OK, picture this. It's a Tuesday morning.
You're walking down your hallway, maybe you're balancing
a cup of coffee in your phone, just minding your own business.
And then your eyes drift to the wall and you stop dead in your
tracks. There it is, a jagged, dark line
running from the corner of the door frame up toward the
ceiling. You swear on your life that line
wasn't there yesterday. Oh, that is the universal
homeowner stomach drop. That specific sinking feeling
it. Is it's a media physiological
panic my heart starts racing. I start thinking that's it.
The foundation is crumbling. The.
Whole thing's coming down. The house is snapping in half
like a dry twig. My investment is turning into
dust and then naturally, I do the worst possible thing.
Let me guess, you open the laptop and go straight to the
Internet forums? I go to the search engine of
doom, I type in crack above door frame and I mean within 5
minutes I've diagnosed my house with terminal subsidence and I'm
looking up how much a structural engineer costs versus how much
UTT tent costs. Which is exactly why we are
doing this deep dive today. Because that cycle, the
discovery, the immediate panic in the Internet search that only
fuels the fire, is incredibly common.
But as we're going to find out, it's largely unnecessary.
OK, so today we are unpacking a resource that is designed to be
the antidote to that specific panic.
We're looking at a book called Cracks in Residential Buildings,
a practical visual guide for busy people.
It's written by Tomas Sikorsky. Who is a heavy hitter in this
space? He's a principal property
surveyor and a registered valuer at a firm called Survey, all in
London. So we're not talking about an
academic. No, not someone theorizing from
a university lecture hall who has never held a torch in a dark
loft. This is a guy who spends his
life crawling into crawl spaces, staring at masonry and,
crucially, talking people off the ledge when they find a crack
in their living room. And that field experience really
comes through in the tone of the source material.
It feels less like a textbook and more like a surveyor putting
a hand on your shoulder and saying, OK, let's actually look
at what's happening here. Take a breath.
The mission of this deep dive is to see if we can borrow that
survey fair's eye. We want to move you from anxiety
to, let's call it, informed observation.
But honestly, is it really possible to look at a crack in
your wall and not freak out? It is, but it requires A
fundamental shift in how you view your house.
Informed observation is the perfect phrase, because the core
thesis of Sikorsky's work, and it's the pill you have to
swallow, is that buildings are not static sculptures.
We tend to think of a house is this rigid, immovable object
that should stay exactly the same as the day was built,
right? But it's not.
It exists in the real world. It's fighting the elements.
Exactly. It sits on soil that moves and
compresses. It gets rained on.
It heats up in the summer, it freezes in the winter.
Secorski knows right in the introduction that cracks are the
number one cause of concern for his clients.
But he also points out that the vast majority of that concern is
driven by uncertainty. We see a break in the pattern
and we assume failure, but often the building is just responding
to its environment. It's the jaws effect we fear,
the shark we can't see, or in this case, the structural
failure we think is happening behind the plaster.
Precisely, and the current information landscape doesn't
help. Sakorski identifies a massive
gap in the market, which he calls the information void.
On one extreme, you have the alarmist forums where every
hairline crack. Is subsidence underpinning
required? Call the insurer.
Which is where I usually live. Right.
And on the other extreme, you have dense engineering textbooks
full of calculus and load bearing diagrams that are
totally impenetrable unless you have a degree in structural
mechanics. And I am definitely not reading
1000 page textbook on load bearing mechanics just to figure
out if I need some spackle or a new house.
And that's where this guide fits in.
It's built for the busy person, home buyers, landlords, estate
agents or just homeowners who want to sleep at night.
It aims for proportionate guidance.
Proportionate. I like that word.
It implies matching the level of freak out to the actual level of
danger. Exactly, and the way the source
achieves this is by being a visual guide.
This is a crucial detail that really stood out to me.
Sikorsky didn't use stock photos.
Yeah, I noticed that immediately.
These aren't those perfect high res photos of a pristine white
wall with a digitally added black line.
No, these are photos from real inspections.
They show the messiness of real homes.
The lighting is sometimes a bit off, there's peeling paint,
there's a skirting board that seemed better days, maybe a bit
of damp in the corner. It adds a layer of reality.
