Joe Truini: When using caulk to seal cracks and holes around the house or outside, it's important to make sure the crack is no wider than a quarter of an inch, because if you just put in caulk, the caulk will fail, because the crack is too wide.
Caulk's gap filling properties have their limitations. Gaps above 10mm will be difficult to fill with caulk alone.
It is a flexible material that allows the best possible finish to be achieved by covering cracks, removing gaps and generally creating a neat and tidy edge to interior & exterior surfaces. While it is classed as a filler, caulk is not sanded down to create a smooth finish.
In order to fill a large gap, it is best to work in single, well-done layers one at a time. Instead of filling a gap from bottom to top all at once and in a vertical orientation, lay down one excellent line of caulk, then another above it and so on until the gap is one layer shallower.
How wide/thick should I apply caulk? A line of caulk (called a "bead") should be no thinner than ¼." Thinner beads shrink while drying, creating too thin a seal to tool or seal properly.
Expandable foam caulk is a better choice for sealing larger gaps and holes.
Choose acrylic latex
Alex Plus is one good choice, but there are several others. If you are dealing with a large recurring crack in a wall corner or in a crown molding joint, choose a product with better flexibility such as a hybrid formula or Big Stretch acrylic caulk.
Certain places on the exterior of the home should not be caulked, since they'll cut off openings needed for air circulation or drainage. Elegant Painting says these spaces include the gap created when trim boards sit atop the siding, any wood to metal joints, weep holes on windows, and garage door panels.
Gaps up to 1/4″ inch in size can be caulked in the usual manner, without any concerns. If the gap is larger than a 1/4″, you will want to install a foam backer rod into the joint, prior to caulking.
A quarter inch deep and quarter inch wide is the limit for caulking. You can fill a deep crevasse with foam backer rod. It's a plastic foam that comes in different diameters. Limit your caulk to a quarter inch deep.
Applying a new layer of caulk to an old layer of caulk isn't recommended, but it is doable if the old caulk is still in relatively good condition. Damaged, cracked, and worn caulk won't provide a firm surface for the top layer of caulk, often leading to cracks and damage in new caulk.
Crack Length
Typically, a crack less than three inches long (or the length of the short side of a dollar bill) can be repaired by injecting the outer layer with a clear, curable resin.
Crack Size and Depth:
Usually, auto glass technicians can repair a chip, which has a diameter of around one inch or less. Likewise, a crack is also repairable, if it is no more than three inches long. If the size of the crack is more than that of a dollar bill, you should rule out the repair option.
Wide cracks in concrete are best patched and sealed with a concrete patching compound. Smaller cracks, less than 1/4 inch wide, can be repaired with a concrete caulk or liquid filler. Patching compounds typically are mixed with water and applied with a trowel.
Silicone caulk is excellent at water sealing and flexibility so it has its place in construction. There are two main places it never should be installed, wood or any painted surface.
While caulk is long-lasting on solid, unmoving surfaces, silicone sealant's flexibility means it lasts longer in areas with higher moisture. Using silicone sealant in a bathroom for sealing cracks in the tub and shower will create a more durable seal without needing to frequently re-apply.
Tape the Area for Caulking
One of the best caulking tips is to make sure that the caulk only goes where you need it. Caulking with tape along the surface will help produce an attractive finish. Apply painter's tape to mask off areas around the joint where the caulk should not appear.
If you need to seal junctions between walls and seal cracks in ceilings or walls then it's better to use Caulk because it dries quicker and is much more resistant to weathering and high temperatures.
Should I use wood filler or caulk? To sum up the difference between caulk and wood filler, caulk is to be used to fill in corners and gaps between two materials, whereas wood filler should be used to fill nail holes and other damage on flat wooden surfaces. Wood filler can be sanded and caulking can not.
Caulk: Generally made of flexible acrylic, mastic caulk has a smooth plastic type texture. Best used for filling gaps between skirting boards, doorframes or the edges of shelves and the wall.
Caulk and silicone are both types of sealants that make joints air and watertight. While latex caulk is less expensive and easier to work with, silicone is more durable under extreme weather conditions, and can be used as a binder as well.
Let the Floor Caulking Set
The answer is yes! Caulking will help to seal any gaps that may exist, which in turn will help to keep pests, moisture, and air from infiltrating your home. It's an easy way to improve the insulation of your home and can be done in just a few minutes.