wind code. The factor of 0.613 is related to the air density but it boils down to Newton.. Force = mass x velocity squared.

 

 

I know and agree that in most parts of the Uk 100 mph is not likely.. but we design on a 3 or 10 second wind gust speed depending on which commonly UK design code we use. It's these wind gusts that cause problems.

 

Looking at @jayc89's design I think there will be issues at a much lower wind speed. I'm sure that can all be dealt with no drama.. main thing for me is to do it so you understand where you need to improve and where you don't.. thus not waste money and time.

 

 

Well you have nailed that. As SE's we call this disproportionate collapse. In other words we design so a small local failure won't result in the whole building falling down.

 

A good example of this is when we design steel reinforced concrete beams. We make sure that the beam will fail by the stretching of the steel (steel is streatchy stuff) reinforcement rather than a sudden explosive failure of the concrete  as it is compression. Doing this way means that folk inside will hear noises, see big cracks and think.. I need to leave the building. The same applies to the straw bale construction.

 

@jayc89 I think that you could build this and you could have big problems with the operation of the windows and doors. Now you can kill two birds with one stone. By making it safe you'll get the best service life out of it. I don't think you need to spend loads extra.. just understand what you need to do structurally and find off the shelf products that will do the job.

 

 

 

 

 

 

 

 

Not sure I was meant to be tagged in this one 🤣

[Gus Potter]

Yes you were as it is your project and love what you are doing and your approach.

 

I'm chipping in with partly my SE hat on in the hope you will make it safe but also to encourage you as best I can. On the other hand you have been on a course, know other stuff, taking an innovative design approach so we are all learning from each other. This works both ways.. I learn from you and visa versa.

 

Where I think you are going off track I say so and try and justify why I think so.

 

Think about this another way.. a garden room on average adds 20 -25k to the value of your house (think it was Which magazine that said something like that).. Imagine if you can do this for 4k, justify that it is safe and when you come to sell.. now you have pocketed 20k tax free, have enjoyed building it and using it..

Edited September 27, 2023 by Gus Potter
typo

[Sparrowhawk]

@Gus Potter are you sure you mean @jayc89 and not @Nick Thomas?

[Gus Potter]

@Sparrowhawk

 

Distaster strikes at my end. Thanks for pointing out my error and the heads up @Nick Thomas

 

Can you all for give me please.

 

I just use my own name.. not forgotton that yet.. but time may tell as I age .. further.

[Nick Thomas]

Hah, easy mistake to make, no worries. Thanks for the pointers @Gus Potter. Yep, some more calculating to do, for sure. To pick out a few things -

 

3 hours ago, Gus Potter said:

The uplift forces are large so you need to deduct this from the self weight of the structure.

 

Yup, makes sense, thanks. I guess one approach in the absence of data about how the uplift / lateral forces would split (which I assume is quite dependent on specifics of structure shape) would be a sensitivity test; I'll see what I can knock up.

 

 

3 hours ago, Gus Potter said:

I think that even on a windy day the front wall will start to skew sideways (you also need to transfer what are called shear loads and the bales I don't think will do this well)

 

I don't know if you've taken it into account or not, but the straw bale walls are (or rather, will be after this winter 😬) rendered with lime plaster externally, which adds a lot compared to just stacked straw bales, or even stacked-then-compressed bales.  https://www.sciencedirect.com/science/article/abs/pii/S0950061821006711 has some experimental results vs lateral loads, to see the kind of difference it makes.

 

3 hours ago, Gus Potter said:

think you really need to stop the front of the building moving sideways and will struggle with bales. One solution that springs to mind is to make the frame around the doors very stiff and strong so it resists the sideways forces. We do this when making big openings in the walls of buildings that are intended to hold things up and stop the building moving sideways. You door frame could be a portal (two columns and a top beam very well connected together) or a box frame, I think this may be best to look at first... the box frame You could make the structural door frame a feature to compliment your attractive design?

 

The detail for the door (and window) supports is 4x4 timbers anchored to the box beam either side of the door, running up to the roofplate where they are similarly anchored post-compression. So it's pretty much a portal as you describe it, I think? I've got the ones for the doors landing directly over piers (the ones for the windows *might* have to cheat a tiny bit, or I might have to dig a bit more ground out, but I'd like to think I'm finished digging for the moment 😅).

 

Normally it's lime render right up to the posts, with clay plaster internally, both at a nice curve that increases daylight penetration; I don't mind losing that if I can prove the structure needs it for stability, but less keen on adding it "just in case", since it would lose those features.

