Marathon Insulation is the real deal! They check every box: knowledgeable, caring, honest, committed, trustworthy, communicative, and accountable to their work. You can tell that they pride themselves in the work they do and go above and beyond. Jonathan, Ralph, and his crew were phenomenal from start to finish and made sure they took care of all things related to their work. On top of this, their pricing is super competitive! It's hard to find an ethical and caring company like them nowadays but I'm so glad I found them. If you're looking for insulation needs, look no further - seriously. Thank you Marathon Insulation! read more

These guys are great. From start the finish the whole team were very professional and respectful of our home. The materials they used were top notch and eco friendly which we were looking for and dropped the interior temperature of our home significantly which is helping us save thousands of dollars on electricity bills. The process was fast and non invasive and they left our home clean after they finished. I would highly recommend these guys to insulate your home. read more

Everything about this company is 5 stars, starting off with Jonathan coming out and giving a quote, to Ralph and his team removing the old insulation and cleaning the atic. Could not be any happier and exactly the kind of company I want to hire and do business with. The communication, and professional work is second to none. Thank you Jonathan and Ralph for doing exactly what you said you would do and at a fair price. read more

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Straight to the point. Easy quote. Very responsive. Straight to the point. Easy quote. Very responsive. read more

I highly recommend this attic insulation company both for their experience and expertise but also reasonable rates. Ralph and his crew did an excellent job and it's a great feeling to have everything clean and renewed after 20+ years. I'm pleased that I chose Marathon Insulation for this job. read more

I can't speak to work done since this company/Jonathan never called me back or sent a quote after 6 follow up texts and calls plus one message through Yelp. After reading all the great reviews, I am stumped as to why I'm getting no response, so I want to warn others you may not hear back. * 10/14/25 I called for a visit/quote for attic insulation. He came out 10/19/25. He asked me to text him my email address so he could email the quote. I texted him my email address using the same phone number that he texted me on initially. I never got the quote. * 10/27/25 I texted asking for the quote. No response. * 11/9/25 I texted asking for the quote. No response. I then began home renovations, which took some time. * 6/4/26 I called asking about the previous visit and asking if I could get the quote. He was driving and asked that I call him back in a half hour. * 6/4/26 I called 45 min later, no answer, left message. No response. * 6/5/26, I called, no answer, left message. No response. * 6/8/26 I called, no answer, left message. No response. * 6/8/26 I submitted a message through Yelp. No response. read more

I moved in to a house that had been built in the 1950's but was recently renovated. During the renovation, they did not touch several of the exterior facing walls and I came to realize that those walls were not insulated. I used Yelp Projects to get a few quotes from various reputable companies for blown-in insulation. Jonathan came out to give a quote very quickly. He was polite, considerate of my home, explained the process clearly, and his quote beat out all the others that were done in-person or virtually. He offered to plug the holes which was not a service all the other companies offered in their quotes. When the guys came out to do the job, they were clean, and efficient and did a great job protecting my house. It has definitely improved the temperature in those rooms we did and was worth the effort! It was a great experience and I would highly recommend them. read more

Marathon Insulation - After the insulation was done and the holes were plugged - Insulation Installation Near Me - Sylmar , California

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I had the pleasure of working with Jonathan and Ralph for my wall insulation, and honestly, words cannot describe how grateful I am. Their pricing is unbeatable, their work is fast and clean, and they are extremely responsible, friendly, polite, and respectful. They treated me like family from the moment they arrived. Not only did they finish my house perfectly, but even my neighbor saw their work and immediately asked about it. Since Jonathan and Ralph already had their equipment on-site, they offered him an amazing price too and got his house done the same day--two houses in one shot! Their professionalism and quality of work are on a completely different level. I 100% recommend this company to anyone looking for insulation. These guys are winners, and they truly deserve all the support and success. Thank you Jonathan and Ralph--if you ever need anything from me, even a glass of water, just ask. You guys earned it! read more

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Great experience. Honest and straightforward with their service and pricing. No hidden fees. Insulated my entire attic in about 4 hours.

