Posts tagged with "How To"

Best Way to Waterproof a Chimney

Asking what’s the best way to waterproof a chimney or what are the best waterproofing products are both understandable enough questions, but they’re also too broad for a simple answer. Best way to waterproof what kind of chimney? Are we waterproofing a vertical wall or the breast of the brickwork? There are brick, concrete block, stucco and stone chimneys and there are different considerations for all of them – meaning you might use different products on different types of chimneys. Let’s peel this back like an onion. Continue reading

How to Block a Chimney

I’m sometimes asked “What’s the best way to block a chimney?” You really should ask another question first. Ask “Should I block the chimney flue?” Not necessarily, and in general I wouldn’t (though I will tell you how to do it.) The other, and more important, question you should ask is “Is it safe to block a chimney?” Continue reading

Removing 3rd Degree Creosote with Poultice Creosote Remover

Since the other articles were written, there is something new to add. There is a new chemical by Saver Systems called PCR (Poultice Creosote Remover) and it works really well and really fast. By fast I mean overnight. In extremely bad situations it is conceivable that it could take two applications. It is available through chimney service companies, not available to the general public.

Before Poultice Creosote Remover


After Poultice Creosote Remover Image


Who is it good for? It’s good for people who have 3rd degree creosote and… Continue reading

Best Way to Waterproof a Chimney

[vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]Asking what’s the best way to waterproof a chimney or what are the best waterproofing products are both understandable enough questions, but they’re also too broad for a simple answer. Best way to waterproof what kind of chimney? Are we waterproofing a vertical wall or the breast of the brickwork? There are brick, concrete block, stucco and stone chimneys and there are different considerations for all of them – meaning you might use different products on different types of chimneys. Let’s peel this back like an onion.


Choosing the Right Waterproofing Product

rain on clear surfaceBefore getting started, please understand that the less a waterproofing product costs, the less likely it is to do you any good. One major brand costs fairly little but lasts a rather short amount of time because it breaks down in with UV exposure (sunlight.)


You want a product that uses poly siloxanes or silanes. Basically, that means that it doesn’t use solids to block up the pores of the masonry, rather it sets up an electrostatic charge that outside water can’t overcome. At the same time, if the masonry has trapped moisture in it the day you decide to waterproof (and it very well may) the head pressure of the water inside will be able to overcome the electrostatic charge and escape. In other words, water can’t get in, but it could get out if need be. The good stuff does cost more – not prohibitively more – but it is oh so, so worth it.


Sealing Brick Chimney

Since about 99% of the people reading this have brick chimneys, let’s start there (I will address non-brick chimneys later). One of the central issues concerning waterproofing is the porosity of the material being waterproofed. This makes sense: you don’t have to waterproof steel or vinyl because water doesn’t penetrate them in the first place. While bricks are generally less porous than many other materials (like a cinder block) different types of bricks vary in porosity themselves.


This explanation is to set the stage for understanding that sometimes you have to waterproof a chimney more than once. You should know this too: though we don’t like to admit it, the fact is that sometimes professionals misjudge how much waterproofing a chimney needs and wind up coming back when they get a complaint. We sure don’t like that, nor do we like people being dissatisfied with our work, but where waterproofing is concerned, it seems to be a fact of life. Moral of that story is 1) ask your waterproofer to go over it twice just for good measure (even if it costs a bit more) and 2) don’t be too tough on your guy if you have to call him back. I thank you on behalf of all the guys who ever get caught in that squeeze! And please look below for special information concerning re-applications.


A last item before moving onto specific information: If you have spalling brick, i.e. the faces of the brick are popping off, don’t bother to waterproof the chimney; it’s too late. Instead kick yourself for not having done it ten years ago and have the brick structure rebuilt. Then waterproof it so it doesn’t happen again.


Now for some specific information, still with bricks:

Chimney Anatomy Diagram


How is chimney waterproofing applied?

Waterproofing is applied with a sprayer. On the vertical walls, i.e. most of the chimney, waterproofing should be applied from bottom to top because as the waterproofing material comes out of the sprayer it runs down the chimney and gets absorbed into the chimney below the area being working on. It sort of amounts to doing it twice. Obviously, the top needs extra attention or it’d only get one pass. And as mentioned before, I’d do it twice. After you finish about 10 minutes’ worth, do it again just to make sure the whole structure gets a good soaking.


