Informal Open House

Last Sunday we had a gaggle of people come over to chat to Grant and I about our building experience thus far. Nic contacted me via Twitter and we ended up with half a dozen or so wanting to know more about what we are doing. Nic was pleased to be able to get his hands on the finished product and I mean literally, probably a good thing as we are hoping to be able to get the place rendered soon. We have had many visitors over the build time from all over Australia. It's quite exciting that from our small build (Grant wouldn't agree about the small bit) we have garnered so much interest in hempcrete. I hope it is a sign of things to come and the industry continues to grow.

Nic, Martin, Adriaan, Grant, David and Paul

Ceiling insulation - doubling up

When you have spent so much time building walls that have amazing insulating capabilities, when you have the slab super insulated and the the windows either double or triple glazed it seems crazy to skimp on ceiling insulation. With that in mind we have decided to double up on our insulation. We have the hempcrete insulation that will keep us warm and toasty in winter and we have decided to add Wavecore Silverbatts under the sarking to reflect the heat away in summer. We are going to have a beautiful living space with a stable temperature.

Great idea I hear you say, and it will be, we just wished we had the product prior to starting the ceiling. Grant has been scrambling around the limited ceiling space attaching the batts. He has started using blue strapping (see below) to hold the batts in place - the plan is that the straps will make it easier to install.

These batts come flat and you make them up on site

The blue strapping for the silver batts, the black formwork is placed
up there for Grant to lie down on the job! - or possibly work

Alan keeping an eye on what Grant is doing

One kilometre of tape- should be enough!

Hempcrete and the box guttering

The first bit of hempcreting we did was underneath the box gutter. It had to be done prior to the plumber coming and fitting the gutter. Grant used hessian under the hemp and OSB to hold it securely as it dried. The OSB was then removed so it could be replaced with MgO boards. The plan was that the hessian would hold the hempcrete in place long enough to set up the boards.  Unfortunately when we tried to place the boards it bowed out and the boards were unable to be secured flat. We realised that our first couple of mixes were too dry and the mix hadn't set. Grant ended up having to remove the hemp and then use some wool insulation (the only part of the renovation that doesn't use hemp-don't tell anybody).
It was disappointing, however you sometimes have to be pragmatic and just get on with it. Once the plan was adjusted and we used the alternative insulation it didn't take long to complete the box gutter.

You can see the hessian, above that is the hempcrete insulation

The hessian and hempcrete was removed

The completed box gutter

The walls are now complete and the ceilings have begun....

We finished our walls on the last day of May, so over the June long weekend we began to place the MgO boards to the ceiling. The mix used for insulation uses the lime, hemp and water. There is no sand and all that needs to be done is to place it on the MgO boards and rake it smooth to about 150mm deep. What is lovely about this is that is quicker than we thought...now that's a first! We will have a perfect seal between the ceiling insulation and the walls, oh the joy!  We haven't used any struts to hold up the ceiling and wet insulation as other hempers have done, so far so good.  When it has dried out it will be much lighter than it is now. Interestingly there has been a lot of condensation on the ceiling, even to the point that it drips along the board. I was going to show this condensation with a photo, unfortunately for the sake of the blog it has dried out, fortunately for us it has dried out.

The plaster lift isn't tall enough for our ceilings                       The first MgO boards are up!!

so we had to raise it by placing it on the black

formwork

Using hempcrete as insulation.

We use conduit for the electrical wires to protect them from the lime

Hemp insulation above the kitchen

Slightly confusing image of me, looking glamorous
in my thermals and limey top

Some of the equipment for the insulation works, protective gloves, silicone broom and light rake

Liz up in the ceiling placing the hemp insulation. We have made
great use of the pulley system, a must have for any hemp renovation

The ceiling in the kitchen is almost complete, we just need to
 complete inside the pantry.

We are probably a quarter of the way along the living room space,
it is really exciting how it is coming along.

May progress

May 31st was a very important day for us......tada.....we finished all the internal walls!! Well what does that mean exactly? It means a couple of things, firstly we can now begin the countdown to when we can begin rendering. The newest hempcrete requires 7-8 weeks of drying time before rendering can begin. Secondly, it means we can start installing the MgO boards for the ceiling and then insulating it with hempcrete, thus creating a perfect seal! Oh the joy of it all.

