75% Of Homeowners Are Unaware Of This Amazing Product 

As a retired 22+ electrician we used it all the time interior and exterior. We used to call it "C4". Good stuff. If you have a larger hole, pack it with steel wool 1st. Mice can't chew through steel wool

Worked 48 yrs for a utility company 75% of the time we used duct seal outside to seal open end pipes, outdoor cold roll bends going into building foundations worked during all four seasons. Excellent product, excellent video 👍

As an employee of a major HVAC manufacturer and distributor, duct seal is commonly used for both interior and exterior use in installation!

The US Navy introduced me to this product in about 1964. In that environment it was commonly known as “Monkey $h!t”. A valuable asset indeed. The most common usage was on penetrations between watertight compartments on surface ships and submarines. These penetrations passed vital cabling and piping systems both internal and external to the watertight hull and other compartments. I have personally been in situations when this material served as life saving equipment. During application, if you wet your fingers and smooth the external surface of the product, a shiny, weather shedding surface will be created. This stuff lasts for many years. I still use this product for home and auto applications of all kinds.

I retired from the phone company. We used duct seal to seal up ducts in manholes. When I retired 25 years ago, I grabbed a couple of bars for myself. After 25 years it’s still good! It’s great outdoors too. Hasn’t dried up in 25 years ! When I need it, it’s always there. I also use it like “museum putty”,

I'm 72 years old. My Dad, who was in heating and air conditioning, use what he called moretight. It was good back then as now. This is excellent way to seal exterior gaps.

This is a great product, I used it for installing a shower / bathtub faucet in the 70s. When I hat to change this faucet 45 years later, this sealant was in as good condition as when I installed it back then. I did not hesitate to use that same stuff again for the new faucet.

For building exteriors I'd recommend butyl tape. It's outdoor rated and is commonly used to seal gaps externally (lap sealing of metal panels/roofing, roof vents and pipe flashing etc). It has a very similar consistency to duct seal, but again is a specific formulation for external use (flexible in cold weather, stable in high temperatures, intended to compensate for settling, has some adhesive properties). I've only seen it sold as a coil with a paper backing.

As a Rescue specialist for many years we carried this , what we called: " electrical putty", on the rescue truck for sealing or plugging punctured fuel tanks on rolled over vehicles etc... gasoline and diesel fuel did not affect it's sticking/adhering ability. Just saying...

Caution to homeowners when selling in Florida. Home inspectors may note this on the 4-point inspection, buyers will not be able to secure insurance/financing to close the deal until you have it replaced with an "approved" exterior solution.

keep in mind that duct seal is not adhesive. the reason it is used to seal electrical conduits is because it can easily be pulled back out if the wiring needs to be changed. that means if there is vibration or movement, the seal will pull away.

I worked as a meterman for years. We used duct seal on the entrance cable entering the meter socket. I would dry out eventually. We were responsible for maintaining the meter equipment so we replaced the DS when we noticed it was dried and cracked.

I am an Amateur Radio operator, we use a very similar compound called CoaxSeal (nicknamed "Dinosaur Sh!t") to seal connectors on antennas. I have had antenna installations, some over 60 feet in the air, up for years - the connections were well protected from moisture. I usually cover the antenna connection with good quality electrical tape to help prevent drying. I have used Duct Seal to seal the cable entrances to the house with great success.

Electrical company used that goop to seal around the vertical conduit coming into the meter box about 20 years ago when my house was upgraded to 200 amp service. I kind of laughed inwardly as I watched one of the workers forming it in a cone shape, thinking "that stuff ain't gonna last - it's just Play-doh." But after 20 years of being bombarded with rain and sun, it still looks as good as the day it was applied. (And it wasn't painted over.) I think one of the "secrets" to applying products such as this (I use Alex Flex caulk, for example) is to take your time and smush the product in tight with a finger and treat it as if it were a car paint repair blend at the edges. Neatness counts, but not just for aesthetic reasons. Caulk will fail if you don't do this - whether it's painted over or not - otherwise it will last and last, if it's a quality product to begin with.

Duct seal is made from organic ingredients, which is why it's not ideal for exterior applications. Use Butyl tape (applies in a similar manner), as it's designed for exterior and UV applications.

GREAT timing! I was just about to use spray foam on a tricky section of electrical conduit that comes off of my septic pump. This seams like I could get the job done under much better control! Thanks Scott!

