November 30th, 2018

Your Fireplace Is Only As Strong As The Mortar You Choose

In recent years we have seen vast changes regarding building code requirements for mortar used on firebrick (fireplace) and clay flue liner (chimney) installations. Jobsite prepared mortars that may have included fireclay and Portland cement no longer meet code. Factory prepared refractory mortar is now the accepted standard. Refractory mortars have become easier to use, safer, are more readily available, and meet all of the local and national building codes.


Homespun formulations can become liability issues because fireclay mixes break down and lose strength as they pass through temperature ranges of 600-800 degrees. They simply don't take the heat like refractory mortars do, nor do they have the strength or acid resistance.


The International Code Council (ICC), the International Residential Code (IRC) and the National Fire Protection Association (NFPA-211) now all require refractory mortar tested to American Society for Testing Materials, ASTM C-199, medium duty.


There are basically two kinds of refractory mortar conforming to ASTMC-199 and permitted by code. Non-water soluble refractory mortar (sometimes called hydraulic setting) is a dry blend, requiring only cold water to be added, usually ships in a bag, and sets up or cures much like a regular mortar mix. The second type is a premixed version and it comes in a pail and is about the consistency of drywall compound. It usually requires no additives, and with a little mixing is ready to use.

Non-water soluble refractory mortar is the only refractory mortar that should be used in outdoor applications. Premixed refractory mortars may wash out even after drying. Due to the previously mentioned characteristics, non-water soluble product is also the preferred choice for clay flue installations that may vent gas or oil appliances or in any other instance where moisture may be present within the clay flue. This is our overall refractory mortar of choice. It is used four to one vs. other types of refractory mortar in residential construction.

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4 Reasons to Clean Your Chimney

May 1st, 2017

Spring is finally here, and as we look forward to warmer weather, your fireplace is probably the last thing on your mind. Before you shift your thoughts to landscaping and skimming the swimming pool, give your chimney the attention it needs after a winter of use.

4 reasons to clean your chimney regularly

  1. Prevent fires. Over 24,000 house fires each year are started in the chimney. Cleaning your chimney 1-2 times annually helps eliminate soot build up, thus drastically reducing the risk of fire.

  2. Remove unwanted guests. No, we don't mean kicking your in-laws out or throwing your grown children to the curb! A dirty chimney makes a great home for birds, small animals, and pests. Cleaning the chimney is the best way to keep these unwelcomed visitors from making themselves cozy inside your home.

  3. Reduce the risk of Carbon Monoxide poisoning. Carbon monoxide is much more likely to creep its way into your home if you have build up in your chimney. Soot and ash can block the necessary vents which allow for chemicals to be released if your chimney is not properly maintained.

  4. Prevent smoke damage. Along with blocking access for chemicals to leave, a dirty chimney also makes it more difficult for smoke to rise. When there is blockage involved, the smoke will have no other route than back down the chimney and into your home, which can lead to damage within the fireplace surround as well as several health concerns.

Before you retire your fireplace for the season, give your local chimney sweep a call. If nothing more, it will help you celebrate spring with peace of mind and take one item off of your to-do list when the weather cools down again in the fall!

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Product Spotlight: INSUL STICK

March 1st, 2017

Insul Stick is ideal for use in smooth parging over firebrick in the fireplace smoke chamber. With its combined insulating value and strength, Insul Stick meets the strict ASTM E-136 requirements for sealing walls for utility passthrough.

Insul Stick is very versatile in nature and can be cast, parged, troweled, or sprayed.

It is typically used to cast special shapes for:

  • wood stoves
  • fireplace hearths
  • walls
  • boilers
  • furnaces
  • and other high temperature applications.

When using Insul Stick, add clean water (¾ to 1 qt.) for each 5 pounds of product and mix thoroughly. For best results, Insul Stick should be applied no thinner than ¼ to ½ inch thick. When applied correctly, approximately 2.5 pounds of product will cover one square foot.

Insul Stick will stick to virtually any non-slippery surface and will strengthen any wall. Click here to watch our instructional video on Parging with Insul Stick.

Learn more about Insul Cast and download the Safety Data Sheet here.

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Fireplace Safety 101

November 17th, 2016

Fireplaces and chimneys are to blame for 42% of home heating fires, and ‘tis the season for cozying up near the glow of embers. With cold weather approaching, taking these three steps will help you stay safe and warm this winter.

  1. Check for damaged brick and mortar. Inspect your chimney and firebox for damages or cracked bricks and deteriorating mortar. If you find issues, click here to build new firebrick using Heat Cast 40.

  2. Sweep it out. Hire a chimney sweep at least once per year to clean out the chimney and inspect for any damages. While you have them there, you might also want to install a chimney cap to keep out any unwanted birds, critters, or debris.

