Render Update

Well, we finally finished the first coat of render on the outside of the strawbale walls on new years eve and we are pretty happy with the result. Our technique in mixing the mud and applying changed as we went along.

We actually ended up taking longer in putting the mud on the walls by about halfway around and taking time in making sure the render penetrated the bales for good adhesion. This was done by pushing the mud into the bale wall with thumbs and fingers, I would estimate that we got around 50mm penetration and you can tell the difference between the earlier walls and the later walls. The other advantage of working the render into the straw was that the render mix changes as it is worked, it is actually hard to explain but it is certainly noticeable when doing.

In mixing the mud we ended adding the sand and then clay and then water to a wetish mix (not too wet) and then mixing the sand, clay and water with a shovel. Once mixed only then add the straw which dries the mixture slightly. We also often left a wheel borrow load of mixed sand, clay and water without straw overnight.

The next step is to build and install the window and door frames. For this we are using 140x35 hardwood planks for the window frame and 140x45 for the door jam sourced from a local sawmill. We are using 4 edge joined to make a single ~560mm plank. The planks are joined with floating tenons at about 200mm spacing and glue, the boards are clamped using homemade threaded rod clamps. I did initially use some Irwin Quick Grip clamps but while being quick were not able to apply the required pressure, while the cheap homemade threaded rod clamps apply more than enough.

Because the walls are curved the upper and lower planks have to be curved, to do this we make the plank as above. Once the glue is dried (left overnight) the outer curve is marked through the center of the board and a jigsaw is used to cut it, the two pieces are then swapped and joined. Once the join is dried the inner curve is then marked and cut. You just have to make sure that the initial plank width is the desired width plus the difference between the inner and outer curve. You can see one of the curved pieces in the picture below.

I have currently joined enough timber to make two door jams and one window and hopefully in the next week I will put together the first window frame.

As we put the window frames and door jams we will also be able to apply the next coat (may end up being final if good enough finish) of outer render which should come upto the frames with a ~10mm overhang. We are hoping this coat is easier to apply, at least there wwill nt need to be any working the mud into the bales.

Lining the ceiling

Its a few weeks now (time really does get away from you sometimes) since we finished lining the ceiling.  We decided to use ordinary pine lining boards (V-groove), as a reasonably eco-friendly material (Radiata Pine is plantation grown - and although there is some potential that the plantation was planted on what was previously old growth forest, most of the pine plantations I know are on what was previously degraded farmland, and it is renewable).

nailing the first board!

The lining boards were hand nailed to the bottom of the purlins, which allowed us enough space to put in some serious insulation (R5 batts), which  added to the wool blanket on the sisalation that was put in when the roof went on gives us (we think) a total of R7 insulation in the ceiling.  Not too bad, and will complement the high insulation qualities of the strawbale walls.

putting in the insulation batts as the boards go up.

It took us about one day to line each 'wedge' of the ceiling, working between our main beams that form the post and beam frame.  So sadly now much of that heavy timber is not visible, but a good insulated roof is more important that showing off big timber.  We got quicker in our methods, pre-cutting the angles on the boards (since each wedge is the exactly the same there were only two angles to cut, the centre angle and the outer facia angle).  The full ceiling is lined completely, including what will be eaves.

So about ten days in weekends, and its another big job done.  Its nice to start seeing 'finished' parts come together instead of digging away at trenches that will be filled in with concrete!

All done!

Now onto the most exciting part of building a strawbale house, the walls!

Framed signed off (possibly), and a roof!

We did get the extra timber to finish off the frame and had it up in September. Some cross bracing was then added and all the bolts had to be tightened.

Once done we called the building inspector to come out and check the frame for sign-off. Because we used the coastal grey box which is rated pretty well instead of what the engineer specified in his documentation for the frame the inspector wanted the documentation changed to reflect what we used was in fact ok. For instance the engineers report specified for the main beams 2 290x35 nail laminated to make a 290x70 beam, We used a single 290x70 beam. The engineer also specified mostly F17 kiln dried hardwood, we used unseasoned coastal grey box which is rated to F22 unseasoned, but when it eventually dries it goes upto F34.

We have submitted the updated engineers report to the inspector but to date and after several attempts to check that the extra information was adequate we still don't know if we have the frame signed off, but taking a positive outlook on it and assuming that no news is good news we have moved onto the next step, the roof.

We got several quotes and finally settled on one from a local roofing company, a bonus is that the owner of the company lives just down the road and is a nice guy. One of the things that we did want is to either put the roof on our selves or at least be involved in putting the roof on. As owner builders we want to do as much as we can, the roof is one of those jobs that the authorities want a certificate for. The roofing company after some negotiation were happy to knock off some of the cost of the roof and let me take part as a general laborer.

