BACK to Products

Firestop Page

Main Page

Contact

WHY (ON EARTH) USE A FIRESTOP MORTAR???

Firestop Mortar, form powder to gunk to lightweight rock

Please scroll down.

Main Site

Firestop Site

Code Evaluations AVAILABLE!

Glossary of Fire Protection Terms

3M Fire Barriers

Vectorising Drawings and Maps; Paper to CAD

Circuit Integrity Fireproofing

Bounding

Code Req's for Firestops

Essay on Performance Based Codes

Master Spec. Section 07840 Firestopping

Related Sections to 07840

Penetration Seal Drawings

Building Joint Drawings 1

Building Joint Drawings 2

Building Joint Drawings 3

History of Firestops in North America

Warnock Hersey Experience

Firestop Trade Jurisdiction

Achim Hering Bio

Man Made Mineral Fibres

Fire Protection Industry Links

Firestop Products and Equipment

Firestop Mortar

Firestop Silicone Foam

Intumescent Products

Endothermic Products

Insulation Products

Caulking & Paint Firestops

Firestop Pillows

Firestop Devices

Firestop Slide Show 1 of 10 Basics

Firestop Slide Show 2 of 10 Code

Firestop Slide Show 3 of 10 No Seal

Firestop Slide Show 4 of 10 Deemed-to-comply

Firestop Slide Show 5 of 10 Misinstalled

Firestop Slide Show 6 of 10 Re-entered

Firestop Slide Show 7 of 10 Faulty Spec.

Firestop Slide Show 8 of 10 Proper Firestops

Firestop Slide Show 9 of 10 Test

Firestop Slide Show 10 of 10 Smoke and Trays

Sample Firestop Listing

Kitchen Exhaust Cleaning; Boiling-Hot Pressure Washing

ULC           UL

T O S

(Theory of Survival)

DIBt

TU Braunschweig iBMB

CONTACT

Firestop mortars, such as 3M Fire Barrier Mortar, are a logical choice when firestopping most electrical penetrations, and indeed most large penetrations. (I admit to being somewhat biased in this regard.)

The baseline still remains 'BOUNDING', of course.

Fire testing as such is no longer revolutionary. What is critical is how realistic the coverage of the testing is, when compared to actual field installations (BOUNDING). This is where the 3M Fire Barrier Mortar "shines". But there is also other data to support the use of this material over most others, particularly in large openings.

There are other firestop mortars of course. In general, most utilise hydraulic cement as the curing mechanism. Cheaper ones use portland cement, while others use calcium alumina cements or other inorganic hardening means. But essentially, you start with powder, add water, turn the mixture to slurry or thicker gunk, which then turns hard (cement stone). Changes to the most basic mortar or cement based products, for adaptation to firestopping needs, can include a host of add mixtures for the properties typically desired, such as added pot life, lower densities, pumpability, adhesion, cohesion, shrinkage compensation and so forth. All the very basic tricks of the cement trade apply here, which somewhat removes all chances for patentability of these products.

Here, you can see a pump being used to mix and deliver a firestop mortar:

Mortar Pump in Use

You can see more of the same on this page:

http://www.oocities.com/astximw/profistops.html

ADVANTAGES:

1. Reliability - Of course everyone says this about everything. But the proof is in the pudding. With thick enough firestop mortar, you have superb impact resistance. Check the testing page! You are not depending on a chemical reaction, such as intumescence or endothermic properties or somesuch. The stuff is there, it's tough and it's durable and will withstand a great deal of abuse. Caulking and paint based systems could be breached by a three year old child. Even teenagers would find better things to do than attempt to mess with a decent firestop mortar that has been installed thick enough. Paint and caulking, on the other hand are tested, sold and installed in esoteric colours and so thin (cost-driven) that damaging the seal takes about as much effort as poking in one's nose. Not so with firestop mortar. It takes real effort to remove it, yet it can be re-entered with greater ease than cast concrete or concrete block wall.

