Is silicone sealant compatible with extruded polystyrene insulation?
Why would you want to use silicone it does not stay stuck and it is the worlds best release agent. Silicone won’t even stick to silicone,in the area that silicone was applied. The only propose is high temp applications. Polyurethane caulk is far superior and should be compatible with extruded but what is the application remember the sun will eatup extruded
Anonymous should check his or her facts before claiming silicone doesn’t stick to anything – this is simply wrong, and there’s plenty of testing and product experience to verify that. Both urethanes and silicones have appropriate uses.
The place to start to answer Dawn’l’s question is to talk to a few of the major silicone sealant manufacturers. They can advise if they have tested for adhesion, and also advise on the specifics of the application - there may be a better choice than silicone. You can also perform a simple test, which the manufacturer’s can advise you on as well. The question I would pose is this - if the sealant needs to stick to the insulation, then I’m wondering if the insulation is exposed to the atmosphere. If it is, UV degradation of the surface could affect the ability of anything to stick to it over the long term.
I believe someone needs to reread my post. I did not say or imply that silicone does not stick to anything, it sticks to everything initially. The problem is that in more cases then not the bead will break from one surface or the other, not fail in the bead (within a year). So based on this observation it would appear that it has a small problem staying stuck. Then at this point to be able to go back and recaulk you need to completely remove the existing caulk and the residue that remains on both surfaces left by the silicone. Everyone should try this so they can have a good understanding as to how wonderful silicone is. So now call you manufacture or rep and ask to see their testing data on recaulking an exiting silicone joint or their adhesion to silicone and or silicone residue.
I guess “someone” would have to be me, since I’m the one who responded to the post! Anon, you are welcome to address me by name, rather than “someone” even though you conceal yourself.
Still, I do not believe that the facts bear out adhesive failure as described by anonymous as being a common or universal failure mode with this product. If this is so, tens of thousands of building facades built worldwide which are sealed with silicone would be leaking. Perhaps there have been some documented failures due to improper priming or substrate preparation, or incompatible substrates.
If anonymous (or anyone else reading) can cite some references in the literature or publications, or documented cases of significant failures (known to the industry) where these products have been shown to be inherently deficient as a product, I’d certainly like to know about it so that I can reach my own judgement. I think that the professional readers of this forum would also be interested.
this seems as good a time as any to address the issue of Anonymous postings. I find it very difficult to lend any credence to information provided from an anonymous source. This thread is an excellent example of why. It sure sounds to me like Anonymous (in this particular case) is somehow connected to, or a representative of, a polyurethane sealant manufacturer.
Ive heard in other posts about the perceived necessity of protecting ones identity to keep the bosses from finding out about use of this forum on company time. I, for one, would be thrilled to have an employee who was actively seeking (and sharing) information with the vast body of knowledge and experience available here in 4specs.com
Anonymity may protect ones identity, but it conceals any significant background knowledge or credibility.
Doug,
Unfortunately, your viewpoint is rare in my experience.
I have difficulty in answering my current “boss” (previous one was not any different either) about which project (sometimes gov’t, which BTW do run audits on occassion) I charge this “overhead-function” time to. I’ve already been threatened with possible layoff and no “merit” raises for not putting forth “significant” overtime efforts (I expect by upcoming annual personnel review to be less than positive).
PS - I’m NOT the Anon above
I agree with Doug’s comments regarding anonymity. Perhaps if references or technical information is presented along with their post, it could lend more credibility to their statement.
Regarding Silicones in General…
The posting regarding failure problems is totally incorrect. Perhaps there are some failures to adhere to substrates incorrectly primed or cleaned, but the same can happen to any sealant. Also, there are failures attributed to many sealants of all kinds where it adhere’s to the immediate substrate (like a coating on metal or masonry) and the coating fails. That’s not the sealant’s failure or fault. Silicone provides one of the better and longest lasting bonds of sealants for architectural uses - better than polyurethanes in both life of the sealant joint and strength of bond.
Over much of my career for building facades, I used polyurethanes almost exclusively. Now for the past 8 years or so I have used silicones almost exclusively. I still use polyurethanes for walking surfaces and for the base of building joint.
If silicones were such poor performers, then the course of history would have been changed, and there would be no such thing as ‘exterior flush glazing’ where insulated glass units are adhered to the curtain wall framing in not only 2 sided structural glazing but 4 sided structural glazing. Polyurethane’s simply can’t do that.
There are other conerns that one needs to pay particular attention to with silicones, as one does with any material.
