I recently had an Energy Recovery Ventilation (ERV) system installed due to low fresh air flow through my house after crawlspace encapsulation and attic insulation. The HVAC consultant told me to seal the baseboards of the outer walls of the house after the ERV was in...
I recently had an Energy Recovery Ventilation (ERV) system installed due to low fresh air flow through my house after crawlspace encapsulation and attic insulation. The HVAC consultant told me to seal the baseboards of the outer walls of the house after the ERV was in place. He recommended Flex Shot sealant because it has enough stretch to allow baseboards to expand and contract during seasonal temperature changes. Some Amazon customer comments for that product were low, so I investigated other elastomeric sealants, narrowing it down to the brands listed below. To avoid problems, I checked the “1” and “2” ratings at Amazon and at other websites for potential concerns:
Sashco Lexel Adhesive Caulk – This caulk had high ratings at Amazon and other sites, especially by experienced contractors. However, some regular homeowners remarked that it dried so quickly that they were not able to keep up, and they ended up with a goopy mass. Lexel also has “superior adhesion,” which made me worry it would cure before I could fix a mistake.
Sashco Big Stretch – Big Stretch also had high ratings, and DIY types said the handling characteristics were good. A number of people said it is a magnet for dirt and dust, so people should paint over it. It is NOT marked as mold and mildew resistant, but it was labeled for baseboards.
Red Devil 0770 Lifetime Ultra Premium Elastomeric Acrylic Latex: If I had a big job and cost was an issue, I probably would have gone with Red Devil ($3.98 Amazon add-on item). It is mold and mildew resistant and paintable and ratings are strong, but at least one person noted handling issues.
A few other brands of caulk were for seasonal weatherproofing, which was not practical in this case.
For my average DIY skill level, Big Stretch was the best choice. It had such superb handling characteristics that I finished all of the outer wall baseboards in my small ranch house in about 5 hours. The ALLWAY TOOL CT31 3 In 1 Caulk Tool made it easier to work efficiently and accurately. Big Stretch took long enough to cure that I had plenty of time to switch tubes when the first tube ran out halfway through a baseboard. Stray drops on the floor and my hands were easy to remove with Windex.
This may not be best practice, but I applied painter’s tape to create a border on the floorboards once, applied the caulk to 2 walls in a row, then went back to the first wall (about 20 minutes later) and applied white Behr Premium Plus Paint and Primer in One with a soft brush and light strokes, then lifted off the tape. The caulk held up well, but since it was still an opaque white that early, I couldn’t tell whether the paint completely coated it. The picture shows the baseboards the day after application, by which time the caulk was clear. Although a few streaky paint areas (right side of picture) showed by then, almost all of the caulk line was completely covered by paint.
Warnings: the bead size markings on the tip underestimate the width of the opening if you cut the tip at a 45° angle. E.g. if you cut at 45° halfway between the 1/8” marking and the end of the tip, you’ll get a 1/8” angled opening that is perfect for baseboards. Also, when the tube was almost empty, caulk leaked out all over the caulk gun base. Fortunately, this was easy to clean up with a few Windex-soaked paper towels.
This is a superior caulk that scores an easy 5/5. With minimal preparation, DIYers can expect perfect results the first time.