Honestly, I ignored my crawl space for far too long. At first, it was just a bit of dampness under the house, something I figured I could deal with later. But as time went on, that small issue turned into a big one. Mould started to grow, my floors felt cold and damp, and the musty smell crept into the rest of my home. By then, the damage had already been done.
If you’ve found yourself in a similar situation, you know how quickly water in your crawl space can cause bigger problems. The good news is, it doesn’t have to be this way. Waterproofing your crawl space is a simple, straightforward process. With the right steps, you can stop water from ever becoming an issue in the first place.
In this guide, I’ll show you three easy steps to keep your crawl space dry, protect your home’s foundation, and avoid the frustrations I faced. Let’s dive into the solution before the problem gets worse.
Step 1: Install a Vapor Barrier to Block Moisture
What is a vapour barrier, and why is it essential for moisture control?
A vapour barrier is a thick, durable plastic sheet that you place on the ground of your crawl space to block moisture from rising into the air. Think of it as a shield that stops water vapour from entering your crawl space, preventing it from causing mould, mildew, and wood rot.
Moisture from the earth naturally rises, and if you don’t have a vapour barrier, it can easily make its way into your crawl space. This increases humidity and creates the perfect breeding ground for mould and pests. Installing a vapour barrier essentially seals out moisture and keeps your crawl space dry and protected.
Not only does this help maintain the structural integrity of your home, but it also ensures that the air quality inside your house stays clean and healthy. For a relatively simple solution, a vapour barrier is one of the most effective ways to prevent long-term damage from water.
Materials to consider (plastic sheets, 6-mil or thicker)
When choosing a vapour barrier, picking the right material is essential to ensure it works effectively. Plastic sheets are the most common option, and you want to go with a 6-mil thickness or thicker for maximum durability. The thicker the plastic, the stronger it will be at blocking moisture.
- 6-mil plastic is often enough for most crawl spaces, but if you’re dealing with high humidity or extreme conditions, 10-mil or even 20-mil plastic can provide additional protection.
- Look for reinforced polyethene plastic, which is durable and resistant to punctures. Some vapour barriers are designed with a special coating or fabric layer for extra strength, which can be beneficial in a crawl space that may see foot traffic or occasional equipment use.
By choosing the right material, you’re setting yourself up for long-term success in keeping moisture out of your crawl space.
How to install a vapour barrier properly in your crawl space
Installing a vapour barrier is easier than you might think, but it does require some attention to detail.
- Clean the crawl space floor: Before you install the vapour barrier, clear the area of any debris, rocks, or sharp objects. This will help prevent punctures in the barrier after it’s installed.
- Measure the area: Measure the length and width of the crawl space to determine how much plastic you’ll need. Make sure to get a little extra to cover the edges and seams.
- Unroll and lay the plastic: Start in one corner of the crawl space and unroll the plastic. Lay the sheet across the floor, ensuring it covers the entire area. The plastic should extend up the walls by a few inches so water can’t get underneath it.
- Overlap seams: When joining two pieces of plastic, overlap them by about 12 inches. Use strong tape or adhesive to seal the seams and ensure no moisture can sneak through.
- Secure the edges: Once the plastic is laid, make sure the edges are secured. You can use staples, bricks, or heavy-duty adhesive to keep the barrier in place along the walls and edges. This will help keep the barrier tight and prevent shifting.
Common mistakes to avoid during installation
While installing a vapour barrier isn’t overly complicated, a few common mistakes can reduce effectiveness. Here’s what to avoid:
- Not covering the entire floor: One of the biggest mistakes is leaving gaps in the coverage. The barrier must cover every inch of the crawl space floor to be effective. Even small uncovered areas can let moisture in and defeat the purpose of the barrier.
- Incorrectly sealing seams: Moisture can get through if you don’t overlap the seams properly or fail to tape them securely. Seal those seams tightly with heavy-duty tape or a compatible adhesive to ensure no gaps are left.
- Not securing the edges: If the edges of the barrier aren’t secured properly, the plastic can shift over time, especially if the crawl space experiences foot traffic or movement. Staple or weigh down the edges to keep the barrier in place.
- Using the wrong material thickness: Plastic that is too thin can tear or puncture easily. Stick with 6-mil plastic or thicker for durability.
By avoiding these mistakes, you’ll ensure your vapour barrier works effectively to keep moisture out and protect your crawl space for years.
