How to best clean a clay tile lined fireplace flue in a masonry chimney?

What’s the most effective way to sweep and remove the creosote from a clay tile lined fireplace flue in a masonry chimney?

Honestly there is no single and no easy answer.  There are many different creosote types encountered and some require slightly different techniques.  The advancement of tools in the industry helps a lot and there are other factors as well such as rooftop or chimney access.  Bottom line if there is more than 2mm of creosote – it should be cleaned.

Historically the way to clean was from the top working down using either round or flat wire brushes; this can be effective when there is a powdery creosote buildup or even a thin layer of glaze present.

However, due to technology the rotary sweeping method from bottom up using nylon or poly rods attached to a drill has become quite effective and popular.  These also are very effective at removing the powdery creosote buildups as well as thin layers of creosote glaze – they can actually be more effective than the older brush method – although the older brush method does give a feel when using which is beneficial in a masonry chimney and lost in the power sweep.

However, if the creosote glaze becomes thick and is not flaky, then it can be very difficult to remove with traditional methods from either the top or the bottom.   Chains can be used – however this method often will damage the flue liner – and should be used with caution – especially true if the liner is old and in not great condition.  Chemicals can also be used to assist in removal of the glaze creosote buildups.  Some of these are designed to be used with fireplace/insert/woodstove in use – these often work well to help in reducing buildup but caution should be used if there is already significant creosote deposits present in the flue.  Having a fire in the appliance with large buildup is asking for a chimney fire!  There are products we can use when the appliance is not in use – but it has to remain in place for a time to effectively loosen the creosote and does become an expensive job.  It can however be very effective at loosening the hard deposits from the flue surface.

It is also important to note that most chimney sweeps also now have very sophisticated and expensive chimney cameras; capable of looking closely at the chimney walls from inside.  This can be done before the sweep to examine how and where the flue gases flow,  based upon buildup, or after the sweep is performed to closely examine for cracking in tiles.

Inspecting during the sweep is important and should be done by an professional Certified Chimney Sweep.  Which is why a proper Chimney Sweep is not going to be performed in less than an hour in most cases.  You should always hire a Certified Chimney Sweep or Certified Advanced Chimney Sweep.

Chimney Height Rules

How high should your chimney be with a woodstove?  Well did one yesterday; and as soon as I got out of vehicle I said chimney may be too low.

Well, they had a WETT Inspection from a local Midland area inspector who showed the chimney as being compliant apparently for their insurance company.

Pulled out my TruPulse laser height measurement tool – and with a quick measurement it showed 2 feet from where chimney exited roof to the top of the liner.

Now other company likely did not get onto the roof and perform a measurement and likely did not have a laser height measurement tool.  As far as I know there are no other Chimney Sweeps or individuals doing WETT Inspections in Simcoe County who have one – certainly not in North Simcoe / Midland / Penetanguishene area.  Wish I had taken with me sweeping yesterday in Blue Mountains though – a chimney clearly too low which a Collingwood company had pointed out to homeowner.   I clearly was visually; looking out approximately 10 foot range (guessing by eye) the top of chimney was essentially level with the roof at that point.

People wonder why or how a chimney can be in place for years and then be suddenly non-compliant.  Especially when they have had previous inspections done by WETT Certified individuals who say it is okay!?

Problem is a WETT Level 1 inspection is visual in nature; many/most do not venture onto the roof and none that I am aware of have capability to actually measure the height from the ground.  Yes it is not inexpensive – bought mine half a dozen years ago – but they have not come down at all in price!  Here is place to buy one if interested.  Below is video showing one being used.

So bottom line if the WETT Inspector does not get onto the roof; and does not have technology to measure the height of chimney; how do they know?

So some even ask when the code changed.  Or how it has been okay for this long?  Well the simple reason it has been okay is again nobody measured it – or simply overlooked it as they could not be certain.

The actual Ontario Building Code states: Height of Chimney Flues
1) A chimney flue shall extend not less than
a) 900 mm above the highest point at which the chimney comes in contact with the roof, and
b) 600 mm above the highest roof surface or structure within 3 m of the chimney.

These rules have been in place for a long time.  There is no reason or excuse why any previous WETT Report would not pick these items up.  At minimum anybody who did these on regular basis you would think would notice immediately from ground when driving into the laneway – as I did. A Home Inspector who also does WETT Reports may miss this; as they realistically do not do enough of this work to necessarily pick this up.

Those who are thinking of building their own chimney (be it masonry or factory built (stainless steel) – follow the code.  Some may have trouble grasping the measurements – however the picture above should help.

