D105 PreCut Brick Oven Kit Building Instructions

D105 PreCut Brick Oven Kit Instructions

Firstly, congratulations on the purchase of your D105 PreCut Brick Oven Kit! Our PreCut Brick Oven Kit is the result of years of design and development and is something that we at The Melbourne Fire Brick Company are immensely proud of. We have been blessed to have had some incredible customers over the years who have provided great feedback to help us make the PreCut Kits as good as they can possibly be. At the end of your project if you have any suggestions for ways we could improve our kits, please don’t hesitate to let us know.

INCLUDED IN THE KIT CALCIUM SILICATE BOARD

4 x Calcium Silicate Boards 1000x500x50mm

This is the 50mm thick insulation board layer underneath your oven; it comes with printed paper templates & drawing pins so that you can pin the templates onto the CalSil board and cut out the pieces you need, following the lines shown on the paper templates. REFRACTORY CASTABLE

Novaref Refractory Castable: 5 x 25kg bags

Refractory Castable is premixed high temperature concrete, which you will use to form the 25mm sub-floor heat bank under the Fire Brick Floor Tiles, and for pouring the dome keystone. The castable comes with small sachets of white Activator powder, which you will find in an envelope. FIRE BRICKS - OVEN DOME

All bricks for the Oven Dome are provided, carefully cut to keep the internal gaps on the inside face of the oven to an absolute minimum. The fire bricks used in the oven dome are 38% Alumina, rated to 1350°C and are 115mm thick.

You will need to grind down a keystone brick for the end of each row in the dome. We supply you with a number of dome bricks that are smaller than the rest to use for making keystone bricks. As your keystones will be unique you will need to grind them slightly, using an angle grinder with a standard masonry grinding disk. FIRE BRICKS - FLOOR TILES

All of the Floor Tiles are cut to size and ready to lay, the center tile has a 3mm hole predrilled in the middle for the trammel tool to lock into. The fire bricks used in the oven floor are 42% Alumina, rated to 1400°C with an exceptionally hard wearing surface, and are 50mm thick. FIRE BRICKS - ENTRY & VENT ARCHES

The bricks for the Entry and Vent Arches that form the mouth of your oven are all cut precisely to size from fire bricks rates to 1350°C, ready to lay.

The Entry Arch Bricks (the opening into the dome) are machine-ground on their back face to follow the curvature of the dome, to give you a smooth transition from the dome into the opening.

The Vent Arch Bricks are carefully selected as these will be on display at the front of the oven. They are all cut to size, and are cleverly designed to 'key' into the Entry Arch for strength and stability.

FORMWORK - ENTRY & VENT ARCHES

We provide CNC machined timber formwork with your kit to construct the Entry and Vent Arches around, to ensure that your brickwork is exactly as per our design.

The Formwork is clearly marked to allow you to position the arches accurately, and also shows the height and thickness of each mortar joint. TRAMMEL TOOL

The trammel is a tool that you will clamp each dome brick into, enabling you to lay the dome bricks in a perfect hemisphere. It has a pin in the base that fits into the 3mm hole drilled in the center tile. FIBREGLASS DOME FORMWORK

To lay the last few rows of bricks in the dome we provide you with a custom made fibreglass dome form. It also comes with a circular plywood support, to spread the load when you jack it up into position. REFRACTORY MORTAR

42% Alumina Airset Refractory Mortar: 3 x 20kg bags

This is the mortar you will use to assemble your brick oven kit. Please be aware that you will need to mix the Airset mortar with General Purpose Cement, Lime and Washed Sand in the ratio shown in the plans and on the mortar bags.

These are available at all hardware stores and will need to be purchased in addition to the kit (please see notes on Additional Materials Required below). CERAMIC FIBRE BLANKET

One full roll and a half roll of 25mm thick Ceramic Fibre Blanket, which will give you two full layers over your brick dome for 50mm coverage which is precisely what we recommend. PERLITE RENDER

LiteFill Perlite: 3 x 100L Bags

This is the Render you will use to cover the Ceramic Fibre Blanket layer, which you will be mixing with GP Cement, Lime and Washed Sand (please see the note for the Refractory Mortar regarding these materials). There is more than enough Perlite in the kit to build up a 50mm shell of render over the oven dome. PRECAST FLUE GALLERY

The PreCast Flue Gallery is the molded piece that fits over the brick arches at the front of the oven. Made from stainless steel fibre reinforced refractory castable, it comes fitted with 7" Stainless Steel Flue Sleeve, ready to attach the other flue section onto. STAINLESS STEEL FLUE & HAT

1 x 7" Stainless Steel Flue - 900mm Length (extra lengths are available for purchase) 1 x 7" Stainless Steel 'Chinaman Hat'

EXTRA ITEMS PROVIDED

- 75mm Plastic Formwork for Sub-Floor Heat Bank - Plastic Strips for supporting the Arch Formwork - Box of drawing pins for Calsil Templates OVEN DOOR