Working with Jonathan and Ralph was a 10/10 experience. The communication was clear and they arrived on-time for both the consultation and installation. I engaged Marathon for both dense pack blow-in roof insulation and crawlspace insulation. It was discovered that the roof was already insulated, but they were straightforward and honest with that discovery and I was not charged for it. When it came to the crawlspace insulation, their team was efficient and thorough despite the tight confines of my house's crawlspace. They even noted and fixed a HVAC duct that was disconnected from the register box. The pricing was straightforward and fair. They were neat and clean and didn't leave a mess behind. It was obvious that they care about the work they do and it shows. The Marathon team was friendly and personable. I will definitely be reaching out to them for other insulation needs. read more

Just amazing! I inquired about services on Wednesday, received a quote the next day, and by Friday Jonathan and his team were out here. They installed insulation in my backyard studio within an hour. They're the definition of fast and efficient. They cleaned up the area and were respectful of my mom's garden. read more

Marathon Insulation - Insulation Installation Near Me - Sylmar , California

These guys are amazing! I had numerous projects going on at my house at the same time and they had to come back several times to work around other people. They were incredibly accommodating and never complained. This was all during the hottest days of the summer with guys crawling into my tiny attic. If you want someone who returns your call, shows up when they say they're going to, and does the job at an incredibly fair price., then Jonathan and his crew are your guys. read more

We had insulation installed about a month ago, and we felt the difference immediately. Our heater hasn't turned on at all during the night, and it's definitely quieter inside. When Johnathan came over to give us an estimate, he was on time, communicated clearly, and never tried to upsell us. I also appreciated that he gave his honest opinion when I was deciding whether to clean out the attic before installing new insulation. In the end, we opted for attic cleaning, new insulation, and wall insulation injection. On installation day, his team arrived on time, Ralph explained the process again, and answered all my questions. They were respectful of our property and did a thorough cleanup afterward. After they patched the holes in the stucco, I painted over them in just 15 minutes, and now you can't even tell they were there. As a business owner myself, I found Johnathan's communication and professionalism truly inspiring. I highly recommend this company! read more

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Used Yelps "Request a quote" and responded promptly and was able to speak with someone without delay. Came to house supplied a quote and performed work within the time frame and proposed amount. Professional work and honest sales representative. read more

Highly recommend. I used a different company before but like this one more--and bonus the price was better. Honest, professional, and friendly. Owner is a good communicator and is extremely responsive and caring. The rest of the team is hardworking, too! I've already recommended Marathon Insulation to neighbors as I find this company trustworthy and helpful. read more

Having heat problem at home, summer of 2024 (just move in Sep 2023) with new HVAC and bedroom still hot and very cold in winter. Heard about insulation and start researching it. Called around until I got to Jonathan. I called him last year just asking for price and you know, you can tell, just by talking to him that he knows his business, he was not worried about his business as he informed me of what I need to know without hesitations. So when we are ready, I called him back and we did the insulation this January. And been very happy with this. We can feel the difference and temperature is now manageable They work fast and methodically. Finish the job, all walls and attic, about 4 hours. Thank you Jonathan! read more

Super friendly service and better pricing than the popular insulation company I used in the past. They were able to accommodate me on my only day off which was a plus. They arrived on time and cleaned up after themselves. I had a garage wall insulated due to the noise and heat coming into the interior spaces. Noise levels have definitely decreased and I'm sure the heat/cold will be noticeable when the weather isn't so mild (75F as I'm writing this). A+ rating for friendliness and quality of job. read more

Marathon Insulation - Patched holes after blown insulation installed. I drew the grid since I installed another layer of drywall after. - Insulation Installation Near Me - Sylmar , California

Marathon showed up on time. for both the quote and work. Everyone who worked on my house was pleasant and friendly, and they did excellent work including cleanup. I recommend Marathon. read more

I had a fantastic experience with Jonathan and his team. They were on time, polite, and kept the workspace super clean! Jonathan really went the extra mile to make sure everything was completed perfectly. Our house already feels so much cooler from the insulation they installed! Extremely happy with our results working with Marathon Insulation. I highly recommend them. read more

Jonathan had responded to my Yelp request for a quote very quickly. He was the only insulation vendor to give me an upfront price per sq ft. All the other vendors wanted to come out and give a quote. Because of his straightforwardness and honesty, we went with him. He came out to assess the job and gave us the price for a few attic spaces. Within an hour he called to offer scheduling options. Jonathan and Ralph showed up this morning, as promised, to perform the work. Very very nice guys! They worked cleanly and thoroughly the entire time. Jonathan is a small business owner with integrity. read more

