How to Make Common Chimney Repairs | Ask This Old House

In this video, This Old House mason Mark McCullough shows host Kevin O’Connor some common issues with brick chimneys and how to repair them.
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At a job site, mason Mark McCullough talks about chimney repairs. Mark shows Kevin O'Connor what to look for when planning out a repair before the pair roll up their sleeves and get to work.
Difficulty: ⅗
Time: One day
Cost: Around $100
Where to find it?
Mark & Kevin discuss common chimney problems and arm homeowners with the information they need to hire a licensed professional to carry out the repairs, including safety protocols.
They then work together to repoint the chimney, by first grinding down the mortar joints. To do this, they use a grinder [amzn.to/3Dg9UHT] with a vacuum attachment and hand chisel and wear the proper safety equipment, including safety glasses [amzn.to/3SbfSxP] and earplugs [amzn.to/3VCcQp9]. They remove excess dust with a damp masonry brush [amzn.to/3S9gRi4], then use type-N mortar [thd.co/3EOsYhm] to fill the joints. For this process, they mix the type-N mortar to an oatmeal consistency, then use a finishing trowel and margin trowel [amzn.to/3s5PsTw] to apply the mortar to the chimney.
Based on the age of the chimney he repointed (over 100 years old), after the mortar cures (cure times vary, check the label on the mortar), Mark will apply a waterproofing agent [thd.co/3s4h7nP] to the chimney. Mark suggests first cleaning the chimney exterior with a masonry detergent [amzn.to/3CKYlGO], then using a waterproofing agent by applying one coat to the chimney with a spray attachment [amzn.to/3CESrXX]. To apply the waterproofing agent, work your way side-to-side, beginning at the bottom of the chimney, then moving up the chimney to the top.
All products can be found at a local home center.
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Materials:
Type N mortar mix [thd.co/3EOsYhm]
Waterproofing agent [thd.co/3s4h7nP]
Earplugs [amzn.to/3VCcQp9]
Masonry detergent [amzn.to/3CKYlGO]
Tools:
Respirator mask [amzn.to/3TvV2dv]
Work gloves [amzn.to/3TdGNdu]
Safety glasses [amzn.to/3SbfSxP]
Grinder with masonry wheel and HEPA attachment [amzn.to/3Dg9UHT]
Masonry chisel and hammer [amzn.to/3CHewFh]
Shop vac [amzn.to/3T9jpxO]
Masonry brush [amzn.to/3S9gRi4]
Bucket [amzn.to/3zcJVyD]
Sprayer [amzn.to/3CESrXX]
Variety of masonry trowels, including pointing trowels [amzn.to/3s5PsTw]
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From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment-your home.
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How to Make Common Chimney Repairs | Ask This Old House
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[@FrederickDunn]

This is a very good demonstration, thanks. I'm wondering why the individual brick condition wasn't discussed? What if some of the bricks are cracked or spalling? I wish some of the bricks could have been replaced as part of this tutorial. Also would have liked a tiny introduction to the mortar selection and preparation. This Old House has been my go-to for more than 30 years :) Thank you!

[@ccjohncc1]

When you can spend $25,000.00 on safety equipment and stair installed scaffolding to do a $4,000.00 dollar chimney repair!

[@peapotfairy]

Must be nice, eh?

[@petevella9285]

FYI, Mark, the chimney cap on the other brick chimney does not penetrate the flue or the concrete contrary to your statement in the video. That particular cap as well as every other flue mounted cap that I have ever seen is designed to be secured with pressure bolts which tighten to the corners or sides of the flue without penetrating the surface.

[@pawelfronczyk1579]

u r absolutely right, guy with 4o years experience saying things like that, crazy, and all that stairs is to make more money,

[@routtookc8064]

@@pawelfronczyk1579 taken 'em to the cleaners in Mass for sure.

[@ccjohncc1]

Your comparing an apple to an orange. The often used stainless steel chimney cap that bolts with tension on a clay flu liner not what you are looking at rather it is the cap that attaches to a new round chimney flu installed in a very old and likely unsafe creosote soaked 100 year old chimney that was likely built without clay flu liners. Clay flu liners were not common until the mid to late 1940's.

[@PerfectCleanVA]

Did you guys add sand into the cement that you’ve used? If so, what is the proportion?

[@jessewilliams2180]

As soon as he said OSHA compliant the correct answer is yes overkill...

[@JIMMYS1180]

That man has never tuck pointed a day in his life.

[@ralph5450]

Got a lot of respect for a guy that does good jobs working in joints like that.

[@robertbamford8266]

Always a pleasure to watch. Speaking of watches, wearing one while chiseling - shock resistance. WRT metal caps on wood burners, here (Calif) we have a cap that attaches to the protruding flue with horizontal machine screws that are tightened to create a friction fit.

