Batch Box Rocket Mass Heater Workshop 2nd to 6th Nov – Mallorca

Batch Box Rocket Mass Heater Workshop 2nd to 6th Nov – Mallorca

Its been a long time!!!

We have been hard at work building the house, having a baby and getting up and running with my new business running Wim Hof Method workshops, but we are back!!

From the 2nd till the 6th of November we will be hosting a batch box rocket mass heater workshop by Peter Van Den Berg.

We are bringing Peter over to help us build our Bach Box Rocket Mass Heater as we thought it would be a great opportunity to do our first “Permaculture” related course and get one of the best in the game to help us build our heater.¬† Multiple functions and all that ūüėČ

We have chosen Peter Van Den Berg because, as far as I can make out on the internet, he is “THE MAN” when it comes to batch box rocket stoves.¬† He took a concept put forward by someone else and improved and expanded it.¬† He is basically the inventor of the batch box rocket mass heater as we know it today, even though the concepts that are used are from other people.

In¬†Peter’s own words “I took an idea of Lasse Holmes and added the venturi port, among other things. The implementation of bell technology in the batchrocket concept is all my doing but of course it existed before, as is the venturi.

I see myself more as developer and designer, bringing diverse pieces of tech together. That’s what most inventors do these days, building on the work and combining work of others.”

What is a Batch Box Rocket Mass Heater?
A¬†Batch Box Rocket Mass Heater is a very efficient wood burning stove that burns at a very high temperature and then feeds the gases of the burn through (in our case) a masonry bench.¬† The bench captures the heat and then acts as a radiator a.k.a “butt warmer”.

batch box

A batch box burning palette wood from one of Peter’s builds.

A “batch box” rocket mass heater is different from the more commonly known rocket mass heaters(RMH) in that it has a firebox that looks more live a conventional fireplace instead of the “j-tube”.¬† This means that you can actually see some flames in the box and gives you a more traditional feel although it burns very differently, so you wont be getting the nice little flames that you get from a conventional fireplace.¬† It also allows you to put a big “batch” of wood in (which is where it gets its name from) light it up and walk away as opposed to the normal RMH that you have to¬†keep feeding throughout the burn.¬† The batch box RMH generally doesn’t have the oil drum burn chamber that is customary of RHM’s and instead has a brick “bell”.¬† This isn’t always the case though.

The classic RMH with

The classic RMH with “J tube” firebox

With Peter’s help we designed our heater to fit in a corner of our house with a nice “butt warmer” bench.¬† We chose the batch box over the¬†normal type RMH because we didn’t want an oil drum in the middle of our lounge and because I like the idea of being able to chuck in a batch of wood and forget about it.

batch box rocket mass heater

Peter’s design for our batch box rocket mass heater

From what I have seen on the internet, it is usual to just have to burn one or two batches per day to keep the house warm, as opposed to a conventional fire place that needs to be constantly on the go.¬† This is because a rocket mass heater heats the “mass” of the bench that then keeps on radiating heat into the house (even though the fire is out).

Another¬† benefit of¬†RMH’s is that you can burn any type of wood, from logs from trees to scrap wood like palettes etc.¬† The high temperature burn also means that these are very safe, as they don’t form creosote in the chimney, so there is no risk of creosote fires.

All in all we love the efficiency of the batch box rocket mass heater, the “butt warmer” and the fact that you can build one yourself.¬† They are much more efficient than anything you can buy and they use only 1/4 the wood of other wood burning stoves, which will save us a lot of money in the long run.

If you want to learn more about batch box rocket mass heaters you can visit Peter’s website or better than that you can come to our workshop, meet Peter and learn directly from him while you help us build our heater.

In full disclosure, we are not making any money from this course.  We will try to cover some of the costs of getting Peter over here to help us build the heater. Part of our motivation for this blog and building our home is to inspire  and empower others to go out and do the same, if that is what you want.  This all means that the course is very cheap! and its a win win for everyone involved.

Link to Peter Van Den Berg’s site:

Link to the Batch Box Rocket Workshop on the 2nd November 2017

I will also try to do a video update soon as the house has changed a lot since our last update!

Its been a long time!!

Its been a long time!!

Its been since February since we put up a post but a lot has happened since then!

I have just added an instagram widget which you can see on the right of the screen. ¬†I take a couple of photos and videos a week, mostly when I go outside and have a “wow” moment. ¬†The scenery here is always changing and really beautiful around sunrise and sunset. ¬†So you will find plenty of photos to see what we have been up to lately there.

This summer we took the roof off the building and insulated with 15cm of polystyrene. ¬†We went for polystyrene over something more “eco” because of the cost. Our sustainable ethics can only stretch as far as our budget and we have maximized the use of natural building materials elsewhere. ¬†Also for the same price we would have only been able to insulate with 5 cm of natural cork instead of 15cm, and polystyrene has much better insulation qualities at the same thickness than¬†natural cork.