Marathon Insulation - Truck backed into driveway. - Insulation Installation Near Me - Sylmar , California

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I needed my attic insulated and am so happy I chose to go with Marathon. They provided an estimate based on photos and were by far the most reasonable of the few who didn't require a visit before providing me with one. I didn't want multiple people trampling through my house before I knew whether they were reasonable or not. They were the quickest to respond and answered my questions thoroughly without dodging the question of price. The estimate and final invoice was the same. No surprises. I'm glad I went with them in lieu of having a ton of people going to my house first to get a quote I may or may not like read more

Marathon Insulation - Before - Insulation Installation Near Me - Sylmar , California

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Fast and efficient. As quoted. No issues. Would recommend. Project completely quickly. Very responsive. read more

When I see glowing, unblemished reviews on yelp or anywhere, I'm immediately very skeptical and prepare myself for disappointment, but my experience was no different than those reviews. My quote request went out via yelp's system and Jonathan from Marathon Insulation was first to reply. He answered all my questions clearly, and having spoken to 4 other reps, Jonathan's friendly/immediate/informative communication was unmatched. Jonathan came out for a free inspection exactly at the time scheduled and was in and out in a jiffy. Another inspection with Pure Eco left a very bad taste in my mouth, so the difference was night and day. Marathon's pricing was also very competitive and they're not the type of business to push for any sneaky add-ons like a car salesman. On the morning of service, Jonathan and 2 technicians showed up right on time and were very respectful that we had a newborn and let us take a moment to figure that out before starting their work. The job from start to finish was approx. 1.5 hours with plenty of photo evidence of their service. The crew tidied up well, but as constructive criticism, a quick vacuum would've been appreciated; no biggy. Overall, I wouldn't have any issue recommending Marathon Insulation. read more

Marathon Insulation - Before - Insulation Installation Near Me - Sylmar , California

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Marathon did an excellent job cleaning our attics after the fires. They were quick, reliable, clean, and efficient with both our times. We did a full removal and replacement of insulation, and radiant shielding, and did it at a better price than pretty much everyone else I called to get an estimate from. Well worth the price and value. read more

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Marathon Insulation was the lowest quote we received for adding blow-in insulation to our attic and to the interior of our bedroom walls. Jonathan was very prompt and communicative in answering questions, and their technicians were efficient, polite, and overall did great work. We can tell a HUGE difference in the interior temperature of our home that I wish we did this project years ago! I was worried how our walls would look after being patched but Marathon also put us in touch with a fantastic and well priced painter who came the very next day and took care of all the sanding, prepping, and repainting. Would definitely recommend working with Marathon! read more

Jonathan and team made the attic insulation process very seamless and was flexible enough to clean up and install the insulation before and after my new heat pump installation. I met with Jonathan to give me an estimate and he was very diligent when he went up into the attic. Compared to the other companies that quoted my home's entire square footage, Jonathan noticed a section of my home's attic that was blocked off so he adjusted my quote down (since they can't install insulation there anyways). He also measured my home's square footage from the outside to confirm. When I set my new heat pump installation schedule, I contacted Jonathan and he was flexible enough to schedule Hazel and Angel to do the clean up first. It was during the summer August heat wave so they did their best to clean up old insulation for 6 hours. After the heat pump installation, Ralph and Pablo came to blow in cellulose insulation. They were careful to not damage the new air ducts. Overall, everyone kept my house clean which I appreciate with three small kids in the family. Working with Marathon was a great investment because with the new insulation, my home's internal temperature is maintained at around 70 degrees in the summer and winter. Before the new insulation, my home's internal temperature would go to the upper 80 degrees during the summer and upper 50 degrees during the winter without the HVAC on. I would highly recommended them. read more

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Great service and they kept the area clean. Would recommend them to anyone looking for insulation!