2. T Ratings - Mortars have DENSITY near the water mark typically, one kg/L, give or take. While that is unimpressive compared to structural concrete, which can weigh two or three times that, it is significant compared to stuffed rockwool and whatever token glorified rubber may be over top of it. This means that mortar absorbs heat from the penetrant, which means less heat is conducted through to the other side. This also means advantages in terms of ampacity derating. Higher T ratings reduce the risk of igniting combustible matter on the unexposed side. T ratings in Canada are mandatory for all occupancy separations as well as fire walls.

3. Re-enterability - 'Re-enterability' is a non-scientific, non-quantified buzz-word used in the firestop field to 'describe' the degree of difficulty involved in making changes to installed firestop systems, i.e. changing or adding a new cable. Apart from doing actual comparisons side by side, between competitive materials (and no-one has had time or funding to do this in a non-biased fashion) one is forced to either accept someone else's ideas or invent one's own concept of what constitutes a 're-enterable' versus and 'non-re-enterable' firestop. One of the more common themes is to analyze whether or not power tools are required to 're-enter'. Of course, for those of us who watched the movie "Shawshank Redemption", we realise that concrete and masonry are re-enterable. It is simply a matter of time and effort. If you do need power tools for efficiency, presumably you need more time to prepare as you need to find the drill, the right bit, see that it's sharp, find power and get an extension cord or re-charge your portable battery. Apart from that, for firestop mortars, the degree of resistance offered by the mortar against any piercing objects is simply a function of the compression strength as well as the depth of the material. Therefore, the thinner and the softer, the easier to re-enter. Even heavy-weight concrete is 're-enterable', given adequate equipment. Compression strengths of such concretes are typically in excess of 2000 PSI. Any firestop mortar, as well as any other cementitious compound, including concrete, is severely affected by the water/cement ratio employed as well as the placement methods. The more water, the lower the compression strength. The more 'pounding in place' or vibration used, the fewer air pockets, the higher the strength and vise versa. For instance, 3M Fire Barrier Mortar has been tested at water to powder ratios of 1 part water to 2.5 to 4 parts powder. This is the ratio between self-levelling and an extremely firm hand packing mixture (likely in excess of what would realistically be used as this becomes too cumbersome). The compression strengths here varied between 187 and 790 PSI. At this point, it is still possible to re-enter the material by twisting a screwdriver through it (no use of power tools). At the same time, it should still be strong enough to offer significant resistance to a twisting and contorting cable tray, in case of a fire. 3M Fire Barrier Mortar can, therefore, be judged re-enterable by most people's 'standards' or concepts in this regard. Repairs of holes in 3M Fire Barrier Mortar seals can be done with more of the same material, not just because the manufacturer is convinced the material will 'stick to itself' but because such a repair with new cables and more of the mortar has been incorporated in the fire test, which is documented in the listing.

4. Structural Integrity: Metal expands when exposed to heat ("D'oh!"). That's why we use spray fireproofing on structural steel. Otherwise, the metal expands and then collapses, under the influence of fire, as we all know. Ferrous cable trays are no exception to this basic law of physics. Thus, a twisting and contorting, expanding and collapsing cable tray has been proven to absolutely shred soft firestops, such as all the glorified or unglorified rockwool or ceramic fibre packings with all the assorted rubber coatings, intumescent, endothermic or ablative - it doesn't matter. Elastic properties of a soft firestops are of no consequence with the motion that a ferrous cable tray can undergo when exposed to a fire. Nothing stretches that much under fire conditions, without letting go. Evidence to that effect is on file in Germany and Canada. But the issue is largely ignored, as our furnaces in North America, as well as the intestinal fortitude to address the issues of millions of useless firestops in buildings across the continent is simply absent. We only require one foot of that tray to be inside the furnace when we run testing to S115 or E814. There is no operational or fire induced motion testing required for firestops. Thus, the token expansion that occurs in the tested tray goes towards the fire side, without any effect upon the tested firestop. This means that junk passes our testing and is being installed in this application across the continent. Even reputable firestop vendors have jumped on the bandwagon of selling these flimsy systems made of wool and rubber, simply to survive and make the sale that feeds the hungry bulldog. Addressing this issue through codes and standards is pretty much pointless because no one wants to admit it and/or jeopardise their capital investments in testing, listings, literature, marketing of all the flimsy soft firestops, which are touted with so much fanfare, though they all really only aim at one item: CHEAP! Low cost. the rest is window dressing. Rest assured, that when it comes to any large penetrations and all cable tray penetrations, soft seals are all junk. You can't escape the simple physics of it,  if you passed grade 11 physics or have any common sense. The only alternative to thick firestop mortars for these applications is MCT. Why? Because with MCTs, the tray is terminated on both sides of the fire separation. Only the wiring goes through and MCT will hold the wires. In testing, (a test run by the German government, where trays were subjected to fire induced motion, which cannot be duplicated by North American testing because our furnaces are too shallow) it has been proven that soft seals quickly tear open, whereas mortars will not even budge.

