The BrickWood Refractory Mortar Guide
Refractory Mortar for Pizza Ovens: The Non-Water Soluble Mortar for Outdoor Fire Brick
What refractory mortar is, why outdoor builds need a non-water soluble mortar, how much to order, how to mix it and how to cure it. Written in plain English for first-time builders.
BrickWood Refractory Mortar is a dry-mix, hydraulic-setting, medium duty refractory mortar rated to 2,700°F. You add water, lay your fire brick, and it sets by chemical reaction. Once set, it is non-water soluble, so rain and snow won't wash it out of your joints. That makes it the mortar to use for outdoor pizza ovens, fire pits, outdoor fireplaces and chimneys.
Building an oven? Download the FREE step-by-step pizza oven plans. They include a full materials list.
Refractory Mortar: Quick Answers
- What it is: a dry, hydraulic-setting refractory mortar for laying fire brick.
- Rating: 2,700°F maximum service temperature.
- Outdoors: non-water soluble once set, so it's safe for outdoor builds.
- Mixing: 3.75 quarts of clean water per 50 lb bag (0.75 quart per 10 lb).
- How much for a pizza oven: 6 bags (300 lb) for a Mattone Barile, 7 bags (350 lb) for a Mattone Barile Grande. Ovens have wider joints, so they use more mortar.
- Other projects: one 50 lb bag makes about 60 lb of mortar and lays about 150 standard fire bricks with thin joints.
- Working time: mix only what you can use in 15 minutes. Don't add water once it starts to set.
- Curing: sets in 48 to 72 hours. Wait 7 days before the first fire.
- Sizes: 50 lb bag or a 4-pack of 10 lb pails. Minimum order of 2.
- Shipping: FREE to the contiguous United States. Non-refundable once shipped.
Inside this guide
What Is Refractory Mortar?
Refractory mortar is the high-heat glue that holds fire brick together. Regular masonry mortar breaks down at oven temperatures. Refractory mortar is made from heat-proof alumina and silica with a refractory binder, so it keeps its strength at temperatures far beyond what a wood-fired oven ever reaches.
BrickWood Refractory Mortar is about 46% alumina and 44% silica. It's hydraulic setting, which means it hardens by a chemical reaction with water rather than by drying out or by being fired. That's the key to its outdoor durability: once it sets, it won't dissolve.
It replaces the classic 4-ingredient homemade high-temperature mortar (silica sand, fire clay, Portland cement and lime). No measuring, and no shopping around for four separate ingredients.
BrickWood Refractory Mortar Specifications
| Type | Dry mix, hydraulic setting, medium duty refractory mortar |
| Maximum service temperature | 2,700°F |
| Pyrometric cone equivalent (PCE) | 29 to 30 (melts at about 3,018 to 3,029°F) |
| Water soluble | No, once set |
| Bonding strength (ASTM C-198) | 125 psi after 230°F; 734 psi after 2,450°F |
| Pier test at 2,730°F (ASTM C-199) | No flow from joints, no cracks or shrinkage |
| Water to mix | 3.75 quarts per 50 lb bag (0.75 quart per 10 lb) |
| Yield | One 50 lb bag makes about 60 lb of mortar |
| Coverage | 35 to 40 lb of mixed mortar lays 100 standard 9 x 4.5 x 2.5 inch fire bricks with thin joints (pizza ovens use more; see below) |
| Working time | About 15 minutes after mixing |
| Set time | 48 to 72 hours |
| Density | About 105 lb per cubic foot |
| Chemistry | Alumina 46.1%, silica 43.5%, calcium oxide 5.5%, titanium dioxide 1.9%, iron oxide 1.9% |
| Building codes | Accepted by the International Code Council, International Residential Code and NFPA |
| Sizes | 50 lb bag or a 4-pack of 10 lb pails |
Values are typical results from standard ASTM testing and can vary slightly from batch to batch.
How Much Refractory Mortar Do I Need?
It depends on what you're building. A pizza oven takes a lot more mortar than most fire brick projects, because the mortar joints in an oven are much wider.
For a BrickWood pizza oven
Order by oven, not by brick count. These amounts already account for the wider joints:
| Oven | 50 lb bags | Total mortar |
|---|---|---|
| Mattone Barile | 6 bags | 300 lb |
| Mattone Barile Grande | 7 bags | 350 lb |
Your plans include a full materials list for your oven.
