I have a house without a sill plate, meaning the rim joist and floor joists sit directly on the block foundation walls. I'm dealing with a lot of bugs and some airflow coming through the box sills, so I want to seal them up. I've heard it's not a good idea to use spray foam in this situation because it can trap moisture, leading to rot since the joists aren't green-treated. Would using caulk instead at the joints result in similar moisture problems between the caulk, wood, and foundation? Thanks in advance for any insights!
2 Answers
Caulking the joints could be a better option than spray foam, as it allows a little more flexibility and potential airflow. Just keep an eye on any spots where moisture might be an issue. You want to ensure airflow is still possible, or you could end up with the same problems you're facing now.
Hey! Before you seal those box sills, check if you have any foundation vents. They’re crucial for airflow and can help prevent moisture buildup. If you seal everything up tightly without proper ventilation, you could create an environment where moisture gets trapped, which isn’t good for your joists, even with caulk.