Special considerations should be given to breast walls, re-application, the crown, the flashing area and the mortar joints. The breast wall is where a chimney doesn’t go straight down to the ground, rather goes around something (almost always a fireplace.) They aren’t usually outright horizontal areas, a 30°-60° angle is pretty common. These areas should get different treatment.


Sealing the Chimney Breast

exterior chimney breast

Because the chimney breast has a more severe exposure to rain and particularly snow, it needs more coats of waterproofing. Most waterproofing used these days is water-based material. This is for a couple reasons: one is that water-based materials cost considerably less than solvent based materials. They are safer to ship, store and use and they are perfectly adequate to the task. The exception to the advantages is on non-vertical surfaces.


One way to deal with a non-vertical surface is to waterproof it over and over and over. Another is to use a solvent-based material, still with polysiloxanes, because it soaks deeper into the substrate. For a chimney with a breast below, opt for the more expensive solvent-based waterproofing.


A special note about re-applications. If one needs to re-apply waterproofing after the water-based material has already dried, solvent-based waterproofing should be used. This is not common knowledge, even among the trade. Whether re-applying the next day or ten years later, use solvent-based waterproofing. Don’t be alarmed that if after reading this article you know more than the people you hire to do the job; most people don’t know all this. Just patiently insist on getting what you ask for.


Sealing a Chimney Crown

smooth chimney crownThe chimney crown is an almost flat surface and it’s made of concrete or mortar. It shouldn’t be made of mortar, but there’s a good chance that it is anyway. Based on what you’ve just read about waterproofing the chimney breast, you’d reasonably think that you’d just use a solvent based waterproofing material there. But that is not so: a crown requires more than ordinary waterproofing.


The crown is rather porous. If you’re lucky the crown will be made of concrete and will have been worked in a way that makes the top quite smooth and non-porous. But on average, crowns are fairly porous and have more exposure to rain and snow than all of the rest of the chimney, and accordingly more problems (e.g. leaks) that the rest of the chimney as well.


There are coatings made specifically for crowns (the two major brands are Weather Tight and Saver Systems and both are generally available to the trade only.) Regardless of the brand being used, crown preparation is key. All the moss and dirt must be wire-brushed away. The crown should be wetted down before the material is applied. Crown coatings applied to dry surfaces don’t develop the necessary bond you’re looking for. Large cracks should be caulked with high resin filler before the crown coat is applied.


A note on horizontal surfaces which are not chimney crowns, such as driveways etc. Siloxanes are not the best choice here because driveways are made of concrete. A similar material (silane) is appropriate in order to get proper bonding with the substrate. It’s not that chimney waterproofing material won’t work; it’s just that silanes will last longer in this instance.


chimney flashing


The flashing area needs special attention

Traditional flashing, which 99.9% of all of us have, is not actually so great. I’m sure traditional in-the-mortar-joint-flashing was a huge improvement over whatever was before it a hundred years ago, but don’t imagine it keeps water out the way you wish it did.


There are terrific flashing products which, in my opinion, are sadly underused. Flash Seal and Flash Tight (once again, Saver Systems and WaterTight products) are high-resin coatings specifically for this purpose. To waterproof the flashing really well, ask for one of these products. Your sweep may or may not even know what you’re talking about, but don’t hold that against him. In this case you’ll be educating him. As I said, they are still under-appreciated products at this point.


Now for the big one: the mortar

Since most leaking occurs at the joints, you want to be extra sure you soak them real well with the waterproofing. You should know that as a rule mortar joints are often not as well bonded as you might think they are, and there are actually small cracks in the mortar (usually not visible though.) The joints themselves have different properties on different chimneys depending upon whether mortar cement or Portland cement was used, not to mention the particle size of the sand used and the pH of the water that was mixed to make the mortar.


How long does chimney waterproofing last?

Before moving on, let me answer another FAQ. The question is how long does chimney waterproofing last? Answer is, as a general statement, probably about 20 years for most people. If you have the wind blowing sand at your chimney a lot, perhaps in the desert or by the sea, the brick surface can wear away, but most people don’t have that. There are guarantees, generally about 10 years. When those guarantees were instituted they were basically guesses from studies done in wind tunnels and freeze-thaw cycles. After a lot of years of observation, 20 years seems to be a generally good answer. Having it redone every 10-15 years is reasonable maintenance.


