Building description

by Roelof Groenenboom and Steve Cassidy

In this description you can learn step-by-step how to make your own Roquetinho. All you need is some basic do-it-yourself skills, and for the metal work (someone with) welding skills. Materials costs will be less than

€ 200,-; if you build in series it can even be as low as  € 125,- per stove (Portugal, 2018).

Roquetinho outline


    Roquetinho is…

Structurally, the Roquetinho stove consists of a brickwork “bell” that absorbs and stores heat, within which is a rocket burner, consisting of a firebox and a riser to combust the hot gases. Firebox and riser together is called the “core”.

The bell consists of two parts: the lower part of concrete blocks and the upper part of firebricks. On top of the stove there’s a steel plate on which you can boil water.

    Off-site prefabrication

This building description assumes that as much work as possible is done off-site, so as to minimise the time required on site. The preparatory (off-site) work consists of the following: making various special castings, building the first layer of the bell on the bottom slab, constructing the core, making the steel door, the floor channel, the top frame and top plate, and glueing the riser and the firebricks for the upper bell.


The first site work is construction of the plinth. The lower section of the bell is set on the plinth and the core fitted into the bell. Then the bell is completed on-site, before completion of the stove with the metalwork.


    Archive

In the archive you can find older versions of the Roquetinho.

To accompany the building description of the former model there was a YouTube instruction video (building overview of the 2018 model).


And here’s the Sketchup file for the 2019 model, the one this description is about. The folder also contains seperate 3D files for the core, the floorchannel, the frame & door unit, and the moulds.



Step 1 Preliminary considerations, tools, materials


Before getting started with the stove it’s important to check a few things: the supporting floor needs to be strong enough, the chimney should be okay, and volume and insulation of the space to be heated should be in such a way the Roquetinho can do the job. Read more...



Steps 2 - 6 is the off-site prefabrication; steps 7 - 9 the on-site installing.



Step 2 Concrete castings


It's practical to use plastic coated chipboards as a bottom for the moulds, since they are already waterproof and don't need to be painted. Saw the laths that form the mould and fix them on the bottom with screws (not with glue). Paint the laths (2 layers). When the paint has dried, fill the inside brims with a bit of acrylic sealant.

Read more...



Step 3  Refractory concrete castings


Working with fire concrete is very different from working with normal concrete. Things like temperature, amount of water to be added and the open time for handling come very exact. Mixing  and vibrating are skills to be learned by experience; if you do this for the first time consider your first castings to be try-outs. Read more...


Step 4  Making the lower section of the bell and the core’s firebox


Place the cast bottom slab in a suitable place for working. It must be level. Construct the first layer of concrete blocks on the bottom slab. Use mortar with cement : sand in proportions 1:5. Take care to control the dimensions (height is 170 mm + 10 mm joint) and make sure the structure is square and level. Read more…



Step 5  Lower part of the riser and assembling the core


Cut two riser castings to the same height as the port, less one mm to account for the Moviset at the bottom of the casting. This height should be around 251 mm, but it should be measured. Best is to mark a pencil line at the exact height, then use a grinder to cut along the line such that the pencil mark just disappears; this will give the 1 mm allowance for the Moviset. Read more…


Step 6  Metalwork: p-channel, frame and door unit, top plate


The dimensions of the floor channel and the frame and door unit assume a core with outside dimensions of 220 x 301 x 506 mm. If these dimensions differ you need to adapt the blue figures in the pictures. Read more...



Step 7  On-site: plinth, lower section of the bell, installing the core


Once on site, determine the location of the Roquetinho. The rear edge of the bottom slab should be placed at least 160 mm from the rear wall (to allow space for connecting the flue). Mark the footprint of the plinth on the floor according to the chosen overhang. Note well when aligning the plinth that the flue does not exit in the centre of the Roquetinho. The floor can be protected by sticking lengths of masking tape 10 mm outside this footprint. Read more…


Step 8  Lower bell construction, upper part of riser, insulating the riser


Put in place a piece of superwool of 303 x 490 mm against the right side of the core. Place the partition on a 7 mm layer of cob. Push it against the superwool and keep it on its place with a lath. Read more…



Step 9  Upper bell construction, steel top, frame & door unit


Building up the rest of the bell it is best to have some kind of guides. One method is to clamp laths to the four corners at the bottom slab; mark them with the layer heights (which are height of the concrete blocks + 10 mm joint for layers 3 and 4, and height of the firebricks + 7 mm joint for layers 5 to 8). Use spacers to bring the laths 2 mm away from the bell and level the laths carefully. String can be used between the laths to get each layer exactly level. Read more…