There has not been a lot to report of any real interest of late, hence an article about drips. However, before getting into the drips, I should record what I have been up to. This almost exclusively concerns the roof: finishing of the roof plate (cutting holes and driving down hazel pins, inserting noggins and insulation, glueing and nailing down the top plate), and putting in place the remaining roof frame elements (the purlins on the ridged element, securing the rafters on the lean-to element, exending the ridge rafters on the side where they have to overhang the walls). This has all been rather boring work.
The roof itself has arrived, although not without problems as some of it fell off the forklift when being taken from the lorry to site. I am using basic pre-insulated box profile steel sheeting – so it is very simple to install, albeit not a one-man job hence why I am waiting for Builder Tim to have a couple of spare days. I am very much looking foward to the security of having a permanent roof on.
This brings me onto drips. For the last few months I have had a temporary roof in place – i.e. tarpaulins fixed onto the basic roof frame. I had to do this, rather than install the roof sheeting earlier beause of the need to access the top of the walls to drive pins down through the bales. Having tarps is a bit risky because they are always prone to being torn-off by heavy winds and when there are winds there is usually also rain. It is easy to get to a point where you have fixed the tarps and then stand beneath them on a rainy day and feel comfortable with the fact that no rain appears to hitting the straw. However, this can cause you to overlook the issue of drips. It is almost certain that there will be some small holes somewhere in your tarpaulin, possibly where you may have hammered some battoning onto it to hold it down. Water will probably be getting through these holes – maybe only a very small amount, but as you know from what happens if you put a bowl under a dripping tap or leaking pipe, this can very quickly mount up. You therefore have the potential to be channeling a very large amount of water into a very concentrated area, yet not be able to see this happening.
I fact, I found three areas where this had been happening which I only noticed because grass was starting to sprout from the straw. In these places a narrow strip of straw, only two or three inches wide had become saturated to a depth of about 5 or 6 inches into the straw, down to a depth of around five bales. In all instances I was able to track this back to a small hole in the tarp. Fortunately I don’t think this is a major problem because the dampness is very localised, should dry out now the leak has been plugged and I could probably pull-out and replace the straw if necessary.
However, this is something that it is worth paying attention to if you are likely to have a temporary roof up for any period of time. Also bear in mind that a tarp will channel water and if you are not careful in how you secure it (or if it breaks loose from its ties) it does have the potential in a heavy shower or storm to direct a lot of water into a place where it can cause real damage in a very short time.
I have also had some issues where windblown rain has got into the face of a wall, but this hasn’t got to any great depth. However, I will make sure that before I put render on I have checked to make sure that walls are completely dry.
Here endeth the precautionary lesson about drips.
Last week I completed putting in all the straw and it now feels slightly strange that, in building a straw bale house, the straw part is now over and was actually a relatively short part of the process. That said, there will still be some more straw work to do – filling in above and below the windows and working out how to do the gable ends.
The next task is to finish of the roof box beam by driving hazel stakes down through the bottom plate, compressing the walls, fixing the window and door supports into the beam and then putting on the top plate. However, before that I needed to give the straw walls a trim, both because it is easier to to this before the compression straps are in place and also because it makes it easier to see if the walls need to be knocked around a bit with the ‘persuader’ to straighten them out before fixing them more securely with internal stakes.
I started doing this with a chainsaw but found that the loose straw clogged-up the air intake and also got inside the casing and started to burn. I know that Barbara Jones recommends an alligator saw – but I don’t have one of these and they are quite expensive to buy – so instead I tried using a petrol-driven hedge trimmer. This worked-out pretty well. It is not so aggressive / effective as a chainsaw and having it attached to a long pole (because my hedge trimmer is actually just a strimmer with a hedge attachment) was a bit cumbersome, but I worked out a way of using it to simply ‘stroke’ down the sides of the wall from the bottom to the top. It is therefore good for basic neatening, but not so effective if you need to do any radical sculpturing.
Ultimately, I think that the final finish of the walls – trimming and dubbing-out with a long straw / render mix – is something that will have to happen when applying the first coat of render. Until I can experiment with this I am not sure how much more wall trimming and persuading will be required, or how complex and time consuming this will be and thus what quality of finish I might have to settle for.
We now have one of the long walls of the building up, thanks in no small part to Ros and Dave Goodchild who came over again this weekend. These walls are now safely clad in hessian and the tarp covering above them strengthened, in terms of ensuring no gaps or run-off channels which could allow rain water into the roof ring beam box. It feels like a huge relief to have got one wall safely ‘put to bed’. I am now gradually settling the ring beam onto the top – to give it just enough compression to stabilise the wall, but allowing enough freedom to finesse the bales into place (if whacking things with the persuader can be called finessing).
This has also been a week of research into render (of which more in a future post) and fiddling around, mostly correcting the mistakes associated with setting the ring beam too low. I have decided to bite the bullet and replace all of the window and door posts with longer ones and have bolted an extension onto the four already in place with straw notched around them. Not an ideal situation, but should be fine given that these posts are not structureal in the sense of carrying any load. They mostly give additional stability to the walls and can probably aid as a tie-down to the roof once they are fixed into the roof ring beam (after compression).