In total it took 4 working days to complete the job, and there were three of us. Myself and two qualified roof plumbers. The guys did a great job of the roof even though they constantly made cracks about the wonky frame. We ended up putting on wire mesh, then foil with 50mm fiber insulation (fire proof, and an >R2 rating) and a "Surf mist" colourbond corrugated roof. We also got a round gutter (called smoothline) which looks great. The head roofer was in charge of cutting all the gutter joints and the roll top flashing. He did a fantastic job of lining up the flashing as you can see from the picture.

Now that the roof is on we have to save money up for the next big jobs, lining and insulating the underside of the roof and doing the slab (or maybe strip footings). While we save money we will start making mud bricks which will make up the inside walls, this is a relatively cheap job but pretty labour intensive.

The frame almost finished

The frame is almost finished now, and would have been finished if not for a change of plans. Originally when ordering the timber we were going to leave the two north facing outer segments without purlins since the roof was not going to extend to the fascia, but when we started putting the purlins up I made the mistake of putting them up in the two northern outer segments and upon reflection decided it was good and to leave them. This change though meant that we were 5 x 6m lengths of timber short.

I made the decision to leave the 3.6m and 2.4m lengths out of the last 5 segments (the ones either side of the ring beam). I did this because I should be able to fit those lengths onto the trusty old ute and pick them up myself, saving on delivery charges.

Due to the weather the timber mill has been unable to get extra bits of the Coastal Grey Box for the last few months, but today I got a call to say that it is in and ready to be milled (yippee!). Which means that we should have the timber within the next week.

Little by little

Our little building site has still been fairly quiet.  We managed to get a quarter of the purlins (the timber that will hold the roofing iron on and our ceiling up) up a little while ago, with the help of a friend Garryn. 

quarter of the purlins up (half of the long ones though!)

 The purlins are all different lengths for each segment of the decagon shape of the roof (confused yet??).  They are held up with a custom made bracket and 2 bolts into the pulin and 2 into the main beam.

View of the brackets and the attachment to the main beam

This timber is the smallest (and supposedly the lightest) of the timber we have used in the frame.  Still too heavy for manual lifting, so we have kept using our lifting device for these too.  Its been an invaluable tool on the building site, and made the whole process safe and fairly easy.

Brad, Garryn and the lifter in action!

Hopefully the next post on this blog will be a celebratory one to say that the framing stage is finished!  Then our building surveyor will inspect it and hopefully give it a big tick of approval, which will mean we can get started on the (white) roof, and then the luxury of undercover workspace!  

A little progress - the fascia boards

Its been a bit quiet on the building site lately.  Such is the life of an owner builder!  But some progress has been made.

We had brackets made up to put the purlins up.  140 brackets and they needed to be painted as well!!  We have purchased the bolts to attach the brackets and purlins to the main beams.

We spent a whole day cutting and putting up the fascia boards (literally a full day, as Brad finished up in the light of the full moon!  They went up fairly quickly with our trusty 'lifter' - the lifting device we built to handle the heavy timbers.

All that remains to finish the frame are the purlins (70 beams that go between the main beams).  This will probably be a pretty intensive job as there is a lot of timber to put up.  We hope to get stuck into that soon!

Then we will be gearing up to put the roof on which will make building life a whole lot easier!

all the posts and main beams are up

We finally finished putting up all the posts and main beams recently.  It was a proud moment to get the last post and beam up.  A job, that before we started it seemed 'too hard', got done fairly easily and simply (we were lucky to get a bit of help from friends and family which is greatly appreciated!).  We didn't need to hire a crane or borrow a tractor to lift the timber, just a bit of ancient 'technology'! 

These posts were prepared a little differently to the the 'inner' posts.  Instead of having a bracket at the top of the posts, a slot big enough to fit the main beam was cut out of the top.  All the posts sat on top of the stirrups that were concreted into the ground.

Its nice to see most of the timber up in the air, where its supposed to be, rather than in a stack waiting to be prepared and put up.  Now we have the 'small' timber to deal with - the purlins and fascia boards, timber that we can carry by hand!!  What a novelty that will be!!!!  This timber doesn't need to have slots cut into it, more or less just cut to length and put up, so it should be a much quicker process. 

The frame is self supporting

Since the last post the tower we built to hold up the central collar (the metal bracket that holds all the beams as they meet in the middle) has been removed, and (thankfully) the frame is self supporting.  Obviously we expected it to do that, but there is a moment of concern once its done and you remove that support as to what it may do!

