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Water/Bug Infiltration Into Metal Home

BACKGROUND: Hello, and thanks in advance for your assistance. I'm renting a Metal-Sided/Roofed home that sits on a concrete slab... and whenever wind-driven water comes against the house/foundation... the water seeps in. Also... there are HORDS of bugs that appear as though they walk right through the walls (house wide... every room)... including spiders, crickets, pill bugs, roaches, centipedes, etc. I've sprayed along all walls of the interior with a home insecticide... but I still have hundreds of dead bugs I have to vacuum up periodically. I put down an exterior caulk bead at the edge of where the metal siding meets the concrete slab... and that curtailed some of the water seeping into the home... but did nothing about the bug problem. This home is on my sister's property and sits in close proximity to her sheep herd... so I cannot use outside pesticides (although I have sprayed with dishwashing soap & water before... not seeming to make much a difference). I've ensured that the door footings are NOT letting through water/bugs... and there doesn't appear to be any holes in the exterior that are unsealed.

QUESTION: Is there anything I can do about the bug/water infiltration? It seems like perhaps some underlayment between the concrete slap and the structure was forgotten for this much infiltration to be happening. I've considered caulking the entire interior perimeter at the floor (painted concrete floor inside)... but am afraid that will just allow moisture/bugs to sit under the walls and eventually damage the structure. The slab has those slits they notch into it to prevent the slab from cracking... and the bugs are infrequently hiding in those slits. PLEASE HELP!

Re: Water/Bug Infiltration Into Metal Home

Be careful caulking around siding. It wasn't designed to be 100% water tight, it was designed to be water resistant and shed water effectively and efficiently. If you're not sure, it is best to give the original installers of the siding the benefit of the doubt and assume they were correct in where they did and did not apply caulk, only replacing the stuff that was already there and which has failed without trying to reinvent the wheel. Usually before siding is applied a house is wrapped in a water RESISTANT (NOT WATER PROOF) plastic material. It's all set up so if water seeps through at higher points in the structure it will seep down and exit from the bottom through weep holes and certain other gaps without having a chance to pool anywhere and cause rot. Although alot of the generic DIY guides list where the siding meets the foundation as an appropriate place for caulk during a normal winterizing/weather-proofing maintenance routine, alot of experts say this is a bad idea. You are effectively sealing up one of the places where moisture that infiltrates the siding is allowed to evacuate.

Are there gutters on the house?

Downspouts extended?

What does the grade of the surrounding terrain look like?

Re: Water/Bug Infiltration Into Metal Home

Typically, when framing an exterior wall, the framer puts foam or rubber liner under the sill plate to form a tight bond between concrete and lumber and to prevent water from sipping in. If there is no foam/rubber gasket, usually in older homes, non expanding caulking can do the same job. Use caulking that won't harden and crack.

Now, between the siding and the sill plate - that's a different story.

Re: Water/Bug Infiltration Into Metal Home

With water entering after a rain, you definitely do not have a good seal at the bottom plate. Ideally you'd get to the plate/sheathing from the outside to reseal this but with metal siding that is a big chore (and a big reason vinyl overtook metal siding as it's much easier to work with after installation). Since you can't get to there, then go to the inside, but behind the baseboadrds, not on the front of them. Yep, that means removing them, recaulking, and repainting them. I'd use minimal expanding foam, cutting off any excess after it dried, then caulking the bottom edge of the foam to the slab with something like silicone or Siroflex. When you replace the baseboards they need to be held above the slab 1/8 inch minimum and that should be pressed into the wet caulking. Use the minimal expanding foam at the sides of the doors, either by removing the casing or by drilling a hole 1 inch from the bottom to put the foam tube into. Also caulk the sills. If you're really into DIY you should open the wall where utilities come up from the slab- probably only plumbing there. You're likely to find some large holes there which I'd fill with cement, mortar, or concrete grout. That's about all you can do the seal the home to the slab without a lot of siding de-construction.

Simply sealing the bottom of the baseboards from the inside will only create a barrier for the bugs after they have access to the walls, so that's not going to get rid of them. It will also help hold water to rot the structure (including the baseboards) rather quickly. Don't do it that way. If you can get the bottom piece of siding off that is where the seal really needs to be and it should extend up the wall 4 inches or more. Do the doors anyway if you do this- you'd be surprised how open those areas are in most homes.

Before doing any of this, I'd have an exterminator treat the house and do a re-treat when you're done. Let them know what you're going to do so they can tell you how long to wait for their treatment to be touch-safe as well as any other precautions they want you to take doing the work. They can use baits outside so the sister and her sheep are happy. BTW, the sheep shouldn't be close to the house anyway- I hope they're fenced off at least 10 or more feet away. Expect to do a lot of bug-vacuuming during the process and immediately afterward, but this should get most of them.


Re: Water/Bug Infiltration Into Metal Home

THANK YOU all... for the great insights! You've given me GREAT advice and direction on this task. Since I'm only a renter... I'm going to share the information you've given me with my sister... and hopefully she'll pursue this topic further. Thanks again for your time, effort, and expertise!

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