I have 35 years of experience in the electrical field. After I applied duct seal I used a little bit of silicone caulking on the duct seal. Without it the duct seal dries out and cracks. I've gone back to meany years later and ind the stuff was still good.

I've used it for filling in voids around the outside... Using it to fill under bottom of siding where it meets the foundation...Critters like to try to gain access so that's great material to fill any access holes ...It's paintable also

I used Duct Seal to better seal my A/C refrigerant lines set entering my home. The lines are covered with a sheet metal cover, and the sheet metal cover is sealed with silicone like elastomeric sealant, but I wanted the hole in the wall under the cover to be better sealed to prevent moisture and bug intrusion. I packed the Duct Seal in; I imagine it'll last a long time being covered and not exposed to sunlight and water. I painted the silicone sealant, so that should hold up really well too. 👍👍👍

The electrician that installed a new line into my basement used duct seal on the exterior where the line entered the house. That was 10 or more years ago, and its still pliable and still keeping the rain out. Thanks for the video.....

I was going to ask questions about this, but the comments have already been answering them! Thanks for bringing this product to wider attention!

Used plenty of that stuff in the Air Force when sealing vacuum bags for fiberglass and various carbon fiber repairs.

This is a great product and I discovered it by accident a few months ago while shopping at Menards in the electrical section. Thanks for highlighting this excellent sealant.

Really useful stuff and it stays in place and doesn’t harden. I’ve used it to keep bees from building nests in nooks and crannies.

For the wires in the panel, it might also be worth mentioning that a great place to seal that up is actually at the LB entering your house. You can seal the inside of the conduit there, and there should not be any junctions there, so the wires are fully insulated.

Working on merchant ships, duct seal is used to keep water from pooling inside watertight penetrations. I have experienced that it does dry out and crack when subject to direct UV (such as on top of the bridge, etc.). To combat this, I've seen Denso tape used on top of duct seal to protect it from UV. I've also seen silicone used instead, but silicone fails much sooner (at least on brass connectors). Maybe silicone works better on PVC? Don't know.

This was used to seal where air conditioner line enters my house. I replaced it after 7 years, so did last long time.

I’ve used this on my RV in place of the gum tape for years and had no issues that I know of. In some cases I prefer duct seal over the gum tape the industry uses.

I suggest that in addition to keeping the clay wrapped, store it in a vacuum sealed mason jar or one of those jars that clamp down and have a gasket. It will ensure it doesn't dry out.

I've used a boat load of this stuff doing electrical, but rarely exposed to the elements on the exterior. Primarily to stuff and fill conduit to prevent condensation transfer/leaks on the interior of the conduit where it enters and exits an external wall. Also on large jbox and equipment chases passing from exterior to interior, but not on the outside, only on the inside of the box where conduit connections are, or interior. We typically use a window/door grade silicone product like vulkem when it comes to sealing and edging around a penetration that will remain exposed to the elements. Duct seal won't stay adhered to the different materials like silicone/vulkem type compounds that can handle extreme heat/cold changes, and direct sunlight. This is best used to fill pipe's empty spaces, and seal openings that will not be exposed to the elements.

This is my favorite DIY channel. You have an uncanny way of posting videos about projects I’m just about to start. This happens almost every week, it’s unbelievable. Well done and much appreciated!

I was told by my roofer that spray foam as an exterior sealant is a bad idea. It's permeable so it can suck in moisture and that can cause mold in dry wall bays. I've been using Quad but I'll give this sealant a try. Thanks.

Great video and I love when you pointed out about the exterior use. I’m a retired electrician and I’ve used this item a lot and it does work well except over time it does seem to shrink thus no seal anymore. Maybe if it is used to seal the penetration from the inside and maybe some kind of silicone on the outside it may last longer. Again a Great video!

It is a requirement to have Duct Seal on top of the Raintight fitting atop the meter channel which is typically outdoors. We also use it on the inside of condulets where they are used to penetrate the wall of a structure from the outside. This aids in combating condensation from forming due to cold air which not only flows but conducts a path before meeting the warm interior air. I use Lexel clear as an alternative to silicone. I won't post selling points as I'm not a salesman for the product but I've used it for: controls, security and electrical installations. I've also used it for carpentry although I'm not a carpenter. When you have everything from bugs and critters to the elements working on getting into your structure - 24/7/365 - you want something that will last. Duct seal will age and form a hardened skin where exposed to the elements. Depending on the length of time exposed you can either remove that film or work it in to the rest and reuse it.. It's a personal choice.

