Basement Assessment Question#2: Is It Structurally Sound?

INTRODUCTION: Is It Structurally Sound?

Your job now is to honestly determine if your basement is worth finishing, apart from any issues to do with moisture. I’ll explain more about the different types of basement construction next week, but in the mean time just take a general look at what you’ve got. Basement height is a good place to start. Insufficient basement height is more likely to be an issue with older homes than new ones, and the trouble is obvious. A short basement isn’t worth finishing because it doesn’t afford enough headroom. So how high is enough for finishing a basement? Many jurisdictions require at least an 84” ceiling height (not including occasional areas of lower height for heating ducts) before they’ll issue a building permit for a basement renovation. Can a home be raised to create more basement headroom? Yes. The basement floor can also be lowered by removing the existing floor, digging out some soil, then re-establishing a new concrete floor, new support posts and by shoring up the area around the footings. The thing is, all this is quite expensive.  In extreme cases it can cost as much to raise a house as it would to finish the basement space lavishly. So a low basement ceiling height could be a deal breaker as far as finishing plans go unless you’re committed to making more headroom first. As you think about all this, remember that you’ll lose a little height for floor coverings and ceilings.

Assuming the height of your basement is suitable, examine the condition of foundation walls and the floor. You’re looking for significant deterioration in the form of cracks and crumbling masonry. Both of these conditions could be insignificant or they might matter a lot. That’s what the questions up next will help you determine. Choose the first set of questions if your basement is unfinished, and the second set if it’s currently finished.

Questions for assessing unfinished basements . . .

Are There Visible Cracks in Walls and Floors?

It’s not unusual for masonry structures to develop narrow, short, hairline cracks here and there. These don’t matter so you can ignore them. But are there obvious cracks in the walls or floor that have some visible width to them? Are they longer than a foot?

If NO, proceed to Unfinished Basement Assessment Question#3. You’ve got a crack-free basement and that’s a good thing.

If YES, your job is to figure out if the cracks matter and what, if anything, you can do about them. Continue with the following questions.

Monitor cracks over time. A stable crack is probably a harmless crack.

Record the width of all cracks at designated places every two months. Also, draw a marker line across the crack so you can see if one side is shifting relative to the other. The time required to prove that your basement is dry is also a good time to monitor cracks. Vertical cracks in a poured concrete basement wall usually indicate harmless shrinking of the foundation wall. Horizontal cracks are potentially more serious because they can indicate an inward failure and bowing of the foundation because of soil pressure. In both cases, monitor crack widths. In the case of horizontal cracks, also monitor how flat the wall is and remains. The video up next shows how and why this is important.

VIDEO TUTORIAL: Assessing Basement Cracks

If You Find Stable Wall Cracks

If stable cracks are wider than the thickness of cereal box cardboard, then consider filling them with injected epoxy. You can get DIY kits for this or call an epoxy injection specialist. Some people get overly concerned about filling stable cracks, assuming that unfilled cracks make the basement more likely to leak. This isn’t as true as you’d think. Masonry is not very waterproof on it’s own, and when water is present outside a foundation wall, it’s probably going to get in, with or without cracks. Go ahead and fill small stable cracks if you like, but it’s not a make or break issue as far as moisture-proofing goes.

If You Find Stable Floor Cracks

You can fill these with epoxy the same way as with stable wall cracks. Floors are less likely than walls to have cracks large enough to fill because floors aren’t under the same stress as walls, but you might as well fill if you want.

If You Find Unstable Cracks

I’m afraid this is bad news, but better to know now rather than after you’ve spend a bundle of money finishing a basement that may have serious structural problems. Finishing a basement with active, unstable cracks is almost as unwise as finishing a basement that gets wet periodically. If you’ve got unstable cracks or sunken floor areas, call in three or four structural basement repair specialists and see what they say. You can assess the trustworthiness of their advice by talking to at least five previous clients from each contractor.  Don’t skip this step unless you don’t mine the horrible feeling of paying thousands of dollars to someone who doesn’t know or care what they’re doing. This sad situation is much more common than it should be.