[@rovert94]

Is there any concern with using a modern type N mortar with these old bricks, or are these not old enough to be made without portland cement?

[@mikedevo363]

For a flat roof you need to put up all those barricades? Give me a break, what did "This Old House insurance polcy lapse.

[@javiergalvan242]

Another great video guys 💯💥👍☝️

[@j0258169]

Counter flashing?

[@grantmeyer03]

What about the chimney cap? As for the mortar joints is that really a job a homeowner could do?

[@johncarlos7810]

The mason is a homeowner?

[@zackzander425]

For repointing grind the vertical joints out first and then the horizontal bed joints. Take a plugging chisel and clean out the half moons where the head joints meet the bed joints. Apply your mortar in 1/4" lifts. Should be about 3. No need to acid wash if you're neat and using a hawk with the correct size pointing tool. FYI those paper masks are not doing anything to protect you. Might as well use nothing at all. Need a fitted respirator with the magenta colored filters.

[@bfrost7]

wish they would start posting the potential price ranges, materials and cost of labor.

[@mr.g937]

In 2022 in New England, you aren't going to get a mason to show up at your house and repoint a chimney for less than $2000. Materials are like $40, so obviously if you are a DIYer you can save a lot by doing this yourself.

[@flaviuskern225]

That set-up is 8-12k. Worth the one time investment if you have a real pro who cares, not so much if you get one of the many ham & eggers running around pretending to be tradesmen.

[@Avital4414]

@@mr.g937 how much to just re-seal?

[@machfive916]

Excellent video on how to properly repair and waterproof a chimney.

[@hotsauce2007]

the quality of the video footage is amazing,

[@RandomVids519]

Like that plastic fence is safer then a harness 😂😂

[@saulgoodman2018]

I know

[@zackally828]

Definitely a lot more comfortable to work in that’s for sure, wearing a harness sucks

[@Mike_Greentea]

Shhh! Don’t tell

[@Handygrrl]

Is the goal to strip out the old mortar completely or just get down to a solid mortar?

[@wheresbicki]

Pretty sure just to solid mortar.

[@dk3-02]

Down to solid. Only going to get about a inch deep with a grinder anyway. As long as it’s solid and not still crumbling out is the difference between it needing tuckpointed and it needing tore down and rebuilt.

[@chadvaillancourt]

154 brick rebuild. Could be demolished and rebuilt in one day with new brick by any mason I’ve ever worked with, no scaffolding needed. Be nice to get some counter flashing on there too, it would help stop the water infiltration.

[@FrederickDunn]

Oh! I hadn't thought of that. You're saying demo the old chimney and replace with all new? I like that idea and think it would result in a much more lasting system. Thanks! Particularly when some of the bricks may be deteriorating, mortar replacement just may not be enough.

[@Chris-ml3hw]

The missed the finishing of the mortar/how you smoothed it out.

[@joralriver9052]

need to know what type of mortar use for re pointing brick?? i started use the quickrete mortar but it doesn't have the consistency like in the video, it's got a lot of sand.

[@BamBamBigelow.]

Is it cheap and effective?

[@ranger1244]

Is the waterproofing agent a sealer or is it a different product? I remember in a different video repairing stairs Mark explained a sealer isn't necessary because the mortar or concrete is waterproof and a sealant could cause damage. So which is it???

[@pjmorgan]

That HEPA vac is doing wonders right enough 😷

[@joshcowart2446]

Glad that netting is there to stop a 200# human from falling. Anything the keeps a harness off you though is nice. You either have to drag around a strap or use a yo-yo. The strap makes a trip hazard so you’re more likely to fall but at least you won’t hit the ground. The yo-yo just makes my back and neck sore from constantly moving just slightly too fast and it tanking me back. I know a floor finisher who had to do a job in dc next door to osha. I guess they were strict and made them wear work boots and hard hats in a finished building. When doing floors the boots can mess up the finish and the hard hats fall off easy doing the same. However they didn’t requires respirators, the one piece of ppe that made sense. This is why one size fits all doesn’t work. He made $2000 on the job and lost $8000 in fines. Isn’t osha lovely.

[@bgjr2304]

I wrap my terracotta chimney flues in a Blueskin membrane (where the concrete crown will form around). This provides some room for expansion during freeze/thaw and prevents the flue from cracking. It also seals the joint from water entry.

[@thomasdennis6718]

Anybody else just use type s?

[@NightTracer101]

TOH stepping up their production value with the slow mo action

[@gpslightlock1422]

You'll spend more time messing with repointing that chimney than you would if you just tore down the top 8' and rebuilt new.

[@BlakeFA_TECH]

Nice

[@Peter-976]

I'm surprised they didn't use a grout bag to apply the mortar, then follow with a joint striker.

[@rickfromthecape3135]

Yes, much neater.

