Polyurethane versus Silicone Caulk for Vinyl Windows

16 years ago

Any opinions on which caulk would be better to use when installing retrofit Vinyl windows. They both claim they remain flexible, both claim they last a long time, and both cost exactly the same, $4.97 a tube. One advantage I see for polyurethane is it is paintable. Does one stick better to vinyl than the other?

Featured Answer

PRO

HomeSealed Exteriors, LLC

3 years ago

^^ HA!

For record, each has pros and cons. Silicone has some nice properties but the big drawbacks are that it not paintable, a new paintable caulk won't stick to it or the surface it was on if future painting is desired, and it collects dirt like crazy. I see white on white window/trim jobs that look like someone caulked them brown a few years down the road, but its just dirty silicone. Something like OSI Quad, Solar Seal, or Vulkem depending on the application are good options... And silicone can be as well, in the right circumstances. The others are simply a better "one size fits all" solution IMO.

Sort by:Oldest

Comments (10)

fhiwindows
16 years ago
Silicone is garbage, stay clear of it. Poly caulking is great if you can get it to cure without dust or dirt sticking to it.
planetjc
16 years ago
Professional grade silicones such as Dow Corning products are not garbage. I pay @$8 per tube for DowCorning 795. Silicones withstand UV better than polys, however, both will last 30+ years. Good polys, such as sikaflex15LM have 50% joint movement capability while some only have 25%. Other professionals have there preferences as well. Both products are only good 12-15 months after production and should be stored at less than 85 degrees. I have had products break down prior to there expiration dates because the distributors do not quality control storage temperature. This is one area we watch very closely and I respect your asking your question. With silicones there is neutral cure and acid cure. You want neutral cure. Acid cure has a vinegar smell from the acetic acid and over time will eat trough most products such as vinyl. I believe you are also referring to 1 part polys, etc...there is alot more to your question than you may know.We use both products for exterior use when installing vinyl mainly using color as a guide as to what is available.
Related Discussions
silicone caulk as glue
Q
Comments (2)
I think if you took a razor blade window scraper and just broke the seal of the silicon caulk you could peel it off of the vinyl fence with just a little prying. I have used that technique to break the seal and take apart other pieces that I had glued together.
...See More
Caulk Around Windows With Brick Exterior?
Q
Comments (6)
The window should be located just above a sloping brick, stone, composite, etc. sill with sealant on all 4 sides because you want to keep rain water out of the cavity. Water that gets into the cavity should drain out through weeps at the bottom of the wall and above openings. Leaving the bottom of the window frame nailing fin unsealed allows water that gets inside the window frame to drain into the cavity and then down to the weeps.
...See More
Caulking exterior windows
Q
Comments (6)
I have a brick veneer exterior on front of home. Had a leak in bedroom beginning of March after a driving rain. Observed the window caulking around that window to have many gap/splits. See pictures at: http://photobucket.com/outwindow In mid March when weather was decent here in ohio I spent two hours getting all old caulk off window frame and brick and caulked new along sides top and bottom. I do not have pictures of the new caulk job but all joints are sealed now. April 4 we had a driving rain again and again water leaked but not as much as in March. After reading the post, are you saying I should not of caulked along the upper seam at the bottom of the window as pointed out with the red and yellow markings in the picture? Thanks
...See More
Leak in vinyl window frame
Q
Comments (1)
Do not caulk any of the weep holes. Post up a picture of the windows in question and I will let you know what might be the issue(s).
...See More
Michael
16 years ago
Garbage?...Have you ever used Novaflex?

You must have been using the cheap end products to have that kind of experience.

Michael
fhiwindows
16 years ago
If Novaflex comes in a blue and white tube and you have to screw on the end, then yes I have used it and it is a good product.

The garbage I am talking about is the stuff that the home centers sell. After a few months it tends to lose it's bond and can be pulled off. Since most of the homeowners on this site will make their purchases at home centers products from contractor only supply centers are out of their reach.
allaboutdoors
16 years ago
We use Solar Seal 900. It's a tripolymer rubber caulk. Beats just about anything on the market. We didn't trust studies put out by the companies themselves, so we did our own.

We caulked two piece of PVC together with about every caulk you can think of and put them on our roof. The Solar Seal is still the last one still pliable and intact.

It's expensive, but worth it in the long run.

Here is a link that might be useful: All About Doors & Windows
Michael
16 years ago
Is that advertising I see there?

Please read the terms of agreement.

Michael
terry1022
12 years ago
I agree with planetjc. Products like dow corning 795 is about the best you can get when it comes to silicones. Ive used many polyurethane brands over the years and in my opinion I havent found anything better then Tremco dymonic fc. The stuff remains pliable and holds like iron. It doesnt matter what kind of caulk you purchase, it can be the best that money can buy and it could turn out to be totally useless and fail immediatelly. Its all in the prep work and applying it properly.Prep work is key to any good, long lasting caulk job. Even the cheap home center polys and silicones will last far longer if you prep and apply properly. Truthfully, not just anyone can caulk, to be a pro you have to know your product, what sticks to what, and most importantly, preperation and applying it properly.
Pete Moore
3 years ago
We are talking about vinyl right? Use silicone on vinyl, not polyurethane, there two different breeds learn the application before you use anything....do a pull test if you think its right, before you proceed ,24years of just caulk for me .
PRO
Windows on Washington Ltd
3 years ago
Hopefully they have sealed them in at this point.