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-   -   What type of Caulk to Use (http://www.diychatroom.com/f2/what-type-caulk-use-112817/)

Einhorn 08-03-2011 08:28 AM

What type of Caulk to Use
 
Our condominium was built 9 years ago. Most of the caulking is still looking good and filling the gaps, thus we don't feel that a complete removal of old caulking and re-caulking is required. (A total of 150 windows, doors, dryer and bathroom air outlets, etc..)

We've found a contractor we'd like to use who offers us three choices:
1 Removal of old caulk, clean, reapply new caulk (very expensive)
2 Simply patch areas where caulk has a gap between frame and brick.
3 Apply new caulk the entire length of the old caulk, just applying more of it, to form a wider seal.

We'd like to go with option 3 because its the same cost as option 2 (except for more caulk). Again, we don't feel that complete removal of old caulk should be required on a 9 year old building.

The contractor told me that good caulk is expensive, but will last much longer. So what I'm looking for is recommendations on what is a "good caulk".

The contractor specializes in painting. He does caulking also but he is not a dedicated caulking contractor.

He mentioned that there's Oil and Water based caulks. I asked if he could tell us what was originally applied but he says that with 9 year old caulk, he can't really tell.

For paints, the thinking was, historically, oil based paints will stand up longer when used for exterior purposes. Is this the same for Caulking?

Essentially, we have a good contractor, but I want recommendations on what to use for caulking material. I know that there's a lot more than Oil and Water based, there's silicone, and lots of other options, so any recommendations would be appreciated.

Mr Chips 08-03-2011 09:26 AM

Butyl Flex lasts a long time, but shrinks a lot. will not become brittle over time. Can be painted once it cures

Oil based is probably cheapest, but it shrinks some, and overtime the oils dry out, causing it to crack and pull away. Will not last very long before needing to be replaced.

Latex is a little more money, will shrink a little less, but doesn't stick that great to metals. You really should paint it if used outdoors to slow down UV damage

Silcone is most expensive, barely shrinks at all, will stick to just about anything, but can't be painted over ( if that matters)

You should remove any areas of old caulk that are in really bad shape and pulling away

Maintenance 6 08-03-2011 10:58 AM

I'd find a new caulking contractor. A good one can tell the difference between one caulk and another. At least reasonably close. Applying patch caulk on top of old caulk is a bad idea. You'll create a much wider joint. Probably exceeding the working width of the caulk, meaning that it will fail too in short order. Second is you'll have caulk adhered to an area outside of the joint. In the future, when it's time for a building wide recaulk effort, you'll have the stains from the patch caulk to deal with. Or you'll end up with a really terrible joint design trying to hide all the stains. Your best bet is to have the split areas cut out and recaulked without stripping out the entire length of joint. A good caulking contractor should also be able to evaluate why the caulk failed in some areas and not others. The biggest reason for caulk failures are bad joint design, poor surface prep, material misapplied or wrong type of caulk for the surface.

Broughton 08-03-2011 11:13 AM

Ge makes a paintable silicon caulk.

Maintenance 6 08-03-2011 05:05 PM

No-one here knows how big a caulk project you are looking at, but I think you really want to stay away from any consumer grade sealant. I would look for something from Tremco, Pecora, Dow or others. Not something in 10 oz. tubes from a box store.

Einhorn 08-05-2011 08:24 AM

In reply to all

-the caulk will never need to be painted over...as long as its something close to white/off-white, all is good
-any old caulk that is pulling off will be removed. any areas that are already too wide to cover will have old caulk removed and be totally re-caulked. But areas that are otherwise in good shape, and might have 1/2 an inch of caulk, would be caulked over, so we have a width of 3/4 to 1 inch (1/2 inch on either side of crack, max, which shouldn't be too much for exterior caulk to handle)
-the caulk is to fill the gap between brick wall and plastic/pvc window/door frames. so it will need to stick to plastic/pvc, brick

Any specific brands or product lines would be helpful. A quick search turns up people recommending Tremsil Silicone, others a product called "Quad".

Thanks for any additional suggestions.

kwikfishron 08-05-2011 08:38 AM

I use almost exclusively polyurethane caulk (never silicone) on exteriors such as Vulkem or Quad.

It you’re not going to cut out all of the old caulk the why do anything with it.

I can’t imagine looking at a inch wide bead of caulk. :eek:

joed 08-05-2011 12:20 PM

I second polyurethane. I wouldn't waste money going over the old caulk. If you don't want to remove it all then just patch the bad spots. I assume the bad spots will be cleaned of any loose caulk.

