Heat Stop refractory mortar
Heat Stop is a refractory mortar for laying firebrick and clay flue lining in masonry fireplaces and chimneys. It meets ASTM C-199 and is rated for service well over 2,000°F. Yankocy stocks it wholesale in 15 lb and 50 lb premixed pails and 50 lb Heat Stop 50 bags, with Insul Stick and fire clay, for mason yards and dealers.
Heat Stop refractory mortar: what we stock
| Product | Sizes and options |
|---|---|
| Heat Stop, premixed | 15 lb and 50 lb pails |
| Heat Stop 50, dry mix | 50 lb bags |
| Insul Stick | 20 lb pail, high-temperature repair mortar |
| Fire clay | 50 lb |
| Per pallet | Heat Stop 50: 50 bags; premixed: 30 pails |
Which Heat Stop should you order?
Heat Stop comes two ways: premixed in a pail, ready to trowel, or as Heat Stop 50, a dry mix you add water to. Both lay firebrick. Only the dry mix is rated for flue lining, exterior work and wet locations, because it is not water soluble once it sets.
| Product | Form | Pack Yankocy stocks | Use it for | Limits |
|---|---|---|---|---|
| Heat Stop premixed | Ready to use, gray | 15 lb and 50 lb pails | Laying firebrick in fireboxes | Can be water soluble in service. Interior only, not where moisture is present |
| Heat Stop 50 | Dry mix, add water | 50 lb bag | Firebrick and clay flue lining, interior or exterior, bread ovens | None for moisture. Do not retemper |
| Insul Stick | Dry-mix insulating castable | 20 lb pail | Parging the smoke chamber; repairs to brick, stone and clay flue | Apply no thinner than 1/4" to 1/2" |
| Fire clay | Dry clay | 50 lb | Mixed with Portland cement for a heat-resistant mortar joint | Not a code-listed refractory mortar (see below) |
Coverage and joints
For estimating, 50 lb of Heat Stop lays about 100 firebrick 2.5" thick at the recommended 1/16" to 1/8" joint.
Keep joints thin. If the job needs a thicker joint, use the dry mix: Heat Stop 50 accepts joints up to 1/2". A 50 lb bag of Heat Stop 50 mixes out to about 60 lb of mortar, the lowest cost per pound in the line.
Insul Stick covers about 2.5 lb per square foot at 1/2" thick. It can be cast, troweled, parged or sprayed.
Standards and ratings
- Heat Stop 50: meets ASTM C-199, ASTM C-1283 and ASTM E-136; Heat Stop cites NFPA 211, the IRC and the IBC.
- Heat Stop premixed: meets ASTM C-199 medium duty.
- Insul Stick: meets ASTM C-199 and ASTM E-136, and is non-water soluble in service.
- All three are rated for applications well over 2,000°F.
- Heat Stop 50 takes masonry mortar color.
Fire clay and building codes
Many masons still mix fire clay with Portland cement for a heat-resistant mortar joint, and it is what most of our fire clay goes into. Heat Stop points out that codes call for refractory mortar meeting ASTM C-199 to lay firebrick and clay flue lining. ASTM C-105, the old fire clay spec, is discontinued, and fire clay mixed into regular mortar does not meet current codes. For firebox and flue joints, order Heat Stop.
Order it with
Order mortar on the same truck as the firebrick, flue lining, thimbles and Vestal hardware. Heat Stop says to wait one day after the masonry is finished before applying heat.
Questions about Heat Stop refractory mortar
Is refractory cement the same as refractory mortar?
Not quite. Refractory mortar is the thin-joint material for firebrick and clay flue lining. Heat Stop 50 is a dry-mix refractory mortar made from high-temperature cements and aggregates that won't expand and break the joint when heated. Castables such as Insul Stick are cast, parged or sprayed in thicker layers rather than used as a thin joint.
How do you mix Heat Stop 50?
Add about 3/4 to 1 quart of clean water for each 10 lb of Heat Stop 50 and mix thoroughly. No additives are needed. Cold water works best; warm water shortens the set time. Don't remix or retemper it the way you would regular mortar. A 50 lb bag yields about 60 lb of mortar.
What temperature can refractory mortar withstand?
Heat Stop rates its refractory mortars, including Heat Stop 50, the premixed Heat Stop and Insul Stick, for applications well over 2,000°F. Heat Stop puts ordinary masonry materials at about 600 to 800°F.
What is the best mortar to use for firebrick?
Use a refractory mortar that meets ASTM C-199. Heat Stop recommends Heat Stop 50 or Heat Stop II for firebrick and clay flue lining, because they are non-water soluble after the initial set. The premixed Heat Stop also lays firebrick, but only indoors and away from moisture. Yankocy stocks Heat Stop 50 in 50 lb bags.
How many bags of Heat Stop are on a pallet?
A full pallet holds 50 bags of Heat Stop 50 dry mix or 30 pails of premixed Heat Stop. Yankocy sells Heat Stop wholesale to mason yards and dealers, on the same truck as firebrick and flue lining.
Does Yankocy sell Heat Stop to contractors?
No. Yankocy is a two-step wholesale distributor: it sells Heat Stop, Insul Stick and fire clay to mason yards and dealers, and masons and chimney contractors buy from those yards. Yankocy delivers on its own trucks across Connecticut and nearby states. Call (203) 261-4955 or email info@yankocy.com to set up an account or order.
Last updated
Yankocy sells Heat Stop wholesale to mason yards and dealers, on the same truck as firebrick and flue lining. Buying for your own home? Your local lumber or mason yard can order it for you.
Heat Stop refractory mortar data sheets and sources
- Heat Stop 50 and Heat Stop II product page
- Heat Stop 50 / Heat Stop II safety data sheet (PDF)
- Heat Stop premixed product page
- Insul Stick product page
- Heat Stop FAQs
Related to Heat Stop refractory mortar
Wholesale pricing on Heat Stop refractory mortar
Tell us the products, sizes and quantities, and where the order is going. Inside sales will get back to you with pricing and availability.
- Delivery
- Weekdays on our own trucks to Connecticut, southeastern New York, northeastern New Jersey, Long Island, western Rhode Island and southern Massachusetts. Delivery area
- Pick-up
- Monday to Friday, 8:30 am to 3:00 pm in Monroe, CT
- Accounts
- New to Yankocy? Open a wholesale account
Prefer the phone? Call inside sales at (203) 261-4955.