The final part of your kit is our Stainless Steel oven door, coated in a satin black finish. The handles are beautiful oiled hardwood, with solid stainless steel rings top and bottom. The door comes fitted with a vacuum sealed temperature gauge accurate to 550°C. ADDITIONAL MATERIALS REQUIRED

- 4No. 20kg Bags GP (General Purpose) Cement - 2No. 20kg Bag Lime - 5No. 20kg Bags Fine Washed Sand (if you can’t find this, look for Paving Sand or Gap Sand) - Chicken Wire (also called bird wire). Approximately 5m x 1.2m - Roll of tie wire - Household aluminium foil - Masking Tape - ~15No. screws (50mm or longer) - ~15No. long screws or nails (around 100mm)

We don’t put these items in the kit for several reasons – they add a significant amount of weight (which takes the kits over 1000kg, greatly increasing the cost of freight), they’re available at all good hardware stores, and we find that many of our customers already have these materials on hand! That being said, if you would like to purchase these materials through us we have them available for sale. TOOLS REQUIRED

- Trowel - Small Plastic ‘Flexi’ Tub for mixing mortar & castable - Large Plastic ‘Flexi’ Tub OR a Wheelbarrow for mixing - Angle grinder with masonry grinding disk (for grinding keystone bricks for each row) - Jigsaw - Drill/driver for putting in screws - Level - Straight Edge (can be a nice straight piece of timber or metal) - Stanley knife/scissors - Car Jack

SAFETY GEAR REQUIRED

- Safety Glasses - Ear Muffs - Heavy duty rubber gloves - P2 rated Dust Mask - Suitable clothing - Safe access to climb onto your oven stand

SAFETY PRECAUTIONS

Dust Exposure – Respirable Crystalline Silica

Inhalation of airborne dust may cause irritation to the mucous membrane and upper airways. Symptoms can include coughing, sneezing and breathing difficulties. Repeated exposure to respirable silica may result in pulmonary fibrosis (silicosis). Silicosis is a fibronodular lung disease caused deposition in the lungs of fine respirable particles of crystalline silica. Principal symptoms of silicosis are coughing and breathlessness. The following materials used in building your wood fired oven contain respirable crystalline silica and a suitable dust mask should be worn while handling them;

• Airset refractory Mortar • Refractory Castable • Firebricks (when cutting or shaping them with an angle grinder) • General Purpose Cement • Perlite

While the Ceramic Fibre Blanket doesn’t contain respirable silica, the fibers are very irritating to the respiratory tract and can cause scratchiness in the nose and throat, and chest discomfort. Eye Protection

This is a very hands-on project and you are advised to wear safety glasses when mixing materials or cutting/grinding bricks. This also applies to applying the ceramic fibre blanket insulation, which is irritating to the eyes. If in doubt, wear safety glasses! Skin Protection

The mortar mixture that you’ll use to lay the firebricks in your Wood Fired Oven Kit is very alkaline, and repeated exposure to your skin can result in chemical burns. This is compounded by having to handle wet bricks, which (if done without gloves) makes your skin softer and more vulnerable to being affected by the alkalinity. To avoid this, wear heavy duty rubber ‘washing up’ gloves underneath ordinary gardening gloves to protect your skin. Rubber gloves alone will not work well for long, as handling the firebricks will wear straight through them in minutes. Keep your hands dry, and if you notice a hole in the rubber gloves you would be well advised to replace them immediately.

SUB-FLOOR INSULATION

The first step in building your oven is to prevent all of the heat in the oven floor from being conducted into your concrete slab, and from there into the air to be lost forever. To do this we use Calcium Silicate (CalSil) board as it has excellent insulating properties and is easy to work with.

Cut the CalSil board to fit the ‘footprint’ of your oven. The kit comes with a set of printed templates for cutting the CalSil board to size, showing how to arrange the boards on the slab. Make sure you allow 100mm (4”) from the edge of your slab to the rear and sides of the CalSil. Leave as much room at the front of the oven as you can, to use as a landing area. Mark the centerlines shown on the printed plans on your concrete slab, so you can transfer them back onto your castable slab later.

If your concrete slab is flat and level, you can lay the CalSil directly onto the slab. If your slab is uneven use a thin layer of dry sand to bed the board down, to ensure the Calsil is uniformly supported. SUB-FLOOR CASTABLE HEAT BANK

To store additional heat in the floor of the oven, we pour a 25mm (1”) thick slab of dense refractory castable on top of the CalSil Board which will act as an additional heat bank under your fire brick tiles, and give you a nice flat surface to bed the fire brick tiles onto later on.

