Render Stops

At this point I would like to talk about a little problem I’m encountering all too frequently. There’s a prominent figure in the strawbale scene in S.E Australia who is obviously pretty crash-hot in the marketing department, but not particularly interested in actually helping people to get a decent looking house.

For some reason, this person’s encyclopedic notes he hands out (after people have handed over a pretty substantial amount of cash) don’t make even the slightest mention of a render-stop.

Putting a piece of timber at the top and bottom of a strawbale wall to give the renderer a “given” plane or surface to work to is not a new concept. In order to create a good looking finish on a rendered strawbale wall, you can do it the easy way, or the hard way.

The hard way involves a lot of guess work, averaging things out, hoping for the best, and working out how to do the ‘fit-out’ to accommodate a dodgy looking render job.

The easy way? Have a look at this diagram. Pretty simple, yes?

Next time….the bottom…..

Mia Mia Project

Professional Strawbale has been fortunate enough to win the job to stack and render a house for Unicorn House, based in Daylesford. The house is in Glenhope, near Mia Mia, which is just out of Redesdale in Central Victoria. This is about an hour’s drive from home – quite a luxury! At this time of year, the countryside around Redesdale is extremely pretty, which makes me very grateful to be doing a job that lets me work in some of the most beautiful places in the state. (See picture)

As with all the strawbale homes I’ve worked on for Unicorn House, this frame is a ‘buck’ style frame, where instead of using a simple post to support the perimeter beam, a large upright box is built from 90x45mm pine and 5ply, the cavity of which is filled with polyester insulation. The buck style of frame is an American system, not used very commonly in Australia. Its main attraction from a builders point of view is the lateral bracing afforded by the width of the thing – it’s effectively a post that’s as wide as the bale wall itself. Another advantage of the buck system is that it provides a series of pretty predictable vertical fixing points right throughout the strawbale sections of the building. Not only are they predictable in their position in the wall, but should be under a uniform depth of render, making fixing after rendering fairly easy. Provided it’s been built pretty accurately, and is properly fixed to the slab (or sub-floor frame in the case of timber floors) it does brace the wall against any lateral movement. Another attraction of this system is that with a ‘buck’ on either side of every opening, there is no need to worry about trimming bales to form nice, neat corners at the doors and windows. As you can see from the photograph, the bales are stacked as infill in between the bucks that form the sides of the door, (on the left) and a curving window section (on the right).

From a strawbale subcontractors point of view, it makes the stacking of the bales extremely easy, but this is probably offset from the builders point of view by the extra work in actually making the bucks. A series of long fixing battens are required for mounting a kitchen cupboard unit which was overlooked in the stacking stage, so I’ll photograph and describe the process for the next blog entry. Hooroo! LOOKING FOR BALES? This week we’ve been contacted by a fellow in Mt Evelyn in the Yarra Ranges who runs a stock feed supply business, and has an oversupply of good quality straw and is looking to move it in a hurry. We haven’t seen the bales in question, but he says they are suitable for building- any interested parties should use their own judgment to decide if they are dry and clean enough to use. John Wright of Complete Hay Supplies can be contacted on 0427 001803 or jsw504@bigpond.net.au

Strawbale and Bushfire

Given the recent tragedy of the Victorian bushfires, in which many lives have been lost and at least 1800 homes destroyed, we thought it pretty timely to write about the information available regarding the fire resistance of strawbale walls. The susceptibility of strawbale buildings to fire hazards is a surprisingly common question when talking to the uninitiated, but most people don’t take long to realise that for any material to burn, it needs a good flow of air, and trapping air, not allowing it to flow through the bale, is what the insulative value of strawbales is all about. During the stacking of the straw, large amounts of loose straw accumulates very rapidly, and this loose, dry mass can be extremely flammable, but this period is relatively brief, and a bit of basic housekeeping with a plastic garden rake quickly minimizes the risk. The most recent Australian work we have found available was conducted in 2002. The principle organiser and motivator behind this testing was architect, Bohdan Dorniak, past president of Ausbale (Australasian Straw Bale Building Association). Bohdan is to be commended on his dedication and hard work in getting strawbale established as a widely accepted building material in Australia. The testing we are referring to was conducted by the CSIRO Building, Construction and Engineering division in North Ryde, NSW. (See link to Earth Garden article below) The bales tested were rendered in earthen lime, and cement based renders, and all performed well enough to exceed the required standards. According to Bohdan’s Earth Garden article, the “samples were subjected to a simulated bushfire front with the maximum heat intensity being rated at 29 kilowatts per square metre” (imagine 29 1000 watt heaters all crammed up against one square metre of wall). In the article alone, we aren’t given a time period over which this energy is applied to the wall. Brian Menadue, of the South Australian Country Fire Service was present at the testing and was quoted by Bohdan Dorniak as saying “rendered strawbale would be an acceptable wall material”.

http://www.earthgarden.com.au/strawbale/fire_test.html

Check out this link for information from the Australian Government on strawbale and fire resistance.

http://www.yourhome.gov.au/technical/pubs/fs58.pdf

There are plenty of other aspects to fire proofing your strawbale home which i will cover in coming weeks.