 

2 hours ago, SteamyTea said:

Why not use rope to tie the roof structure to the ground.

 

I actually had the same thought on my initial read-through. A few (or many, depending on what numbers end up saying) guy ropes into earth anchors wouldn't be the end of the world, and easy to fit - or retrofit, if things started going wonky.

 

If I'd gone with piles, I'd be tied down into the earth already, of course, but it could easily have been £1K in steel to do it.

 

Got the final two piers in, at least. Lots of rejigging to do, still need to turn a load of the blocks, etc, but hopefully no more digging.

 

 

Soil away to the HWRS at the weekend, I think.

[Nick Thomas]

No more maths yet, but a bit more progress:

 

 

That's the foundations and the box beam pretty much done. I found a supplier of OSB3 that's £20/sheet rather than the £60/sheet being asked for by Big Builder's Merchant, so I've decided to just follow the instructions and clad it top and bottom with that, which will add lots of stiffness. It's being delivered tomorrow. Baseplate on top after that, and I can get the uprights in for the door and windows, so it'll have some height.

 

The eagle-eyed will spot that some of the foundation blocks are still on their sides. Those are the 430x215x140 ones - sat upright individually, they're not very stable, it turns out. Managed to overturn one filled with gravel while dragging the frame around 😬. So I'll leave them on their side but will fill the voids with something cementitious in an attempt to improve their strength.

 

Excavated soil went to the HWRS, and not a moment too soon - the lawn is not happy. I guess it was about a couple of tonnes across 70 bags.

 

One more thing I've thought of - I'm currently taking the 2.5M height restriction to stay within PD from the ground by the apple tree. Behind the retaining wall, however, the ground is maybe 50cm higher than that (I haven't measured it precisely, just guessing). If I could use that as my level instead, I'd have so much more freedom, but it may be a case of wishful thinking. The wording is the highest ground level "immediately adjacent" to the building, and I have a 50mm gap between the garden room and the wall; but then, the wall is kind-of-maybe part of the structure, since it provides essential rain shielding?

 

I can pay them £60 to find out, which seems worth a punt if it's at all arguable. Anyone had a similar situation?

Edited October 3, 2023 by Nick Thomas
s/point/punt/

[Nick Thomas]

So here's a very nice book - "Straw Bale Building Details". https://newsociety.com/books/s/straw-bale-building-details . Published by the canadian straw bale people (CABSA). Its chapter 3 is dedicated to structural stuff, including shear forces. A relevant snippet:

 

 

 

The units are all rather awful, but I'm quite impressed by how much stronger than clay the lime render is; it's definitely pushing to use it inside as well as out. They go on to talk about various shear wall designs, including the "internal pins" style of things. More reading to do before I understand it well, though.

 

OSB3 is here; I've done one last level and tied all the foundation blocks to the wood with the straps, and started cutting the cladding for the box beam.

 

Before I can get those glued & nailed into place, I need to get the upright posts in for the openings (or at least prepare the box beam to receive them, I guess). I've sourced the windows - local curio shop had a single-glazed wooden casement set that's ~800mm wide by 1200mm high, and I've ordered a 440mm HDPE bubble window(!) for the apple tree view. Just a little bit like https://www.sopocottage.com/2019/01/for-love-of-bubble-window-but-dont-try.html . Figuring out how all this fits together to keep the water out is, uh, absorbing.

[SteamyTea]

7 hours ago, Nick Thomas said:

HDPE bubble window

HDPE is usually High Density Polyethylene, clear plastics are usually acrylic (the best) or polycarbonate (the worse).

Do you know what the bubble is really made from?

[Nick Thomas]

They say "clear HDPE"; I have no reason to doubt them. https://www.onlineplaygrounds.co.uk/children-playground-bubble.html

 

 

[joe90]

On 03/10/2023 at 19:18, Nick Thomas said:

I can pay them £60 to find out, which seems worth a punt if it's at all arguable.

How do you get on with youre neighbours?, it’s only them that will dob you in it, I am yet to come across council officials that measure height unless a complaint is received. Great to see your progress, well done, slightly jealous as straw bale construction was my plan years ago and I helped on a couple of house builds. I recently pointed an old garden stone wall in lime and really impressed with its plasticity (compared to cement). No idea of the mix, it was left over from a worker next door re rendering an old cottage. Watching many programmes and articles on straw bale building I was impressed with spraying the line render on, gets into the straw very well but maybe OTT for your little project.

[Nick Thomas]

11 hours ago, joe90 said:

How do you get on with youre neighbours?

