How to Seal Up Your House to Keep Stink Bugs Out

by Chuck Owings


Site Admin's Note: This is a very detailed article for only the handiest do-it-yourselfer! Chuck is a member of our Stop Stink Bugs online community and is President of Short Hill Design & Construction in Purcellville, VA.

Brown marmorated stink bugs are tenacious. They can get into any crack in the exterior of your house that you can get the tip of a large screwdriver in or slip a nickel into. They just love your roof. Nice and warm up there late into the fall and high up where they like to fly. Once they have found a way in, they leave a stink trail so all their buddies can find their way in right behind them. Once in your home, they continue to move to warmer places as it gets colder outside and in your attic. Next thing you know, they are in your living room watching TV with you!

So, how do we keep stink bugs out? Well, let's start with the outside and work our way in.

Depending on what you house has on the outside: vinyl siding, hardboard or wood siding, brick, stone, etc., you will need to caulk and/or fill all the cracks and spaces where they can come in without blocking the ventilation of the walls or roof that allow moisture and super heated air from escaping from your walls and roof. This is done with lots of caulk, spray foam and weather stripping.

First, check all your windows and doors, including storm windows and screens, to make sure the weather stripping is tight and in good condition. If it's worn out and you can see daylight around the door or window, replace the weather stripping or augment it with adhesive backed rolled foam around the perimeter of the window or door. On window screens, this should be done from the inside along the frame. Make sure that your screens don't have any holes in them. If you have a window air conditioner, make sure all the filters are tight and in good condition and all the edges around the window frame are filled so there are no gaps.

Second, let's look at your siding. If you have vinyl, aluminum or hardboard siding, you will need a good sturdy ladder a caulking gun, start with about 25-50 tubes of caulk, a couple of cans of spray foam and some rubber gloves so you can handle it safely. The caulk I suggest is non-silicone, paintable clear caulk. It's available at most hardware and paint stores and costs about $2.50-$3.00 per tube. This caulk goes on milky-white but dries clear and may let you do this without having to repaint your house if you are careful with it.


Start with the windows and doors. There is a molding called 'J' channel around all the openings. You will need to caulk around the edge of this molding between the window frame and trim. You will also need to caulk around any other window or door trim you find there.

If you have storm windows, you should caulk around the perimeter of the aluminum frame where it is attached to the window frame. Be sure not to calk the small drain holes on the bottom edge, usually a set of two 'bumps' along the bottom edge of the aluminum frame.

Vinyl siding is a problem. It is supposed to have a vapor barrier installed underneath it with the joints taped  before the siding is installed. If that is the case, the bugs will live under the siding but, shouldn't be able to enter the house from there. This vapor barrier should have been taped to the flanges of the windows and doors in the process. Way too often, the original installers didn't do an complete job of taping the vapor barrier. The only real fix for it is to remove the siding and have it done properly. An expensive venture unfortunately. If you feel you need to go to that extent, consider using cement board siding to replace the vinyl. It's a better product and all the edges can be caulked so the bugs can't get in and live under the siding.

Although not advocating the use of insecticides here, they may be your only real option to keep the bugs off and from living under vinyl siding. There are several brands of Stink Bug specific insecticides available at your local hardware/lumber store. They can be used to spray the corners and joints. I suggest you hire a qualified exterminator to do this work for you as these chemicals can be harmful to your health if proper precautions are not taken.


If you have the one piece vinyl or aluminum corner then you will need to take the spray foam and fill the bottom cavity of the molding. I suggest you do this to all the corners at one time so the can of foam does not clog up on you while you are caulking other things.


This is also a good time to check under the bottom edge of the siding up against the foundation wall. You may need to caulk or foam under there all along the perimeter of the house to keep them from getting under the siding or into the foundation or basement. When using the foam, understand that it expands. Once it dries, the excess can be easily cut off with a sharp or serrated knife. An old steak knife works well.


If you have brick on your house, to this point, make sure you do all the caulking around your window and door trim.


If you have wood or hardboard siding, you will need to caulk the bottom edge of every strip of siding. That is a big job and will probably require repainting the siding even if you use clear caulking.