Maintenance 6 08-05-2011 04:13 PM

Why would you want to create a 3/4 to 1 inch wide joint? At some point you will recaulk the entire joint and have to somehow clean that up to create the proper 1/2" joint. Urethanes such as Tremco Dymeric 511 or Pecora DynaTrol have excellent adhesion to masonry and will do a decent job sealing against PVC. There are some "next generation" silicones like Dow Corning 791 that have decent adhesion to masonry and remain more flexible, but won't accept paint. I've used both and it looks like the silicones are holding up as well as the old tried and true urethanes. These are not the same silicones that you get in a 10oz. tube at the orange or blue apron stores. Caulking over top of old caulk is a failure waiting to happen. In your case, instead of adhering to the window and the masonry, the new caulk will adhere to the old caulk and shear in the exact place that the old caulk did. You create a joint that is completely wrong for the properties of the caulk. There is a reason why the old joint failed. Now you'll create a joint with even much worse characteristics.

kevsprojects 08-06-2011 08:04 AM

You might want to look at the difference between DIYing it Vs Contracting it out.

http://www.liquidnails.com/pro/index.jsp

Liquid Nails makes a caulk/sealant for anything that can be caulked or sealed.

This one http://www.duspec.com/DuSpec2/produc...Type=datasheet

would be the one to use. A good caulk (above) applied to a clean surface will likely outlast the project being caulked and/or the person applying the caulk!:eek:

I for one would be curious what they charge.

tpolk 08-06-2011 08:17 AM

if they are not tooling their joints keep looking

Einhorn 08-07-2011 10:42 PM

Ok I've read enough from this board, and elsewhere, to understand that caulking over caulking is bad. We won't do that. It was tempting because its only got one or two small holes in each window, but if we just re-caulked the spot, it would look like a patch job. In my mind, we would have been creating the ultimate seal with a 1 inch caulk joint !!! And we were only going to do that on the windows that aren't viewable from street level, which is most of them. For cosmetic reasons, we would have removed all the caulk and re-done it properly for anything thats easily visible. Ah, the best laid plans ...

So now that we're looking at a total removal of all caulk from 150 plus windows and doors, I really need to know how you decide between a Silicone based product like Corning 795 and a Urethane based product like Tremco Dymeric 511. We have no need to ever paint it.

After typing the above, I looked at the last comment, about figuring out why the original caulk failed before we recaulk. I paused for 1/2 hour to examine them and here's my conclusion. The builders had very poor quality of workmanship on everything else they did, so this shouldn't be an exception. On the front doors, it appears that they used the caulking to make up for too much extra space between the door frame and the brick. So imagine your average builder-quality caulk being stretched to fill a 1-inch gap in several spots, and how that would look 9 years later! Those are the major failures and fortunately those are less than a dozen.

The other failures, at the window, would appear to be simply a guy applying caulk too quickly. In some spots, they just didn't tool it into the joint or get a good seal with the brick or pvc, and it just pulled away, probably the day after it was applied.

Maintenance 6 08-08-2011 07:19 AM

Please reread the last sentence in post #3. Sounds like you suffer from at least two reasons for failure. When you recaulk, be sure the contractor uses backer rod and/or bond breaker tape where needed. Too often I see joints an inch wide and caulk piled in an inch deep. There is just no way that the material will work in that kind of joint. Most pro grade caulk today is very good, it's the application that suffers.

Einhorn 08-10-2011 12:39 AM

Will "Backer rod and/or bond breaker tape" solve the problem of too much space between the wall and the door frame? One solution that I've seen on some other doors was an extra piece of plastic/pvc midway between the door and the wall. So the brick is caulked to that extra piece with 1/2 inch of caulk, and the extra piece of plastic/pvc is caulked to the door frame with a 1/2 inch of caulk. In those instances, it looked ok, and the caulk did not fail. But in other instances, the builder tried to span the gap with caulk and it pulled away.

Incidentally, I grabbed some of the caulk with a pliers and pulled it off, in order to evaluate it. I was surprised to see that even the caulk that had pulled away from the wall was rigidly stuck to something behind. That something is a thin, black plastic material that resembles black electrical tape, but just not as flexible. Ist that bond-breaker tape?

Maintenance 6 08-10-2011 08:14 AM

Whatever the black material is, it does not sound like bond breaker tape. It sounds like this may have contributed to the joint failure. If the caulk bonded to that, it had to give up somewhere else. Caulk bonded on three sides is a very bad joint design since the caulk cannot stretch in 3 dimensions at once. A backer rod installed in the wide joint is a must, along with a caulk that has the correct dynamic properties. A joint that is an inch wide will not last if the caulk is an inch deep. The caulk needs to stretch and compress with changing weather/ temperature. In a real thick bead of caulk, the amount of force needed to stretch the caulk will overcome the adhesion to one or more sides and the joint will fail. Splitting the joint into two smaller beads may be a solution, of course that still depends on the smaller beads being properly installed.


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