The ceiling insulation is a huge job, I will post again in the near future with the highs and lows of this task. I have to say, wool insulation does seem like a much quicker and simpler solution?!.....Because we are doing it ourselves, with no (well at least very few) quality compromises, we may as well get the best performance out of our house, hemp insulation will provide that, but at a rather slow pace.

Matilda helping with the tamping. Having a combination of both short
people and tall people works well!

Grant's legs on show as he fills in the wall above the kitchen

Toffee enjoying the sun in what will eventually be the living area

Repairs to Hempcrete

These pictures below show a hole that was created on a very windy night when the tarp we were using to protect the new hempcrete from the 'elements' was in fact the cause of the only damage. It wasn't the first lesson we learnt but it was quite an important one. We never bothered with tarps after that. I think tarps may be more important in extremely wet climates. Our concerns with exposed hemp have tended to be more towards the hemp drying too quickly. 

Back to the holes....Firstly I damped down the hole using the mister on the hose. I then held a piece of formwork over the hole and shoved the hempcrete down behind it, filling the hole up. It was rather rudimentary but it seems to have done the trick. It's certainly one of the things that I really like about hempcrete, it is quite forgiving. I am also hoping that the rendering will hide many of these small imperfections. 

A rather large hole caused by a tarp hitting the
wall all night by strong winds

The hempcrete wall filled.

Aww cute, it looks a little like a love heart

The repair 2 weeks later, I am very pleased with the result.

Gable Ends - one down three to go

There was a great feeling of satisfaction building out the first gable. Seeing a wall completed to the highest point after so many weekends spent forming, mixing and placing, it feels like we are over a hump. The gable ends are being built out on the east end of the building. We have left the western end open so that we can access the attic for filling the ceiling in with hemp.

The gable ends don't need to be 300mm thick. They are really only there for weatherproofing and to provide a continuous external wall for rendering. We thought about sheeting the gable and rendering, but we had enough hemp to build them, so we opted for a 150mm thick hemp wall instead. This should also eliminate any risk of a crack that could occur at the joint between sheets and the hemp wall.

The main technical challenge was to set up formwork that could be removed. Attaching direct to the outside of the frame would lock the formwork in. Dad and I cut 6mm OSB sheets to fill in the frame spaces and attached them to the spacer blocks for the battens. The battens were installed to embed in the hemp since the frame would not be embedded in the thinner wall.

Closeup of the formwork for inside the gables. They weren't too neat, but good enough for a wall you can't see!!

The gable wall is only 150mm thick. It sits in front of the frame and won't envelop it. So the battens will be embedded in the hemp to secure it.

The 90 x 45 blocks served to space the battens from the frame. They also allowed for attachment of the OSB sheets for the internal formwork.

The lintel over the bifold doors. Battens with a bevel cut top and
bottom are fixed to the face to retain the hemp.

The conduit for our outside light over the eastern deck.

The rope and pulley on the right are used to haul the hemp buckets up the scaffold.

The renovation will be finished by Christmas

Everyone wants to know when we think we will finish the renovation. We just don't have any idea as there are a number of factors at play, our standard answer is now Christmas...although we aren't sure which Christmas.

However we are working hard over the Easter break (who said break!) and we are up to some of the very tricky bits to hemp. Mainly above the highlight windows and then onto areas such as below. I hope to have another blog entry next week with some more progress shots, fingers crossed.

An old photo from a few months ago, however I wanted to show
the area above the windows and high up towards the roofline
that still needs to be hemped.

Grant preparing the timber to place above the sliding door near the
kitchen and bifold door near the dining space.

The angled timber will be placed on the boards to help support the
hemp and anchor it to the wall where it doesn't envelop the frame. 

Note how the timber has been cut to provide a hemp anchor.

Sam working hard today.

The set up of our scaffolding, tamping and hemping tools ready to go.

The parapet

Hemping around the parapet, near the link to the old part of the house.

That's me looking rather fetching if I say so myself, particularly like the
sombrero and knee pad combination.

Grant amongst the rafters hemping above the highlight window, not
the easiest of tasks, Sam also got to do some of this tricky stuff. Don't
worry Alan, we have left some for you! I, on the other hand was a bit
too scared to climb up to the very top of the scaffolding.