Next is the molding along the eves and gables of your roof. This is where the sturdy ladder comes into play. Remember; don't stretch to get to places beyond your easy reach. Move and reset the ladder!


On many houses, there is a board called a frieze-board laid flat against the wall at the top of the siding and under the eve. On a sided house, there may also be a 'J' channel or siding termination strip there. This will have to be caulked on all edges and along the top of the siding.


Next is the soffit which is the flat surface extending out from the house wall to the edge of the roof. If it is flat plywood, caulk the inside and outside edges as well as the butt edges usually at about 8' apart where the pieces come together. This type of soffit should have some kind of vents along it. Typically rectangular vents, round plug vents or a continuous 2" aluminum strip vent with either slits or holes in it. If it does not have vents you should install them or have a qualified remodeler or roofer install them to properly ventilate your roof.


The rectangular vents or the round plug vents should have a screen on the top side of them. You may have to remove one to see if it does. If there is no screen above them, get new ones that do or take window screening and cut pieces to fit above each one and reattach to the soffit. Once that is done, caulk all around the perimeter of them. 


The 2" continuous vents come in two styles. One with small round holes and one with small slots. The one with holes will need to be caulked along the edges to the plywood soffit material on both sides. The same with the ones with the slots but, there may be a problem with the slot style. These slots may be wide enough for stinkbugs to get in. If that is the case, you may need to consider replacing them, which is no easy task, or cover the whole soffit with perforated vinyl soffit. Both are big jobs. The slotted soffit was designed before this stinkbug thing. It keeps bees and such out butt, not necessarily stinkbugs. There are instructions for installing the vinyl soffit on most of the siding manufacturer's websites if you plan on doing it yourself. 

If you have vinyl or aluminum soffit, you will need to caulk along the 'J' channel along the house wall and along the 'J' channel or aluminum fascia cover along the edge of the roof. This is critical as this is the primary entry point for stinkbugs to enter your attic. BTW: the Fascia board is the vertical strip of wood or aluminum that runs along the edge of your roof that the gutter is attached to.


The vinyl and aluminum soffits have groves about every 4". Where the material sits in the 'J' channel, these grooves provide a highway for stinkbugs to enter the attic. You will need to be sure each and every one is filled with caulk. It will take about a tube of caulk to do 10 feet of soffit so don't be surprised if you use a lot of caulk here.


A note here: The soffit material should be perforated with lots of little ventilation holes. This provides ventilation for your attic. If the material on your house is not perforated, you need to get with a home improvement guy or roofer to check out your attic ventilation. This is very important for the life of your roof. It keeps the roofing materials from overheating or collecting moisture. Either could cause eventual failure of your roof. If you have solid plywood soffits with no vents, this is a problem as well.


Moving along, you will find the same sort of materials along the gables of your roof. Caulk and seal them the same way. If you have gable overhangs, the soffit material is non-perforated and that is as it should be as there is no ventilation needed there.


You may have vents at the top of your gable walls. You will need to get into the attic and be sure there is a screen on the inside of these vents and that it has no holes, is tight and sealed along the edges. While you are in the attic, check all along the edges and gables to see if there are any holes where light is coming. Take note of these holes and caulk them from the outside. If you see big holes, you may need to use the spray foam for those holes. The screening on these vents need to be no larger than 1/8"x1/8" holes. Some use 1/4"x1/4" screening or have 1/8"x1/2" slots and that will need to be replaced or covered with smaller screening.


Note: this may be a good time to add another 6"-10" of insulation to your ceiling while you are up in the attic! Blown in insulation is the best as the bugs that may get into your attic have a much harder time getting through it and into your house.


If you have roof or power vents on your roof, check that the screening in them is in good shape and the edges are sealed. The screening must be no larger than 1/8"x1/8". Most vents come with either window screen or 1/4"x1/4" screen. The 1/4"x1/4" screen will need to be replaced. The bugs can walk right through that stuff.