Calcium Silicate (CalSil) board is highly absorbent, and will soak up any water that comes into contact with it almost instantly. This means if wet refractory castable mixture contacts the surface of the CalSil board it will dry out and harden straight away. To overcome this problem, we cover the surface of the board with household aluminium foil, taping the joints with paper masking tape. We use aluminium foil not because of any insulation value, but because it waterproofs the CalSil effectively.

Cover the top surface of the CalSil board with aluminium foil, taping the joints with paper masking tape, then secure the plastic formwork around the perimeter using long screws (approximately 50mm, or 2”) through the plastic edging, into the Calsil board.

There are five 25kg bags of refractory castable in your D105 Kit. To pour the sub-floor heat bank you will need to use three and a quarter bags. The remainder is for filling large gaps in the oven dome as shown later on. There are two sachets of white powder provided, this is activator to ensure the castable sets properly. Without the activator, the castable can take days to set.

1. Mix the activator through the dry castable, following the ratio of ¼ of the sachet per bag (for the 3.25 bags you will need about ¾ of a sachet).

2. Add water and mix until the castable reaches a consistency similar to thick porridge. See the video instructions for a clearer understanding of this consistency. Mix it and pour it quickly.

3. Pour/shovel this mixture onto the foil, and use a trowel to spread it over the entire surface.

4. Use a straight edged piece of timber or metal to screed the top surface flat. By moving the timber back and forth as you screed, you’ll get a nice smooth finish.

5. Once you have screeded the castable layer flat, wait for it to start setting. This will take anywhere from 10 minutes to several hours depending on the ambient temperature & wind conditions. Once the castable has started to set, cover it with plastic or a wet sheet. This prevents drying shrinkage cracking from wind or high temperatures. If you do see any surface cracking please don’t worry, this is very common and will not affect the performance or longevity of your oven in any way. In ambient temperatures less than 20°C (68°F) you may need to cover the castable with black plastic – this absorbs radiant heat from the sun and heats the castable, accelerating the curing time.

6. Leave covered to cure for at least 12 hours.

5. Transfer the centerlines that you had previously marked on your concrete slab onto your cured castable slab with permanent marker, as shown below.

6. Use a wet sponge to soak the castable layer in the center of the floor. Mix up some mortar (see Page 6 for mixture ratio) and spread a layer approximately 10mm thick on the top of the cured castable. Use your fingers to notch this mortar mixture, to bed your refractory tile into. Only prepare one small area at a time, enough to lay a single tile. If you try to cover more than this at once, the mixture will dry out before you have a chance to lay the tiles. Lay the tile back from the center first, lining up the corners of the center tile with the centerlines as shown below. If you get your first tile positioned correctly, the rest will follow suit. Make sure you really take your time getting this right, so that your oven sits straight on your slab.

7. Soak your floor tiles in water and bed each one down into the mortar mixture, ensuring that each is level and the edges are flush with each other. Use the diagram over the page to set out the remaining floor tiles. Get the joints between the tiles as tight as you can, and once they’re all laid, fill any gaps with the refractory mortar mixture.

We designed the layout of the CalSil board to be about 20mm larger than the floor tiles all the way around the perimeter of the oven floor, so that there is some tolerance on the positioning of your floor tiles. The extra CalSil/Sub Floor extending around the dome of the oven will be covered by the insulating blanket and render layers, while the sections protruding under the front and sides of the square section of the oven floor can be either cut back using an angle grinder, or left in place and covered over once a landing is fitted (see page 31 for details).

8. If there are any raised edges at joints between the tiles once you have completed the floor, these can be ground back using an angle grinder with a masonry grinding disc or sanding disc. Do this before you build the dome, while you have easy access. Don’t grind the tiles unless you absolutely have to!

BUILDING THE DOME

Firebricks are very porous, and just like the CalSil board will absorb a significant amount of water, so if you apply mortar to a dry firebrick this mortar will dry out and harden immediately. To overcome this, soak your bricks in water before you lay them. We find the best method is to put all the bricks for a particular course into a wheelbarrow or tub full of water well before you start laying them, then when you grab a brick to lay, give it a quick dab on an old towel to remove the excess surface moisture and set the brick in place. The same problem applies to bricks that you laid earlier, maybe the day before, which will have dried out. To wet these bricks before you lay over them, a dab with a wet sponge works well, or a light spray with a garden hose.

Be very careful not to ‘bump’ any part of your brickwork as you go. This can break the bond between the mortar and the affected bricks. This is a big project, so take your time and be careful. Give yourself good access to your slab, you may want to make a step or use trestles to get better access once you reach the higher courses. MORTAR MIXTURE

• 2 Parts Airset Refractory Mortar • 2 Parts Fine Washed Sand • 1 Part GP (General Purpose) Cement • 1 Part Lime

These measurements are by volume. Mix well while dry, before adding enough water to make a smooth mixture. Take a small trowel of the mortar and hold it upside down, it should stick to the trowel. The pot life of this mix is around 20 minutes.