For fire pits, fireplaces and other fire brick projects
Projects laid with thin, standard joints use much less. Count your fire bricks, then divide by 150 for 50 lb bags. Round up and add a little extra for waste. The minimum order is 2.
| What you buy | Mixed mortar | Lays about |
|---|---|---|
| 1 bag (50 lb) | About 60 lb | 150 fire bricks |
| 2 bags (100 lb) | About 120 lb | 300 fire bricks |
| 4 bags (200 lb) | About 240 lb | 600 fire bricks |
| 1 four-pack of 10 lb pails (40 lb) | About 48 lb | 120 fire bricks |
These numbers assume thin joints. Thicker joints use more mortar, so order an extra bag if you're unsure. Since refractory materials are non-refundable once shipped, it's worth checking your count before you order.
How to Mix and Lay Refractory Mortar
- Gear up. Put on a NIOSH-approved dust mask, gloves and safety glasses before you open the bag.
- Measure the water. Use 3.75 quarts of clean, cool water per 50 lb bag, or 0.75 quart per 10 lb. Cool water gives you more working time. Warm water speeds up the set.
- Mix small batches. Only mix what you can use in about 15 minutes. Blend until it's smooth and lump-free.
- Lay the brick. Butter each brick and set it in place. For a pizza oven, follow the joint widths in your plans. For fire pits, fireplaces and other standard brickwork, keep the joints thin and even.
- Don't retemper. Once the mortar starts to stiffen, throw it out. Adding more water after the reaction starts weakens it.
- Clean up. Wipe off excess mortar before it sets.
Never add anything to it
- Don't mix in fire clay, sand, cement, lime or accelerators. It's already a complete mix.
Curing and the First Fire
Refractory mortar sets in 48 to 72 hours, but it needs time to fully cure before it sees heat. Wait at least 7 days after your last brick before you light the oven. Then cure the oven with several small fires, building up slowly, so any moisture left in the mortar and brick can escape as vapor instead of steam. Your plans walk you through the curing fires step by step.
Why Outdoor Builds Need Non-Water Soluble Mortar
Many premixed refractory mortars sold in pails are air-setting and water soluble. They're great for indoor fireplaces, but rain, snowmelt and humidity slowly wash them out of the joints of an outdoor oven. BrickWood Refractory Mortar sets chemically and stays non-water soluble, which is why it's the only one of our four mortars we recommend for outdoor pizza ovens, fire pits and outdoor fireplaces.
Safety and Handling
Like all refractory products, this mortar contains crystalline silica. Breathing the dust over time can damage your lungs.
- Wear a NIOSH-approved dust mask or respirator while mixing the dry powder.
- Wear gloves, long sleeves and safety glasses. Wet mortar can irritate skin and eyes.
- Mix outdoors or in a well-ventilated area, and don't eat, drink or smoke while you work.
- If mortar gets in your eyes, rinse with water. Wash skin with soap and water.
- Store unopened bags in a dry place.
WARNING: This product can expose you to chemicals including crystalline silica, which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.
Refractory mortar mistakes to avoid
- Using water-soluble mortar outdoors. It will wash out of the joints over time.
- Mixing too much at once. You have about 15 minutes of working time.
- Retempering. Never add water to mortar that's starting to set.
- Ordering too little for an oven. Pizza ovens have wider joints and use far more mortar than other projects. Order by oven: 6 bags for a Mattone Barile, 7 for a Mattone Barile Grande.
- Guessing at joint size. Follow the joint widths in your oven plans. On standard brickwork, keep joints thin and even.
- Firing too soon. Wait 7 days, then cure with small fires.
- Skipping the mask. Wear one every time you mix dry powder.
Which Refractory Mortar Do I Need?
