Deciding whether or not to re-insulate your crawl space after a rodent problem depends on a few factors. Dirt crawl spaces are incredibly common in Seattle and it’s estimated that 40% of new construction in the area still relies on this type of foundation (per the NAHB, 2013). Crawl spaces make accessing your plumbing and wiring for repairs simple and they’re ideal for Seattle’s hilly terrain. These benefits aside, they are extremely vulnerable to rodent problems.
When to leave a crawl space un-insulated
- If rodents are tunneling into the crawl space (as opposed to chewing in).
- If your crawl space lacks a permanent rodent barrier such as a rat slab, trench and screen, or rodent-proofed joists to protect insulation (keep reading for more info).
Don’t spend money on new insulation only to have another infestation next winter!
When to re-insulate a crawl space
- If rodents are chewing into the crawl space and you’ve done a good job sealing off the entry points you could gamble with re-insulating. They may begin tunneling sometime in the future so this is still a calculated risk.
- If you invest in permanent rodent barrier like a rat slab, trench and screen, or rodent-proofed joists to protect insulation you’ll have peace of mind that your insulation and your living space is safe for the long haul.
What is a permanent rodent barrier?
Exactly what it sounds like! There are three main long term solutions for protecting a dirt crawlspace from rodents:
Rodent-proofing insulation with wire mesh
Traditional fiberglass insulation is by far the most common type we find in crawl spaces. It is also a perfect place for rodents to nest. Protect your new or existing insulation from nesting by installing galvanized steel mesh to the underside of your joists. You’ll get end-to-end protection for your insulation and your living space if a rodent tunnels back into the crawl space.
Trench and screen
To install a trench and screen the soil around your foundation is dug away and galvanized steel mesh is buried against the house to prevent animals from burrowing into the crawl space.
Rat slab
A rat slab is a non-structural layer of concrete that completely seals the dirt floor of your crawl space off from tunneling.
Are rodents chewing or tunneling into the crawl space?
We find that rodents are most likely to access a crawl space by chewing a hole or pushing their way in through a vent. Builder-grade crawl space vents use flimsy mesh that doesn’t stand up to a determined rat. Rodents are also incredible chewers since their teeth grow constantly. They will find a small gap around a gas line and gnaw the opening until they can squeeze through. Sealing off openings and setting poison-free traps are your go-to solution.
Tunneling into the crawl space is also very common. Norway rats are aggressive diggers and they will burrow under the side of the house and pop up in the crawlspace. You’ll need a permanent rodent barrier to stop them from entering once and for all.
Need some help with a rodent issue at your house? Give us a call or book an inspection online!