While you can mix a quantity of dry mortar ahead of time, please make sure you use this mixture within 24 hours, as the GP cement in the mix will react with moisture in the air after this time and the strength of your mortar mix will be significantly reduced. Any dry mix left over after this time should be discarded, so it’s wise to only mix the amount you think you’ll need.

The mortar gap on the inside face of the oven should be kept to a minimum. Aim for brick-on-brick joints! The mortar gaps between each brick in your vertical columns that form the entry and vent arches should be a uniform 3mm. There are markings on the formwork to show you where each joint should be and how thick to make them. IDENTIFYING BRICKS FOR THE OVEN DOME There are 4 different types of bricks in your kit that you will use to build the dome of your oven. We ship our oven kits all around the world, so we have to be certain that you have more than enough bricks to complete the oven even if you drop a few of them. To make sure of this we have put about 5 extra bricks of each type needed to build the dome into your kit, so don’t be surprised when you complete the build and find that you have quite a few dome bricks left over.

Use the descriptions below to help you identify each of the different dome bricks. While the floor tiles are easy to spot, as they’re all 50mm thick, the bricks for the rest of the oven can be more tricky to identify. Please watch the video series that support these instructions, which will clearly show you how each of the bricks will look and help you to sort them into their types, ready to be laid. Type 1 Bricks are shown in the 3D model coloured brown. They are tapered in only one section. There are 120 Type 1 bricks in your kit.

Type 2 Bricks are shown in the model coloured dark grey. They are similar to the Type 1 bricks, but are tapered in two sections. There are 80 Type 2 bricks in your kit.

Type 3 Bricks are shown in the model coloured white. They are tapered in two sections, and are approximately half the size of the Type 2 Bricks. There are 28 Type 3 bricks in your kit.

Stagger Bricks are very similar to Type 1 bricks, but smaller. These are shown in the model coloured yellow. We identify them with a wiggly line across the back face of the brick in permanent marker. These can also be used as keystones at the end of your rows (you may find that when you reach the end of a row you will need a specially sized brick to fit – there are two different sized stagger bricks in the kit to accommodate this, you may need to grind them down slightly to get the perfect fit). There are 18 stagger bricks in your kit. The Entry and Vent Arches

This is the most complex part of the oven construction, however if you take your time and read our instructions carefully you will find it easy to identify the bricks that make up this section. The bricks that make up the walls of the Entry and Vent Arch are shown in the photos below. Put these bricks aside to avoid damaging them, as there are no spares for these provided.

There are 8No. ‘Entry Arch’ bricks in the D105 PreCut Oven Kit which you can see in the image on the above left. On the right you will see a set of bricks numbered 1-9, this is the Vent Arch brick set.

Please put these aside and be sure not to accidentally use them as keystone bricks in the dome!

With the floor tiles laid, it’s time to position your entry arch. Use the trammel, along with a pencil, to mark out the continuation of the inside edge of the dome across the opening. Also mark a line along the center of the floor as shown below.

1. Without using any mortar, position bricks L1 and R1 such that their curved edge is in line with the

arc you have drawn. Use the formwork marked ‘1’ to set the gap between the two bricks. The centerlines on the formwork must be in line with the centerline you drew earlier.

2. Once you have positioned L1 and R1, mark the position of these two bricks with pencil onto the floor tiles. Mortar the two bricks into place. Prop the #1 formwork on top of the two plastic strips provided. The reason for doing this is to ensure you can remove the formwork without damaging your arch. By pulling out the strips, the formwork is lowered, which should allow you to remove it easily. We advise that you leave the #1 formwork in position until you have completed this arch – please note that we have not shown the formwork in the other images so that you can clearly see the layout of the brickwork.

3. Position the trammel tool in the oven using the steel pin located at the base of the tool. This pin

fits into the hole in the center of the oven floor. Occasionally grit or mortar gets into this hole as the tiles are laid or during the building process, if this happens you can use a small drill bit to clear the hole so that the pin will fit all the way into the hole properly. The trammel tool will be used to position most of the bricks for the dome section of your oven.

4. Laying bricks with the Trammel Tool – Firstly, thoroughly soak the area that you are about to lay the brick onto, using a wet sponge. Apply mortar to the area that the brick will be touching, then clamp the brick into the trammel tool, and bring the brick down into position. You need to keep the inside face of your brick joints as tight as possible, so we recommend ‘wiggling’ each brick into place, until you feel it rubbing on the bricks underneath it. You can further tighten the joint by giving the brick a tap with a rubber or dead-blow mallet if you want. Then the joint is as tight as you will be able to achieve. There will be a 5mm mortar joint between the first row of bricks and the floor tiles due to the taper on the dome bricks – this is part of the design, and the normal mortar mixture can be used here.

5. Place the two bricks at the front of the oven, using the formwork marked ‘2’ to set the gap between the two bricks. Again, make sure the centerlines on the formwork are lined up with the centerline that you have drawn.

