Lanco 5-Gal. Ultra-Siliconizer Roof Sealer-RC905-2 - The Home Depot
Message to Our Customers


Model # RC905-2

Internet # 202086637

Store SKU # 548821

5-Gal. Ultra-Siliconizer Roof Sealer

Lanco 5-Gal. Ultra-Siliconizer Roof Sealer

This item has been discontinued.
The Home Depot no longer carries this specific product.



Model # RC905-2

Internet # 202086637

Store SKU # 548821

This product is a single component 100% acrylic silicone sealer for roofs and walls with outstanding adhesive properties that will provide a thick, high performance, water and weather resistant seal on most surfaces, usually without need of a primer coating.

  • Waterproof for immediate repelling of water
  • For commercial and residential roofs
  • Applies blue, dries ultra white
  • 50 sq. ft. Coverage
  • 2 hour Drying Time
  • 100% Acrylic/Silicone Technology

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.


Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Coating Base 
Coating Consistency 
Color Family 
Commercial / Residential 
Commercial / Residential 
Container type 
Dry Time 
Fire Rating 
Roofing Product Type 
Roof Coating 
Surface Recommended 
Modified asphalt membranes, built-up roofs, polyurethane foam, concrete, aged galvanized metals, bonded tar and gravel. 
Warranty / Certifications
ENERGY STAR Certified 
Manufacturer Warranty 
Limited Warranty 


Rated 4.4 out of 5 by 11 reviewers.
Rated 5.0 out of 5.0 by Wrong specs, 300 sq. ft. coverage per bucket! The coverage area is not 60 sq.ft., it's actually 60-80 sq. ft. per gallon! You should be able to do about 300 sq. ft. with a 5 gal bucket. Read the PDF guidelines on Lanco's website "Apply the first coat by pouring container of Lanco® Ultra Siliconizer™ onto the roof and spreading at a rate of 2-4 gallons per 120-240 sq. ft.." October 24, 2011
Rated 5.0 out of 5.0 by Reduced kitchen ceiling temps by over 30 degrees My metal strips supporting my drop ceiling in kitchen add on to house would be too hot to touch in the afternoon even with lots of insulation. The AC Was working hard. After first thin coat applied on Labor day, the strips were only about 78 degrees when it was well over 95 degrees outside. It rained about 5 hours later and nothing leeched off the roof. Put on 2nd coat 6 days later, is so white it hurts to look at it even with dark sunglasses. No doubt that my next electric bill will be lower as it no longer runs as long to cool the house. This is over a mostly flat roof wtih a gentle slope that mostly dries quickly after a rain. Next question, should I try it on the Architectural Shingles? The light gray color is getting darker after 14 years. Would definitely help cool the attic. September 12, 2011
Rated 5.0 out of 5.0 by Great Product Excellent Product. i applied a coating on my winter Home at Melbourne Beach 3 years ago and not only did it completely seal my spray foam over steel roof, but the cooling electric monthly bills became half. The only problem i am trying to resolve is how to purchase (12) 5 gal. buckets of SKU # 548821 in my local summer store #2715 in Grand Rapids, Mi. . @ under $90/ 5gal. bucket, i certainly would be the 1st. in my neighbor hood with an excellent, long lasting New Roof. i can not say enough about the inside thermal reduction after using it. Also: having the Dade County " Approval " means , It Works ! Doug B. June 9, 2014
Rated 5.0 out of 5.0 by Awesome Product I own a roofing company in the Virgin Islands and we do strictly waterproofing and minor repairs of roofs. We have been using this product for many years now and it is the only water based Acrylic product that we use. When properly applied, according to manufacturer's specs, it forms a superb waterproof membrane on your roof that does an awesome job of repelling water. Best when used on roofs with good drainage and little to no water ponding. Be sure roof is properly cleaned first in order to get a good bond. September 13, 2013
Rated 5.0 out of 5.0 by Older roof completely looks new! I had a leak on my South Florida home where the back flat roof was 10 years old and starting to leak. I had just at 2000 square ft of flat roof. I used 7 X 5 gal buckets. The roof looks great. Reflects the sun and the interior of the house stays cool. Be sure to prep the roof. I used a stiff broom to sweep all the debris off and cleaned with a mixture of bleach and water. Allowed to dry for 2 days and then applied Ultra Siliconizer. I did 2 coats. 1 then the second 24 hours later. It looks like a new roof. Had many roofers give me quotes for a new roof at 12K. Very happy this stuff works as good as it does. I plan on re coating with 1 coat each year. Should last just about forever. All flat roofs in Florida should be coated with this stuff. But of they did the Roofers would be out a job. January 23, 2012
Rated 5.0 out of 5.0 by This is the greatest stuff EVER!!! Why am I so excited about this product you might ask? I live in hot, humid South Florida and our house was built in 1930. There's no attick, only wind turbines, and the roof is torch down. There is no central AC due to the lack of attick and even though the pipes could be run externally, I won't due that due to the six month hurricane seasonal stress. The entire inside of the house is cement stucco - both walls and ceiling - no dry wall! So, when it gets hot and the sun starts beating down, it turns the inside into a brick oven. The ceiling inside gets hot to the touch. I painted my roof with this product and the results were mind-blowing...I mean literally! Now, the inside ceiling is stone cold, I no longer have to run all of my window 'bangers'. The roof is so white you need a pair of sunglasses to look at it. What's really mnid-blowing (besides the extreme tempeture drop) is that the only room I didn't paint was my office which is a flat roof that occassionally puddles. The ceiling in that room still gets hot to the touch, and when you walk through the door way into the rest of the house you can immediately feel the difference! This stuff works so well, I used it also on a huge hydro NFT system I have in my yard (10' 4" pvc tubes) and the chiller no longer struggles to keep the water temp at 75! I'm completely sold on this product and have recommended it to just about everyone I talk to! April 20, 2012
Rated 5.0 out of 5.0 by best of the best 2 coats of this stuff no primer needed roofers dont want u to know about it it will waterproof ANY kind of roof even palm frawns if your in a hut February 2, 2012
Rated 5.0 out of 5.0 by bernard I want to complement the Lanco company on how well they stand behind there product. I used there product and when I need needed assistance with the product they were very good at helping me get the job done right. Not many companies do such a great job at taking care of there customers and Lanco did Great. I highly recommend this product. Thank you Lanco. March 25, 2014
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Store Exclusive. This item is available for purchase in select stores only.