These measurements are to not only meet code, but the wood burning appliance will operate better and often cause less problems.

Essentially the rule states the chimney must be 600mm (2 feet) taller than any structure within 3 m (10 feet) of it and at least 900mm (3 feet) taller than the roof where it exits/penetrates the roof.  c

These as mentioned are designed to ensure proper draft at fire as well as reduce likelihood of house fire.

A chimney which is too low or close to the roof (less than the necessary 300 mm height) is more likely to cause a roof fire from flying sparks and less likely to draw well.

It should also be noted that as a rule the minimum total length should be no less than 15 feet, this is the height the wood stoves are tested and certified at.  Note this is 15 feet from top of chimney (where smoke exists) to the floor on which the wood stove sits.

On the other side of the coin, too tall of a chimney can result in over drafting which can in fact cause damage to some appliances.  Now some manufacturers do offer dampers in double wall stove pipe – but must be used with care.

However a good inspector should not need to go onto the roof to identify some chimney defects; one that is too low is one of these.  You can recognize some problems as soon as you arrive – if you are luck enough to have a high precision laser height measurement tool then that works as well.  There are other defects I will grant you that are more difficult; I did one in Port McNicol earlier this year that the fire department said was okay – however the chimney was too high and actually should have had braces/support down to the roof.  Why did they pick this up?  Likely two reasons – first the fire departments in townships are likely volunteer and not as experienced with this work as those who do it full time – secondly they did not go onto the roof for a real measurement.

Bottom line – best to consult a professional if working on building a chimney!  This becomes particularly so if your property is near different terrain which maybe be near high hills; higher elevations or even out on a lone island in Georgian Bay – requirements may vary slightly.

When You Get A WETT Inspection Will The Inspector Show You How To Use System

Does your WETT Inspector show you how to use your wood burning system; do they actually know how it functions and what makes it work best?  Did they recommend a Chimney Sweep or do they even know if or when one should be done?  ( I know of at least one case where an inspector said the owner did not need a sweep – and they called an actual sweep for a second opinion – good idea!  It was not me they called, but I heard about it – apparently the chimney was well overdue and may not have been cleaned for two or three years!)

Sadly – many of the entry level Inspectors don’t .. they do not own a word burning system themselves in many cases and did not grow up with one .. the do not service, maintain or clean them.  Often times they may even miss parts of the inspection or do it incorrectly!  Why?  Well simply because they have not been trained to do anything beyond the most basic inspection which is intended to be used for assurance the system is still what it was installed as (the inspection after installation or change – or during a real estate transaction requires a more extensive inspection).

But it is always good to hire an inspector that actually knows what a wood burning system is – how to install and repair one as well as clean and maintain one.  Look for a Certified Chimney Sweep as the first option .. and protect yourself.


Hiring A Chimney Sweep – What To Look For – Ten Things You Might Consider

Beware of any phone calls from Chimney Sweeps offering to clean your chimney regardless of price!  There are many who claim to be Chimney Sweeps and are NOT Certified Sweeps – have no education or training – no insurance – and put you at RISK!  Their goal is to take your money for a service that they have no skills to perform.  Often times these people who claim to know what they are doing will then point out expensive chimney repairs that are needed, for safety sake!  They may even try horrendous scare tactics!  It is best to choose carefully and look for WETT Certified Chimney Sweeps or WETT Certified Advanced Chimney Sweeps.   Keep in mind this is for your safety; and peace of mind; if your chimney is not maintained properly it can become a serious fire hazard.

  • Chimney Sweeping is an Unregulated Industry

Despite the face that chimney safety is important there are no requirements to be Certified.  The good news is that Certifications do exist; and you can use the WETT database to find a WETT Certified Chimney Sweep or WETT Certified Advanced Chimney Sweep.

  • Check for Membership with WETT and the NCSG

All Canadian Certified Chimney Sweeps MUST be a member of WETT and you will find them in the WETT database.  Some will also be members of the American counterpart; the National Chimney Sweep Guild.


  • Check for an Individual’s WETT Certification

As mentioned above the minimum nationally recognized standard for a professional chimney sweep in Canada is attained through WETT Inc – and the WETT Chimney Sweep certification is one of the more advanced certifications in Canada on the study of wood burning appliances.  Ask the Chimney Sweep if they are WETT Certified as Sweeps (some may have a Basic certification – and NOT the Chimney Sweep Certification – so beware).  WETT has a Certified Chimney Sweep and Certified Advanced Chimney Sweep Certification.  Verify here.

