Compromised Fire Separation: One of the key purposes of the door between the garage and living areas is to provide a fire barrier. If the door does not close fully, it may allow smoke, heat, or even flames to pass through, increasing the risk of fire spreading from the garage into the house.

Failure to Contain Hazards: A door that doesn't seal properly could fail to contain dangerous fumes, such as carbon monoxide, which can seep from the garage into the living spaces.

Unauthorized Access: A door that doesn't close fully can be an easy target for burglars or intruders. The gap might allow someone to pry open the door or access the area more easily, putting your home at risk.

Weakening of Entry Points: If the door does not close tightly, it can weaken the security of the entire home by making it easier for anyone to bypass the locking mechanism.

Carbon Monoxide and Fumes: A door that does not close fully could let harmful gases, such as carbon monoxide from vehicles or chemicals, escape from the garage into the home. This poses serious health risks for you and your family.

Energy Loss: Gaps around the door can lead to drafts, causing warm or cool air from inside your home to escape. This can make it harder to maintain a comfortable temperature and increase energy costs.

Noise Transfer: If the door does not close completely, sounds from the garage (e.g., car engines, tools, or music) can travel into the living spaces, disrupting peace and quiet, particularly in bedrooms or other sensitive areas.

Check for Misalignment: The most common cause of a door not closing fully is misalignment between the door and the frame. Check if the door is sagging or if the hinges are loose, which may prevent the door from closing completely.

Examine the Door Frame: Sometimes, the door frame itself may be out of alignment, which can also prevent the door from closing fully. Look for gaps between the door and frame that may indicate an issue with alignment.

Tighten Loose Hinges: If the door is sagging or not hanging correctly, check the hinges for loose screws. Tightening the screws may be enough to realign the door and ensure it closes fully.

Shimming the Hinges: If the door is still not aligned, you may need to shim the hinges. Shimming is done by placing a small piece of material (such as cardboard or plastic) behind the hinge to adjust its position and help the door fit more securely within the frame.

Check the Weatherstripping: Weatherstripping is designed to seal the gaps around a door to prevent drafts, noise, and air leakage. If the weatherstripping is damaged or worn out, it could prevent the door from closing fully. Replace or repair the weatherstripping to ensure the door seals properly.

Ensure a Tight Seal: Make sure the weatherstripping fits snugly along the entire perimeter of the door to help it close securely.

Check the Strike Plate Alignment: The strike plate, which holds the latch when the door is closed, may be misaligned, preventing the latch from catching properly. Inspect the strike plate to ensure it is aligned with the door’s latch mechanism.

Adjust or Replace the Strike Plate: If necessary, adjust the position of the strike plate by loosening its screws and moving it slightly. In some cases, the strike plate may need to be replaced if it is worn or damaged.

Examine the Door for Warping or Swelling: Wood doors, in particular, can warp or swell due to moisture or temperature changes, which may prevent them from closing fully. If the door is warped, it may need to be planed or replaced.

Inspect for Cracks or Splits: Any damage to the door itself, such as cracks or splits, could prevent it from closing properly. If the door is damaged, it may need to be repaired or replaced.

Seal the Bottom Gap: If the gap is at the bottom of the door, installing a door sweep or bottom seal can help close the gap. This will also help with energy efficiency by preventing drafts and keeping harmful gases from entering the living spaces.

If adjusting the hinges or shimmying the door does not solve the problem, it may be time to consult a professional carpenter or door installer. They can assess the door’s condition and make any necessary repairs or replacements to ensure proper alignment.

If the issue is related to the structure of the door frame, such as a warped or bowed frame, a contractor may need to repair or replace the frame to ensure the door fits properly and closes fully.

If the door is a fire-rated door, it is essential to ensure that it meets local fire safety codes. A professional can assess the door to ensure it is up to code and functioning as a fire barrier.

If the problem is related to inadequate ventilation in the garage, or you are concerned about carbon monoxide, you may want to consult a specialist in home safety or a ventilation expert to ensure the garage is properly ventilated and that the door seals effectively.