Things to watch for:

There are three infantile items leveled at firestop mortars by novices or those firestop vendors who do not possess a firestop mortar:

1. Shrinkage: The 'big fear' with shrinking firestops is twofold: (1.) that the seal may fall out of the hole and (2.) that the shrinkage will result in gaps large enough to permit smoke travel. There are a number of products on the market, containing cement, for a variety of applications, including firestopping, which use the nomenclature of "non-shrink", "expanding" or "shrinkage compensating". These adjectives are addressed by testing to standard ASTM or CSA tests, which may have precious little to do with YOUR project. Shrinkage happens as a result of hydration of the cement, or setting of similar inorganic binders. It is affected by heat of hydration, pre-mature moisture loss through the heat (internal or external), excessive air velocity across the surface of the freshly placed product etc. While a product in a laboratory may gain a test report certifying "true expansion", "0-shrinkage" or any given percentage of shrinkage, this presumably established material property can be totally reversed on site, depending on the placement and curing of the product. Many in this business have inspected severe shrinkage of firestop mortars rated "non-shrink" and even "expanding" while others that say nothing about the matter are fine. The difference is not so much in the formula of the product (though that has an effect or course) as in the care taken during placement and curing. Structural engineers and even the Portland Cement Association will confirm that a correctly placed and cured ordinary concrete slab can be made to expand and stay that way (if kept cool and wet long enough). Under common ASTM methods, many firestop mortars have been found to produce negligible shrinkage in some cases. Yet during normal placement and curing during the fire test, no gaps appeared whatsoever. In fact, the 30PSI hose stream test was passed by all rated firestop mortars with no through-projection of water to the other side. During fire testing, any smoke penetration emanating either from a penetrant or cracks in the concrete slab itself, which may contain significant cracks prior to the burn and fare not nearly as well as the mortar during the fire. In the case of one of the earliest tests of 3M Fire Barrier Mortar, after the fire and hose-stream test, a 127kg (280lbs) concrete block load was applied to the assembly for 5 days, without so much as a crack. The 3M Fire Barrier Mortar possesses tremendous adhesion to most materials, which more than compensates for any shrinkage that may occur, as that shrinkage does not result in a delamination from any of the contact surfaces on the seal. This mortar contains a careful blend of shrinkage compensating admixtures. Still, the key is proper placement and curing methods, regardless of which cementitious (or other inorganically bound) product is used. This is really true for any building product. Have a look at the integrity of the 3M mortar in this test.

Oftentimes, the question is posed whether or not this product is "loadbearing". The best reply to that is the following questions: "In accordance with which test?" "What compression strength do you deem to be loadbearing?" "What particular load do you need to carry with this mortar?"