We noticed a difference straight away in how cool the house was over the summer.  If we closed all of the windows in the morning while the house was cool, it stayed that way all day.
photo of roof with insulation

We have just finished plastering the outside of the building.  We chose to go with an insulated lime, cork and diatomaceous earth plaster at about 1.5cm thickness.  This  is really a minimum, but we think that with the roof being well insulated and the fireplace, we will make it just fine through the winter using a minimum of wood.

At the moment the temperature is about 9 degrees C in the mornings and the house is staying at around 19 – 20 degrees C even with the windows open.

Here is a video about the plaster:

The house looks great!  And that is one of the major jobs we had left that is finished.
house with lime plaster

Here is a video of the final lime plaster coat being applied over the insulation base layer:

The boys hard at work! #limeplaster #naturalbuilding

A video posted by Luke Wills (@lukemallorca) on

The lime plaster for the finish coats is made locally and the company that makes it have been very helpful with recommending good workmen for applying lime.  It is also great to be able to support a local company that make sustainable building materials.
You can find out more about them here:

We now have just the final coat on a couple of walls on the inside of the building and a bathroom to finish, and that will be all of the big stuff done!

This week I have been digging trenches for the cables to the solar panels. Today I have to dig some holes for the foundation of the solar panel structure which is arriving next week.  After the solar panel structure is built, we will order the rest of the solar panels and the batteries and install our big system.

I often put up videos on our youtube channel and dont update the blog so you can get small updates there and on the instagram feed.

Click here to visit out youtube channel

Click here to visit our instagram

New Year, New Home!

After two years of hard work, we are finally in!

We now have running, hot water in the house, electricity from solar panels and internet!

We have been living here since just after Christmas and are really enjoying it.  We get to watch the sunrise every day while having breakfast and then see the stars come out at night.  Its amazing how disconnected you get from all of this when living in the city.  In the last place we lived in, we were surrounded by buildings and never saw the moon or stars, you couldn’t even tell if it was a nice day from inside the house. Its a real pleasure to live in a house that faces south, with big windows that let the light stream right in all day long which is a massive bonus on these short winter days.

Here is a quick video showing our progress on the finca and going over the basic things that we needed to get sorted so that we could start living here.

We will make more in depth videos on each of the individual components solar, water, chickens etc.  this video is just a quickie to wish you a Happy New Year and show some signs of life as our last post was a while back.

The general pace of the build has slowed down now and we have more time for other things (apart from just trying to get in) so I will make an effort to put up videos on a more regular basis.

Big Update! – Lime Plaster – Floor Tiled – Terrace – Sep 2015

We have been hard at work even though the blog has been quiet.

Building a house with no previous experience is a lot of hard work, both physically and mentally.  You spend long hard days doing physical labour and then when you get home its time to get stuck into books, internet and youtube to figure out what comes next and how you are going to do it.  Its one long learning process.

My initial idea for the blog was that I was going to do more “how to” videos and quickly realised that this wasn‚Äôt going to be possible.¬† Its too difficult to film, edit, upload while you also have to learn to build and build.¬† The filming tends to get in the way.¬† I shoot mainly on a small point and shoot camera and so cant just set it up and leave it filming while I get on with it.¬† That wouldn‚Äôt be all that interesting anyway and would mean hours of sorting through footage and editing which I just don‚Äôt have the energy for.

I have been filming bits and bobs as I go along and am now going to make an effort to try and post an update every week or two.  When most of the building is complete I have the intention to make some more in detail write ups and videos on our building process.

So what has been going on at Ca’n Mandala?

Lime Plastering

Base Coats

We have almost all of the walls finished with a base coat.  The only room left to do base coats on is the master bathroom which has been our bedroom up until now.  That bathroom will be the last room to get finished as we are currently working on the smaller guest bathroom so that we can get in this winter.

Insulated Lime Plaster

As we aren’t going to be able to insulate and finish the outside of the building this winter we decided to do an insulated lime plaster on the north walls of the house.  In the winter, this will keep the heat in the house and the cold out.  I will upload a video on that some time soon.

Lime Plaster – Finish Coats

We have the finish coats done on the big walls in the living room and the kitchen.  We got two guys that were recommended to us by the place we get our lime from(Unicmall) to do the big walls and they did an excellent job!

Pic of the boys in action:
lime palstering in action

Here is a quick video on that:

On the second floor where we have done the insulated plaster, we have decided that in order to get in sooner we would just lime wash the base coat.  We might apply a finish coat later on when most of the more important things have been done.

Trial and Error

We have also done a finish coat in the bedroom where the wardrobe will be.  This was a test to see how this fine finish coat would go on.  Unfortunately we started doing this just when it started to get really hot.

Lime plaster needs to “set” or harden slowly, if it sets too fast then it doesn‚Äôt “carbonate” and it just powders off the wall.¬† This is especially true of thin finish coats that are only 1 or 2 mm thick.¬† It was 40 degrees C the day we wanted to do it and so it was setting so fast that it was turning to powder and not letting us polish it.¬† The plaster we had chosen was a type of stucco or polished lime finish, but the conditions made it impossible to finish properly.¬† Luckily, we did do a trial run inside the wardrobe before going on to do this process on one of the main walls in the house.