What is the difference between beading and repelling water?

water beading on smooth surface

A related subject: there’s a difference between “beading” and repelling water. Right after anything is waterproofed, there is a very satisfying effect called beading. This is where you see beads of water just sitting on the surface, kind of like seeing water sitting on oil. As neat as it is to see, at effect is temporary. I don’t know why, but the fact remains that waterproofing remains effective for many, many years beyond the beading effect is gone.

How to waterproof chimney cinderblock

Now concerning waterproofing concrete block chimneys. Concrete block chimneys are the most porous of all, and they are at the same time most in need of waterproofing and most difficult to get a good result. But not impossible – you just need extra passes, and it’s a good idea to use a solvent-based waterproofing material here as well. As you know, I trash-talked solids in your waterproofing at the beginning of the article. I’ll backtrack just a little here.


Polysiloxane waterproofing material is still the superior technology, but for pores this big, you might do well to outright seal them. You can do that with stucco or by using a waterproof paint. Boat paint might be overkill, but it should work like a charm. There’s also a special hybrid product from Saver Systems that has some solids in it (Chimney Saver for Concrete Blocks).


Stucco chimneys are a bit trickier. (Disclaimer: I know less about stucco than I do about bricks) Old stucco was made with gypsum and I can’t help you with what kind of waterproofing material, if any, should be used. Modern stucco for plastering a chimney however would be made with Portland cement. Porosity would be “not too bad” so you could use a waterproofing material on it, i.e. – it will bond to it.


That said, I’m not sure it’s necessary as I believe stucco is pretty good at keeping water away from the surface below. It’s applied almost an inch thick and it’s pretty good at drying out. I suppose there is the danger of several days of rain and the stucco getting saturated; again I don’t know enough about stucco to comment on how long it will hold how much water. My observation in life is that most stucco surfaces are not falling apart, yet it seems that freezing and thawing should destroy them. Sorry to be of so little help here.


How to waterproof stone chimneys

natural stone chimney

Finally, there are stone chimneys. Depending upon what kind of stone, the surface may be quite dense or quite porous. Regardless, stone usually doesn’t waterproof well with chimney waterproofing materials. The reason is that siloxanes and silanes bond to silica, and stones may or may not be silica. If they are, it’ll work, and if they aren’t, it won’t. Faux stone on the other hand is made with Portland cement, and you can waterproof it.


A Final Cautionary Word

Let me finish with a fun (in retrospect) cautionary tale. Be careful where you spray your waterproofing material. We once had an employee get cute and draw a smiley face on one of our customer’s driveway. It dried right up, no problem. But, when it rained the smiley face showed up just great. We wound up waterproofing that whole driveway just to keep it from smiling in the rain. Put down cloths on the roof so you don’t get it on the shingles. Never get it on the windows (you’ll mess them up permanently.) And of course, be real careful not to get it on the driveway.[/vc_column_text][/vc_column][vc_column width=”1/6″][/vc_column][/vc_row]

How to Buy Firewood

It’s that time of year again: the wind is blowing and cold nights are becoming more common. There’s only one thing to do—start a roaring fire! Before you kick off your fire season, however, you must be prepared. This means purchasing the right firewood! Knowing how to buy firewood isn’t complicated, but there are a few rules to live by to get the best results, so let’s talk not only about getting your hands on firewood, but about how to buy good firewood.

1. Choose Seasoned Wood
firewood-cord-largeNo, the firewood you buy doesn’t have to be sprinkled with salt and pepper. By “seasoned” we mean dried. Seasoned wood may have some “checks” or cracks in the logs, indicating a lack of moisture, and if the bark has not been shaved off by the dealer, it will begin to flake off of dried wood (and in fact should be removed prior to burning!). Firewood burns best when it has been properly dried outside, generally for about a year.

2. Get Efficient Wood
Wet logs, or “green” wood, on the other hand, attract mold and mildew, are home to insects and dirt, produce excess smoke when burned and cannot reach maximum heating potential due to using energy to burn off water. Whatever dealer you seek, be sure that the wood is in prime burning condition. If not, you could be looking at pests invading your home (wood roaches, beetles, spiders, rodents) and the unwanted habit of constantly replenishing your fuel source during each burn.