Freezing temps combined with difference in expansion rates between the duct seal and exterior material will break it loose and you'll lose the water-tight seal. Not that this isn't a problem with many other types of sealant methods, though.

I have helped install roof panels that were metal and we used something just like that for keeping the roof panels from rattling and side blowing water leaks and it made the job easier because when we had put a new panel down we could walk on it and it was basically stuck down and we could move it if we needed to change something . It was probably the same thing we used it for soundproofing on ductwork in the same building . Was completely water resistant if it was adhered to its surface .

Seal the inside of the conduit too when transitioning thermal zones. When doing commercial refrigeration work, I was always impressed by light bulbs burning under water in ceiling mounted weatherproof light fixtures with a glass globe which were installed inside walk in freezers and the conduit wasn't properly sealed by the electricians (which was almost always the case).

Thanks for this info. Just the other day I was debugging my sprinkler system and opened the controller box where the wires attach to the terminals. Yellow jackets had created nests all around the wires. Now I am going to use this product to keep them out.

Another option that my electrician recommended is hydraulic cement. It's pretty inexpensive, and you can get it in a small bucket that keeps it dry until you need it. Then you just mix enough water to make it like clay and apply the same way you did. Less forgiving though, in that it dries hard and solid. But works great.

That stuff was colloquially called "dum-dum" back in the days of NTSC, landlines, leaded gas, and before spray foam. Installers and repair folks used it regularly. It's easy to use and make look nice, doesn't make a mess. But come back after a few years, and it dries out and cracks, loses adhesion, and likes to break away with any movement. That's usually not discovered until trying to figure out how the bugs and sometimes mice are getting in. Oh, and it's cheap, too. My recommendation, drill your hole the OD of your pipe, coat the inside of the hole thoroughly with silicone caulk, likewise the pipe itself, then force/twist the pipe into place. Then touch up around the interface on the inside and out. But only if you really care.

I've been a homeowner for 20 years and never heard of this. I do remember that my HVAC line into the house may have had this stuff on. I will check this out at the big box store. thanks,

A low-key hero around here wherever there's an exterior wall penetration. Good vid.

I bought a block for a sealing the inlet of an electric meter fitting on a renovation job several years ago. Since then, I have used it on other projects that require sealing out water.

As a retired electrician with 55 years experience we quit using duct seal as it does over time get hard and being that pvc conduit tends to expand and shrink with temperature changes gaps in the seal would always happen leaving areas for water to enter.

As a telecommunications installer we used it and then changed to silicone

In my area the electrical inspectors want you to at least seal one side of any electrical penetration coming in and out of a house. So either the lb on the outside or the TA on the interior going to the panel needs to be sealed with duct seal.

I use it to seal wires at the ends of conduits, especially in underground "hand holes" to prevent water from moving through the conduits and into places you do not want water. Also works to control septic gasses that might migrate from the pump chamber and into the electrical control panels. And helps keeps bugs from migrating into electrical control panels through the conduits. Pack an LB or "condulet" body with the stuff, and not much will be able to get through.

As a retired electrician I always had duct seal on my truck. Handy stuff.

It DOES dry out over time. I have yet to return for service to a house that I have used it on. I have removed my fair share of it from services and panels that I have changed. I will, as a curtesy, remove it and replace with silicone on a service that I am not changing. I have switched to silicone caulk. I still use duct seal in conduit that passes through exterior walls as an insulation barrier.

where i live, rigid conduit isn't required for ser cable, it's fed directly into the meter box from above. every single one i've ever seen had duct seal around the cable and connector on the top

UV light for exterior use is a problem. Many people just paint over it with a UV block paint.

Thank you for this video. My HVAC used this to seal the PVC exhaust and intake for my furnace when it was installed a 4 or 5 years ago. It needs a little attention and I could not figure out for the life of me what it was!

We have used it for 30+ years in southern California for things from sealing exterior walls to keeping manholes from rocking.

Just like you’re not supposed to put Q-tips in your ear but that’s the main reason 99% of buyers use it for.