 

Sadly, there are quite a lot of them and we don't know them very well - only moved here recently. They'd only have the road level as a point of reference themselves, but my feeling is better safe than sorry. Although my backup plan if I ran out of room for a roof was to just apply for the planning anyway - can't see any reason why it wouldn't be granted, but I'd rather avoid the admin if possible. A certificate of lawful development seems easy by comparison.

 

11 hours ago, joe90 said:

Watching many programmes and articles on straw bale building I was impressed with spraying the line render on, gets into the straw very well but maybe OTT for your little project.

 

We were told that spraying render onto straw - certainly the first coat - is inferior to getting it on by hand, to the point where sometimes they spray it on but have a team of people going along behind the sprayer to really rub it into the straw. Our practical was with clay slip, but we were (engloved, to protect fingernail beds) pulling the straw fibres apart and really rubbing it in, in a way I couldn't see a spray gun matching. It was messy enough that I was thinking about toothed rollers to emulate the action though.

 

Really need to get on with pre-rendering / french dipping the ones that're going up against the brick wall; today I cut more OSB and got it nailed down, so ~¾ of the box beam is complete, giving me a platform for those bales to stand while they dry. I mixed up some lime putty from hydrated lime last week. It's really meant to age for months and months, but a good session with a paddle mixer apparently replicates some of the chemical process of ageing (more complete hydration and smaller, flatter Ca(OH)₂ crystals result in a stickier putty that forms a superior render). I just need the sand, now I've got a place for the bales to sit. 2:1 sand:lime for this coat, apparently; the other coats are more usually 3:1.

 

Bit busy over the weekend but I'm hoping to get the posts up and doors installed Sunday or Monday. The windows are going to be a fair bit more work - I've just got the glazed panels with half the hinges (the lift-off type), so I need to build a square frame for them to sit in and either replace the hinges or find something whose pin will fit the existing barrel. Hopefully the mitre saw will make short work of it all ^^. The HDPE window is so light it won't need any posts, I've decided. Time will tell whether that's a good decision or not.

 

The windows in question:

 

 

(Didn't pay £120 for them though)

[Nick Thomas]

Bit more progress \o/

 

 

Straw goes onto baseplate, hazel stubs in noggins to pin the first course. Loose straw gets packed into the gaps in the baseplate, and stuffs any gaps between bales. Dressing the bales (with a hedge trimmer) generates plenty of that.

 

Got the doors in as well but that's a botch job so won't show it yet 😉. Once the paddle mixer is here i can whiz up some render for the bales along the brick wall and get those in permanently; have a strong urge to get the posts surrounded by straw before strong winds come along, though.

 

Packing straps pre-installed under thebaseplates,ready for conpression time. Unsure juat now whether I can use them to do the compression, or if I'll be running truckers straps under the box beam and around the wall for the extra beefiness.

 

Edited October 10, 2023 by Nick Thomas
packing straps

[Gus Potter]

Hi @Nick Thomas

 

Really like what you are doing and how you are thinking about making it safe and what not.. to last a long time.

 

But your solum space is..a bit of a mess. I think need to get that ventilated big time or you could end up with serious issues.

 

The bales seem to be touching the retaining wall or close to it. There is no ventilation at that interface.. I think you need at least 150 -200mm of a gap between the bales and the walls. Also you need to think seriously about the weathering details at the retaining wall.  Can wind driven rain hit the retaining wall and flow down? The retaining wall will be damp anyway and if you close off the ventilation the surface of the retaining wall it will become more damp. The water gas inside will pass through the bales and if touching the cold retaining wall will condense and wet the bales.. you'll have compost really quickly!

 

Have you thought about spiders / infestation etc ..bugs..  they will love that. Are you sure the straw can be left exposed for say 20 years in the gap at the rear?

 

For me I think you have spent a lot of time thinking about this and then spent more time posting on BH which I really appreciate.. I have learnt a lot from you so it is not a one way street where you post and get slagged off.

 

I hope that once you digest and take a step back you will see  where I'm coming from.

 

What about making the back wall a timber frame with wood fibre insulation? Make the panel and stand it up? or something like that? The really weak spot here is the rear / retaining wall interface. I think you need to review what you are doing here and how you are going to achieve the weathering details. Also you should get a good air flow under the floor.