Some species of seasoned wood make for better fires. Knowing how to buy firewood means avoiding inferior “soft” woods, such as the likes of firs, spruces, pines and poplars. These may be easy to handle, but they’ll leave your home cold—with a maximum of 13,000 – 15,000 BTUs per cord, stinky, smoke-ridden and throw sparks all over (both unpleasant and a safety hazard!).

The better bet is to go with one of several “hard” woods. Some of these include ash, beech, red and white oaks, hickories, maple, locust and birch and they ignite easily and burn hotter and longer. Hard woods are manageable because they’re easy to split for use in your stove. Additionally, they give off copious amounts of heat while minimizing smoke output—giving off 19,000 – 26,000 BTUs of heat per cord! Think about it; would you rather be warm and toasty or cold and shivering?

3. Buy Firewood by the Cord
Firewood is typically sold by cords—stacks of logs equal to 4 feet wide by 8 feet long by 4 feet high—it’s the universal measure! Reputable dealers will sell by multiples of this and fractions of cords—i.e. half a cord. In fact, according to the State of Maryland, such a practice is required by law, so a dealer you found on Craigslist who shows up with a truckload of loose timber might not be treating you fairly in price or volume.

Cord Wood Measurements Maryland State

In addition to knowing that you’ve bought from an ethical business(more on that in our Washington DC Firewood Guide) , buying firewood by the cord also ensures that you can keep track of how much you need and use during the burn season. We usually recommend investing in 3 – 4 cords of wood each year, though this may vary. Knowing these details as well as your own fireplace habits will give you an idea of how many cords you will actually need for a single burn season.

Let’s recap. To enjoy your fireplace all winter, you’ll need 1.) seasoned wood to produce the best possible fire and make good use of fuel, 2.) efficient hard wood to promote warmth and avoid problems like smoke, and 3.) selling firewood by the cord required by law in Maryland. Find a reputable dealer to buy from, it will guarantee you quality and adequate fuel supply. And remember: store your firewood supply in a cool, dry place away from pests or flammable materials to keep it in prime condition for fireplace use! Questions or comments? Sound off below! Happy burning!

Closing Out Your Fireplace and Chimney for the Season

At the beginning of February, Punxsutawney Phil made the prediction that spring was well on its way when he failed to see his shadow on Groundhog Day. Whether that adorable critter is entirely accurate is up for debate, but Spring is finally coming. It appears last weeks’ snowfall will more than likely be the last the Washington DC area will see for a few months.

As fireplace season is starting to wind down, home owners should learn how to close down the fireplace and chimney for the year. There are a few quick steps that should be taken to close out the cozy season:

  • clean the fireplace,
  • perform a chimney inspection,
  • shut the fireplace damper,
  • turn off the pilot light on gas fireplace units

Clean It Up

Prior to closing the fireplace for the year entirely, you will want to clean up whatever you can your own.  This includes dusting off any soot or ash deposits from the base of the unit.  You can accomplish this with the handy-dandy Shop Vac.  Additionally, remember that the chimney should be swept annually by a certified chimney sweep to remove any soot and creosote in the body of the chimney.  Most sweeps, including us, feel that Spring is the best time to hire a sweep to get your chimney cleaned and inspected. When the weather gets significantly damp during the spring months, any leftover gunk in these areas will moisten and give off unpleasant odors inside your home.  As an added guard against odors, various deodorants designed for chimneys can be put inside of the firebox.


While you have a chimney sweep there to do the cleaning, you might as well have an overall inspection completed too.  In addition to looking for residue buildup, a sweep can check the condition of various components, inspecting them for cracks and leaks.  Two key components that may prove troublesome in the spring are the flashing system and rain cap.  Each of these items works to protect the chimney from water leakage, which is more likely during the spring rainy season.  A chimney sweep will ensure that these parts are intact and undamaged, keeping your home safe from flooding.

The inspector will check all other key items, including chimney piping, which could have become corroded from prolonged heat exposure, and replace it if needed.  To further guard your home, the chimney damper/cap should be securely closed too, which will keep out pesky animals that like to invade your chimney, like chimney swifts or raccoons.

Shut the Damper

When your fireplace goes unused for a length of time, the damper should be closed.  Why?  Because it’s just one more way that air and odors come in and out of the house.  So, at the end of this fireplace season, be sure to shut the fireplace damper near the firebox.  Even better, if air is escaping from your home and into the fireplace unit, glass doors can be installed and work together with the closed damper, creating a tighter seal.  Please note, however, that this is only for wood-burning units, as gas fireplaces should always have an open damper.

