There are a lot of options out there to pick from when it comes to caulking new vinyl windows. Two brands I see every now and then are DAP and QUAD. DAP Alex Fast Dry Caulking, in my experience, does not adhere very well and is likely to dry out and crack. DAP does not expand and contract very well, so with movement in a house over time, it’s going to separate. It is a low-end caulking, and I would recommend something more resilient for this type of project. On the other hand, QUAD is a very good product. The only reason I prefer not to use QUAD is because it is not a water-based product. This means that you’ll have to use mineral spirits to clean up any mess, and this is not a good fit for the sponge caulking method I like to use. The back of the QUAD product also says “Do Not Tool”, which means that you’ll have to go very slow to get a nice bead and will have to get it just how you would like it on the first try out of the tube without touching or smoothing it out.

The caulking, or sealant, I like to use is Tower Sealants AU-1 from Paint Life Supply Co.  It expands and contracts better, with more flexibility than QUAD and DAP. It’s a water-based product, and in my experience, it bonds better than any other product that I have used in the past. This is a great product to use with the sponge caulking method, and it fits in a standard caulking gun. It is a construction-grade sealant that will give you a good seal and is paintable. Fun fact, it was originally designed for the large gaps in concrete tilt-ups.

For the sponge caulking method, I start by getting my sponge wet in a bucket of warm water. It’s good to keep this nearby so that the sealant doesn’t get built up on the sponge - it’ll start to get messy real quick. After I wring out my sponge, I cut the tip of my caulking at a 45° angle. As long as you do not hold it sideways or up, this cut is going to make it so the caulking lays flat on the surface and help it get into the crack you are trying to fill. I apply just enough caulking to fill the gap. Too much caulking applied and you will end up wiping off a lot of sealant - it’ll end up being wasted material.

Take your time once you start. Create a nice bead and go slow to make sure you’re filling that gap. Another great feature of the AU-1 sealant  is that it tools amazing - just like butter. Once I filled the gap with caulking, I wet my finger and press down just enough to where I can feel the sealant. Make sure it fills the whole gap and keep it off of your surface as much as possible. Personally, I don’t use any tools that are sold to tool caulking and sealants with. In my opinion, nothing works quite as well as padding your finger. You fingers have nerves that give you feedback that no tool will ever do.

Here’s some additional caulking tips for you!

1. On windows where the gaps are bigger, it’s helpful to use backer rod. It’s a flexible foam that can be placed in gaps to lessen the amount of caulking used.
2. When you’re caulking exteriors and it’s hot outside, you want to be aware of the weather and how fast your caulking is drying. You won’t be able to caulk very far before the caulking will start to skim over the top and not be very toolable.
3. Clean your caulking sponge frequently. When you get a lot of caulking built up on the sponge, it’ll get messy real quick!