[@Peter-976]

@@flat-earther ESAD, please

[@CH-gx7xh]

Chimneys aren't that much of a thing in my country and english isn't my fist language so is it possible for anyone to confirm if I understood this correctly: a chimney draft is what pushes the smoke up and out of the chimney. When there are trees around, they reduce the draft (why?) and when there's a hill nearby the wind that comes from its side pushes down the air below and result in a reduced draft. Did I get it right?

[@MayMay11_21]

Can you do a video about cleaning a chimney?

[@matthew-h]

Watch the opening scene of Many Poppins. Follow all steps exactly.

[@socksincrocks4421]

Must have taken a week to assemble that scaffold and setup the safety barriers. Just for that chimney... How much did that prep work add on to that project? $10k? LOL

[@markwilson9063]

The modern osha rules ether ridiculous overkill or a complete joke and all seem to be aimed at preventing smaller business from being able to complete - I'm sure some unions paid some lobbyist at some point...

[@kingsterr323]

Use a grout bag to put the mortar in the gaps.

[@FrederickDunn]

I like that idea! Or, I hold up the trowel right against the chimney and slide the mortar right into the joints. :)

[@IIIllllIIIIlllll]

Wish Bill Burr would come do my chimney too

[@peapotfairy]

So many bots in here. Its nuts.

[@collinram96]

That fence is about as useful as a chocolate tea pot

[@DennisZylstra]

You guys..... love your show and all that go's with it but say it like it is. Sometimes regulations go too far. It's ok to buck the system a little. Some people can't afford all the hoopla.

[@oogiesmuncher]

nothing safer than a flimsy plastic fence 20 ft off the ground.

[@Farm_fab]

OSHA doesn't apply until one has a certain number of employees. However, some townships and municipalities may require these standards of safety.

[@odoroussmegma2191]

@@Farm_fab thanks for clearing that up brain fly.

[@zack9912000]

@@Farm_fab OSHA causing accidents as usual.

[@jakedixon6086]

Lol I love they call it a “barricade”

[@VineekVineek]

😂😂

[@RealTylerBell]

that totally safe orange fence, totally stop you from falling

[@ianbutler1983]

My chimney guy climbs up my TV tower......

[@ecstasyofgold888]

#1 protect investment but what is #2???

[@MariaPerez-xq2bo]

For real.. turned 41 on December. But for some reason I feel like 30

[@leoshepard1496]

You should wet the spots where the new concrete is being applied.

[@malikdigger4544]

I know u should always check to make ur chimney is up to date & right but orange plastic loose fence u guys are on is not safe.

[@bluecollarwanderer21]

🤟🇺🇸

[@gravenewworld82]

Eh, this is one job you contract out, because by the time you rent scaffolding and spend all of the time doing this, you are barely saving any money over hiring a contractor. Repointing actually isn’t hard, but getting up that high is dangerous without experience and scaffolds. Type N mortar is correct to use for most repointing jobs, because it has about 750 PSI of strength. However, you must be cognizant of the fact that older homes often used lime based mortars if you need to repair your chimney on an old home. Type N and all the stuff you can buy from big box stores contains Portland cement, which you typically do not want to use on older homes where lime mortars were used. Older bricks are weaker, so if you use cement mortars it can damage older brick. Also, color matching can be difficult, which is yet another reason to contract this type of work out to a pro.

[@FrederickDunn]

I like what you've mentioned here. Matching mortar to old mixes is something experienced masons are aware of. What about just removing all of the surplus chimney and completely redoing the chimney with new brick and mortar? Since he mentioned that it's much taller than it needs to be?

[@anjaananjaan5107]

I have a chimney that is bent for a house that may be 100 years old. Any one in DC, MD, VA who can aspect for structural fitness.

[@josephcofrancesco4123]

Here's the proper procedure- all that scaffold cost the home owner probably $2000. I don't like a harness but its a flat roof and if you fall off your not aware of your work environment or if your afraid stay home. Next you grind the chimney with good diamond blades pay attention to what you are doing and you won't screw up the edges of the brick. You take your hammer and chisel and leave it in the truck! When your done grinding get a hose or a power washer (I use a power washer)and wash all the dust and dirt off the chimney. If I get the grinding and washing done that's usually all I do that day. Next day I dampen the chimney with a sprayer and point, probably 4 to 6 hrs. And that chimney is done. There is no washing when I finish because I not a slop artist. I go back a few days later and use 2 coats of breathable waterproofing. Also that flat tool is slicker not a margin trowel.

[@johnmcknight790]

Do you use water based or solvent based waterproofer?

[@rattkiller01]

I could point that chimney in 15 minutes,I could cut it out in 15 minutes, use dry mortar with a pointing tool, and hawk

[@rattkiller01]

I could point that chimney in 15 minutes,I could cut it out in 15 minutes, use dry mortar with a pointing tool, and hawk

[@mojesus680]

All that safety Money to calk your Fired gangster💥👀🚬

[@Guillotines_For_Globalists]

Say what?