Turn Off the Light

Gas fireplaces are equipped with what is called a pilot light.  Essentially, this is a small flame that remains lit at all times while the fireplace unit is connected.  What are the odds that you’re going to light a fire in the next several months?  The pilot light, while it isn’t very strong, uses up plenty of energy over a period of time, costing you money.  So, turn off the pilot light on a gas fireplace in the springtime.

Taking these steps now will ensure that your fireplace is in tip-top shape for the next burn season, which means you will have one less thing to worry about next winter!  There’s nothing worse than being left in the cold, so oil your fireplace components so they function correctly, take the necessary cleaning and corrective steps, close and turn off components that need not be used and relish in the fact that you’re in good shape for next year!

Winter Chimney Checklist

winter chimney checklist

Before firing up your fireplace for the first time this winter, there are a few things you must check for the sake of your family’s health and safety.  Cozying up to a warm fire can be delightful on a chilly winter night, but be safe about it!  Follow the winter checklist below to ensure a pleasant and safe experience.

Chimney Inspection and Cleaning. The best way to be sure that everything is in proper working order and is safe for use is to have the chimney checked and/or cleaned.  The National Fire Protection Association suggests having your chimney inspected on a yearly basis for maximum efficiency and safety.  Common chimney problems include build-up of deposits and chimney fires.  Bring in a Chimney Safety Institute of America certified chimney sweep to assess the situation.  A few things on their chimney checklist will include looking for:

  • Soot. Soot is a brown or black soft powder.  It is made up mostly of carbon and sometimes combined with ash.  The threat this buildup poses depends on the amount of ash it contains, as more ash reduces the problem.  Carbon is flammable, posing a larger risk of a chimney fire.
  • Creosote. Creosote, another flammable substance, starts off as a residue of smoke and vapors from wood.  It clings to the venting system as it builds up as a hard, flaky deposit resultant from incomplete combustion.  It is recommended that a cleaning be performed when either soot or creosote buildup reaches ¼ inch or more.
  • Glaze. Glaze is the toughest chimney intruder to remove.  This is a tarry, shiny substance which puddles up in the chimney and sometimes even drops down into black icicle-like deposits that hang above your fireplace.  It’s the most dangerous chimney fire culprit because of how dense it is, allowing the glaze to burn longer.  Glaze should be removed when buildup reaches or exceeds 1/8 inch.

If the above residues are found in your chimney, or other problems are detected during inspection, the chimney sweep may decide to clean out the system.  Aside from the risk of a chimney fire, cleaning will help to ensure proper chimney ventilation, eliminate undesirable odors and remove blockages that would result in CO poisoning.  While cleaning, the chimney sweep will employ:

  • Standard cleaning. Standard cleaning is recommended for the elimination of both soot and creosote.  Brushes and high-powered vacuums are run along the chimney walls to eliminate and prevent the substances from entering the home.
  • Mechanical cleaning. Mechanical cleaning is the high-powered version of the standard method.  Wire brushes, cables and chains are twisted and turned by a motor at a quick speed to rid the chimney shaft of hard creosote and glaze.

Some chimney sweeps also choose chemical cleaning, which involves spraying various substances to break down and dissolve hard glaze and creosote.  In any case, at least one of these methods will be used.

In addition to cleaning your chimney, there are some fairly obvious safety measures you should take in preparation for your fireplace’s first seasonal use. Add the following to your winter checklist:

  • Proper firewood. Only use dry wood that has been split and seasoned outdoors for 6 months to 1 year. To learn more about firewood, read our articles on environmentally friendly firewood and firewood in the Washington DC area.
  • Clear the Area of Fire Hazards. Move all furniture, curtains and other items away from the fireplace.
  • Smoke Detector. In the case that you leave the room for a minute or dose off, a smoke detector will alert you of problems near your fireplace. Make sure yours are installed and working.
  • Carbon Monoxide Detector. CO is a major concern when burning fires in the home.  It is virtually odorless and unnoticeable unless you have the right equipment installed, and is the primary chemical that comes from burning wood and having chimney soot.  Do not be caught off guard!  Install one of these.
  • Fire Extinguisher. Accidents happen to everyone.  Maybe the fire burned to hot or big, maybe the door was not shut and a log tumbled down onto the floor.  In cases like these, be prepared to deal with the situation by having a fire extinguisher nearby to avert a crisis.