The frame is very solid now, like all the pieces are locking into place, and each piece of timber just makes it more solid again. 

The frame is truly beautiful to look at, we just don't get sick of it!  Or taking photos!

We are currently half way through putting up the 'outer' ring of posts and beams.  All the timber is cut up and ready to go.  Its nice to see the stack of timber dwindling, although I think there will be a degree of sadness (and celebration!) when its all done.  Its been a great learning curve, so many little tricks and tips we have learnt (the hard way) so far.  Plenty more to learn though!

sort of like a giant wheel....

With the help of Brad's brother Paul, we have gotten the 10 'inner main beams' up - which was the next step of the house frame.  These beams were about 4.5m long, and pretty heavy to move about.  It took about a day (although it was in 2 half days) to get them all up and it was a bit fiddly fititng them in once a few were up. 

Firstly we built a tower out of the standard house framing pine timber, and got the collar up on top of it (we used our trusty 'lifter').  Then it was just a matter of lifting each beam up with the lifter, and jiggling it till it got into the right spot so that the bolts would feed through the holes in the collar and the bracket.  Again, I say its a credit to Brad that it all fitted together so well.  There is alot of maths involved in building a round house!  And with timber like this you really do want to follow the rule 'measure twice, cut once' or in our case 'calculated twice, cut once'.

the centre of the roof - note that when the photo was taken, the 'tower' was still in place.

 

So the frame is really starting to take shape now, it looks fantastic, so photogenic against the amaing blue skies we are having.  Very proud, and very happy with it!

Since the photos were taken the central tower was partially removed, and the frame is self supporting.  The next stage will involve putting up the 'outer posts' and the connecting beams to the brackets seen in the above photo.

A frame rises up!

Over one and a bit days (we probably could have sqeezed it into one LONG day) we got the inner ring of posts and the connecting ring beams up, as part of the house frame.  I was determined to not see the year end without having anything up, so we went ahead, despite the forcast for a very hot day today (luckily we finished up by 10:30am!).

Despite the weight of the timbers, and the complexity of the angles involved this first stage went up quite easily.  We used a home made 'lifter' which was built of timber and used a boat winch (all rated to well above the weights in our timber).  This worked quite well, the hardest part about using it was dragging it around the house site (nothing Brad builds is lightweight!!!!). 

The bracket on the post, this connects the post to the ring beam and the main beams, and involves several angles.

first post going up! 

We put up the first post, and found that the slots needed to be cleaned out a little with our electric chainsaw, to get them to sit down far enough on the stirrup to feed the bolts through the pre-drilled holes. 

Cleaning out the slots for a better fit. 

 Most of the other posts were cleaned out before they went up, but a few had to be done whilst hanging there....  After bracing the first post, we put up the second, and then the ring beam that holds together the inner ring of posts. 

The first ring beam in place

the frame taking shape

 The ring beam is structurally one of the most important parts of the our house design, as it stops the weight of the roof from spreading out the posts and collapsing.  From then on it was just a process of putting up a post and then the connecting ring beam, around the circle.  10 posts and 10 ring beams all up.  We were lucky to have my mother down to entertain the kids and a couple of friends helped for the afternoon/evening with actual building.  Thanks so much!

the beauty of natural timbers

the last beam 'slips' into place

This stage was a bit of a test of the design and our accuracy with everything we have done so far.  If any calculations had been done incorrectly, it would not have gone together properly (if at all!).  The stirrups were concreted into the ground and we could not test the fit of the posts on the holes until we actually started to put them up (they were just too heavy to move around too much).  Its a credit to Brad that this part of the frame went together almost perfectly (we had to fiddle around with a few posts/beams to get the bolt through - but nothing serious).

Yep, we are excited!

So the first stage is done, next stage is to get the main beams from these posts to the central collar.  That stage will involve a tower, pullies, and a few other low tech gadgets!

the central collar

Preparing the posts

Since we got the timber a few weeks ago I have been trying to work out a) how to handle the timber and b) how to cut it up. The posts are unseasoned 200mm x 200mm (8" x 8") x 2.7m dense hardwood. As mentioned in an earlier post they weight around 150kg. The main beams are 300mm x 70mm x 4.8m.

The first challenge was to move them around and handle them. The came in packs, there were 2 packs of the posts and then the several packs of mixed beams, ring beam, purlin and fascia. We have started to sort the mixed packs out into their own stacks and in the process putting spacers between the timber so that air can get around the timber and help minimise uneven drying and warping. To move the bigger timber members we purchased a furniture trolley with big heavy duty wheels. Myself and Sharon are able to load the timber onto the trolley and between the two of us are able to move the timber to where we want.