Hooroo

February 7th 2009 – Daylesford

Hot, hot, hot!!
Last Saturday we were forecast to get a maximum temperature of 43 degrees, so I thought that arranging a drive to Daylesford to repair a crack in a strawbale wall and meet some prospective clients was a pretty bright idea.
More often than not it’s at least a couple of degrees cooler in Daylesford than in our home town of Bendigo, but when the temperature is in the low to mid 40’s , it’s pretty much academic!
So, it was a real stinker. My ever-informative wife, Cathy, called me just after 1pm to tell me that it was 44 degrees on our back verandah at home – and true to form, it was only 41 degrees in Daylesford.
I was delighted, as usual, to see another beautiful strawbale home being thoroughly loved and enjoyed by its happy creators.
Penny and Wayne owner-built their two-story dream cottage a little over three years ago and they love it to bits. The house is a little less than ideal thermally as it has single glazed windows, is exposed on a hill side to the hot northerly wind, and has three big dormer style windows sticking out the front like great big solar collectors. However, despite this, on a roasting hot day, after a week of days 39 degrees, it was still only in the mid twenties inside, and quite comfortable, and all this without any kind of air conditiong at all.
Another strawbale success story!
Thanks very much Penny and Wayne for inviting me into your home, its truly lovely!!
I’ve a few theories on the crack in the north facing wall, but I’ll have a bit to say about that next time!
Bye!!

We are back Blogging!!!

 

Happy New Year!!!

It looks like Professional Strawbale has a pretty busy year coming up – we’ve had a staggering amount of interest and enquiries over the previous twelve months, and I know plenty of those enquiries  will be turning into exciting jobs this year so I can pass on more strawbaling info to you.

We’ve just finished a very little job in a spot called Walmer – it’s about half way between Ravenswood and Maldon, about 20 km southish of Bendigo. (It’s always fantastic to get work close to home).

The job was only a single wall, about 8 and a half metres long and 2.4 metres high, in a pretty unique and attractive building clad in a composite of strawbale, corrugated iron and western red cedar weatherboards.

The builder, a fella from Barkers Creek, just outside Castlemaine, was given a pretty crook frame design, but has made a pretty good job of it.

As you can see from the diagram, the posts and beam carrying the roof are positioned towards the inside surface of the wall. Because the owner wanted a nice deep window reveal on the inside, the windows themselves had to be situated at the outside of the wall. The solution that George came up with was to build a box out of melamine coated particle board, which he then screwed to the 50mm x 50mm RHS posts supporting the beam and rafters. The window was then fitted inside the box so that it protruded about 20 or 30mm from the outside surface of the render. What this arrangement means is that the window and its surrounding box aren’t supported by anything underneath it – it’s relying solely on the rigidity of the box to hold it in place. The long centre window was already sagging to the point where it couldn’t be opened and closed properly, so I suggested we cut a groove in the bales to squeeze a pine stud under the window – this straightened it out to its proper shape.

The architect, as well as recommending a dodgy frame set-up, only allowed 20mm for render – this is woefully inadequate. The frame set-up has also meant that in between the plaster sheet on the ceiling and the surface of the render, there’s a 250mm deep chunk of laminated timber and the outside of the render stop (about 45mm deep) to cover. You are not going to cover that up with a length of plaster cornice!!!

Anyway, there are a few more issues, but I will save them for next week.

Cheerio!

 

Frame set up at Walmer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Last Week In Mansfield

Hooray! The final week of our job in Mansfield is upon us (I know I said the same thing last week but these jobs inevitably blow out by a few days. The seven niches in the job, which have to be charged as extras, took a minimum of three hours each, which adds up to a bit over two days labour for one person, and the first four weeks of rendering we had to cart water to the site, which took 45 mins per day for one person, about 12 hours all up – so it all adds up!