Couldn't have asked for a better experience!!! From setting up an estimate appointment with Jonathon (the owner) and he answered all my questions (air sealing, rodent proofing and disinfecting attic were included and they even taped any loose ducts at no additional cost!!!!), to Ralph and his team members arriving on time, setting up to remove our old insulation and install in the new R-38 batting insulation. They were extremely hard working, friendly, and they did a thorough job with smiles on their face the whole time. They were also clean and tidy as they finished up. Be sure to ask Jonathan about federal tax credit for insulation. I highly recommend Marathon Insulation team if you have the need for an insulation contractor. Thank you, Marathon Insulation Team! read more

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I was experiencing heat pockets in some parts of my condo and did a yelp search to locate a company to come and check my attic. Marathon was the first company to respond and Jonathan was able to come out asap within the week. He went up there and informed me of all the issues with my attic. His estimate was very affordable and they were able to work a few days later. Fast forward to today. They arrived promptly at 8 am and Ralph the lead was awesome from start to finish. Answered ALL my questions (i had a lot), and was super communicative. They were super accommodating to the fact my place is on the third floor and worked FAST and most of all CLEAN. There were no surprises and everyone seemed honest and trustworthy. From start to finish 2.5 hours for a 400sq foot attic. I'm absolutely amazed with the work and Ralph was able to take tons of before and after photos at my request and video. Definitely would recommend this company. Jonathan and Ralph and the team are honest, hardworking and great at what they do. read more

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Marathon did a great job on my attic. It was a mess up there. They cleaned, sanitized, pest proofed and put in new insulation. They showed up on time and did the job for the price we agreed on without any b.s. They did a great job for me and I highly recommend them. Thanks Marathon! read more

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They did such a great job! Had to put insulation in interior walls and cleaned up so well after the job was done. They were very nice and patient and answered all my questions and concerns! read more

Marathon did an amazing job replacing our attic insulation. The bid was very reasonable and they provided updates as the job was in progress, provided photos upon finishing the job and let me look in the attic myself to see the work. They were quick and efficient, and very informational, and professional. I highly recommend them. read more

Update: a few weeks ago, I texted Jonathan that we had some insulation falling from the air vents. He stopped by our house the next day. We had a disconnected duct and also had signs of rats. I should mention that Marathon Insulation only did the insulation for one of our attics. Our other attic was newer and didn't need to be redone. Unfortunately, the people who flipped our house that we bought took some shortcuts on things and left open an area that opens to the attic on the roof. Jonathon reconnected the duct and also got up on our roof to seal our house. He did this work completely complimentary. It was so awesome of him and just honestly so above and beyond. I had to update my review to say that I was very happy with Marathon Insulation before and now after this experience am just beyond impressed. By the way, our pest control company stopped by the next day and set out traps. No more rats! read more

Fantastic experience! Jonathan responded very quickly, and his team was professional, respectful, and highly knowledgeable. The owner and his team were involved every step of the way, ensured I was happy with the results, and offered the best price compared to other quotes.Thanks to them, I no longer have rodent issues, and my house is well insulated. If you want excellent work, fair pricing, and a team that treats you with respect, look no further. Highly recommend! read more

Jonathan is so professional and a pleasure to work with! He quoted us a great price and got our drill and fill insulation done quickly and efficiently. If we ever need more insulation, we won't call anyone else. read more

I had blown in insulation in my attic through marathon insulation. Everyone in the entire process was professional, quick, honest and the price was competitive. The team who did the install was quick, respectful and cleaned up after themselves. read more

Super great company. Jonathan is very responsive by phone or text. His crew is awesome, flexible, professional, friendly snd hard working. I recommend them highly. read more

Everything everyone says about this company and owner in the other reviews is 100% true. He got ack to right away, set up a time the next day to give me an estimate. He was right on time and explained the process, answered my questions and measured out everything and gave me an estimate right then and there. I called him back later that day and setup a time to come do the work. When the day came for them to come and do the insulation, again on time, the guys were al very friendly and they did a great job and fixed any and all holes they had to do on the inside as well as some we had to do on the outside. I would recommend them over and over. Just amazing! read more

I inquired through yelp, they responded quickly and answered all my questions. They were able to come out the same week. They broke down everything they were going to do, arrived on time, were professional and courteous, and were efficient with time. Overall was a pleasant experience and would definitely recommend them to anyone else looking to insulate their home! read more

I'm a single-family home developer so I deal with installing insulation all the time. These guys were great, their price was wonderful, and getting the work done was quick and easy. I highly recommend them. read more