Roof ridge vents are a big problem. It is recommended that you remove the ridge vent and install 1/8"x1/8" screening underneath the vent strips along the slot at the ridge of the roof sheathing. This screen should be installed underneath the last row of shingles. The ridge vent will then need to be re-installed. If you have the 'shingle-over' vinyl ridge vent, you will need to replace that as it really can't be re-used. The fiberglass insulation in these vents will just not keep the bugs out. The metal ridge vents have slots in them that will not keep the bugs out either but, if removed carefully, it can be re-used. Using smaller than 1/8" screening is not recommended as it may restrict the air flow and cause ventilation problems in the attic. This is another one of those things that you may want a professional roofer to do.


You will need to check along the bottom edge of your roofing above the gutter to be sure there are no gaps that go into your attic. There should be an aluminum drip edge along the eves of the house up under the shingles and down onto the fascia board. If it's not there, have your roofer install it. If it is loose or shows gaps, you will need to caulk along the drip edge to the fascia board.


Check at the bottom edge of your roofing at all the ridges and valleys. Often the roofing material doesn't sit entirely tight there and may leave a gap. Fill any gap like that with your spray foam.


If you have a chimney or fireplace that is direct vented to the outside (gas fired) you need to check these out thoroughly. If it is a masonry fireplace make sure it is caulked to the wall and the flashings to the roof are completely sealed. Then , you need to buy a chimney cap with a screen mesh around the perimeter with a screen that has no larger than 1/8" x 1/8" holes. Check it to be sure the screening is tight to the metal surfaces on the inside. You may need to buy some fireproof caulk or sealer to be sure the edges of the screen are sealed. Then, when you install it, be sure to caulk the bottom edge to the chimney to seal it all up.


If you have a prefabricated fireplace and it has a triple wall metal chimney, be sure the chimney cap you get covers the chimney completely including the cavities around the center flue. These prefabricated fireplaces will usually have an outside air intake for combustion air. It will be located on the outside of the house on the side or back of the chimney or encasement and look like a dryer vent. You need to put some of that 1/8"x1/8" screening over that inlet as there is nothing in the vent to keep the bugs out. This is a common place for them to get in. If it is a direct vent unit, it may have a larger outlet at the top. You will need to check that outlet for screening. Most of them have some sort of screen but be sure the holes in it are not too large. If there is no screening you may need to be creative and put some heavy gauge 1/8" x 1/8" screening over it. 

If you have a brick fireplace and chimney, there is only one effective method that I have found to keep the bugs out. These chimneys are magnets for stinkbugs and all kinds of other critters too. They look like nice dark caves to the bugs and other critters. There are no chimney caps that I have found that have a small enough screening to keep the bugs out and still provide enough air flow for the chimney. However, they do make what is called a Damper-Cap. This is a spring loaded damper in the chimney cap that replaces the damper in the chimney that is located directly over the firebox. You will need to remove the existing damper which usually just lifts out of it's mounting bracket. (it is the damper you have to open with a lever before you start a fire in the fireplace) The Damper-Cap is installed on the top of the chimney with a steel cable extending down inside the chimney to the fireplace. There is a handle on the cable that has a mounting bracket that needs to be attached to the side wall of the fireplace with masonry screws. This operates the Damper-Cap. When you pull the cable and lock it in place, it pulls down a sealed damper on the top of the chimney that will keep everything out of the chimney. Bugs, critters rain and weather. It's a good system and really works. Not too many places stock them but, you can find them on the internet and can order them there or find a local dealer. Search 'Chimney Damper Cap'. I recommend you have a professional chimney/fireplace company install it for you if you are the least bit worried about heights. They should be able to find one for you as well.

I suggest you have an exterminator spray insecticide dust along the eves of your house from inside your attic just to be sure to kill any stinkbugs that find that hole that you missed.


Now for the inside! No matter how good a job you did on the outside, a few of these little bugs are bound to get into your ceiling and walls. Or if you can't do the outside work thoroughly and need to keep them out of your living space. This is a big job too but, it can be done rather effectively. Let's start with windows and doors again. Be sure to repair, replace or add to any weather stripping that isn't tight. Caulk all your window and door trim to the window frames and to the wall. This may already be done but be sure there are no cracks or gaps. Be sure to check the trim at the top of the doors and windows as painters have a tendency to ?forget? to caulk there as you can't see it. If you have storm windows, be sure the slide panels are firmly in place with no gaps.