6. Lay course number 1. This is made up of Type 1 bricks.

7. Lay bricks L2 and R2, followed by the next two bricks for the vent arch.

8. Lay course number 2, this is also made up of Type 1 bricks. Start at the back of the oven, in the middle of the row. Keep the vertical joints staggered for optimal strength.

9. Lay bricks L3 and R3, followed by the bricks for next layer of the vent arch columns. This layer ‘keys’ into the entry arch columns, using specially cut bricks which are easy to identify in your kit.

10. Lay course number 3. This is made up of Type 1 bricks, remember you may need to cut/grind a

keystone for each end of the course.

11. Lay bricks L4 and R4, followed by the two 25mm thick bricks for the next layer of the vent arch columns.

12. Lay bricks L5 and R5, followed by the two ‘springer’ bricks that complete the vent columns.

13. Lay course number 4. This is made up of Type 1 bricks, and a couple of ‘stagger’ bricks will be

needed to keep the joints in the brickwork staggered.

14. Lay course number 5. This is made up of Type 1 AND Type 2 bricks, in an alternating pattern. Remember you may need to cut/grind a keystone for each end of the course.

15. Do a ‘dry-run’ of the Entry Arch, to check the gaps between each brick (they should be almost

brick-on-brick). Once you know the gaps that are required, lay all of the Entry Arch bricks over the #1 formwork, working from the outside in. With the full arch in place, the weight of the arch keeps the joints in compression and the arch becomes self-supporting. The Entry Arch bricks are a full sized arch brick with a chamfer cut off the back face, so they should be easy to identify.

16. While you can remove the formwork quite quickly after the arch is completed (if the bricks in course number 5 have been set for several days), we advise that you allow at least 12 hours for the entry arch bricks to set in place. When you are ready, pull the plastic strips out from under the formwork, it should drop slightly which will allow you to carefully remove it. If the formwork gets stuck, don’t panic! Just undo the screws that hold it together and gently tap the back piece out using a rod or similar through the holes in the front piece. With that gone, you can tap the front piece out and remove the side pieces.

17. Lay course number 6. This is made up of Type 1 AND Type 2 bricks, in an alternating pattern. A couple of stagger bricks will be needed. You will need to use a small amount of the castable to fill in the gap left between the first bricks and the entry arch.

18. You have now reached row number 7. You will notice that there are some large triangular gaps

between the arch and this course. These gaps will need to be filled with the refractory castable found in the brown paper bags.

Mix up a small amount of the castable with enough water to make a fairly stiff mixture (remember to add a small amount of Activator). Wet all of the brick surfaces that will be touching the castable, so that the castable will bond to them properly.

Fill the triangular gaps with your castable mixture. If you are finding that it runs through the other side, you can temporarily ‘form up’ the inside face by using a piece of plastic or cardboard held in place with a stick as shown below.

19. Lay course number 7, starting at the center of the course at the back of the dome. This course is made up of Type 1 & Type 2 bricks, in an alternating pattern. A couple of stagger bricks will be needed. You may find that the two bricks over the entry arch will need the undersides ground back slightly to fit. Alternatively these can be left out, and the space can be filled with castable (note that we have used the fiberglass dome to form up the inside face of this section).

If you do decide to use the castable method, make sure that you keep the circle even and level! 20. Lay course number 8. This course is made up of Type 2 bricks only. You may need to grind a

Type 2 brick to make a keystone to complete this course.

21. You have now reached course number 9. At this stage you have the option of removing the trammel tool and using the fiberglass dome to lay the remaining rows of bricks on. Put the fiberglass dome into the oven through the door or the hole in the top of the dome, and prop it in place using the circular plywood and a car jack as shown below.

You can continue laying the dome bricks with the trammel tool if you choose; it gives you more control over the final position of each brick in the dome, as you can actually feel that the brick is flush with its neighbor, which is something you can’t do when using the formwork. If you are finding that the bricks are starting to slide once released from the tool, use this trick: soak your dome bricks in hot water rather than cold. The heat accelerates the chemical reaction in the mortar mix, making it set much more quickly, which means you don’t have to wait for 5 minutes for each brick to set before removing it from the trammel.

22. Lay the bricks for course number 9. This course is made up of Type 2 bricks only.

23. Lay course number 10. This row is made up of Type 2 and Type 3 bricks in an alternating pattern.

24. Lay course number 11. This row is made up of Type 3 bricks only.

25. THE KEYSTONE. At this point you have two options – you can cut your own fire brick keystones using the remaining bricks in your kit, OR you can simply fill the hole with refractory castable. You will have the fiberglass formwork positioned in the oven at this stage, so the formwork will leave a perfect dome shape on the inside of this castable keystone.

We prefer to use the castable; it sets just as hard as the fire brick, and it makes a great keystone because it has perfect surface contact with the surrounding ring of bricks.