  •  Check a Chimney Sweep’s Identification

Every WETT Member will carry an ID card – which will have their WETT InspectorPhotograph, the year the Card is valid (it is reissued each year), their Unique WETT # and their Certifications (which will say Chimney Sweep or Advanced Chimney Sweep if they are in fact Chimney Sweeps).  It should look similar to this one.

  • Verify Insurance Coverage

Another good test of whether a chimney sweep company has experience and longevity in the industry is if they have liability insurance coverage.  A chimney sweep company with insurance can protect you against damages which could occur during their visit.  It is very unlikely that any damage will occur; however if it does and the company has no insurance then you are the one who pays the bill!

  • Check References Chimney Referrals

Any good Chimney Sweep will have references; and I have lots of them all over. There are many online you can simply look at – Google or other sources have references of legitimate and reliable Chimney Sweeps in the local area.

  • 7-Hiring the Right Chimney Sweep is a Safety Issue

Sometimes it is not all about price; although it is about value for the dollar.  A good Chimney Sweep should cost around $150 to $200 based upon looking at various websites in the Central Ontario listings – from Grey/Bruce County across to Haliburton area.  Some might be a bit more but should not be much higher.

  • Expect Prompt Service

Good Chimney professionals will be on time; and generally will call if running late.  Sometimes a job does take longer than we expected and I can get backed up half an hour or more really fast.  I do leave time between each appoint to help as a buffer zone, but sometimes not enough.

  • Expect Professionalism 

Reputable chimney professionals usually wear identifying company clothing.  It may have the WETT logo on the clothing somewhere as well.  There should be zero mess left behind when they leave, the Chimney Sweep should be helpful in answering any and all questions about yoiur system.

  • Be Alert to Telephone Scams

Good Chimney Sweep companies DO NOT call and solicit their services, PERIOD.  Keep in mind that an annual chimney cleaning is the best way to ensure that your chimney system is safe to use.

Give us a call for chimney services if you live the Midland or Penetanguishene area and be assured you are choosing a Certified Advanced Chimney Sweep to help you.

More Home Inspector Errors On Websites

Few more items of interest to highlight.

One local Home Inspector states that the most common problem they find in WETT Inspections is the hearth pad size.  Well actually not – the most common BY FAR is lack of fasteners on flue pipes – followed by insufficient chimney height (which most Home Inspectors would never be able to tell).

The same inspector goes on to mention the typical size of ember pad for wood stoves and indicates this can be reduced by certifications – wrong.  Any data plate which shows smaller sizes is likely a very old one – the dimensions CAN NOT be reduced on ember pads.

And same inspector goes on to state that the hearth for fireplaces is also a common problem – indicating the pad dimensions as calculation of opening at 6ftor less fireplace opening have a hearth out 16 inches to front and 8 inches to side; but a fireplace with an opening of over 6ft2 needs a pad of 20 inches in front and 12 inches on each side.  They also mention additional sizing to pad if hearth is raised off of floor – which is true.

Actual rules in Ontario are (now note these are all metric): Hearth Extension

1) Except as required in Sentence (2), fireplaces shall have a non-combustible hearth extending not less than 400 mm in front of the fireplace opening and not less than 200 mm beyond each side of the fireplace opening.
2) Where the fire chamber floor is elevated more than 150 mm above the hearth, the dimension of the hearth measured perpendicular to the plane of the fireplace opening shall be increased by not less than
a) 50 mm for an elevation above 150 mm and not more than 300 mm, and
b) an additional 25 mm for every 50 mm in elevation above 300 mm.

So let’s compare what is on the Home Inspectors website with the rules.

Note there is NO indication of 6ft2 or any area in the Ontario Building Code.  This training is in the Carson Dunlop Home Inspector manual which also indicates beside the rules a notation that some areas may require this.  Note the Carson Dunlop training is very American focused with some notes on Canadian content.  Use the Ontario Codes ONLY.

Rule is 400 mm in front which is approximately 16 inches and 200 mm on each side which is approximately 8 inches.  Yes there are increases in size if hearth is elevated – if hearth is more than 150 mm (6 inches) but not more than 300 mm (12 inches) then it needs to be extended another 50 mm (2 inches to a total of 18 inches) out front.  And for every 50 mm (2 inches) in elevation higher add another 25 mm (1 inch) in extension to front.