Good stuff Scott. Easy to use and forgiving as you say. Like this better than the foam spray as you can use as little as you need for small jobs. Not so with the spray foam!

Dow Corning finds 56 tons of unused Silly Puddy in storage. New product named Duct Seal rushed to market for DIY and Technicians.

My brother was in HVAC for years, and gave me some of that. He called it "thumb gum". Lasts for years as far as ive experienced

The man said in the beginning of the video about three times at duct seal will not Harden, it does Harden when is it supposed to the environment so it's best to go ahead and reseal the package after you use it. And every so many years check the places where you put it in case you have to ship out the old hard duct seal and replace it with new duct seal , because it does Harden!!

I have used this for exterior sealing for many years, works great. I have no idea why it's not rated for exterior use. Maybe in dryer climates it will dry out and crack. I haven't seen that happen yet.

It has been used on my electrical box here in wetlands area southeast MA, USA since 2016 without any issues other than some discoloration. Started off a black color and is now a darker grey. I am able to manipulate it still as the material is still malleable. Hope this helps. 8-9 years and going strong.

When my father-in-law helped us replace an outdoor spigot, he used Great Stuff to seal around the pipe and we hadn't had any issue. I think I may pick up that product for extra insurance because in the Blue Ridge mountains of Virginia, it has it own weather system that can seesaw between lovely, spring day to downright bitter cold in matter of 24 hours.

It does dry out some over time. It was used on the AC lines coming through my brick home back in 2018 & shrunk a little leaving a small gap. I tried reforming it to seal that gap but some of it was dry & cakey & fell off. I just removed the old & applied new.

I’ve used clear silicone, but It easily peels off after a year or two in the sun. I’ve had excellent results with a product called OSI clear I’ve had it last three years and it still looks perfect. It comes in a caulk tube like silicone cost a little bit more, but it’s my secret weapon

I’ve been a carpenter for 50 years, can’t tell you how many times I seen that clay dry out and pull away from opening’s! The real world says different.

This looks exactly like what I need for my AC lines going into the wall from my outdoor AC unit!👍🏻

thanks for the laugh, I'm a second generation electrical contractor, yes DUC seal is used by us all the time, i remember my dad was working on my brothers house in FLA, we are from CT so dad wanted some duc seal ,they went to the Depot ,No body knew what it was Dad explained like you did a hour later and a forklift they found it high on a shelf , nobody knew what it was till that day LOL

This stuff is awesome. We use it on electrical service weather heads and where the SE cable enters the meter trough

I use this stuff to seal around my electrical boxes that I installed outside on my foundation.

Use this for sealing the hole in the bottom of your water fountain where the cord for the submersible pump goes out.

Thanks for this video! I've used the spray stuff and it doesn't last long and as mentioned it's hard to control. Will definitely buy this when I do my spring checklist.

Another similar product that cures solid with metal reinforcement would be epoxy putty. Some common ones are made by ProPoxy 20, Oatey Fix-it-stick or JB Weld. Most can be painted too.

I've seen this used all over, but I've also seen contractors and DIYers use plumbing stainless putty the same way. No idea what the chemical differences are, but I had an old building inspector tell me plumbing putty is the easiest, but good to best quality goes stainless putty to duct seal to butyl rope (best). I do agree that the putties don't always last if placed in direct sunlight unprotected.

So THAT'S what this stuff is! It seals the line from the street going into the top of the meter. Looks pretty cracked and I'm worried about rain. Thank You!

I used it to seal at least one end of the conduit so there is no air exchange, hot air in the house going through conduit can cool down and condensate and the water will run into your panel board

Large Communications Buildings use the stuff as a Fire Block where conduit or cable is going between separate areas.

There's a similar putty that comes in a paper separated roll appx 1/2 inch wide. Meant to seal lap joints in R-panel. This is outdoor rated.

It will eventually dry out. It turns lighter in color and small cracks appear. The good side of this is it usually takes around forty years of outdoor weather exposure!

"Tool Belt of Knowledge " should be the name of your second channel. Great stuff man, thanks!

Use inside any conduit or LB going inside to outside or different environments. Pack around wires. Stops air transfer inside conduit. Stays flexible enough to remove wires if necessary. The greatest use of duct seal Is in the back of a pellet trap. We shoot 10s of thousands of pellets indoors. Greatest thing ever found used world wide for this purpose. Pick stuck pellets with needle nose an smooth duct seal after a few thousand shots.