Step 2: Improve Drainage with a Sump Pump and French Drains
Why good drainage is crucial for a dry crawl space
Proper drainage is essential when it comes to waterproofing your crawl space. Even with a vapor barrier in place, moisture can still find its way in through the soil or from the outside. Without a system to remove water, it can pool in the crawl space, leading to mould, wood rot, and even structural damage to your home.
Good drainage prevents water from settling in your crawl space, keeping the area dry and preventing moisture-related problems. Essentially, it’s about directing water away from your foundation so it never becomes an issue inside. For many homes, drainage improvements like a sump pump and French drains are the perfect solution to keep water out for good.
Installing a sump pump to remove accumulated water
A sump pump is one of the most effective tools for managing water in your crawl space. It collects water in a designated sump pit (a hole in the lowest part of the crawl space) and pumps it out to the exterior of the home.
- Prevents flooding: If your crawl space experiences occasional flooding or water accumulation, a sump pump will automatically remove the water, preventing it from damaging your foundation or insulation.
- Keeps the area dry: Even if you don’t have major flooding issues, water can accumulate over time, especially after heavy rain or thawing snow. A sump pump ensures that water doesn’t stay around long enough to cause mould or mildew growth.
- Automatic operation: Modern sump pumps have automatic switches that turn on once the water reaches a certain level in the pit. This gives you peace of mind, knowing that your crawl space is protected without needing to check it constantly.
How to install a sump pump:
Installing French drains to redirect water away from the foundation
French drains are another critical drainage solution for crawl spaces. These perforated pipes are installed in trenches around your home’s foundation to redirect water away from the structure. When water accumulates near the foundation, the French drain catches it, allowing it to flow through the pipe and away from your crawl space and home.
Why French drains work
- Prevents water from pooling: French drains help prevent water from pooling in your crawl space or near your home’s foundation by directing water away from your foundation by directing water away from it.
- Reduces moisture around your foundation: Consistently removing excess water from the ground surrounding your home can prevent soil erosion and foundation issues, helping maintain your property’s structural integrity.
- Works well with sump pumps: French drains often work hand-in-hand. Water redirected to the drain can then flow into the sump pump to be pumped away.
How to install French drains
- Dig a trench: Start by digging a trench around the perimeter of your home. The trench should be sloped slightly to encourage water to flow toward the sump pit.
- Lay the pipe: Place a perforated pipe at the bottom of the trench, ensuring that the holes in the pipe face downward. This allows water to flow into the pipe from the surrounding soil.
- Cover with gravel: Cover the pipe with gravel to help filter out debris and prevent clogging. Then, fill the trench with soil, leaving enough space to allow water to flow into the pipe.
- Direct the water away: Ensure the pipe directs water away from the foundation and toward a suitable drainage area, like a storm drain or a dry well.
Why this step is critical for homes with frequent water intrusion
If your crawl space is prone to frequent water intrusion, improving your drainage is necessary. Even with a vapour barrier, persistent moisture problems can still cause significant damage. For homes in wet climates, those prone to heavy rain, or homes with high water tables, installing a sump pump and French drains is the best way to manage water consistently.
Without proper drainage, you risk compromising the health of your crawl space, which can lead to mould, rot, and structural issues that may go unnoticed until it’s too late. By improving your drainage system, you’re not just preventing immediate water damage; you’re protecting the integrity of your home’s foundation and ensuring a dry, healthy environment for years to come.
In the end, proper drainage with sump pumps and French drains is crucial in ensuring that your crawl space remains dry, no matter the weather.
Step 3: Seal Foundation Cracks and Entry Points
Inspecting your crawl space for cracks and entry points
Before you start sealing, you need to inspect your crawl space for cracks and entry points. These areas are where water, pests, and even cold air can sneak in and cause problems. A thorough inspection involves looking for visible cracks in the foundation, gaps around pipes or vents, and any areas where the walls meet the floor.
How to inspect
- Foundation cracks: These can often be found near the corners or along the perimeter of your crawl space. If they’re wide enough, water will easily seep through them.
- Entry points around pipes and ducts: Check where utility pipes enter or exit the crawl space. These areas are common spots for water and pests to find their way in.
- Vent openings and access points: Open vents allow moisture, humidity, and pests to enter. Also, water can get inside during storms or humid days if your crawl space door or hatch isn’t sealed tightly.
Identifying these vulnerable spots is the first step in creating a barrier to keep unwanted moisture and pests at bay.