Next, you need to check your wall switches and outlets. You may want an electrician to do this for you. There are foam pads available that go on the inside of the switch and outlet plates that will keep any bugs that have followed the wires into the outlet box. You may need to caulk around the outside of the outlet box to the drywall to finish the job.


You will need to do the same for your light fixtures as well. Most of them now-a-days have insulation on the top side of the fixture where it touches the ceiling that will keep the bugs out but, if not, you may need to get creative to seal around the box and place some fiberglass insulation above the fixture to seal the fixture box.


Next are the vents. You will need to unscrew them from the ceiling or wall and/or pull them up off the floor. I use duct tape to seal between the duct and the floor, wall or ceiling surface. Check inside the duct for holes and seal them up as well. Be sure to clean any dust off the surfaces before applying any tape or caulk. 


If you have metal ductwork in the attic, you will need to inspect all the joints and tape them up to keep the bugs out of the system. Same thing for ductwork in the basement or crawl space. This is a good time to insulate your ductwork while you are at it!


Check your attic and basement doors or access holes. Caulk or weather strip these openings as if they were an outside entry. They are for stinkbugs!


Check for gaps around your kitchen and bathroom cabinetry and wherever a pipe or drain goes into the wall or floor. Caulk as necessary. Check and caulk any holes you may have for TV, stereo or other media device wiring.


Caulk along any baseboard molding and crown molding, especially if it is a stained molding to a painted wall. They are rarely caulked. If you have wood floors, be sure there is a quarter round shoe molding along the base molding and it is tight and preferably caulked in place. You may want to install shoe molding along the base of carpeted floors as well if there is a gap there.


Well, there you have it! That should keep the stink bugs out, for the most part, but some may even get through that or hitch a ride in with you or your pet. For these guys, I recommend a couple of solutions. Keep a jar about ½ full of water and dish soap. Grab the little suckers with a tissue and dump them in the jar. It kills them quick and it's safe. I suggest using a tissue so they don't stink on your fingers. You can also flush them down the toilet. I don't advocate letting them go outside as they reproduce at a rate of 6 times a season at hundreds of eggs at a time. This just perpetuates the problem. You don't have to feel a need to be nice to these bugs.


There are specific vacuums available specifically for stinkbugs. You can find them on line and at some stores now. They work well. If you just want to vacuum them up, I suggest you by a small, cheap shop vacuum and designate it to just stinkbugs. If you use your regular vacuum it will soon smell like stinkbug every time you turn it on. Empty the stinkbugs out of your vacuum right after you finish using it as they can and will crawl right back up the hose and out into your house again. Store the vacuum outside as it will stink and attract other stinkbugs.


There are various insecticides available that are safe to use inside your house and out but, you should consult a licensed exterminator before using any insecticide like that. I will not recommend any but, personally I have a few that I use that are very effective even around animals and kids.


- There are a couple of upsides to all this work besides the remediation of stink bugs.

- You have pretty much fully insulated your house and it should help your heating and cooling bills.
- You have made it just about impossible for any other bugs to get into your house.
- You may have been forced to finally get your house painted.
- You may have fixed a major problem with your roof ventilation.
- You can sleep at night without worrying about waking up with a stink bug crawling in your ear!


Author contact info:

Chuck Owings

President: Short Hill Design & Construction, Ltd.



540-668-6800 local  

866-277-6800 toll free

Views: 25516


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Comment by Christy Walker on April 29, 2013 at 1:31pm

Draft Decor      Magnetic Fireplace Vent Covers and our Flue-zee Flue Cover will instantly close off two areas that stink bugs enter and love!   Check our website and see how they can work with your fireplace.

Comment by Lydia Whitney on June 3, 2011 at 9:27am

I just realized that the trail they leave involves gross brown spots all over furniture, floors, even walls.  Luckily, a solution of Murphy's Oil Soap got it off.  They just get more and more noxious...  My latest blog entry discusses this issue.


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