So a fireplace with a hearth less than 6 inches high would need an 16 inch hearth; one 6 inches high would need 18 inches for hearth and one 9 inches high would need 19 inch hearth.  Make sense?

So some of what was posted on their website was correct; some of it not so.

However – if you look at American Code then this information quoted in the Home Inspectors website is actually valid.  

What worries me is when Home Inspectors get into code; they obviously do not know the codes – and there are far too many to know!   They may remember what is in Carson Dunlop training – but beware – does this really properly reflect the Canadian/Ontario code?  Be sure – hire somebody who works in the wood stove industry to do your inspection – maybe a Chimney Sweep or Installer/Technician who is Certified as such by WETT.

Is it any wonder hearth size is a common error for them when they are using incorrect information as their reference!

Pyrolysis – A VERY Dangerous Condition

What exactly is Pyrolysis – why do I care and how does it apply to wood burning systems?

Pyrolysis is a breakdown of organic material which occurs at high temperatures in the absence of oxygen. It is an irreversible physical and chemical change in the organic material and can be extremely dangerous.  The word is from the Greek words pyro and lysis (meaning fire and separating).  In the world of wood burning appliances we observe most often when flue gas carrying systems (pipes and chimneys – often masonry chimneys) are too close to combustible material (often wooden structural material).  The process occurs around 200°C to 300°C and essentially is a charring of the wood.  It is very dangerous and the only reason the wood did not ignite was due to insufficient oxygen present. Two problems really are present when pyrolysis has occurred – first the ignition point of the wood will actually be lower than it was before the process took place – second if oxygen concentration does reach a high enough level at that point in the future combustion will almost certainly occur.

Many Chimney Sweeps and/or Installers would have seen this – most often in older buildings.  Unfortunately many WETT Certified SITE Basic Inspectors neither have seen nor have necessary experience to pick up clues when it does exist.

Fact is that normally wood will ignite no lower than around 200°C, but wood that has been seriously impacted by pyrolysis can ignite at temperatures as low as 100°C!  Problem is that wood which has been impacted by pyrolysis is generally not visible, if you recall one reason this occurs is low oxygen levels, hence it is often buried deep in wall and close to hot combustion gas carrying pipes/chimneys.  Sometimes pyrolysis can slowly progress, even over several decades, but this does not make it any less dangerous.

Keep in mind that any improperly installed fireplaces or wood stoves can cause pyrolysis of the wood in the floor or walls around the appliance.

Pyrolysis can be caused by any wood stove, masonry fireplace, factory built gas fireplace, or any appliance which during operation produces temperatures of over 100°C for extended periods.  It is critically important to have a Level 2 Inspection when you purchase ANY property with wood burning system – a further inspection should be performed with each Chimney Sweep annually – be sure to hire ONLY Certified Chimney Sweeps!


What Important Part Of The System May Be Overlooked In A WETT Inspection?

Do you need a WETT Inspection?  Did you recently get one?  Do you think one from three or for or even five years is “good enough”?

Well let’s take one by one.

If you need a WETT Inspection – find a WETT Inspector who is also a Chimney Sweep – these are individuals who know how to tear the systems apart, repair and/or install them.  They know how the systems work and what makes them work – and more importantly if something is not working as intended.  You can ask almost any WETT Instructor and they will tell you the Sweeps are generally by far the most experienced students in their classrooms.

Why do you need a Sweep to perform your WETT Inspection?  Well there are many articles, and some horror stories of getting a WETT Inspection from those who are lesser experienced or who don’t really understand how the systems work and/or do not perform a full inspection.

Did you recently have a WETT Inspection?  Did the inspector look inside the firebox?  Inside the chimney?  Did they have photographs inside the firebox or inside the chimney?  Did they venture onto the roof or into the attic?  Why not?  Maybe you did not hire the correct inspector after all!  You see there is much more to a proper wood burning appliance inspection than taking a few measurements – which is all some inspectors do!

And final question – how long is a WETT report valid?  Well certainly not a year; the fact is if you speak to a WETT representative it is really valid on the day of inspection ONLY.. but realistically most will provide validity to 30 days.  This is generally written on reports of most of the good inspectors out there – they understand this and feel the need to communicate to their clients properly.


Oh and one final point – try to find somebody who does woodstove and chimney work FULL-TIME.  Much like tree workers – there are far too many who do this on the side – part time.  Have a full time job in another industry – the really bad ones are those which have 12 hour shifts and maybe four days work and a week off.. these guys set up small businesses on the side and pretend to be full time professionals!   Generally certifications will weed these out.. use ONLY a FULL TIME CERTIFIED CHIMNEY SWEEP and SLEEP WELL AT NIGHT!