There is no universal standard to evaluate loadbearing firestops. The answer, and question for that matter, can at the most be a comparison of judgments. People have stood on a 4" (100mm) 3M Fire Barrier Mortar seal in order to attach thermocouples on the unexposed side of the test assembly. They likely weighed between 70 and 110kg (154 and 243lbs), but we are unsure of their shoe sizes, and one would need this in order to calculate the load in PSI. The supportive effect of penetrants is also an as yet unquantified matter. Generally, it is not sound engineering practice to encourage foot traffic across any firestop. No insurance underwriter should sign off on such procedures in the absence of accepted test standards to cover this use. Even if an overweight technician at the test lab stomped on the seal in an attempt to make his mark, a far lighter lady wearing high heals may pose more of a threat to the seal. Testing in the Federal Republic of Germany has evaluated the effect of cable tray expansion and movement on soft (rockwool with intumescent paint) and hard (firestop mortar) seals. Trays, as well as structural steel (beams, columns, decking, etc.) will first expand when heated and, above 500-550°C lose their integrity and collapse. In the case of a cable tray firestop, this causes first a pushing and then a downward pulling motion. Although the soft seals were elastomeric, and flexible in nature (most elastomers are - at least prior to the fire) they were torn out rather quickly by the tray movement. The mortar seal, however, passed. The cement used in 3M Fire Barrier Mortar is actually more structurally sound for use as a fire resistant material as well as refractories (i.e. industrial furnace linings), than the ordinary portland cement used in the material evaluated during this test in Germany. This, along with polypropylene fibre secondary re-enforcement as a soft buffer in the fire, has resulted in a seal that is subject to significantly less cracking during the fire, as compared to most of its rivals. The phenomenon of cable tray expansion, distortion and collapse is not currently evaluated under CAN/ULC-S115 M85 or ASTM E814.

2. "Rotting": Some firestop mortars are subject to primary efflorescence, depending on humidity conditions. Some of the salts, which are not bound within the cement stone can be driven to the surface, where they form a white dust. This can be easily brushed off. The material is neither rotting, nor fermenting or losing strength. It's dead! Inorganic - nothing there to rot. Loss of strength only occurs in secondary efflorescence, which can be seen, for instance in parking garages in cold regions, where road salt is used, which seeps into concrete, dissolves the cement stone and then forms 'stalactites' at the bottom of the slab. One might see this as osteoporosis of the concrete. It is not known to occur in firestop mortars. Usually, firestops are not located in such areas where the conditions necessary to cause secondary efflorescence are prevalent.

3. Movement: Penetrant movement is a valid concern and large factor for product selection in firestopping. It is sort of ironic that proponents of flimsy soft seals bring up movement, despite the fact that their movement compensation abilities remain quite purposely unquantified and the fact that their flimsy soft seals rip open with the fire induced motion of heated ferrous cable trays. However, with a moving penetrant, one generally has three choices:

a) holding the penetrant in place with a rigid seal of sufficient strength and depth (a mostly theoretical approach with the majority, although not all penetrants)

b) moving with the penetrant using a flexible seal (although care must be take in evaluating how flexible an elastomer may be after or during fire exposure), and

c) isolation of the movement by using bounded, certified slip covers. 

Isolation of movement was the approach of choice with the 3M Fire Barrier Mortar. 3M Fire Barrier Mortar was tested with a slip cover around copper piping (i.e. worst case scenario - copper ROASTS). This is a common ceramic paper layer that can be placed around the penetrant prior to placing the mortar and secured in place with duct tape or wire. This provides a bond-breaker and permits a pushing and pulling movement of the penetrating item. Lateral movement is not ordinarily expected unless there are severe problems with the mechanical installations. Some (sideways) movement, such as vibration can easily be absorbed by the 3.2mm (1/8") ceramic paper. If this movement becomes more severe, firestopping is usually not the prime concern. Fixing the piping system should be the main task in most instances. In such cases, the firestopper must be informed so as to permit him to install multiple layers of the ceramic paper in order to compensate more lateral movement. If the movement is really severe, the pipe should be sleeved within the mortar seal and "booted". There is also a common misconception that if a pipe is insulated, the movement will be restricted to the pipe sliding within the insulation. Nothing could be further from the truth. The pipe covering typically is so snugly attached to the pipe that it will certainly follow the movement of the pipe. In the industrial insulation field, this is among the prime contributors to business for insulation contractors and manufacturers. When a large mechanical system (i.e. one containing steam lines) is shut down for routine maintenance or other reasons, there is a shrinkage of the piping that will take place rather quickly, which tends to damage so much insulation that the local contractor is routinely called during all shut-downs to fix the crumpled mess that can result. Some insulators are particularly fond 'removable' insulation blankets, which are meant to give their clients confidence that this damage will not occur - but it does and then is even more costly to repair. What this means to the firestop is that if the piping is insulated - it will move. If the movement is not isolated, it will damage the seal.

