How to seal large irregular gaps
Large, uneven spaces under siding and around doors let in water and cold drafts that force furnaces to run constantly. Standard weatherstripping fails to completely fill these irregular shapes, and attempting to fill wide half-inch openings with caulk requires too many tubes.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Packing weather stripping into the spaceDid this help you?
- 2Pumping a massive amount of caulk into the gapDid this help you?
- 3Installing a piece of galvanized right angle with masticDid this help you?
- 4Filling with expanding foam, trimming it, and sealing with siliconeDid this help you?
- 5Stuffing a foam backer rod into the gap before caulking the edgeDid this help you?
- 6filling the space with a foam backer rodDid this help you?
- 7applying thick, wide adhesive foam tapeDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“the weatherstripping feels non existent at night you can feel the cold breeze coming in and its making our furnace keep turning on due to temperature dropping”source ↗
“it has about a 1/2 of opening when the door is shut(was expecting to add a kerf weatherstrip but that will not happen)”source ↗
“Water gets into this space under the siding of our barn every time it rains.”source ↗
“I tried packing weather stripping into it, but the gap is irregular and it doesn’t fill it everywhere.”source ↗
“I started with caulking, but it would probably take a dozen tubes of it.”source ↗