Winter fire burning can be a tremendously enjoyable part of the season.  Follow this guide and you will be well on your way to preparing your chimney and fireplace for winter!

How to Remove Creosote – About Creosote Part 2

As mentioned before in this series’ first post about creosote, there are three degrees, or stages, of creosote buildup. Chimney brushes are the standard method for removing first and second degree creosote.

chimney brush

However, sometimes second degree creosote will be hard enough to remove that other methods would work better:

  • There are flat wire brushes which are pretty effective.  They are expensive.  If there’s a very thin coat of creosote on the chimney wall a flat wire brush will do a fair job of removing that too.
  • There is special equipment for just this type of creosote.  A rotary loop which is a stainless steel cable fixed to a hub that is put on special metal rods turned by a powerful drill (this process burns up regular drills) This method is quite effective.
  • There are chemical creosote removers.  They come in two kinds: the ones that take time and the ones that work fast.  So said, “fast” still means a couple days.  Fast chemicals definitely work, but they are not used much just because of the safety considerations and the expense of the return trip involved.  They are very caustic and they can make a very big mess.
  • Other chemicals, such as ACS or CreAway are effective over time, but are most useful as good maintenance.  CreAway can actually reverse many problems given some time (weeks to months) provided one changes his burning habits.  Continuing to burn the same way as you did to develop the problem in the first place has to stop if you want your chimney to clean up.  (Consult your chimney sweep or the stove’s owner’s manual for best burning practices)

Third degree creosote removal is the most challenging of all.  And sometimes it’s not worth removing the creosote- there’s often a very good case to be made for taking out the old chimney liner and putting in a new and different one.  But first the removal options:

  • The chemicals mentioned above can work if the creosote hasn’t been on fire.  If the chimney walls just look like they have been coated with tar, the chemicals can work.  The caustic chemicals, if used at all, are usually reserved for this type of problem.
  • The flat wire brush and the rotary loop don’t stand a chance.
  • If the creosote is hard there is a rotary head with chains that will do a rather effective job.  Contrary to intuition, the chains will not break flue tiles.  However, in chimneys that have been abused so that there is 3rd degree creosote the tiles are very often already broken.  As a general statement it’s hard to find a sweep that will do rotary-chain-cleaning because he’ll get blamed for breaking the tiles.  Even so, this is an option, and probably the most effective immediate-removal option.
  • And sadly, you should probably have low expectations for how clean the chimney can ever be again.  Once it’s been full of 3rd degree creosote, even specialized removal tools can get the chimney only so-clean.

In Part 3 we’ll discuss why it’s not a good idea to try to remove 3rd degree creosote from a tile chimney and then reuse it.

DIY Masonry Repair

DIY Masonry Chimney Repair: A Warning

DYI Masonry Repointing Gone BadThe do-it-yourself movement has taken the world by storm. With the ability to bring up video walkthroughs for most tasks, hiring a specialist is often viewed as a last resort. The spread of information over the internet is an amazing and life changing phenomenon. Suddenly, replacing the belt in your vacuum is no big deal. Changing fuses in your car is a snap. Is your garbage disposal clogged? You can find countless walk-throughs to help clear that obstruction.

This prevalence of do-it-yourself walk-throughs, however, has left people attempting do-it-yourself projects that are sometimes best left to the professionals. While saving money in the short term is a great thing, it’s important to remember the long term too. Saving money right now hardly counts if it ends up costing you twice as much later.

Masonry is especially susceptible to the DIY problem. Countless articles exist online about repointing brickwork, filling splits or cracks, or even replacing spalled brick. As chimneys are often in need of some work, many look to these articles when contemplating how to fix their masonry chimneys. While these might seem like helpful resources, in the long run they can cost you more in time and money than your local masonry professional.

Most DIY masonry repair articles mention mortar only in passing. While they mention its use between layers of brick, they rarely emphasize that mortar isn’t just a slapdash mixture of sand and water. This omission can be costly and belies their disinterest in supplying a genuinely useful article as any trained mason knows that improperly mixed mortar can cause massive masonry damage.

Mortar exists as a cushion between bricks. As bricks swell and contract from temperature changes, a proper mortar absorbs these changes. Gradually, that causes the mortar to crumble. This mortar can then be replaced with relative ease by a professional, providing another 25 or more years of low-maintenance service.