To make sure the fiberglass dome comes off cleanly, wipe the dome surface with a small amount of vegetable oil. Remember to add a small amount of Activator to the castable that you’re using.

To prevent the keystone from experiencing drying shrinkage cracking, cover the wet castable immediately after the pour with a wet cloth or cling wrap.

Allow the keystone to set for approximately 12 hours, after which you can remove the fiberglass formwork (it should peel off quite easily, and can then be pulled through the doorway).

26. The next step in building your dome is to ‘point’ the mortar joints on the inside face of the oven,

and clean off any excess mortar that has bled through onto the fiberglass formwork as you can see in the photo top right. To do this, you will need to slide into the oven on your back… Not much fun, but a very necessary part of the process! Take a small tub of wet mortar mix, several scourers, a sponge, a small bucket of clean water and a small paint scraper in with you. First scrape off as much of the excess mortar/castable as you can, then scrub any remnants off using the scourer. Now fill in any holes in your joints using the wet mortar mix, and wipe off the excess (before it sets) with a damp sponge. The finished result should look something like the photos above and below.

A TIP: Don’t wait too long to get in and clean out your oven! If you wait for 12 hours after your keystone is poured, then remove the fiberglass formwork and get in there you’ll find it relatively easy to clean the dome. If you wait much longer than this, the mortar and castable will set rock hard and be quite difficult to clean off.

27. You have reached the last step in your brickwork! It is time to lay the Vent Arch – you will need to position the #2 Formwork at the very front of the oven, in line with the front edge of the two vertical columns. Remember to use the plastic strips provided with the kit which will help with removing the formwork after the arch has been laid. We wait until this stage to build the vent arch, to avoid breaking it when sliding into the oven to clean the brickwork.

28. While you can remove the formwork quite quickly after the arch is completed (if the vent spring

bricks have been set for several days), we advise that you allow at least 12 hours for the vent arch bricks to set in place. After this, pull the plastic strips out from under the formwork, it should drop slightly which will allow you to carefully remove it.

If the formwork gets stuck, don’t panic! Just undo the screws that hold it together and gently tap the back piece out using a rod or similar through the holes in the front piece. With that gone, you can tap the front piece out and remove the side pieces.

Please note the top of the Vent Arch bricks are approximately 15mm higher than the Entry Arch, this is part of the design.

29. The brickwork of the oven is now complete, congratulations! Now, it’s time to install the PreCast Flue Gallery. This is a job for two people, due to the weight. There will be a larger gap (15 to 20mm) between the Entry Arch bricks and the PreCast Flue Gallery, which is part of the design. Some of the images used below are of our P85 PreCast Oven but the process is precisely the same for the brick oven.

30. Wet down the upper surfaces of the Vent Arch bricks and the top of the Entry arch bricks where the PreCast Flue Gallery is going to land. Also soak the underside of the PreCast Flue Gallery in water so that the mortar will bond properly to it.

Please note that some of the images in the instructions for placing the PreCast Flue Gallery are of our PreCast Oven being assembled – the process is identical.

31. Place spacers 3mm to 7mm thick on top of your Vent Springer bricks – in the photos below we have shown an alternative material, using small sections of cement sheet which were left in place (this area doesn’t get much over 200°C so the cement sheet will remain stable), you could also use the yellow plastic spacers that come with the kit as temporary packers that you remove once the PreCast Flue Gallery is set in place.

Trowel mortar around the packers and across the top of the Vent Arch bricks. While the mortar is still wet, lower the flue gallery onto the mortar and ‘wriggle’ it into place until it lands on the packers. Leave the gap between the PreCast Entry Arch and the PreCast Flue Gallery for later. 32. Use the remaining mortar to fill in any gaps that were left behind after placing the flue gallery.

33. With the PreCast Flue Gallery mortared into position you can fill in the gap between the Flue

Gallery and the Entry Arch with a mixture of Refractory Castable. Wet the top of the Entry Arch bricks and the underside of the Flue Gallery to ensure a good bond with the castable.

34. Fill the gap between the PreCast Flue Gallery and the Entry Arch with the refractory castable mixture, smoothing off the inside face. Cover the wet castable with clingwrap so that it sets without plastic shrinkage cracking, and use a trowel to clean up the inside face.

35. Allow all the castable to set for at least 12 hours, then you can remove the cling wrap and proceed

to the next step.

INSULATING THE DOME Your oven will now look something like the photo shown below – please note that you do not have to clean the outside of the dome bricks, this is something we did just so that you could see how the oven is assembled. You now need to wrap the dome of the oven in the Ceramic Fibre Blanket. The photos used below show the Flue Gallery already painted – this is typically done later on.

1. Take the full roll of ceramic fibre blanket and wrap it around the base of the dome, resting it on

top of the castable layer. You will need to cut ‘V’ sections out of the top of the blanket as shown below to allow the blanket to wrap tightly around your dome.