 

Because of the fairly high quality of the work done on our current job, and the unique finish we get with lime renders, the builder in control of the job has asked us to quote some rendering of brickwork on his own house and small extension in the township of Mansfield.

I’ve often rendered internal walls in strawbale houses where the owner or designer has specified walls in brick to provide thermal mass, and it’s nice to know that the finish on the brickwork can be done to match the render on the inside of the strawbale walls. Of course, after rendering, the walls can then be painted, lime washed, wall papered, whatever you like!

The finished render on Stephen and Fiona’s job looks pretty classy, and we’re very proud of it. We’ll post lots more photos’ of the job after the clean up is done, and as soon as the whole job is complete, with furniture, cabinets and kids!

 

Until next time,

Hooroo

 

 

 

 

 

 

 

 

 

 

 

Mansfield June 6

 

 

 

Well, it’s the final week of our job at Mansfield, and I must say I’m looking forward to spending some time at home. We’ve been working away for about 5months now, and I’ve got to admit, it’s getting a wee bit tedious. Our youngest daughter, who’ll be turning one in July, took her first steps a few weeks ago, and I wasn’t there to see it.

Anyway, that’s enough of my tale of woe, let’s talk about building!

Over the past month or so, we’ve had a rash of enquiries about building in strawbale from the Yarra Valley, many of them from people who are looking for a competent designer who knows a bit about strawbale. The only job I’ve worked on even remotely near the Yarra Valley was at Kinglake West, about 5 or 6 years ago, and I can’t even remember the client’s name, let alone who designed it.

If any folk out there are in the process of building or planning a Strawbale home and have been satisfied with the job of their architect, designer or draftsperson, I would seriously appreciate it if they could drop me a line and let me know some details!

Similarly, If you’re a designer who is strawbale savvy, or even if you’re just interested in giving strawbale a whirl and would like to know more, drop me a line, as I’m interested in building up a database of names and contact details to pass on to interested parties.

Of course, this doesn’t only apply to the Yarra Valley, but anywhere in Victoria, New South Wales or South Australia, which is pretty much the limit, area wise, that I can cover without my traveling costs becoming prohibitive.

Any input from interested parties would be most welcome!

We’re also compiling a list of strawbale friendly tradespeople, and though this is a long and arduous process, soon we’ll be able to pass on details of builders, plumbers, electricians etc who are competent and keen in dealing with ‘alternative materials’ in general, but strawbale in particular.

Ok. We’ve got a lot of enquiries to answer via email so it’s bye for now!

 

Here’s a couple of photos taken during the week to give you an idea of where we are at.

Photo 1: North facing – Big double doors to the kids bedrooms for passive solar heat gain. Note how lovely and straight the corners are!!

 

 

Photo 2: The same doorway and the two next to it, from outside, looking at the north facing wall. Note that with only 2 and a half weeks to go until the shortest day of the year, almost all of the doorway is in full sun, giving the greatest solar passive heat gain.

Mansfield Update June 1st

On our current job in Mansfield, Fiona has requested seven niches be put into the strawbale walls. These look great if they’re done pretty neatly, but can look pretty rugged if you don’t pay close attention.

Fiona has two totally different looks in mind – one is the classic look for a niche in a strawbale wall, about 350mm – 400mm high, arched top, flat back and a little sill on the front, projecting about 50mm or so from the surface of the wall, while the others are square, again with a flat back, and no projecting sill – a much more modern look.

 

 

The first photograph here shows the first of the arched niches after it’s been cut out of the wall and first coated. I’ve always cut them out of the straw wall, after compression, with a 100mm angle grinder, but it can also be done with a chainsaw.

ALWAYS TAKE EXTREME CARE – it doesn’t matter how long it takes to perform this part of the job as long as you’re in one piece when it’s finished. It’s dangerously easy to hit a piece of baling twine inside the wall, causing the grinder or saw to get very out of control very quickly. If possible, cut through the twine, grab it with a pair of pliers and pull the whole length out of the wall – it won’t make a bit of difference to the wall, as it’s all compressed by the wire and gripples. Generally, the baling twine is positioned 100-130 mm from the surface of the bale, so cut your way into the bale for 100mm or so, and then poke around with your fingers or a knife until you find it. It’ll make a quite distinctive ‘pop’ when you cut it, and then it can be pulled out from around the bale. Don’t forget that each string will have a corresponding one on the bale above or below it. Depending on the position of the niches in the wall, you’ll also have to be aware of where the trench-mesh reinforcing is, as hitting the mesh with a chainsaw will ruin the chain in seconds. If the mesh is in the wall where the niche needs to be, make sure the wall surrounding the niche has a good heavy first coat of render on it, then cut through the mesh with a small angle-grinder. If the straw inside the niche does happen to catch fire, just pat it out with a rag and keep going, the render on the wall surrounding it will prevent the flames spreading up the wall. Contrary to popular belief, it’s almost impossible to burn a strawbale wall once it’s been rendered – even if it’s only first coated.