It has actually dried a lot lighter than you see in the pic and doesn’t look bad.
lime plaster

Here are some colour tests that we did to choose a colour for a wall in the living room.
some colour tests of lime plaster

Floor is Tiled!

Last weekend we got the floor tiled in most of the house and it looks amazing!  It has really changed everything and being able to live at the finca has suddenly become a reality.  With the dirty, dusty lime slab it all seemed a little far away still but now we are getting very close!


We have finally covered the water tank and now have a lovely terrace!

There have been a few other things going on which I will cover in my next post.

If you would like to keep up to date on new videos and posts then please subscribe to our blog and youtube channel. Keep an eye on our youtube channel as I often upload videos there but dont make a post about them here.

Click here for our youtube channel

I will try and write a post every other week and hopefully in the not too distant future I will be able to give a little back to the internet community which has helped me so much along this journey by doing some “how to” videos.

If you have any specific questions then please leave them in the comments and I will try to get back to you as soon as I can.

Time Flies!

Time Flies!

Where does the time go?

Its been four months since our last update and we have got a lot of work done although the winter has been a little slow.

Slow Motion

We worked really long hard days through the summer and then when the clocks changed in Autumn, it seemed like we were dropped in a vat of honey and everything was going in slow motion.  Being used to the long light hours I got caught out more than once finishing a job in pitch black, in the middle of nowhere, cleaning the cement mixer and tools by headlamp.  Not all that nice when you are tired and all you want to do is get home.
The short days combined with me working mainly on my own (as Tracy had been offered some extra work) meant that progress was veeeeery very slow.¬† This situation ended up running me down and the build started to feel a little overwhelming. I didn‚Äôt feel like all the hard work I was putting in was actually moving us forward much.¬† I was doing mainly prep work for plastering which isn‚Äôt very rewarding.¬† You‚Äôre basically filling in small holes and making the wall as flat as you can for a better finish while plastering.¬† I was also putting off any large walls for plastering as it goes very slow when you have to make mix, plaster, stop and make more mix when you run out and then wait for it to firm up so that the wall can be “floated” to even it out.¬† Also, having done most of the plastering in the summer I was used to it firming up a lot faster.¬† This¬† was one of the main reasons why in the winter the darkness was closing in while I waited to float the wall.

Tracy to the rescue!

Luckily, just at the point where I was hitting saturation, Tracy took a few days off and together we covered 3 big walls.  This made a huge difference and renewed my enthusiasm and energy for the project.

Spring is here and with the extra hours of light we are full steam ahead trying to get in.  We have all of the walls in the south side of the house with the first layer of plaster applied, and soon we will be getting some help to finish the second coats and final smooth coat.

We have lots more exciting stuff to tell you about and I will try to upload a video update of our progress in the next week or so.

We have started Plastering!

Its been a long time coming, but its finally here!

We have started plastering!

lime plastered larder

Our larder with part of its first coat of lime plaster.

We have done the first layer of plaster on some of the walls.¬† Our walls are anything but flat so it will take a couple of layers to get it looking…. rustic..

After a lot of research, a couple of courses and lots of umm’ing and ahh’ing we have decide to go with a base layer of lime and very fine gravel known locally as “cero”.

Benefits of Using Lime Instead of Cement

Our walls are made of a very porous sandstone (called “mares”) that acts like a sponge and sucks up water. If you cover this stone with a non breathable material (like cement)it will end up getting saturated, rotting and the result will be large parts of your plaster falling off.

Lime plaster is breathable, meaning that it lets vapour pass through it.  This allows your walls to regulate not only the amount of humidity in the actual wall itself, but also the level of humidity in the room. So, in theory we shouldn’t have the typical humidity problems that plague old houses on the island.

Another great benefit of lime is that its antibacterial and anti-fungal and so its a lot harder for mold and any other unwanted fungus’s and bacteria to grow in rooms that are plastered with it.

Lime is also thought to be more “eco” friendly as it takes less energy to make and emits less CO2 into the atmosphere than cement.¬† In the long run it actually absorbs more CO2 (from the atmosphere as it “carbonates”, which is the process which makes lime harden) than is used to make it.

Here are a couple more pics:

Master Bedroom
lime plaster wall with window and wooden beams

Kitchen/Front Door

kitchen door lime plaster


Its really nice to have some of the walls plastered as you can start to see glimpses of the house emerging from the barn.

If you are interested in learning how to plaster with lime and clay, Miquel Ramis does a 2 day course here on the island which is very good and cheap too!  He also speaks very good English for those of you with Spanish problems.

We saved a lot of money by going on that course as before it we were going to buy all of our plaster “ready made” and now we are making it ourselves at a fraction of the cost.

Construcción bioclimática y tradicional: Morteros de cal y morteros de tierra / Lime and earth mortars

Introduction to Passive Solar Design

After yesterdays video I thought I would make a more specific introduction to Passive Solar design in Google Sketchup.

Here are some links from the content in the video:

In my first blog post I explain how I used the passive solar design principles in designing our outhouse:
Click here to read the blog entry

The Solar House Book