Insulating the internal walls

We want to insulate the internal studwork walls to stop sound from travelling between the rooms and we had bought some Isonat insulation to try out.  It is made of a mix of wood fibre and hemp and is very dense about 50kg/m3.  It comes in batts which are 1200 x 370mm so it is easy to install within studwork at 400centres.

We installed the small quantity we had ordered and then tried to order enough to finish, but were advised that the product is made in France and that they were pulling out of the UK market.  We have two alternative products that we are looking at.

One is a this new product from Black Mountain Insulation, called Black Mountain Flex.  It is also a mix of hemp and wood fibre and I believe has a density of about 40kg/m3.

The other is warmcel, recycled newspaper which is blown in once the plaster board or what ever plaster substrate is being used, is fitted to one side of the wall.  Open blown has a density of about 30-35kg/m3.  The advantage of blowing the warmcel is that where we have cables and pipes concealed within the wall the warmcel will surround them.  If we were to use an insulation batt like the hemp and wood fibre then we would need to cut the insulation around the cables which would be tricky in places.

Sockets in the straw walls

Where possible we have tried to keep the sockets and switches off the straw walls as these are easier to install in the internal studwork walls.  Some are unavoidable however, and we have run the cable down the straw wall in a conduit which will be covered with hessian / jute and plastered into the wall.  The ply patch to fix the back box onto has been secured in the wall using hazel stakes (as we did with the concealed cistern in the ensuite).

Snow arrives!

Straw house with the bungalow behind - this will be demolished once the new house is complete.

Sealing around the chimney

Where the chimney passes through the roof, all combustible materials needs to be kept a minimum of 50mm away.  To create an airtight seal non combustible insulation was put around the chimney above the air barrier, then we scribed the shape of the chimney out of aluminium.  We sealed this to the airbarrier with airtightness tape.  We sealed between the aluminium and the chimney with intumescent mastic.

The twin walled chimney we are using is classified as being allowed to be fully insulated when passing through the floor/roof zone.  Some chimneys need to maintain a free airflow around them all the way along them including when passing through floor/roof, so we would not have been able to have insulated above it if this had been the case.  When we enclose the lower part of the chimney within the wardrobe space, we will need to ensure that we allow sufficient vents to allow air flow around the rest of the chimney to dissipate any heat.

First fix

Most of the pipework is now in for the hot and cold water supplies to the bathrooms, kitchen and utility room.  Only a few odds and ends to finish off before we can cover in the walls, floors and ceilings ready to plaster.

Putting up the last bit of the air barrier

... and battens fitted

Air barrier on the landing

The last area to put the air barrier up is in the landing...

Master bed air barrier complete

The completed air barrier in the master bedroom.  Now only the landing to go!

More proclima air barrier

The bit the other side of the ridge beam now completed to finish off this room.

And bedroom 2 completed as well.

Air barrier

The majority of the air barrier is now complete in the next bedroom...

Fixings things to straw bales

This is where the toilet and cistern will go in the ensuite bathroom.  The cistern (propped up at the moment) needs to be fixed into the straw wall.

One way to do this is to use hazel stakes about 250-300mm long, with one end pointed.

Firstly we marked the location we wanted to fix into the straw by screwing the piece of plywood we want to fix to the clay. (Interestingly it actually fixed quite well into just the clay!)

With a hand spray we wetted the clay plaster around the area we are going to bang in the hazel to make the clay soft.  Clay always remains volatile, it is not like lime or cement where a chemical reaction takes place when it dries.  This means clay is ultimately recyclable and can always be returned to its wet state.  The hazel stake was then very easy to bang into the clay.

We could then smooth the clay around the stake.  Clay really is amazing - how many materials can you seal a hole so easily in?!!

The four hazel stakes to fix the plywood to.

The plywood fixed to the straw...

...and the cistern hung.

Fitting the shower tray

We fitted the shower tray today - it took a long time!  It is bedded on a lime mortar.  We thought laying the floor tiles was tricky but getting this perfectly level and in the right place was really not easy!

We had some of the lime mortar left over so we used it to screed in the matwell to get it to the right level for the recessed door mat by the back door.

Setting up the bathrooms

Getting the bath in position in the family bathroom and setting up the waste.

This was a second hand bath we bought and went to collect.

Finishing off the first fix plumbing to the shower.

Lagging the pipework

Fitting all the pipelagging.

Proclima breathable membrane

Still going with the membrane - bedroom 4 now complete...

More membrane

Air barrier membrane fitted in the family bathroom.

Magnesium board in family bathroom

...and then laying the mangnesium board on top.

Progressing the floor in the family bathroom

Doing the same in the general bathroom.  Starting with the acousitc underlay...

Magnesium board down on the ensuite floor

The magnesium board on the floor of the ensuite bathroom.

Magnesium board

Carrying on in the ensuite we moved onto progressing the floor.  To try and minimise impact sound from people walking upstairs we are laying a wood fibre acoustic underlay throughout the first floor (foxtrot board).  Generally the floor boards will then be laid on top of this, except in the bathrooms, where the final floor finish will be tiles.

On top of the acoustic underlay in the bathrooms we are laying a tile backer board - in this case Magnesium board.  The installation instructions suggest that to cut the board the 'score and snap' method is used.  When the boards were delivered we were told that they were a nightmare to cut - very dusty and brittle.  We were very nervous about using it - particularly about cutting some of the more complex shapes out!  Luckily though it was neither of these things!

It cut very well and very accurately with a jigsaw.

The first sheet laid in the ensuite.

We also finished off the air barrier by sealing all the edges.  The most challenging edge to seal was the one against the clay plaster on the straw bales.  The manufacturer recommends priming dusty surfaces and then using their Orcon Airtight glue - running a bead in the primer and then adhering the membrane.  However the method we found most successful was to prime the clay, extending the primer slightly below the edge of the membrane.  We then used some of the general purpose flexible sealing tape (Tescon No1) which we stuck to the edge of the membrane and into the primed clay.  This seemed to work really well.

Back after a Christmas break...

First up we thought we would test out the best way to fit the service back boxes into the reed mat.

The noggin the back box is fitted to sits 10mm back from the back of the studs.  Where the reeds are cut either side of the box there was a lot of play in the reeds and we ended up fitting a 10mm packer either side of the box to support the ends of the cut reeds.  When the time comes we will need to do this to every back box.

Next we moved up into the ensuite bathroom.  We constructed the shelf in the shower.

Finally the hemp and lime insulation in the eaves is dry and we made a start on fitting the air barrier.  We started in the ensuite.  The membrane we are using is the Proclima Intello plus, which is a smart breathable air barrier.

Ensuite shower

Setting up the shower...

More plumbing

Pipes in the floor zone will feed the family bathrooom...

...pipes popping up in the family bathroom!

The downstairs WC.

Still more studwork!

Starting to fix the noggins for the electrical sockets, switches and lights.  This will be for the light switch for the ensuite!

More work on the ensuite shower studwork...

At last the hemp and lime insulation in the eaves is pretty much dry, which means we can finish off the sheeps wool.  We have started with the ensuite and will put up the airtightness membrane next.

Electrical cables start going in

Just a few of the many cables!

Cables all pulled through to where they need to be.  The next step is to fix the noggins for the back boxes, light fittings etc

More plumbing