We are still planning to begin raising the walls tomorrow, weather permitting. In advance of that I have just been to collect the special bail splitting device I have had made by local forge Designs on Metal. This would have been a pretty mundane task for them, given the type of work they usually produce, but they were happy to oblige. This device is basically a large clamp, with a plate and spike at either end. The idea is that you drive the spike into a bale where you want to split it and then hold it together with the clamp while separating it and re-tying it. This is a method demonstrated in the excellent online course produced by Barbara Jones at Straw Works and I have decided to give this a go in preference to using bale needles.
I have also made my own ‘persuader’ with a length of hazel and a bit of poplar (i.e. light) to whack bales in order to make fine adjustments.
This weekend we raised the roof, despite the forecast of gales. It took seven of us, Rachel and myself, plus two ‘DIY handy’ brothers-in-law and three very capable neighbours (all of whom were sailors, one also an engineer and another a former Navy officer – thus very familiar with ropes, spars and scrambling around at altitude).
It was actually quite straightforward, once we had worked out a system. This system was:
- To place the apex of each roof truss onto a pile of straw bales – to both get it a little higher of the ground and give a platfrom to pivot them on
- Flip the truss up so that one corner is at the level of the roof beam
- Rest this corner on the beam and secure with a rope and then lift-up the other corner with a combination of rope from above and pushing from below and also swing it onto the roof beam
- Repeat so that all the trusses are hanging upside down between the roof beam
- Raise-up the end truss horizontally (with a rope and pushing from below) and slide its apex onto the end roof beam
- Repeat for all the others so they rest on the base of truss ‘in front’ them – so that all are laid like a pile of toppled dominoes
- Then winch-up the topmost truss, using a pulley from a tree conveniently located at one end of the site
- Repeat for all the others (we abandoned using the pulley once it was apparent that having a rope on the apex of each truss allowed us to control the top, and using a length of 4×2 to push the truss up).
All finished by lunchtime. Then just time to put in some floor platforms to make it easy to work on the purlins and add some more bracing in order to withstand the gales. It is still standing two days later, despite everything Storm Isobel could throw at it. Thanks everyone.
It is easy to underestimate the amount of time required to do what appear to be small jobs. Take, for example, the need to create noggins to hold the hazel stubs in the baseplate, plus the noggins to fix the window and door posts.
The noggins for the hazel subs need to have a 32mm hole drilled through them – and I need to do around 60 of those. Then there are the window posts which require two noggins each which have to have a 20mm deep section ‘routed’ out of them – 40 of these required. Finally 6 noggins to fix the door posts which have to have a 20mm groove cut out of them.
All-in-all a lot of time spent with the router and the drill. The good aspect of this job is that you can do it when it is raining (and it has been raining a lot) and I have also unearthed a benchmounted drill which was one of the things we inherited when we bought Shrub Farm. I had always assumed that this rather dusty object was left lying around in an outbuilding because it didn’t work – but after blowing-off the dust and plugging it in, I found that it did.
I have also invested in some tarpaulins – both to keep the weather of the box beam but also so that when the scaffold is installed these can provide a temporary wall and roofing so we can install the straw in relative protection.
Knocking down a building is relatively easy (at least it is once you have done tricky things like remove and conserve the roof). Getting rid of 80 or so tonnes of concrete is the tricky bit, especially if the access to your site does not allow a 7.5 tonne truck with a grabber arm to get up close to your rubble heap. This is the case with our site – which is why we were looking at having to get a digger to load the concrete in 1/2 tonne mouthfulls into a dumper, which would then carry it to a place where it could then be loaded into a truck, to be taken off to be crushed. This would also have to accomodate the fact that while there is a place a 7.5 tonne grabber could get access to (the drive), there isn’t sufficient space to pile all 80 tonnes there at one time (since it is the drive) – thus requiring a continuous process of dumping and carrying away which would inevitably involve lots of downtime with the digger and dumper, while the truck carts the concerete away and then returns (expensive). Or else having a fleet of trucks on hand (also expensive). And then, because we want at least 40 tonnes of crushed concrete back, the whole process would have to be reversed.
A far easier solution would be to crush the concrete in situ – the only problem here being that portable concrete crushers are rather insubstantial affairs that can digest only relatively small chunks and can only get through 15 or 20 tonnes a day (also expensive because of the days required and also the need to have a digger to load the concrete into them). However, step forward Simon Oliver, of Crusher Trucks. Simon has taken an big, industrial scale fixed concrete crusher and mounted it onto a powered chasis, together with grabber arm and concrete picker from a digger, plus a tipping hopper and a adjustable conveyor belt that can then feed the crushed concrete onto a pile. He has also somehow accomodated a means of weighing what is crushed in order to record how much it gets through. This incredible device can be towed onto site and manouvered into places a 7.5 tonne truck can’t get to. He charges £5 per tonne to do this (bearing in mind that it costs £7 per tonne to actually buy-in crushed concrete without the costs associated with then moving it onto site).
Simon and his machine have just been on site to perform their crushing alchemy. It is astonishing to think that one man, in his workshop, can create such a thing. He didn’t even start with a chasis and engine borrowed from another vehicle – the whole thing, including the complicated hydraulics, is totally handmade. As far as I know there isn’t another one like it in the country, if not the world. And rather conveniently, Simon is based only 10 miles away. His number is 07860 207166.
I can see a Channel 4 series here, sort of George Clarke’s Amazing Spaces combined with Scrapheap Challenge. ‘One Man and his Workshop’ could be the title and it would feature the most amazing things men (I would imagine it would mostly be men) have made in their workshops. Simon would probably win.