How to Seal LP Siding

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Use a ladder that is tall enough to reach high areas safely.
Use a ladder that is tall enough to reach high areas safely. (Image: Jupiterimages/liquidlibrary/Getty Images)

Proper sealants are important for preserving the integrity and warranty of LP siding. Although LP Building Products siding is available bare or painted, cutting the materials to fit during installation exposes some areas to the elements. LP siding requires flexible, exterior-grade, paintable caulk to seal gaps. Two appropriate products are polyurethane and solvent-based caulk. Seal the panels with semi-gloss or satin paint in an oil or alkyd base, as translucent sealers are not appropriate for composite siding. Alternatively, flat alkyd or any sheen of acrylic latex products are acceptable if the manufacturer states that they are compatible with composite siding.

Things You'll Need

  • Caulk gun
  • Caulk
  • Utility knife
  • Long, thin nail
  • Rag
  • Angled trim paintbrush
  • Paint
  • Wide, exterior paintbrush

Sealing Panels

Dip an angled trim paintbrush into the paint and scrape off the excess inside the can.

Coat the top edge of the siding where it meets the top of the wall, the bottom edge where it meets the foundation and all other areas that a larger brush will not reach, such as into the overlaps between siding panels, seams between sections and around doors and windows.

Dip a wide paintbrush into the paint and scrape off the excess.

Coat the siding panels with paint, working from the bottom of the wall to the top.

Let the siding dry, then apply two more coats, or as many as the paint manufacturer recommends.

Sealing Joints, Seams and Gaps

Extend a caulk gun’s drive rod, which is the long rod through the center of the gun, to the back of the gun leaving the curved body of the gun open.

Cut the tip of the caulk tube at a 45-degree angle with a utility knife, or use the cutter on the gun if it has one. If there is a seal inside the tube, use the thin rod attached to the side of the caulk gun or a long, thin nail to pierce it.

Set the caulk tube into the gun with the cut angle facing down. Squeeze the gun’s trigger until you feel slight pressure.

Hold the angled tip flat against the gap to be sealed. Squeeze the trigger until the caulk begins to flow out the tip. Pull the gun along the gap and squeeze the trigger as needed to keep the flow moving. Release the lever or knob to disengage the drive rod and stop the caulk flow when you reach the end of the gap.

Wipe a finger dampened with water or a rag over the caulk to help it fill the joint, but don’t wipe away too much. Flexible caulks often shrink, so some excess will sink into the gap naturally as it dries.

Caulk across the top edge of the siding where it meets the top of the wall, around windows and doors, across the bottom edge of the siding where it meets the foundation and any other area where gaps exist.

Tips & Warnings

  • Mix all paint together in a large container before painting the house to ensure color continuity.
  • All cuts in LP siding require paint to seal out moisture, and old caulk can let moisture in over time. If you prefer to caulk before painting, you should still paint the cut ends first. After the paint dries, apply caulk and then paint the rest of the siding.
  • LP recommends applying primer the foundation of the house before painting the siding to prevent moisture from wicking into the siding.
  • Semi-transparent wood stains, wood shake or shingle paint and vinyl-based resin sealers and paints are not recommended for LP siding.
  • Overlooked or missed spots while painting and caulking will allow water to soak into the siding and seep inside the wall.

References

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