In our last blog, we discussed the importance of foundation integrity for rental properties and the role of regular maintenance in avoiding simple fixes from becoming major problems that can disrupt your tenants’ daily lives, and your income and reputation as a landlord.
When independent landlords notice their property has foundation issues, their first reaction is often to fix them themselves to save time or money. While some small repairs can be DIY-friendly, foundation repairs can be risky. Knowing when to handle repairs yourself or call a professional is essential. This guide will help you draw that line.
We’re going to tell you which foundation repairs landlords could handle on their own, and which ones need a licensed professional. This distinction will help you make better decisions to protect your property value and your tenants, and contribute to your long-term success in the rental industry.
DIY-Friendly vs. Professional Foundation Repairs
Many foundation problems that are cosmetic in nature can be managed by a non-professional with the right tools, attention, and care. The key is to focus on low-risk repairs that don’t affect the structural integrity of the property.
1 – Sealing Small, Non-Structural Cracks
Hairline cracks are one of the most common foundation issues landlords encounter, and in many cases, they’re a normal result of curing (the concrete drying and hardening process) and naturally settling of a building over time. While they may look concerning, as long as they remain narrow (less than 1/16 inch wide), stable, and show no signs of movement, these small cracks are typically cosmetic.
How to Seal Non-Structural Cracks
- Clean the area: Remove all dust, debris, or loose concrete from the crack with a wire brush or a vacuum.
- Choose the right sealant material:
- Concrete crack fillers: Also known as liquid sealants, they are the best option for quick, surface-level fixes
- Epoxy or polyurethane injections: Both options are suitable for projects that need high-strength sealing and extra durability, but if you need rigid strength, go for epoxy, and if the crack is in a dampness-prone area, like a basement, polyurethane is the best alternative for its waterproofing properties and flexibility.
- Apply the sealant evenly:
- Follow the product instructions and ensure the crack is completely filled to prevent water penetration.
- Allow proper curing time, without rushing the process. This will ensure the seal holds.
While it’s true that most of these cracks are unoffensive, sealing them early matters, as even the smallest cracks can allow water, humidity, and pests to enter over time.
When to Call a Professional
The building industry consensus establishes that cracks with a width of 1/8 inch or more should be assessed by a professional. This is because a ⅛ inch crack isn’t normally caused just by concrete shrinkage, and may be an indicator of water pressure, settling soil, or frost heave.
Other structural stress to call a professional include:
- Cracks are widening or lengthening over time.
- Horizontal, stair-step, or zigzag patterns
- Water actively seeps through
- Multiple cracks appearing in the same area
2 – Applying Basic Waterproofing Solutions
Basic waterproofing is a practical, preventative step landlords can take to reduce minor moisture issues in basements. While it won’t fix underlying structural or drainage problems, it can help create a first layer of defense against minor dampness and humidity, protect interior finishes, reduce humidity in basements and improve air quality and energy efficiency in the unit.
Interior waterproofing products are made from materials designed to block moisture penetration through porous concrete, like acrylic or silicone. While sealants are often used to seal expansion joints, roofs, cracks in concrete, and around windows and door frames to protect the building from water penetration in localized, indoor areas, coatings are used in larger areas.
How to Apply Sealants and Waterproof Coatings
- Clean and dry the surface before applying, and make sure there’s no peeling paint, efflorescence, or debris
- Apply the product evenly using a roller or a brush, following the manufacturer’s instructions.
- Allow proper drying and curing time between coats.
When to Call a Professional
These versatile materials have their limitations and aren’t a universal solution, especially for serious issues like:
- Water actively seeps through walls or floors.
- Pooled water or frequent flooding
- Persistent mold or strong musty odours
- Peeling coatings shortly after application
If you notice any of these signs, skip the DIY and call professional help.
3 – Filling the Gaps Around Windows, Doors, and Utility Openings
Areas that are often overlooked, like small gaps around basement windows, exterior doors, or utility openings, like pipes or cables, are common entry points for water, air, and pests, all foundation issues over time. Sealing these gaps is an easy DIY task that protects both your rental foundation and the overall building envelope, ensuring the unit is protected from external weather conditions and the occupants are comfortable in every season.
How to Seal Gaps Properly
A proper DIY gap-sealing starts with using the right materials to ensure it lasts:
- Backer rods: These are flexible, compressible foam strips that are installed into wider joints (more than ¼ inch) before caulking to improve their adhesion and flexibility.
- Caulking: Best for gaps between stationary building materials and joints exposed to moisture.
- Expanding foam insulation: Ideal for sealing larger (typically over 1/2 inch) or irregular gaps around pipes and utility lines to create an insulating barrier against air and water.
Application tips
- Clean and dry the area before sealing
- Remove old or cracked sealant.
- Apply the product evenly, avoiding overfilling.
- Smooth out caulk for a tight seal and a better finish.
When to Call a Professional
While small gaps are usually harmless, they sometimes indicate a more complicated, underlying issue. If you see warning signs like water stains or soft materials around openings, warped window frames, misaligned doors or recurring gaps that reopen after sealing, you may have water damage or a deeper structural issue that needs to be addressed by a professional before they lead to more serious damage.
4 – Monitoring and Documenting Changes
If you’re doing regular inspections and documenting your findings with photos or videos, you’re already doing the most important and impactful DIY foundation work landlords can do. Since many foundation problems develop gradually, keeping track of changes over time helps you catch early warning signs before they escalate.
A thorough foundation inspection doesn’t need to be complex: It needs to be consistent, ideally twice a year, and have visual evidence of cracks and stains (including their measurements) to see its evolution over time and detect abnormal movement on time to bring in a professional, before things get worse and more expensive. Keeping records of the property’s structural integrity can also be helpful for insurance claims or a future sale. We recommend you check out our first blog about house foundations, where we give more details about maintenance and an explanation of the basic concepts.
DIY vs. Pro: The Final Word
There’s no doubt that DIY foundation repairs have their rightful place in a landlord’s tasks, and can be an effective and budget-friendly option to preserve your property’s value, but only when the issues are minor, stable, and clearly non-structural. The DIY repairs we discussed can help prevent bigger problems and extend the life of your property.
However, when it comes to structural issues, unusual foundation movement, or persistent water intrusion, professional help is mandatory. These problems require someone with expert knowledge, specialized tools, and repairs that target the root cause, not a band-aid fix. Prioritizing safety, staying compliant with regulations, and investing in long-term solutions will always be more beneficial than the short-term savings of a risky DIY repair.
