Caulk? Or Something Better?

This is polyurethane caulking. The width of the bead suggests that someone "goofed" big time on a measurement during construction, and it was probably allowed because the store was opening the next day, or something. The primary supplier in the US is Sikaflex. You can find this at Home Depot, it comes in self leveling, (for concrete expansion joints in driveways, sidewalks, etc.), or non-sagging, seen here. It comes in oversize caulking tubes, for which an oversize gun must be purchased. This bead was actually very labor intensive. The applicator probably taped off both sides, applied multiple beads of caulk, and then tooled it with either mineral spirits or soapy water to achieve this result.

It's most likely polyurethane chalk the size of the bead to cover the fact the window is too small for the opening as Kramarat suggests.

There are many manufactures of polyurethane chalk. Our company does installations of windows. We do testing on the products we use our choice is XtraBond 9500. Has good bonding properties, is non yellowing, extrudes at low temperature 0° F.

We do commercial properties multi-family housing low odor was a big point has no solvents.

I have seen that one also. I brought up Sikaflex, because it sounded like he wanted to buy some. It is available at Home Depot, unfortunately, the employees rarely know what they have or where it is. It's not by the caulking, as you would suspect, but tucked away on the side of the store with the sand, concrete, etc. The oversize guns will be found in a completely unrelated section of the store, again, not by the rest of the caulking. ( I guess I should throw out the warning to the OP, that if you are unfamiliar with caulking, this stuff can quickly become a big sticky mess).

We had to address the odor some of these sealants give off while curing. Never used Silaflex so unfamiliar with it. Some of these sealants with solvent base can be quiet strong. We found those with health issues might have a problem. Some just complained about the smell. This was our solution. Just thought to give an alternative in case.

Note do not recommend any that have a rough texture to them. Though they might work well as a sealant. The rough texture will gather dust and dirt in it. Rain washes the air clean of particles as it runs down the rough textured chalk it collects it. They need to be cleaned regularly. Those that are smooth will not hold the dust.

I'd like to give it a try. Is it polyurethane or some type of acrylic? I've been working around solvents for years, so smells don't really register for me.

Modified Polyurethane

www.xtrabond.com

I am not sure what the material is in your photos.

In addition to the comments above, another option may be;

Given the width of the joint, the only commercial grade caulk that I am aware of that will successfully seal a wide gap (up to 6" wide) is Permachink which is used on log homes to seal between the logs, around windows and doors to prevent migration of dirt, dust, water, ect. into the home. This product can be used inside or outside.

I have quite a bit of personal experience with this product and am satisfied with its performance.

You fill in the gap (below the finished surface level) with "backer rod" (closed cell foam strips sold by Permachink), apply "Permachink" caulk and tool the Permachink using a spray bottle of water and a spatula to get the surface appearance that you want.

The purpose of the backer rod is that you only want adhesion on the ends of the adjoining surfaces and not across the entire span. This allows the product to expand and contract without splitting or tearing away.

Here is a link: http://www.permachink.com/?gclid=CNimkof5pKMCFQfyDAod9i2f3Q

Once you apply the "Permachink" and allow it to cure, the manufacturer does recommend an application of a top coat (which the on-line store has available).

Visit the site and read the literature, it may fit your need. I have dealt with this company for years and am 100% satisfied.

Hope this helps – Good luck!

The first posters are all on the right track. KJK/USA hit the point about backer rod, which is the key to success on wider joints.

I have seen successful caulk joints 8" wide; these were not an attempt to cover an error, but a part of the designed building expansion system.

Other than that, caulk material selection depends on service. I have also used SIKAFLEX with satisfaction... expensive, but a good industrial sealant. ^{_{Not really an endorsement of SIKA, but a satisfied customer comment.}}

The finish in your upper right photo is typical of caulking applied with some skill. If it had been post-tooled, it would be smoother. I'd agree with others that is appears to be a modified polyurethane.