After cutting out the basic shape of the niche, it’s then coated with render in the usual way, taking care to ‘evolve’ the shape of the niche required as you go. The final shaping and finishing are done with a plasterer’s small tool and a damp sponge.

Our second photograph shows a finished niche in an east-facing wall, which looks somewhat gritty due to the flatness of the light; however, it will finish up smooth with a good coat of lime wash or lime paint.  

Until next week,

Hooroo,

Mark

Mansfield Update May 25th

 

Here is a photo as promised from last week’s blog entry that gives people an idea of the volume of sand that would be required for the job. This is our second load of sand and should just see out the job of roughly 300 sq metres.

 

 

Hello again,

Top coat has started on our current job at Mansfield, and it looks fantastic. At this point I’d like to say that Mansfield has turned out to be one of the friendliest and welcoming towns I’ve ever worked in, although I’ve got to admit that the vast majority of smallish country towns we’ve worked in have been full of really lovely people. It truly is a pleasure to travel around our beautiful state and meet so many fantastic people.

Many people believe that strawbale is rough and rustic by its very nature, but that’s not necessarily the case. Unfortunately, some of the people that look at our jobs think that super flat and neat is the only way we render strawbale but we’re quite happy to do ‘rustic’ if that’s what our client wants – it’s our job to give our client what they want, not what we think the building should look like.

Our current clients, Stephen and Fiona, were a classic potential strawbale couple – Fiona wanted a strawbale house come hell or high water, because of it’s ecologically friendly nature, but Stephen was pretty hesitant, because the only finished buildings he’d seen looked pretty rough, poorly finished, and didn’t mesh well with the other components of the project. As soon as Stephen saw the finished product at our previous job at Barwite, he was visibly relieved and very pleased that he’d followed his ‘green’ sensibilities and opted for strawbale. Not only had he followed his instincts and opted for the green alternative, but he suddenly realized he could have a pretty slick, professional looking job into the bargain.

Similarly we had a couple last week who drove up to Mansfield from the Upper Yarra Valley, one of whom was a dedicated strawbale convert, and the other was pretty sceptical. By the time they’d had a good look around and asked all the relevant questions, they were both well on their way to starting their dream strawbale home. Good luck to them!

The top coat on the job is being done fairly neat and accurate, not only because the owners like the look but also because it suits the look of the building.

One of the principal motivating factors in doing “the strawbale thing” is giving our clients exactly what they want, and seeing the ‘light bulb moment’ when they see their dream coming together, better than even they could have imagined. That’s job satisfaction!

Until next week,

Hooroo

 

 

Mansfield Update May 20

Hi Everyone.

Our second truckload of plasterer’s sand arrived this morning, meaning that we’ve already used 20 cubic metres of sand, and we’re well over half-way through the second coat of render. The sand that we use for our render is sold by a Bendigo firm called Epsom Sand and Soil, and has been sold for years to hard plasterers and renderers. It’s a fairly ‘lean’ sand, meaning that it doesn’t have a great deal of ‘fat’ or clay in it. This means that it can be put on the wall fairly thick, and doesn’t shrink and crack. If we were to use a ‘fatty’ sand like brickies sand, each layer of render would have to be applied quite thin, to avoid excessive cracking.

If you’re planning on rendering your strawbale home yourself, find your nearest solid plasterer, and ask them where their sand comes from. In all likelihood, this will be ideal sand for thick rendering of strawbale walls. It costs about $1400 to get a truck and trailer full of sand, which is a touch over 20 cubic metres, to Mansfield, but it’s worth every cent to know that we have the right sand for the job. We have the added complication of needing the sand to behave in such a way that it’s ‘pumpable’ in a pressure vessel type render pump, but if a strawbale builder is rendering their house by hand, then a good quality local sand can probably be sourced to do a perfectly adequate job. Keeping an eye on the shrinkage of the render is one of the main keys to doing a top quality job.

Unfortunately we don’t have the photo that was to accompany this blog which was to show you the approximate size of a load of sand and how far that would get you but perhaps that one can wait until next week. Life is very busy…..

See you next week, Mark