The next step has been cutting the timber up to use. We are going to put up the center ring first and then the outer. So we started on cutting up the center posts. This requires cutting the bottom flat and the top on a ~7° angle and then a slot in the top and bottom that is 200mm deep and ~10mm wide. We tried a few different methods for cutting up the big timber

1) Chainsaw - this worked ok, it was the quickest cutting but the draw backs are you have to be careful that you are straight as it does cut quick. The chain tends to chip the timber at the cut and the last thing is that it covers the timber in chain oil.  It also requires maintenance, checking fuel/oil, sharpening and starting.  It uses fuel, is noisy and creates fumes.

2) Handsaw - this method is quite slow, but it is quite accurate as you can monitor the cutting as you go along (usually while giving your arm a rest). the cut is nice an clean with minimal chipping at the edges. I use a Spear and Jackson crosscut saw with 10ppi.

3) Circular saw - The biggest circular saw that you can get from a hardware store appear to have a cutting depth of 85mm, so drawback of this method is that you end up with a bit in the middle of the 200mm post that the saw can't reach. Also the post faces are not exactly perpendicular with each other and vary in size from 190mm to 205mm (so far these are the 2 extremes I have encountered).

The method I have ended up using is a mix of 2 and 3. so I circular saw as much as I can and then finish off with the handsaw.

Marking up the posts has been the most important thing, and as mentioned the posts are not square. The most important part of cutting up the posts is the height and that the slots at each end line up with each other, if they are at an angle to each other then the top bracket will not point to the center of the house which is a big problem. So to line up the slots properly I ended up choosing the face of the post which will face in toward the center of the house and then measure a constant 100mm (to the center of the slot) for all post no matter what the actual diameter was for each post. This will give me a constant distance from the center to the face.

To cut the slots we very carefully marked them up making sure that the top and bottom slots lined up. We did this by marking up the top and bottom together, the distance from the face was the same for the top and bottom and we used a tape measure from top to bottom when marking them. When both sides of the slot were marked we then joined up the side markings along the ends. To cut we used a circular saw. A cut was made on each edge of the ~10mm slot on both sides of the post, the big thing here was to make sure that the saw depth cut was inline with the end marking since each face of the post is not guaranteed to be 90° to the others. I did this by lining up the saw blade angle by eye with the slot end markings and then watching as the saw cut that it was staying true, if not I would account for the difference by slightly tilting the saw while cutting. The top of the slot was pre-drilled using a 10mm auger bit and the material left in the slot was hand sawn out using the crosscut saw (I will have to look around for a rip saw I think, since the crosscut while it worked took a while to get through).

The other issue we had was to drill a 'straight' hole through a 200mm chunk of wood. My drilling is not that accurate that I was confident of doing this for every hole (each post has 4 holes). The stirrups and the top brackets are all pre-drilled with 18mm holes. The bolts are M16 so there is a 2mm allowance for error. Since the timber is green this will allow for some shrinkage too. But because the steel is drilled we have to get the holes in the timber pretty accurate, a crooked hole would look bad but more importantly it will probably mean that the bolt won't fit through. To solve this problem we ended up marking the hole on both sides of the timber off the front face, this involved using a square on the face and measuring the opposite hole from the square, which should align the hole exactly perpendicular to the slot. We then drilled the hole about 3/4 from both sides. any slight variation on each of the holes was then 'adjusted' by re-drilling so that the two hole match up. We bought several sized augers and have found that they are brilliant for drilling nice straight holes through the timber, they literally pull the drill through the material.

We have now cutup the first 10 center posts and they are ready to put up, but before they can go up we need to cut up the ring beam timbers (240mm x 70mm) and get the top bracket made up. The top bracket joins the top of the center posts to the inner and outer main beams (these beams radiate out from the center) and the ring beams (they join all the center posts together).

Our timber has arrived

Yesterday the first truck load of our timber arrived from Bowerbird Timber.  Our house is of a post and beam construction, so instead of the typical pine framing stud walls that most houses are built of, this house will have 20 posts, and then beams between them.  As its a circular house, the posts are arranged in two circles and there will be a central collar where all the beams meet in the middle. 

The timber we bought is Coastal Grey Box and its a very durable and heavy timber.  The timber is quite large, the posts being 200mm x 200mm, and too heavy to lift (approximately 150kg each).

So the next challenge will be building some lifting gear to lift these posts, and the beams into position.  That and cutting all the slots into the timber (and doing it accurately!).