Let's review what will move when:

Electrical:

-Cable tray is generally static (no movement) - UNTIL THE FIRE STARTS!

-Cables are usually held in place easily, unless they are internally oil-cooled, which is very rare.

-Bus Duct can be expected to move somewhat and can be isolated.

Mechanical:

-Insulated piping will always move and must be sealed so as to accommodate the movement. Nude piping is usually not subject to movement. If so, that should be indicated to the firestopper.

-Ducting: (in North America) is usually held in place at the fire damper by angle brackets. Care must be taken in following the listings of the fire damper assemblies, which usually require a gap around the damper (1/8" of gap per lineal foot of damper width). Check these drawings and the accompanying text. This space is concealed by angle brackets. The downfall is that this permits smoke travel around the outside of (even smoke~) dampers. To close the gap or otherwise prevent air travel in this location means to violate the listing of the damper. (All that can be done here is to narrow that gap with the 3M Fire Barrier Mortar to comply with the damper listing.) As such, movement of ducting at the damper can be classified as vibration. Since the damper is inherently isolated in movement, there is no further problem in movement compensation. If there isn't a damper, it is likely pressurisation or grease ducting. In that case, there are specific listings that accompany the enclosure. The DuraSystems ducting is tested with a firestop mortar. the rest are tested with soft seals. Firestopping a ceramic fibre wrapped duct with a firestop mortar should present no problems. However, bounding is required.

Architectural:

-Joints: Who would use mortar in a joint?

The Millwoods Hospital Case:

In the eighties, BIO firestop mortar Type K10 was used at the the Millwoods Hospital in Alberta, by a company, which is now no longer in business. There was some cracking and competitors to BIO used this to try to tarnish the image of all firestop mortars, and BIO in particular, since the hospital had originally been specified to use other products. The general contractor admitted to the mistake and it was fixed. Here is what happened: The mortar was used as a head-of-wall (HOW) joint firestop. Few of the systems sold and marketed by this vendor were bounded, and this was no exception to the rule. There was no test data to support the use of this product in this application. The HOW joints were located just under the roof deck. The firestop installation took place, before the roofing system was installed over the deck. Foot traffic and the added mass and motion of the roofers of course led to cracking of the mortar. The joints were repaired before the building was commissioned. Apart from the disregard for bounding, the problem was that the mortar installation preceded the roof installation. Homer Simpson lives.

BACK to Products

Firestop Page

Main Page

Contact

Main Site

Firestop Site

Code Evaluations AVAILABLE!

Glossary of Fire Protection Terms

3M Fire Barriers

Vectorising Drawings and Maps; Paper to CAD

Circuit Integrity Fireproofing

Bounding

Code Req's for Firestops

Essay on Performance Based Codes

Master Spec. Section 07840 Firestopping

Related Sections to 07840

Penetration Seal Drawings

Building Joint Drawings 1

Building Joint Drawings 2

Building Joint Drawings 3

History of Firestops in North America

Warnock Hersey Experience

Firestop Trade Jurisdiction

Achim Hering Bio

Man Made Mineral Fibres

Fire Protection Industry Links

Firestop Products and Equipment

Firestop Mortar

Firestop Silicone Foam

Intumescent Products

Endothermic Products

Insulation Products

Caulking & Paint Firestops

Firestop Pillows

Firestop Devices

Firestop Slide Show 1 of 10 Basics

Firestop Slide Show 2 of 10 Code

Firestop Slide Show 3 of 10 No Seal

Firestop Slide Show 4 of 10 Deemed-to-comply

Firestop Slide Show 5 of 10 Misinstalled

Firestop Slide Show 6 of 10 Re-entered

Firestop Slide Show 7 of 10 Faulty Spec.

Firestop Slide Show 8 of 10 Proper Firestops

Firestop Slide Show 9 of 10 Test

Firestop Slide Show 10 of 10 Smoke and Trays

Sample Firestop Listing

Kitchen Exhaust Cleaning; Boiling-Hot Pressure Washing

ULC           UL

T O S

(Theory of Survival)

DIBt

TU Braunschweig iBMB

CONTACT

1