Note: This DIY article is provided as a general guide only and is not intended to take the place of product-specific installation procedures; always follow applicable manufacturers’ instructions. Depending on your home’s age and condition, location within the home, and other potential factors, repairs and/or upgrades or other services may be necessary prior to the beginning and/or completion of your project that may involve the services of a home improvement professional. This article does not include advice pertaining to local building codes and/or any related inspections.

Cold air and pests slip in through small gaps around your doors, windows, utilities, and trim. This guide shows you how to seal outside of your house by finding those openings from the exterior. Once you see where the gaps form, you can close them with GE products built for durable outdoor use.

How to seal outside of your house: exterior inspection checklist

Start with a walk around your house. Pick a windy day or use a smoke pencil so you can see how the air moves along the exterior. As you move, check doors, windows, utility penetrations, the foundation band, the sill and rim area, vents, the crawlspace entry, and the garage. 

Look for light under doors, missing or cracked caulk, gaps wider than a quarter inch, torn screens, loose vent hoods, and open joints at trim. Check the siding where it meets the foundation and the edge of the meter base. Leave window and brick weep holes and vent openings clear, since they drain or move air.

Carry a utility knife, along with painter’s tape and PPE. Mark each gap or loose cover with tape or note it on a simple sketch. This gives you a clear map of how to seal holes outside of your house.

Most exterior leaks and pest paths start where two materials meet: around frames, penetrations, and trim. Focus your sealing there, and keep the window and brick weep holes and vents open so water and air can leave the wall system.

Choose the right exterior sealant and foam

Match each one to the product that fits the joint and the conditions outside.

For exterior windows and doors:

For voids and irregular gaps:

Use this list of products with the map you built during inspection, so each gap gets the product that fits the repair.

Seal doors and thresholds to cut drafts and block entry points

To see how to seal outside of house entry points, start at your doors. 

Stand inside and check the door sweep. If you see light at the bottom or feel air at the threshold, replace the sweep so the blade meets the surface with steady contact. Add a compression weatherstrip along the sides and top to reduce movement where the frame meets the wall or trim. Check the exterior trim around the frame. You need a backer rod for gaps wider than a quarter inch before you run a bead.

Move to the garage door. Look at the bottom seal and the side and top stops, the trim that closes against the door. Replace pieces that no longer sit flat against the door surface.

Homeowner applying a steady bead of GE Pro Seal Max Window & Door Sealant along a window casing to block drafts and water.
Homeowner applying a steady bead of GE Pro Seal Max Window & Door Sealant along a window casing to block drafts and water.

Windows and exterior trim: how to seal the outside of your house from water

Now move to the joints around each window. Scrape out any failed caulk, then clean and dry the surfaces you plan to seal. 

For gaps between a ¼ and ½  inch, insert a backer rod to set the depth so the sealant bead forms the right profile. Using the appropriate GE sealant you picked from the product list above, seal the casing where it meets the siding and the joints at the head and jambs. 

Remember to keep weep holes open. These are the small openings at the bottom of the window frame that drain water and must stay clear.

Sealing these connections with a compatible GE sealant helps seal the outside surfaces of your house that see direct rain. 

Drainage rules that prevent hidden damage

Find the features that move water away from your walls, then make sure they stay open. 

At brick walls, look for small openings or gaps along the bottom row of bricks. Leave these brick and window weep holes clear. They drain water out from behind the cladding and should never be sealed. If insects are a concern, use a weep screen made for drainage rather than caulk.

On stucco walls, keep the weep screed slot open at the base. This metal or trim piece lets moisture leave the wall. At vent hoods, seal the trim where it meets the siding and check that the damper moves freely. 

At siding-to-foundation bands, seal cracks in the trim but avoid closing intentional drainage gaps. These rules guide how to seal the outside of your house from water while still giving moisture a way out.

Homeowner sealing gaps around an exterior hose bib with GE Gaps & Cracks insulating foam.
Homeowner sealing gaps around an exterior hose bib with GE Gaps & Cracks insulating foam.

How to seal holes outside of your house at utilities and service penetrations

After you’ve cleared the drainage paths, move to the openings where pipes, cables, and line sets pass through the siding. These spots often pull in cold air, and small pests use the same routes. 

Start by brushing out cobwebs, loose insulation, old foam, or dust. For gaps ¼ inch or smaller, use the exterior sealant you selected from above.

For openings between ¼ inch and 1 inch, press copper mesh into the gap, then cover it with GE Pest Block Insulating Foam so mice cannot pull the material free. This is a practical way to seal the outside of the house from mice at these small holes. 

Work the same way around each hose bib, AC line set, electrical box, cable entry, and outdoor light where the trim meets the wall.

At the dryer hood, seal the perimeter where the hood trim meets the siding. Confirm that the damper moves easily. Never screen or pack the exhaust opening. 

For irregular voids near these penetrations, use a GE insulating foam that matches the gap size. 

Sill plates, rim joists, and small foundation cracks

Move to the base of the wall and look along the top edge of the foundation where the framing sits. That lower joint is the sill plate. Just above it is the rim joist. These spots often carry thin air paths that feed drafts inside. 

Stand a few feet back, then get close so you can see narrow gaps or places where pipes and small vents pass through the band.

Clean out loose debris and check for hairline cracks above the soil line. If the crack is dry and does not show signs of movement, you can seal it. 

Press in a backer rod when the opening needs depth control, then apply the exterior sealant you selected earlier. If you notice shifting, stepped cracks, or active moisture, you should call a professional.

Finish by air-sealing the sill-to-foundation joint before adding insulation to any accessible cavities. This step helps you seal outside of your house’s envelope areas where cold air slips in low and moves upward.

Seal vents, eaves, gable ends, and crawlspace without blocking airflow

Move along the exterior and stop briefly at every vent. 

At the base of the wall, find the foundation vents near the ground. Look up under the roof overhang for the soffit openings, and higher on the wall for the gable vent with its slats. Check that the covers and screens sit tight and replace any damaged pieces. 

Where rodents have been active, add quarter-inch hardware cloth, a stiff wire mesh, to back up the screen. These openings move air through the house, so keep them clear and do not foam or caulk across the slats or mesh.

Seal the trim or metal flashing where these vent housings meet the siding to cut drafts without closing the openings. 

At the crawlspace hatch or access door, add a weatherstrip and seal the threshold so air and small pests cannot slip through the edges. Handling vents and crawlspace access this way supports how to seal outside of your house from mice.

If you’ve mapped the gaps along your exterior and know which joints need sealant or foam, you’re ready to start the work. GE exterior products are available at retailers across the U.S. or Canada, so you can pick up what fits your project and start the work.