The related comment about its the worlds best release agent is disingenuous. Many materials depending on their formulation can be both good at something and good at doing exactly the opposite. Look at carbon - then look at carbon fiber…big difference.
It is incredibly unprofessional to post a comment so critical of something without reference to anything other than anecdotal evidence. Provide the sources, the specific test references and how/where to go get them.
As to Dawn’s original question and adhereing to polystyrene insuation…
I agree with the other points that there is a real concern that the insulation is the substrate. There should be something else there, some coating, cladding, something else. A sealant bead is just that, and it is hand placed material where one could easily leave some part of the substrate exposed which would lead to failure of the insulation due to exposure.
The condition of use, how the insulation is being assembled, would be good to know for any recommendation.
Concerning anonymouse posts…
Colin has mentioned a couple times why he prefers not to restrict them. Some of those reasons are stated by those listed above that have unfortunately obtuse employers.
Having since the mid 1980’s personally moderated extremely large forums with several hundred posts a day, I have to agree with his position. Professionally and personally, I wish we did not have to have them. On the other hand, it can limit participation.
As long as there are those willing to step in to respond to inappropriate postings, there is no problem. It would become a problem if they got out of hand, which currently they are not.
Curiously, some of the threads where people have responded to inappropriate anon postings their technical presentation countering them have resulted in very well thought out and valuable information on the subject.
On the other hand, there are always psuedonyms.
William
Wow what a listing of comments…I have had experience with EPS board and silicone sealant contact..We recommended a neutral cure medium modulas silicone sealant and had great results. Comments reguarding “SOLVENT” based polyurethanes will have a problem with EPS.
p.s. Gettem John
First off, John, Doug, Tomas, William and J, I did not mean to upset anyone. I guess I didnt think about the aspect of someone having put his or her confidence in a product and then hearing a broad statement of failure, it can make anyone uneasy. We have all been burnt on a product thru our careers that was most certainly not my intent.
I am not a Rep or manufacture of a urethane caulk. You think you did not like me as Anonymous wait until you hear this. I am a third generation and plus 25 year roofing contractor Ouch. I so what am I doing here, well there is a lot to learn here and we cant ever stop learning.
So let me explain my frustration with silicones, every trade carries a ton of this stuff around in their trucks and use it for everything they can. Because that is what the reps and supply houses tell them to use. They all say it is the greatest product ever, and we also are not talking about the quality of product that is probably used in a building facade. They use it to plug and seal any and everything, and usually use an entire tube on a hole.
And why am I bringing this up here, well I know you design the buildings and after the first year are free and clear of the project (you know what I mean). Say a crack opens up in a wall in the second year and someone goes out and fixes it with silicone and does not prep it correctly. Well their back every six months to a year recaulking. Now if they used urethane it sticks better with out prep and will last 2 to 3 times longer and can be recauked much easier.
So when you go back ten years later to get the chance to design the addition
Wouldnt you rather hear Well we had one little problem and that was it
Or the building started to leak in the second year and never stopped we are all toast and it wasnt even a leak in the roof. Well this was just a simplified example.
Our trade is probably the only one that lives with the building for ten to fifteen years (due to the warranties) to see all of the problems. The industry just seem to be getting worse and not better maybe its because there are just to many product on the market today.
Well I will go back to the sidelines
CJ
Anon,
It has nothing to do with “… having put his or her confidence in a product and then hearing a broad statement of failure, it can make anyone uneasy.”
It has to do with there simply being no evidence for this when silicones are correctly specified and installed. I won’t (and don’t) speak to the issue of some inexperienced user installing the first tube of any product he runs across at Lowes or Home Depot - and I won’t speak to the issue of trades on the project willy nilly installing something they have no understanding of and that quite likely was not specified or submitted for approval.
When I see something like this said, “…well I know you design the buildings and after the first year are free and clear of the project (you know what I mean).” I can only reply, that, no, I don’t know what you mean, and indeed, I think you have an incorrect opinion of the Architectural profession - at least as it applies to 1st class commercial and high rise residential construction.
Our office has been in practice since the late 1930’s. My personal experience is 27 years.
That entire time I have observed and followed silicones closely. I have used them without failure in major projects dating from the mid 70s in 2 sided and 4 sided structural glazing. Though I favored polyurethanes for general sealants on vertical facades, there have been some projects that date to the early 1980s that due to their construction required silicones. Since last half of the 1990’s, I have used silicones exclusively on vertical facades.
There have been no failures - and the silicones actually seem to perform better than advertised.
We are not a firm, that designs and walks away. And many of our clients do not ‘flip’ their buildings but continue to own and manage them. So I have a continual history for a large number of buildings, multiple owners, and both polyurethanes and silicones.