Are There Visible Rot or Signs of Insect Attack in Wooden Framing Members?

Most basements have some kind of wooden framing members supporting the floor above, even if the basement walls and floor are made of masonry. In the case of a wood frame house, wooden framing members also include the bottom ends of the walls that sit on top of a masonry foundation. Either way, now’s the time to look closely at all these wooden elements for trouble while the basement is still open and visible. Once again, an LED headlamp is ideal for this examination because it leaves both hands free while directing lots of light on the subject. The thing is, bad wood doesn’t always look bad from the surface. Considerable rot and insect attack can be hidden under a thin layer of seemingly sound wood. Always poke around with a large screwdriver or pry bar to make sure that good-looking wood really is good and solid. You’ll need to fix any deficiencies now because the wood framing will be covered later by your finished basement ceiling. Pay special attention where wood framing meets outside walls, and any place where drains have penetrated the floor above. Slow rainwater leaks around the perimeter of the basement or chronically leaking drains are the most likely sources of moisture that leads to rot. The ends of main wooden beams are particularly susceptible to rot where they meet outside walls. Did you find any rot, holes or fine sawdust that might indicated insect attack?

If NO, then proceed to Basement Assessment Question#3.

If YES, then learn all you can about the deterioration by examining it more. How extensive is the area of deterioration? Is there rot only? Insect attack only? Both? Your job now is to figure out what’s going on, then get your unique issue fixed before proceeding.

Deciding what to do about wood frame deterioration is a case-by-case issue and a successful repair often demands advanced carpentry skills of a creative sort. There’s the issue of fixing the cause of the deterioration in the first place (leaky siding, insect entry points, leaking drain, etc), then there’s still the job of replacing the punky wood itself. Fortunately, deteriorating wood framing above basements is relatively rare. And while it’s true that the majority of homeowners need professional help to deal with this kind of issue, you can’t simply ask any carpenter you find for their opinion and expect to get a useful answer about what to do. Not all carpenters are created equal. When calling in help for a unique job like this, you need to understand how to find the right kind of carpenter. Click below for audio tips on the person you’re looking for and what it takes to complete wood frame repairs that require creativity and patience.

Questions for Assessing Already-Finished Basements

Assessing a previously finished basement offers less certainty than examining an unfinished one because the wall board, floor covering and ceiling prevents you from seeing what’s going on. That said, you can infer a lot from what you do see and smell in a finished basement. If there’s any sign of previous water presence on the bottom of walls and floors, then you know something bad is going on behind the scenes. You really shouldn’t ignore anything like this. Also, your nose will tell you a lot. Any smell of mold and mustiness is a strong indicator of a moisture problem that’s affecting indoor air quality throughout the house. If there’s carpet on the floor, get down and smell closely. Carpet has been installed improperly in basements for many decades, so it’s a common source of trouble.  Click to hear a true story about a basement, carpet, humidity and mustiness.

For many years I’ve been answering questions from homeowners about musty basement smells. Sometimes these smells even affect an entire home, and the issue is about more than just odors. The crazy thing is, the natural course of action a person might take towards a musty basement is the opposite of what’s required. “What comes naturally” in this case is making the musty problem worse. Click to listen to my explanation of what’s going on, and how to fix mustiness effectively.

Click below to watch a video animation that shows how carpets installed on concrete promote mold and mustiness. As you’ll see, a subfloor is the solution because airborne moisture is the source of the damaging water. The key is to prevent basement air from ever coming in contact with your concrete basement floor. In a sense it comes down to installing a kind of informal vapour barrier on the warm side of your floor. Ideally this “vapour barrier” comes in the form of the right kind of subfloor.

VIDEO TUTORIAL: The Cause of Basement Carpet Moldiness