If the mortar is mixed so that it is stronger than the surrounding brick, temperature changes actually cause the mortar to squeeze, and thus damage, the brick. This causes the bricks to spall. Spalled bricks cannot be repaired, and must be replaced before further damage accrues. If incorrect mortar mixture is the cause of the spalling, the mortar must also be replaced to prevent further damage.

Mortar that is too soft, on the other hand, quickly deteriorates and requires premature replacement or repair. If it deteriorates faster than surrounding mortar, this can create instability in the masonry, and if left unchecked can even cause collapse.

When so many masonry professionals offer free initial consultations, taking advice from strangers over the internet seems a poor choice. For those in Northern Virginia, Washington D.C. and Maryland, High’s Chimney offers free masonry estimates where we discuss problems with your masonry chimney and how we would fix them. Not just handy-men, our highly trained masons have years of experience, ensuring that your masonry chimney is safe.

How to Repoint a Chimney

Why Chimney Repointing is Essential

Repointing is a necessary component of chimney masonry maintenance. Well done mortar joints can last for 25 years before repairs are needed, but the brick that surrounds them can easily last 100+ years. Weather plays a large factor in determining how long your mortar joints will last.

Time to Repoint this Masonry Chimney

Time to Repoint this Chimney

Washington DC is known for its unique blend of weather. Sandwiched in by the Blue Ridge Mountains to the West and the Chesapeake Bay/Altantic Ocean to the east, our weather is unpredictable. When the weather begins its steady descent into winter, we’re especially susceptible to changes in temperatures, rain turning into sleet into snow, followed by a crisp and sunny winter day. This weather might mess with your head, but it slowly destroys your masonry. Moisture is absorbed into brick and mortar, and with the temperature fluctuations the water expands and contracts. If brick and mortar were equally strong, this thermal expansion would cause irreparable damage to brick and mortar.

For this reason, the compression strength of mortar is less than the brick. As temperatures fluctuate, the expanding brick overpowers the expanding mortar. Over years of thermal expansion cycles, this will cause enough damage to the mortar that it will need to be repaired. If mortar wasn’t calculated to be softer than bricks, regular reconstruction of your masonry would be necessary.

The Chimney Repointing Process

Repointing a masonry chimney requires a skilled professional. Repointing is far more than just slapping some mortar into cracks. The process requires different skills than traditional masonry, and even masons with years of experience might not have significant experience repointing brick.

Before Repointing Assessment: The biggest challenge of repointing is determining the extent of the mortar damage and removing damaged joints without causing new damage. Generally, an expert starts with a visual inspection where erosion deeper than 6mm, crumbling mortar, and cracks between brick and mortar or within the mortar are noted. After the visual inspection, specialized tools such as metal scrapes or special low pressure water sprayers might be used to determine the extent of the damage. Once the determination has been made, the deteriorated mortar joints must be removed.

Removing mortar joints: It’s important that the joint be removed to an appropriate depth without causing extra mortar or brick damage. Once the joints are removed, the new mortar must be mixed. This mortar should be as similar in composition to the existing mortar as possible, lest thermal expansion cause the mortar to react differently to the pressure of expanding brick. Ignoring this step could lead to premature mortar deterioration. Using mortar with excessive compression strength can cause permanent brick damage, such as cracking and splitting.

Applying mortar: The correct mortar is then placed between the brick by layering, compacting and tooling. This helps adhere the old mortar to the new, and ensures a snug fit between brick and mortar.

Professional masons experienced in repointing also take care to match the shade of the new mortar to that of the old. This is purely aesthetic, and keeps the chimney repointing from looking sloppy. A skilled mason will do this with minimal mess, and will ensure the brickwork is clean before finishing the job.

Applying mortar during repointing chimneyApplying Sealant: Finally, a waterproof sealant is applied to the fresh repointing. This will help prevent water from permeating your chimney, and thus will help extend the life of your mortar joints.

Just RepointedGet the Chimney Checked

While all masonry will need repointing at some point, chimneys are particularly susceptible to water damage. Their location subjects them to constant temperature changes while making them difficult to monitor for signs of damage. Before fall slides into winter, have your chimney inspected for mortar damage. Timely chimney repair can save you money, and our free masonry inspection will give you peace of mind that your chimney will be sturdy and safe all season.