Oh, did I mention the answer to the first question?  What may be missing?  Often time some WETT Inspectors do not go onto the roof; okay sometimes we can not – but if not will have a pole and WiFi camera to help out.  Sometimes they do not check attic – okay sometimes not possible but generally not the case.  They do not check inside the chimney itself.. sometimes not possible – but generally can be done with a proper Chimney Camera.

Should I Have My WETT Inspection Done By My Home Inspector?

Well, lets take this one carefully and a bit at a time.

First the short answer is generally “NO“.  Now let’s not get this wrong, some of my best friends are actually Home Inspectors, some who have their WETT Certifications and others not.

Couple of reasons why you should look elsewhere.

First – Home Inspectors are only qualified to look at a stove from the outside, visually, not check any of the functioning, look inside the stove or chimney.  They do not have the training or qualifications to determine if the system actually works.  They are qualified to inspect the installation and tell you if it is code compliant – to a point.  Many will not venture onto the roof or into the attic, which is a part of a proper code inspection.  This is why the NFPA (National Fire Prevention Association) in their document NFPA-211 states that any inspection for the purposes of a Real Estate transition or land transfer should be a Level 2 inspection.  You see, a Level 2 inspection will guarantee those other areas are in fact included.  But a Level 2 inspection is something that Home Inspectors are not qualified to perform!  Ah.. the catch 22.  Because of this many Home Inspectors intentionally do not do WETT Inspections and leave them for wood stove specialists.  However, for whatever reason, some Home Inspectors have delved into the area and do sell WETT Inspections – many with their Home Inspection at a discounted rate.  Problem is the client, YOU and often time the Insurance company simply does not check or even know the difference.  So it passes the Insurance company requirement but not what is required by the NFPA.  Does this matter?  Well, you got your insurance.  What you lack is peace of mind in knowing your wood burning system is actually in a proper working condition.

2nd – for that peace of mind – you need to get a Level 2 Inspection or close to it.. you need the chimney inspected – roof – attic – inside.  You need the inside of insert/fireplace or woodstove inspected and cleaned.  You need peace of mind.

It is not that Home Inspectors intentionally are scamming you – they are

WETT Inspection - WETT Chimney Sweep
Find A WETT Certified Chimney Sweep

not – most are hard working and do their best.  They simply are not educated in the wood burning systems, not familiar with the NFPA-211 and do not understand or realize the need for a more comprehensive inspection.  In fact some would argue with you, despite what the NFPA-211 states.  It is not about or against Home Inspectors – simply their knowledge level in the topic.  They (Home Inspectors) are generalists – for what the NFPA 211 states as a requirement for inspection during a Real Estate transaction – you need a specialist!  Simple as that.

Generally speaking – for a Real Estate related WETT Inspection – find a WETT Certified Chimney Sweep – get the chimney cleaned and the system “properly” inspected.  Have that Peace of Mind you deserve.  Now I am up front and forward – you don’t need to hire me.  But find somebody competent to do the job.

Chimney Sweep Minesing Today

Woodstove and masonry chimney with liner sweep today in Minesing.  Needed cleaning – with almost a full inch of deposits on chimney liner walls in places!

Woodstove also needed work on the gasket – which I was also able to replace.  Another beautiful fall day to sweep chimneys and repair stoves.  Love the fall weather.

How Do I Light A Wood Fire

How many times do I get asked, how do I light a fire?  Yes it can sometimes be difficult.  But there are ways to make fires and some work better than others.

Then there is the top down burn versus the bottom up – and another blog here speaks to the top down burn benefits.  Top down is the preferred way for most new stoves.  Top down produces less soot and ash – and allows the fire to last longer.

Lets make a fire.

Get a couple of larger pieces of seasoned firewood a few smaller logs (no bigger than a couple of inches or 4 cm) and a dozen smaller sticks of kindling – some firelighters or newspaper and matches.

Open all air vents on fireplace or wood stove – put logs on bottom – be sure they are seasoned or they will be harder to light.


Add a layer of small logs on top and then a couple of layers of kindling.  Leave air spaces between the wood (1/2 inch or 1 cm) – fire needs air to burn.  Place the fire starters on top of the pile (or use newspaper – newspaper contributes to soot and ash).

Grab a match and light it.  Close the door – some may need the door open for a bit to get a good draft.  Sometimes you even need to crack open a window for draft.

And don’t forget to call a Chimney Sweep!