We sell four refractory mortars. Only one is made for outdoor and DIY pizza ovens. The other three are for professional and industrial work. Since refractory products are non-refundable once shipped, please check this table before you order.
| Mortar | Comes as | How it sets | Rated to | Water soluble? | Outdoor / DIY ovens? | Made for |
|---|---|---|---|---|---|---|
| Refractory Mortar | Dry mix, add water. 50 lb bag or 4-pack of 10 lb pails | Hydraulic (chemical set) | 2,700°F | No, once set | Yes | Outdoor pizza ovens, fire pits, outdoor fireplaces and chimneys |
| Super Duty Mortar, Dry Heat-Set | Dry mix, add water. 55 lb bag | Heat-set (needs kiln-level heat) | 2,900°F | Until fired | No, industrial | Kilns, furnaces, forges and industrial equipment |
| Super Duty Mortar, Premixed | Ready to use. 50 lb pail or 4-pack of 15 lb pails | Air-set | 3,000°F | Until fired | No, industrial | Kilns, furnaces, boilers and indoor high-heat equipment |
| High Heat Mortar, Premixed (Medium Duty) | Ready to use. 50 lb pail or 4-pack of 15 lb pails | Air-set | 2,700°F | Yes | No, indoor only | Indoor fireplaces, fireboxes and wood stoves |
Building a pizza oven, fire pit or anything that will see rain or snow? Choose Refractory Mortar. It's the only one of the four that stays put outdoors.
Refractory Mortar: Frequently Asked Questions
Can I use refractory mortar outdoors?
Yes. BrickWood Refractory Mortar is hydraulic setting and non-water soluble once it sets, so rain and snow won't wash it out. It's the mortar we recommend for outdoor pizza ovens, fire pits, outdoor fireplaces and chimneys.
How hot can refractory mortar get?
It's rated to a maximum service temperature of 2,700°F. A wood-fired pizza oven reaches about 1,000°F inside, so the mortar works well below its limit.
How much water do I mix with refractory mortar?
Use 3.75 quarts of clean water per 50 lb bag, or 0.75 quart per 10 lb. Mix only what you can use in about 15 minutes.
How much refractory mortar do I need for a pizza oven?
A Mattone Barile takes 6 bags (300 lb) and a Mattone Barile Grande takes 7 bags (350 lb). Pizza ovens have much wider mortar joints than most fire brick projects, so they use a lot more mortar per brick.
How many fire bricks does one bag lay?
On projects with thin, standard joints, like fire pits and fireplaces, one 50 lb bag makes about 60 lb of mortar and lays about 150 standard 9 x 4.5 x 2.5 inch fire bricks. Pizza ovens use more because of their wider joints.
How long before I can light my oven?
The mortar sets in 48 to 72 hours. Wait at least 7 days before the first fire, then cure the oven with several small fires.
Can I use premixed mortar from a bucket for my pizza oven?
Not outdoors. Premixed air-set mortars are water soluble until fired and will wash out of an outdoor oven over time. Our premixed mortars are for indoor and industrial work. For an outdoor pizza oven, use this dry Refractory Mortar.
Can I add fire clay, sand or cement to it?
No. It's a complete mix. Adding fire clay, sand, cement or accelerators weakens it.
Is there a minimum order?
Yes, the minimum order is 2, either two 50 lb bags or two 4-packs of 10 lb pails.
Can I return refractory mortar?
Refractory materials are non-refundable once your order has shipped. If you're not sure what you need, contact us before you order and we'll help.
How fast does it ship?
It's in stock and ships within 1 to 2 days, with FREE shipping to the contiguous United States.
Please Order Carefully: Refractory Materials Are Non-Refundable Once Shipped
Refractory materials are heavy, costly to ship and can't be resold once they leave our warehouse. For that reason, refractory products can't be cancelled, returned or refunded once your order has shipped.
We're happy to help you get it right the first time. If you're not sure which product or how much you need, contact us before you order and we'll walk you through it.
Shipping
FREE shipping on every refractory product to all locations in the contiguous United States (the lower 48 states). Orders ship by ground carrier or commercial freight, depending on size, and freight carriers will call to schedule delivery. Please leave a phone number we can reach you at in the order notes.
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Lay your fire brick with the right mortar
Choose a 50 lb bag or a 4-pack of 10 lb pails at the top of the page. Minimum order of 2, and shipping is FREE.
Not sure how much you need? Our team has helped thousands of backyard builders, and we're happy to help you get it right before you order.
Specifications are typical values from standard ASTM testing and can vary slightly from batch to batch.