2. Run a section of blanket from the PreCast Flue Gallery to the back of the dome, then trim pieces

to fill in the gaps. Providing it’s not too windy, the blanket should remain in place. Remember to wear a good quality dust mask and goggles when working with the ceramic fibre blanket.

3. Repeat the process for the second layer, but this time the horizontal section will come all the way

down to your concrete slab, insulating the exposed castable layer. Don’t throw any offcuts away until you are finished, as there is just the right amount of blanket in your kit!

4. To hold the blanket in place, we lash it down to the dome using tie wire, secured around the base

of the dome. Where do you tie this wire you ask? We use large (100mm long) screws, screwing them through the ceramic fibre blanket into the CalSil board as shown below.

Put these screws through into the CalSil board at approximately 300mm intervals, then use the screws as tie points to lash the blanket down against your dome using tie wire.

5. With the blanket firmly tied down, it’s time to put a layer of fine chicken wire over the dome. This is to give your render coating something to bind to, and gives your render additional tensile strength to resist cracking. Run the chicken wire from one side of the dome across the top, to the other side, securing it at the base using the screws that you installed earlier. You will have sections of the dome where the chicken wire will overlap, this is no problem.

You will find that the chicken wire tends to bulge out, away from the dome. If you have used a fairly thin chicken wire you ‘scrunch’ these sections down, which will pull the wire back in against the blanket. Run the next layer of wire around the perimeter of the dome, hooking it onto the screws around the base, and fold/scrunch down the areas that are bulging away from the dome. Add wire until you have covered the entire dome with chicken wire, running right up against the back of the flue gallery, and in behind the Vent Arch columns. To push down any troublesome high spots you can use more tie wire to lash the chicken wire down against the blanket.

Before you move onto the next step, check the dome for loose wires that are poking out, and fold all of these down, as they will interfere with putting the render layers on.

RENDER

In your kit you will find three bags of LiteFill Perlite – this is a lightweight aggregate that you will be using to make an insulating render layer, over the blanket. The Perlite render layer serves two purposes – it forms a protective shell over your ceramic fibre blanket, and it provides additional insulation to your oven dome.

PERLITE RENDER MIXTURE

• 5 Parts LiteFill Perlite • 1 Part GP Cement • 1 Part Lime • 1 Part Washed Sand

Mix up a full wheelbarrow (or large tub) of render, combining the Perlite, cement, lime and sand while dry, then add water. Mix thoroughly, adding enough water to wet it all out. You should be able to make a ball with this mixture, throw it up and catch it without it running through your fingers.

The Perlite render needs to be put on one layer at a time, for the first layer we simply work the wet mixture into the chicken wire as shown in the photos below. Start by working around the base, then cover the top. This layer will only be around 15mm thick. Allow this layer to cure for 24 hours, covered in wet sheets or hessian to prevent drying shrinkage cracking.

Before the next layer, wet the surface of the previous layer so that it will bond to the new layer. Trowel the next layer on, you are aiming to build up around 15mm or so in each new coat.

Again, let this layer cure for 24 hours before applying the next. Repeat this process until you have used up all of the Perlite in your kit – this should give you a render shell layer approximately 50mm thick. We recommend that you bring the perlite render in behind the vent arch columns, then your render layer remains thick, rather than tapering out to a very thin section which is likely to crack.

We highly recommend that once you have cured your oven, you put a layer of Acrylic ‘Roll-On’ Render over your Perlite layer, as the perlite render is not waterproof. Wait until the oven is completely cured and dry before you put it on, or you will get bubbles forming in the acrylic layer from escaping steam. We have this Acrylic Roll-On Render in a variety of colours available for sale.

You’re not limited to just leaving the oven in a rendered finish – you could cover the dome with tiles, slate, river pebbles or even another layer of bricks. What you do from here is up to you! OVEN LANDING & SURROUNDS The final step in the process of building your oven is to finish the top of the concrete slab with tiles or stone and seal off the exposed CalSil board at the sides and front of the vent area. The CalSil board is highly absorbent and needs to be protected from water. There are a number of ways of doing this, our preferred method is to install a polished granite landing at the same height as the oven floor (we have the granite pieces for sale as an optional extra).

Bring the height of the concrete slab up around the vent area. We use 20mm thick polished granite, so we raise the slab 25mm below the oven floor height (20mm granite + 5mm adhesive). There are two methods you can use, forming and pouring a ‘mini-slab’ of concrete as shown below, or gluing bricks or Hebel down to give you a solid base to install the granite on. Once the mini-slab has set for at least 24 hours, attach the granite pieces using plenty of silicone.

Cut and lay porcelain or stone tiles to cover the remaining surfaces of the slab, and the front and sides of the mini-slab you poured earlier for the granite landing. Attach these with standard tile adhesive and once the adhesive has set, fill the joints with normal tile grout.