  3. Build smart. Building the fire itself is almost as important as building your fireplace. Place larger logs towards the back of your firebox and always use kindling or smaller logs to ignite the flames rather than flammable liquids. A wire mesh screen or glass fireplace doors are also recommended for optimal fire safety.

If you happen to discover damage to your firebrick or mortar, check out our Youtube videos for simple fixes using Heatstop products to get your home winter-ready. Keeping your fireplace clean and free from cracks is the best way to maintain peace of mind while celebrating the season for peace on earth!  

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Product Spotlight: INSUL CAST

September 20th, 2016

INSUL CAST is an insulating castable refractory product typically used as a backup to denser refractories such as firebrick or other solid masonry. This product is ideal for insulating ovens and fireplaces, and possesses cold crushing strength of approximately 200 pounds per square inch.

To use INSUL CAST and take advantage of its benefits, add approximately six gallons of clean water per 50 lb. bag and mix thoroughly. No other additives are required! Apply the solution at a minimum of 2-3 inches thick behind a firebox firebrick wall, as a sub hearth under firebrick for an oven, or over the top of an oven dome.

INSUL CAST can be cast or troweled into place, weighs approximately 35 pounds per cubic foot, and is shipped in a 50 pound bag that will cover approximately 6 square feet when applied 2 inches thick.

For more information on how to use INSUL CAST, watch our informative videos here and here, or read up on the Safety Data Sheet for additional details!

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Product Spotlight: HEATCAST 40

July 11th, 2016

HEATCAST 40 is one of our most popular products, intended for use in place of firebrick and able to be cast into custom shapes for several applications.

This is a unique product in that it is able to withstand extreme temperatures, for applications well over 2000°F, and can withstand approximately 1,500 pounds per square inch of cold crushing strength. Regular cement or mortars found in most mortar mixes are able to withstand only up to 600-800°F, even though most residential installations operate well in excess of 800°.

HEATCAST 40 is typically cast 2" thick for replacement of firebrick in a firebox smoke chamber or oven, but can also be cast thicker based on the specific project. Each bag of HEATCAST 40 contains 40 lbs. of product, and you can generally expect to use 20 lbs. per square foot when applying at the recommended 2" thickness.

This product is specially formulated for application in:

  • Woodstoves
  • Hearths
  • Sidewalls
  • Boilers
  • Furnaces
  • Brick Ovens

All Heat Stop products are tested extensively to ensure their ability to withstand temperatures well above 2000°F, assuring code compliance and quality installation. If you have any questions about the uses and requirements of refractory mortar, we can provide the expertise and support needed to ensure code compliance and deliver appropriate products for your projects.

To view our full product line, click here or shop online through our authorized distributor, Vicar Industries LLC, at

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Having a Moment: Outdoor Ovens

May 20th, 2016

Outdoor ovens are having a real "moment" lately. From backyard barbeques to celebrity soirees, you're bound to see at least one outdoor oven at some point this summer. 

Along with their attractive display, outdoor ovens are appealing to the tastebuds too – with so many recipes for delicious homemade breads and gourmet pizzas, any house with an outdoor oven is sure to be the "go to" spot on warm summer nights! 

Wood-fired brick ovens and pizza ovens have been with us since early ancient civilization, reaching its modern form in ancient Rome. The ovens have gone through many changes over the years, but the original method of using them has essentially remained the same. The most recent change in brick pizza oven design, and possibly the most important in terms of their evolution, has been the use of modern refractory and insulating materials, allowing pizzas and breads to cook in around 45 minutes rather than the traditional 2-3 hours, thanks to improved heat-holding characteristics.  

If you're in the market for landscaping work this summer (or even if you're not!), consider adding an outdoor oven as a focal point to your entertaining space. Your friends and family will thank you and we promise you won't regret it. Just be sure to keep plenty of yeast on-hand for when company happens to be "in the neighborhood!" 

Not sure where to begin? Shop the full line of outdoor piza ovens here, choose a facing material, and don't forget the HeatStop mortar

*images via Pinterest.

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Your Guide: How to Use a Pizza (Brick) Oven

March 14th, 2016

Your Guide: Pizza (Brick) Oven

Heat stop refractory mortar products have a range of uses in the installation of firebrick and clay flues, plus in repair or restoration work. For the do it yourself-er, these projects can be especially fun, rewarding and sometimes, challenging.

As we gear up for nicer weather and outdoor parties, the thought of cooking pizzas in a brick oven this spring and summer is certainly a nice one — building your own pizza oven or brick oven is most definitely an achievable project.