We don’t see failures.
Also, we don’t specify, nor permit the use of, just any tube of sealant. We specify specific sealant types for various conditions of use. We require submittals, and we don’t permit substitutions without considerable documentation (and actually I have not had an exterior sealant substitution request but about 3 or 4 times in 20+ years and they were not permitted).
There is work in what might be called light commercial construction where the architect delivers his documents and that’s about all the Owner wants him for. Then the Owner permits substitutions of just about anything, the Architect is never consulted and there is frequently no repeat business - or when there is, the Owner intends to do things his own way and doesn’t bother to inform the Architect of past problems (which may not have been caused by his selections anyway).
In short, I can take just about any product out there and make it fail due to improper installation or incorrect product for the condition of use - and this is the kind of evidence you seem to point to. But, silicones, correctly specified and correctly installed, have a long history of quality performance and high reliability.
I hate to jump in here over a year later, but the issue of silicone vs. polyurethane just came up in our office. Ive recently been questioned about our specification of polyurethane on working joints and exterior locations. We specify a two-component, polyurethane sealant, typically.
My colleague is telling me we should be using silicone instead, because, as he states, it is longer lasting, it resists ultraviolet deterioration better, it stays pliable longer, and remains moveable through a broader temp. range, etc.
What Im hearing from some of you wiser gentlemen, is that polyurethane is appropriate in some locations, and silicone is appropriate in other locations. I’m talking exterior only in this case.
Can I start up the thread again to discuss possible conditions and uses of each? Perhaps a comparison of properties, and confirmation or refutation of my colleagues statement above?
My experience is that polyurethanes, although not as durable as silicones, provide a greater variety of colors (sometimes custom colors) which the designers like. However, this is changing with the introduction of Tremco’s Spectrum 4-TS field-tintable silicone sealants. I also have some problems with silicones being dust collectors, and you also have to be careful with its use on porous materials like limestone and some bricks.
I have been specifying Sonolastic 150 as my general sealant. Its a Silyl-Terminated Polyether. This product comes in many colors (much like Sonneborns 2 component polyurethanes) can be painted if necessary, deals well with high heat (like silicones,) and generally performs much better than the polyurethanes.
Brett-
Recently Tremco has been doing box lunch seminars in our area on basic sealant information. Since they make both flavors, the presentation was fairly unbiased towards either polyurethane or silicone. They discussed the when to use which issues and presented a lot of good information about selection criteria that was useful for both young pups and old dogs like me. The bottom line is of course that sealants are not really a one-size-fits-all product.
I mention Tremco only because they are actively pushing the seminars in our area, probably as an opportunity to introduce the Spectrem 4 tintable silicone product mentioned above, but I must say it wasnt really a marketing presentation. I am sure if you have interest you can probably get them, or one of the other manufacturers who makes a lot of different sealants (Sonneborn, Pecora come to mind) to do a similar presentation for you.
Thanks George, I’ll contact them. Unfortunately, we have a two month back log on lunch-n-learns. Probably bring them in to sit down face to face.
P.S. I would like to be an old dog someday, just an old pup now, but this job may end up killing me!
I have been on both sides of the polyurethane/silicon issue as it has evolved over time.
Several years ago, the principal silicone manufacturers created a solution to the ‘dirt’ problem. I did not actually switch over to the use of silicons on the facade of the building until mid 2000. I specify only the brand name and manufacturer of the sealant that I know will not get dirty (and even it will if it is dusty during the first 3 to 6 months of the curing process)…and in which case I also require that the sealant manufacturer warrant against it becoming dirty and clean it or wash the facade if it does. That has happened only a few times (lots of dust from adjacent construction during hot summer months typically). There has typically been no complaint, and several years later the very light buff sealant color remains nicely that.
I don’t permit substitutions on this material, they are all rejected, and I specify specific sealants from 4 manufacturers and no one else. I have not even had anyone propose a substitution, and the sealant manufacturers and their reps are all satisfied with the language that I use.
The only place where I absolutely retain polyurethanes is in horizontal traffic surfaces or at the building to pavement joint. Because these joints are subject to foot traffic (and sometimes vehicular), silicone just can’t take the abuse as well as the horizonal grade polyurethanes. The silicones for horizontal use have improved a lot, but they are still not as tough as the horizontal grade polyurethanes.
Tremco and Pecora both make both types, and both have good information. As noted above, Tremco probably offers more education opportunities, though I have found that if you are looking for a one on one they both able to provide equivalent support.
William