 

 

[Nick Thomas]

9 hours ago, Gus Potter said:

The bales seem to be touching the retaining wall or close to it. There is no ventilation at that interface.. I think you need at least 150 -200mm of a gap

 

Sorry, yeah, I should have mentioned this. The two bales there are coming back out shortly - the plan is a 50mm gap, with the bales "french dipped" in lime render before final installation, and then covered over with Tyvek/etc vapor-permeable membrane, held taut, in case there's run-off. You're quite right about the risk of condensation; the ubackus calculator picked it up while i was designing. A 10mm ventilated cavity was enough for its concerns to go away. I 5x'd it but that was about all the space i could make. Its assumptions seemed conservative for my case though - what do you think a 150mm cavity would do that a 50mm wouldn't?

 

I'm less worried about rain; there'll be a little getting in from the east edge, but I can't see it penetrating far. From the north, the roof overhang (once designed!) and wall should do a reasonable job of keeping it out; I'm expecting the membrane and render to protect the straw enough from what does get in.

 

If I'm wrong, the straw - and quite possibly the wood too - will rot, so it's pretty high stakes and thoughts are definitely appreciated!

 

Critters-wise, my main concern is mice and rats. Once the walls are compressed, only gnawers will be able to get through, and the lime should discourage them; I'm also planning on anti-rodent mesh along the bottom and lower sides of the cavity and probably all round the outside of the building. It' going to be a pig to install but if I do it now I won't be able to compress round the box beam if needed.

 

Wasps are an ever-present danger. Again, i'm hoping the lime will keep them away. I'm paying attention to the underside of the base plate and box beam to make sure they can't set up a nice home in the straw from there.

 

On the roof - i've started fiddling with the idea of a hipped roof, which I'm reading can minimise wind uplift with the right pitch. I've not made life easy for myself with the "curved" wall though. Not sure if it's fine with four planes, or if i need to break up the front plane into 2 or 3 to make it work. Might get a professional to work this bit out ;-).

 

This assumes I can get the lawful development certificate though - if I submit plans with a noddy hip on top it'll give them something concrete to evaluate against the ground level, at least.

[Onoff]

1 hour ago, Nick Thomas said:

Critters-wise, my main concern is mice and rats.

 

They'll love it, you've only got to leave a 10mm hole somewhere. I'd be most worried about the gap between brick wall and bales.

 

 

[Nick Thomas]

On 11/10/2023 at 11:48, Onoff said:

They'll love it, you've only got to leave a 10mm hole somewhere. I'd be most worried about the gap between brick wall and bales.

 

Maybe I can train some mice to carry the mesh down the hole for me. In theory I can just lower a 4.5M strip of the stuff down the cavity once the wall is complete to protect the bottom, then put some up at the east and west edges, but I'm pretty sure the implementation is going to be a pain ^^. Everything about this brick wall is, honestly.

 

Paddle mixer arrived, so I got a fair bit more done along that brick wall -

 

 

The membrane is going in longwise, lapped in every two bales (they're 350mm high, the membrane is 1M wide, so it works out nicely. The packing straps, once tightened, and with a lot of gentle tugging either side of the building before it's secured permanently, should hold it taut against the bales, keeping the cavity clear. This bottom strip of it will need its height adjusting so it's not baggy around the bottom of the straw post-compression, which will be faffy, but doable. Originally I was going to have 5x2M strips going vertically, but that seemed even more faffy.

 

Pretty sure the lime won't cure properly - we're late in the season for it and it's a pretty wet mix that's being denied further water - but its main job is to make the outermost layer of straw unpalatable, and I reckon it'll manage that. Will probably give it a miss for the top 2-3 courses.

 

Sunny weekend coming up, and I've got a friend round to help, so hopefully we can make decent progress on it together.

[Nick Thomas]

Welp, storm babet has been and gone and it's all still standing.We got winds of ~50mph and plenty of rain, but it wasn't particularly noticeable in the garden - it really is sheltered.

 

Got to four bales high on the bit I've been working on, drove those hazel spikes in, then got it all tarped up. Once the storm passed, I got the uprights for the window in, and (no pic of this) got the first bale down between them. Lots of notching. Managed to pick up an alligator saw cheaply, which is helping a lot with that part.

 

Plan now is to get the rest of the walls up to four high and staked; get the windows in; then build the wallplate while the top of the wall is still fairly accessible. Ideally you do it while the floor plate is still accessible so you can use it as a template, but I was pretty tired of wood at that point ^^. I've got the dimensions written down somewhere. Once that's ready, I can haul up the bales for the final two courses; wallplate on; compress; build the roof; re-compress; build the floor. Then in spring, lime render inside and out.

 

Pics - two before the storm, one after:

 

 

 

 

The gap in the fourth course on the west side is *hopefully* going to turn into my bubble window, with a lot of shaping. I expect it'll be porthole-sized by the time I'm done.