What to see some examples of how to cook with your oven?  Watch this video from  Chicago Brick Oven:

Taking the time to craft a well-made pizza oven or brick oven is sure to provide you and your family with years of excellent meals. When you're ready to start building, our Heat Stop family of products will be here to help you reach your goals. And once it's built, don't forget about baking the perfect pizza. 

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Your Guide: How to Build a Fireplace

January 12th, 2016

Whether indoor or outdoor, residential or commercial, there are a range of fireplaces that not only add character and functionality to your home — they provide essential heat!

Taking on the task of building your own fireplace is not a small endeavor, but it is most definitely an achievable one. With the number of resources available today, do-it-yourselfers at any level can tackle this challenging and rewarding project.

Top resources to build a fireplace

Tap into these resources for an excellent start for your next fireplace project:

Planning Guide: Fireplaces (Bob Villa). The renowned home improvement expert provides an excellent introduction to the fireplaces you may want to add to your home (including masonry, zero clearance and gas). The most important step in any project is the first, and planning your fireplace project is essential. Villa's introduction and planning guide can help you get your project off to a great start.

How to Build an Outdoor Stacked Stone Fireplace (HGTV). The cable network taps into a range of industry experts for its shows and tutorials, and this tutorial is an excellent resource for DIYers looking to transform their deck or patio this year. Featuring videos, images, lists and a clear, step-by-step breakdown of the process, this robust resource offers tremendous value.

Refractory Mortar for Masonry Fireplace and Chimney Construction. Together with Jim Buckley, I created this guide to refractory mortar for firebrick (fireplace) and clay flue liner (chimney) installations.

Building a Fireplace Step by Step (Masonry Construction). Mason Tom Kasper walks through a how-to from the foundation to the chimney cap. This printable resource is packed with information.

Building your own fireplace is a challenging, yet rewarding project that will provide your home with warmth and style for many years to come. And when you're ready to start your project, the right Heat Stop product will help you get there.

Image courtesy of Geerati from

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Measuring is Key - Determining How Much Heat Stop Product You Need

December 1st, 2015

Whether it's building a bake oven, repairing a chimney or working on fire pits, fireplaces, furnaces or kilns, using the right amount of Heat Stop product is critical. Heat Stop is an important component of many successful projects, but using the product properly is essential to achieving the desired result — and in obtaining the best product performance.

Successful mortar projects rely on successful product use.

In 40 years of using Heat Stop products, I've had many questions about product measuring and use - here are my top four tips and lessons for measuring and using Heat Stop products in your projects:

1. No two projects are the same. There are several factors that affect the amount of Heat Stop product needed for your project. These of course include the type of project being done, joint mortar thickness used, and waste, among other factors. But most importantly - each of these factors varies from person to person. It's important to understand the specifics of your own project and habits to determine the steps and use that will lead you to success.

2. Understanding the basics of product use is key. Before you can consider the variables affecting your project, you should understand the basics. Here is a "quick guide" to Heat Stop measurement basics:

In general, Heat Stop premix and Domestic Fireplace Mortar premix, which are refractory mortar products, should be applied with a maximum joint thickness of 1/16-1/8". Heat Stop II and Heat Stop 50, which are dry refractory mortar products, should be applied with a minimum thickness of 1/16-1/8", and may be applied in thicker joints as desired. For each of these products, installers will need approximately 50 lbs. of product to lay up 100 firebrick (assuming the joint thickness is 1/16-1/8").

Heat Cast 40 should be applied 2" thick when used to cast shapes or installed as a hearth in a heat chamber. Installers will need approximately 20 lbs. per square foot when applied 2" thick.

Insul Stick, which is used to parge over firebrick in a smoke chamber or for exterior applications, should be applied 1/4 to 1/2" thick. Installers will need approximately 2.5 lbs. per square foot when applied 1/2" thick.

Finally, Insul Cast, which is a backup insulating product that can be applied under the hearth or over the dome in a fire pit or bake oven, should be applied with a minimum thickness of 2". Installers will need approximately 6 lbs. of product per square foot when applied 2" thick.

3. Pay attention to the details. While following the guidelines above is the best way to ensure you're using the correct amount of Heat Stop product, paying attention to smaller steps and details is also important. Heat Stop pre-mix products can be used as is, but we recommend installers give the product a thorough mix or stir before using. Depending on your specific needs or preferences, you may want to add a little water to thin the product consistency, but you'll then need to mix the product thoroughly again before using.

4. Be ready for extenuating circumstances. Refractory mortar products may take longer to dry if the joints are thicker than 1/8", and/or if conditions are extremely humid (which occurs in certain climates or after rainfall in many areas). To enhance the drying in such conditions, open the damper, place a fan in front of it, or use other means to get some air or heat passing by the installation.

Consider and follow these tips, and you'll be well on your way toward a successful project!

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