What's the Crack?
Your guide to spotting Structural red flags.
Viewing a potential home? Before you get carried away with the kitchen island, let's talk about the important stuff. Here's a quick guide to what to look out for.
⚠️ The Important Bit (Disclaimer)
While we love sharing our expertise, please remember: The information provided on this page is for general guidance only. Every building is unique, and a webpage cannot see your foundations or feel your floorboards. This content does not replace a site-specific assessment by a qualified professional. If you are concerned about the structural integrity of your property, always consult a Structural Engineer directly.
The "red flags" structural checklist
Before you get that pen out for the paperwork, keep an eye out for these tell-tale signs that might indicate something more significant. C.A.L.C., our Construction Analytics and Logistics Computer, is here to help you navigate these potential issues:
- The "stick" test: Do doors or windows stick or feel "wonky" in their frames? This could be a sign of movement.
- The "mirror" effect: If you spot a crack inside, check the exact same spot on the outside. If it goes all the way through, it’s likely structural.
- The extension join: Look at where an extension meets the original house. A visible gap often means the two parts are moving at different rates.
- Thirsty trees: Large oaks or willows close to the house can dry out the soil, leading to movement in the foundations.
Preparing for the engineer: your next steps
If you've decided it’s time for a professional inspection, here’s how to make the process as smooth (and cost-effective) as possible for you and our team:
- Collect and list: The more information you can give us prior to our site visit and during, the quicker the overall turnaround time. .
- The More we See, The More we Know: If you know a section of floor has failed, carefully expose the area prior to the engineers visit, only if safe and capable. Alternatively, we can send out a team to help an invasive surveys, and reinstate, on the same day where possible.
Tips From STRUCTURA
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Buildings Breathe: Materials like timber and masonry expand and contract. A tiny crack that appears in July and vanishes in January is often just "thermal movement."
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New Build Blues: If your home is less than 2 years old, "shrinkage cracks" are almost guaranteed as the building settles and dries.
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Early Action Saves Money: Catching a small structural issue now is always cheaper than fixing a major failure in five years!
The Crack Decoder
| Crack Width | Technical Category | What’s Likely Happening? | Structura’s Take |
|---|---|---|---|
| 0.1mm – 1mm | Category 0-1: Aesthetic | Fine "hairline" cracks. Usually just the plaster drying out or slight thermal expansion. | Don't Sweat It: Standard DIY filler and a lick of paint will do the trick. |
| 1mm – 5mm | Category 2: Minor | Larger cracks that might show through wallpaper. Could be slight settlement or timber shrinkage. | Keep an Eye: Monitor these over 6 months. If they grow, give us a shout. |
| 5mm – 15mm | Category 3: Moderate | Significant gaps. Might be caused by localized movement, lintel failure, or drain leaks. | Better Safe Than Sorry: This is where we should probably come out and take a look. |
| 15mm – 25mm | Category 4: Severe | Large cracks that may cause doors to jam or pipes to leak. Windows might feel "tight." | Engineer Required: This needs a formal assessment to ensure the building is stable. |
| Over 25mm | Category 5: Very Severe | Structural instability. Visible gaps where you might even see daylight through the wall. | Immediate Action: Keep people away from the area and call an engineer immediately. |
The Crack-O-Meter
Slide to match the width of your crack:
Quick Tips for Measuring:
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The Coin Test: A 1p coin is about 1.5mm thick. A £2 coin is about 2.5mm thick. If you can fit a £2 coin in the gap, you’re moving into "Category 2/3" territory.
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Direction Matters: Vertical is often fine; Diagonal or Stepped usually means the ground is moving; Horizontal often means the wall itself is struggling with weight or ties.
Ready for an expert opinion?
Whether you're after a full structural survey or just a chat about a suspicious crack, STRUCTURA Project Services Limited is here to help. We provide informative, impartial, and truthful advice, all delivered with a laid-back approach. Get in touch to discuss your structural engineering needs.
Preparing for the Engineer: Your "Next Steps"
If you’ve decided it’s time for an inspection, here’s how to make the process as smooth (and cost-effective) as possible:
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Clear the Way: We need to see the walls and floors. If a crack is hidden behind a heavy wardrobe or stacks of boxes, try to clear the area before we arrive.
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The "Paper Trail": If you have old floor plans, previous survey reports, or even old photos of the house from a few years ago, have them ready. It helps us see how the building has changed over time.
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Note the Timing: When did you first notice it? Does it get bigger in summer and close up in winter? This "seasonal" info is gold dust for an engineer.
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Access: If the issue is near the roof or a high gable, let us know in advance so we can bring the right access equipment.