Sealing cracks in the foundation to prevent water from entering
Once you’ve identified cracks and gaps, it’s time to seal them properly. Foundation cracks are one of the easiest places for water to enter, so it’s critical to fix them. Sealing these cracks will not only stop water from seeping in but also prevent dirt and pests from entering your crawl space.
How to seal foundation cracks
- Clean the area: Before applying any sealant, clean out the crack to remove dirt, debris, or loose concrete. You can use a wire brush or a pressure washer to ensure the surface is clean.
- Use a high-quality sealant: Choose a waterproof foundation crack filler or epoxy sealant specifically designed for concrete. These materials expand as they dry, providing a strong seal.
- Fill the cracks: Use a caulking gun or putty knife to apply the sealant to the crack. Ensure the crack is fully filled and smooth it out for an even finish.
- Allow time to cure: Make sure the sealant has time to properly cure and set, usually around 24-48 hours, before exposing it to water or moisture.
By filling these cracks, you’re blocking one of the primary entry points for water in your crawl space.
Sealing vent covers and access points to prevent water and pests
Crawl space vents and access points are another common way moisture and pests get into crawl spaces. Over time, vent covers can become damaged or not sealed tightly enough. These vents can also let in cold air in colder months, leading to increased moisture and higher energy bills.
How to seal vent covers and access points
- Inspect vent covers: Check if your vent covers are cracked, broken, or loose. If they are, they will allow water, air, and pests to enter.
- Replace or repair vent covers: If they are damaged, replace them with new ones. Secrets in good condition should be shod tightly with weatherproof caulking or silicone sealant around the edges.
- Install vent covers with moisture barriers: You can also consider vent covers with built-in moisture barriers. These are designed to block humidity and prevent pests while allowing ventilation when needed.
- Seal crawl space access doors: Check the door or hatch that gives you access to your crawl space. Ensure it’s sealed tightly with weatherstripping or foam seals to prevent air and water entering.
Properly sealing vents and access points will help reduce the humidity levels in your crawl space, prevent pests from entering, and improve overall energy efficiency by stopping drafts.
How sealing entry points also improves energy efficiency and home safety.
Sealing cracks, vent covers, and access points does more than keep moisture and pests out. It also improves your home’s energy efficiency and safety. By preventing drafts and air leaks, you’ll keep your crawl space and home at a more consistent temperature, which helps reduce your heating and cooling costs.
Additionally, sealing entry points reduces the chance of fire hazards by preventing flammable materials like insulation from contacting hot pipes or electrical wires. It also makes your home safer by reducing the risk of pest infestations that can damage electrical wiring and insulation.
When you block off all these potential entry points, you protect your crawl space and improve your home’s comfort, efficiency, and safety in the long run.
Final Thoughts
Waterproofing your crawl space protects your home from moisture, mould, and damage. Three simple steps—installing a vapor barrier, improving drainage, and sealing cracks—can keep your crawl space dry and safe. Taking action now will prevent bigger issues, saving you time and money.
FAQs
What materials are best for a vapour barrier in a crawl space?
The best materials for a vapour barrier are reinforced polyethene plastic sheets that are at least 6 mils thick. For extra durability, you can use thicker options like 10 mils or 20 mils. The material should be puncture-resistant and durable to provide long-lasting moisture control.
How long does a sump pump last, and how do I maintain it?
A sump pump typically lasts 7 to 10 years with proper maintenance. To extend its life, regularly check the pump to ensure it’s free of debris, test it by pouring water into the pit to see if it activates, and ensure the discharge pipe is clear. Also, consider installing a battery backup to keep it running during power outages.
Can I install a vapour barrier and sump pump myself?
Yes, both a vapour barrier and a sump pump can be installed by a DIYer, but it requires some knowledge and proper tools. You need to measure your crawl space for the vapour barrier and securely seal the edges. Installing a sump pump involves digging a pit, placing the pump, and connecting it to a drainage system. Hiring a professional may be a better option if you’re unsure or want the job done efficiently.
How do I know if my crawl space needs waterproofing?
Look for signs like musty odours, visible water stains, damp insulation, mould growth, or pests. If you experience these symptoms, your crawl space likely needs waterproofing. You can also inspect the area after heavy rain to see if water accumulates or the humidity level is too high.
Can I combine these waterproofing steps with other home improvements?
Waterproofing can be done alongside other home improvements, like insulation upgrades or energy efficiency projects. Sealing cracks and improving drainage can also help enhance the effectiveness of any home improvement work, especially if you’re planning to install new floors or replace insulation.