[@johnlebzelter4208]

Troll. You’ll be reported

[@mojesus680]

@@johnlebzelter4208 *report yourself 😷*

[@mojesus680]

@@Guillotines_For_Globalists *get another bid or get flatt roofed off🤑

[@Guillotines_For_Globalists]

@@mojesus680 I love getting flat roofied!

[@phonedave]

Mark is going to need a new watch. I learned after breaking at least a half dozen. Take them off when hammering like that.

[@benkeysor7576]

Maybe if he was actually doing some real work. On TOH jobs people like Mark aren't doing any real work now days. He like most of the others are simply there to be a foreman for a crew of people in their trade.

[@anthonyb2327]

Brush the wetness!! Yaass

[@srharris88]

That is insane, they easily had more money in setting up all that "safety" equipment than the work itself. On a FLAT ROOF mind you! I'm guessing in this case they either had access to the equipment, or had a bigger job also planned. Sometimes safety just CAN'T be number 1. Get real with this crap...

[@flat-earther]

scott I suggest watch a 13 part series called _What on earth happened_ by Ewaranon to learn that the earth is not a globe. Link in my about tab.

[@saulgoodman2018]

I would have used a grout bag. Then smooth it out.

[@grantmeyer03]

Do you get the same penetration if you don't push it in?

[@saulgoodman2018]

@@grantmeyer03 You use the grout bag, then that tool to push it in.

[@AugustKling]

Thank you, people are able to recognize the intelligent use of a mask.

[@crack1270]

Respirator*

[@jacobchonko4640]

I’d rather use a grout bag than use a tuckpointer

[@rattkiller01]

That's because you do not know how

[@Pure_KodiakWILD_Power]

I'd use a spray bottle for water instead of a brush 🤔

[@Bvnbg0]

looks like they forgot to turn on the vacuum with dust cloud

[@69uremum]

No it is definitely overkill!

[@gpslightlock1422]

You need some youngins on that job teaching them the trade.

[@assyrianme]

Why don't people parge the chimney?

[@jasonmanning4683]

Lol😂 as I 20 year csia certified chimney sweep with national chimney guild Nfpa 211 training (*which is the clad book for all residential chimneys both fireplace and heating) along with Virginia lime works historic restoration classes prior fire firebox and heat shield certifications I can assure you this guy is clueless at best 😂 sorry not sorry he should open his irc (international residential code)blue book and do some reading THERE IS LITERALLY NO COUNTER FLASHING ON A FLAT EPDM ROOF 😂 guys a joke 😂

[@zack9912000]

I always laughed about plastic fencing, it wont stop you from falling to your death. OSHA causing job site accidents

[@isaiahraimondo6083]

There was more wrong then right here and the overkill almost kills the video to show a person how to do it

[@flat-earther]

Isaiah I suggest watch a 13 part series called _What on earth happened_ by Ewaranon to learn that the earth is not a globe. Link in my about tab.

[@yeshuamedrano815]

If it's orange it must be safe.

[@pavelgyrya669]

Can Santa Claus fit?

[@philatherton9837]

What?? Just what? Absolute DIY nonsense from start to finish. Would have that work done off a cat ladder, on a pitched roof, in the time it took to watch this video 🤣 Classic US drama 🙄

[@justanotherchannel6097]

Bunch of ladies spending more time setting up than actual work.

[@justanotherguy8791]

No one is putting safety barriers on their roof like that... professional or DIY

[@donaldlee6760]

I'd love to see a price quote to clean leaves out of the gutters each year.

[@ryanroberts1104]

"This is why you hire a professional to do this"..."let me show you homeowners exactly what you need to do"...

[@flat-earther]

Ryan I suggest watch a 13 part series called _What on earth happened_ by Ewaranon to learn that the earth is not a globe. Link in my about tab.

[@ovidiuciuparu6421]

0:40… just get a boom lift!

[@flat-earther]

Ovidiu I suggest watch a 13 part series called _What on earth happened_ by Ewaranon to learn that the earth is not a globe. Link in my about tab.

[@usnveteran4245]

i would have just used Quikrete Mortar Repair Sealant in caulk tubes and a repointing tool quicker faster less mess and no need to have to mix anything.

[@cdyoung976]

Wow that is an incredible amount of money and time into repairing a casing for a metal pipe! Why not just tear the chimney down above the roof and install the appropriate metal chimney?! Thatd have to cost less than just the scaffolding. Or better yet, slather your favorite sealant on that chimney (as it looked fairly structurally sound) and when the appliance hooked up to that pipe is due to be replaced, tear the chimney out down to the roof and get a powered vent appliance that vents out the side. Then you would never have several thousands of dollars in repairs for an unnecessary roof penetration!