PAINTING THE FLUE GALLERY The PreCast Flue Gallery comes in the kit in a plain cast finish, which is a light grey colour. You can leave it in this finish if you want a more natural look, or coat it with high temperature paint which not only makes it look great, but seals it to prevent it soaking up rain. Wait until the Ceramic Fibre Putty layer is dry to apply this paint, which may take a few days from the date you applied it.

There are a range of high temperature paints available, however there are very few colours to choose from. We have tested almost all the available high temp paints and the one we have found performs the best is PPG Temptec 328, which we have available for sale in satin black (this is the only colour available). Mask off the edges of the brick work with masking tape and paper, particularly if you are using a spray can (we use a small brush for the PPG Temptec paint). Apply the paint in several light coats leaving at least an hour between coats and allow to dry for at least 12 hours prior to firing the oven.

FINISHING TOUCHES

There are so many different ways you can finish off your Wood Fired Oven, and we have seen just about all of them! From sleek and modern through to more traditional styling, how you trim your oven to give it your own unique look is entirely up to you.

Remember, once the oven is cured the dome simply will not get hot from being fired, so you can cover it with just about anything you like. We highly recommend using an Acrylic Roll-On Render as mentioned earlier to give your oven dome the right colour, and to waterproof it against the rain. We have this for sale as an optional extra to the kit, in a range of different colours. Some information for the vent arch bricks and the PreCast Flue Gallery – if you really fire your oven up these can reach temperatures of 190°C. Keep this in mind if you’re thinking of building the oven opening through a wall, you will need to use non-combustible materials for this wall if you do so.

FINISHED OVEN EXAMPLES To give you some inspiration, we have included photos below of some of the builds that both ourselves and our customers have done over the years.

CURING

Once you have finished building your wood fired oven, it will be full of water – each brick was soaked in water as it was laid, so your oven will be holding water in the walls, floor tiles and CalSil board. The problem with this is that if you light a big fire in the oven at this point, the water inside the bricks and mortar joints will boil and produce steam, which can actually cause bricks to crack. You need to slowly dry the oven out, or ‘cure’ it before you start lighting major fires.

From the time that you laid the final brick, allow seven days to pass without firing it up, to allow the mortar and refractory castable time to set and reach their full strength before any firing is done.

To cure the oven, we burn a series of small fires to dry the oven out over seven days. These days don’t have to be sequential, but you will need at least seven days of slow firing to cure the oven properly. We have put together a video walking you through this process which you will be able to find on our website.

For the first four days you will be making a small fire, roughly in the center of the oven floor. You want to keep this fire going for as long as you can; 3 hours would be the minimum but keep it burning all day long if you can. Do the same thing for the next three curing days, lighting a small fire and keeping it going for as long as you can. On the 5th curing day you can increase the size of the fire slightly and push it against the back wall of the oven, again keeping it burning for as long as you can. Repeat this on the 6th day of curing. Now, if you are REALLY patient you could continue with these fires for another few days, which will minimise the size of the cracks in your oven (which you’re going to get no matter what you do!).

Once you have gone through these six curing fires, you’re ready to really ramp up the temperature. Follow the same process you have been using for the last few curing days, getting a medium sized fire burning against the back wall of the oven dome and let it burn for a good hour. By then you will have slowly ramped the temperature of your oven up, and you’re ready to push it up to the next level. Load on a few more pieces of timber and get a good blaze going, and keep feeding it until you see all of the black carbon buildup on the inside of the dome burn off – this is known as ‘clearing the dome’.

You may notice that the floor cools down more than you would like at first – this is because the CalSil board is still holding water, which makes it much less effective as an insulator. After a few more of these big firings the CalSil board will be completely dry and your oven will retain its heat for a longer time. CRACKING Please note that it is completely normal to see some fine cracking in your oven, in fact we can almost guarantee that you will! This is due to the fact that you’re heating up a rigid, ceramic structure to extremely high temperatures, which will make the brickwork in your oven expand, and contract upon cooling. This expansion will result in small cracks that run along your mortar joints; it’s very common to see a crack starting at the base of the dome that runs all the way up to the keystone, as well as some fine cracks in the bricks that form your vent arch. You’ll also see some cracks in the outer dome render, radiating from the junction with the flue gallery. Don’t panic! These cracks are normal and there’s nothing that you can do to stop them, so don’t stress. If you do happen to get a large crack in your mortar joints (in excess of 3mm) then we have repair materials that can be sent out to you, however this is rare, and is usually due to the oven being over-fired early in the curing stages. Cracking in the dome render will be covered by the roll-on acrylic coating (stucco) that you’ll apply once the oven is fully cured.

Well, there you have it. We hope that you have enjoyed your project, and that your oven brings you, your family and friends, much enjoyment in the years to come.

Please see our website for more information, as well as how-to videos for using your oven.

If you have any questions at all, please don’t hesitate to contact us.