When I was looking for caulking for my house to use on the windows, I kept finding Sashco Big Stretch which is supposed to hold up better compared to other caulking. Supposed to do up to 2inch. If possible, I would like to see them compared over time.

I just used some last week to hold a disc capacitor in place on a pcb board while I soldered it. Then, it easily comes off the board. Works great.

I was saying prayers last night to find a product for this purpose. Voila! It appeared in my feed today! Thank you Scott for posting, and to God! I can’t wait to buy it. I have so many outdoor stuff to seal. It is amazing how homeowners do not maintain their property!

We use it out side all the time works great.

Working for the phone company in Florida for 42 years, I can attest to the stuff's durability. After a few years in the sun,, it'll get a kind of a crust on the outside but it lasts a long time. We always called it monkey s__t. (lol)

We bought our house here in Maryland in 2001 and the electricians have sealed the electrical and actually gas lines using this product on the exterior. It's 2023 and the product is still pliable and is still there.

Videos like this is the reason I love RU-vid! Thx 👍

Last three contractors used this on my house. I recently found this in HD but I used a combination of Silicone and Duckseal.

We use it for the main service entrance cable coming into the meter, which is outdoors

I personally never use it. Instead I use a high grade of colored silicone. It passes inspection and unlike duct seal, it does NOT shrink/harden in time and fall off. Like duct seal often does on the top of a meter socket allowing water into the meter socket, which often drips through to the SE cable and down into the basement panel.

I will be using this thank you for the video. Is there something similar made for a hole in brick that would match the color of brick even if its a permanent seal..

Good deal. I'm going to use it for exterior use in the desert. We'll see if it holds up.

My cousin who suffers from retardation was staying with us over the holidays. We added a steel line that connects via an eye bolt to the house and connected the other end to a tree. This allowed us to hook her leash to the line and provided her with freedom to run and dig. I pre-drilled the hole for the eye bolt and squirted in silicone. After securing the eye bolt, I used duct seal as an added measure to prevent water ingress. Thank you for this video, I've found it very helpful and informative!

Everyone should know that the generic term for this product is "Butyl Rubber". Some people also call it "Coax Seal". This stuff is awesome.

Use SONALASTIC caulk a one part urethane caulk what they use when sealing joints in precast concrete buildings very tough and for exterior use also known as NP 1

This will dry and crack from sunlight exposure, but it will last for some years, and is easy to replace.

Wrks great to seal up dryer vents!

The handyman’s C-4? This product has been around since the 60s.

That was a handy tip. I don't know if all spray foam does, but some when used on exterior, will break down in sunlight after a time.

Thank you so much for asking & it just shows just how kind I’m certain that you are for asking, “How’s it going you guys”, because it’s been a long hard week already and it’s only Tuesday can you imagine that but since you asked, “How’s it going you guys?” I will certainly tell you that things could be better but then they could be worse also and isn’t that always the case with life ha ha no matter what’s happening it could always be worse and no matter what is happening it could always be better, although there was one time, in fact actually there’s been a few times in my life where when somebody ask me “How’s it going you guys?” I could actually tell him that things couldn’t be better, “How’s it going you guys?” is that things are going so well but then I stop and think you know I suppose something else great could happen and things could even be better so to answer your question “How’s it going you guys?”, I’ll begin by saying things are actually looking up kind of like Paul McCartney wrote that “everything is looking better” and then the severely negative John Lennon wrote, “couldn’t get much worse“, which means obviously that Paul McCartney was an optimist and John Lennon was a pessimist and we all certainly all know that therefore if you were to ask them “How’s it going you guys?” considering they are two people which certainly fills out the definition of guys plural, they would say what they said in that song which they wrote many songs in their career but can you believe they only wrote Beatle songs or actually all the Beatles songs they wrote were before they were 30 years old which really is astonishing therefore if you were to ask them “How’s it going you guys?” they would have been all over the road from the beginning to the end of the Beatles career yet you ask me “How’s it going you guys?” and I can tell you that things are looking pretty good, I’ll come back later to finish answering your question but thank you so much for asking that question.

Will it stick to drywall? Plumbing vent pipe that passes thru a closet is surrounded by jagged drywall. Would like to improve the look a bit, caulk looks like hell, lol.