It does, because when you look at your own wall, it doesn't
look like a stock photo. By seeing real imperfections
from real homes, it helps normalize the idea that homes
aren't perfect. So it's kind of like Instagram
versus reality, but for masonry. In a way, yes.
It grounds the reader. You realize, OK, this house in
the book has a crack exactly like mine, and the surveyor's
explaining it calmly, so maybe I don't need to evacuate.
OK, so before we start tearing apart our walls metaphorically,
we need to establish the scope here for sure, because the
source material is very specific about what kind of buildings it
applies to. We aren't talking about modern
glass skyscrapers or brutalist concrete bunkers.
No, Sikorsky focuses specifically on traditional
residential buildings in the UK, and for the purpose of this book
and our discussion, that largely means brick and timber
construction. Why that specific distinction?
Why not concrete or steel frames?
Don't they crack too? They do, but they behave
completely differently. Concrete and steel are rigid
engineered structures. If you have a crack in a
reinforced concrete pillar, the physics behind that are complex
and usually indicate a failure of the engineering design or the
material itself. It's a calculator problem.
But brick and timber? Well, they're more organic.
Organic like alive. That makes my house sound like a
biological entity. In a structural sense, it kind
of is. Think about timber.
It is hygroscopic. Hygroscopic OK, that's a great
cocktail party. Or break that down for.
Us. It means it absorbs and releases
moisture from the air. It interacts with the
atmosphere. Wow.
Timber joists will physically swell in humid winters and
shrink in dry summers. It's like a sponge.
Now combine that with brickwork. Brick is rigid.
It's clay. It sits on mortar.
These materials are constantly pushing and pulling against each
other. I see the book excludes modern
concrete frames because the confusion usually happens in
these traditional homes where people expect rigidity but get
movement. OK, so we're talking about the
classic house structure. Bricks, mortar, wood beams,
plaster. Let's get into the meat of it.
Let's deconstruct the cracks. Let's do it.
Sikorsky breaks them down into categories, and I want to go
through these because understanding the cause seems to
be the cure for the fear. The first one is the big one,
Movement in age. Right, the settlement factor.
We need to talk about gravity. A house is an incredibly heavy
object. Hundreds of cons sitting on top
of soil over decades. That soil compresses.
The timber joists might sag a fraction of an inch over 50
years just from the weight of the furniture in the floors.
And because brick is hard and brittle, if the timber moves,
the brick can't stretch. It's not elastic like a rubber
band. Exactly.
This is where we need to talk about tensile strength.
OK, define that. Tensile strength is a materials
ability to handle being pulled apart.
Brick has high compressive strength.
You can stack a lot of weight on it and it won't crush.
Right. But it has very low tensile
strength. It hates being pulled or bent so
the ground moves slightly or the timber sags.
The brickwork is put under tension, can't stretch so it
snaps. And that snap is the crack.
Yes, but, and this is the key insight from the book that blew
my mind, that snapping might be the end of the process.
The end. Yes, the house is settled.
It has found its comfortable spot.
The tension is released. The crack is just a historical
record of that movement. It's not a sign that the house
is currently falling down. It's a sign that the house did
move maybe 30 years ago, and now it's stable.
That is a massive mental shift. I look at a crack and see an
active wound that's bleeding out the value of my home.
You're saying it might just be a scar?
A scar is a perfect analogy. You don't put a cast on a scar,
you just acknowledge it. It's a record of history.
But then we have the second category, which I think is even
more fascinating because it happens every single day,
thermal movement. The idea that my house is
breathing. Breathing, stretching,
shrinking. All materials expand when they
get hot and contract when they cool, but they don't do it at
the same rate. This is called the coefficient
of expansion. OK, let's not get to high school
physics class here, but how does that look on a wall?
Why does it cause a crack? Imagine a long S facing wall.
It bakes in the sun all day. The bricks expand, but the
plaster inside the house is in the shade keeping cool, or the
timber roof Truss is expanding at a different rate than the
masonry Gable. This creates a fight between the
materials. Differential movement.
Exactly. They are fighting for space and
since they can't occupy the same space, something has to give.
Usually it's the weakest point, the mortar or the plaster.
You get these fine vertical cracks, often near the roof line
or where two different materials meet.
Secorski explains that these cracks are often cyclic.
They open in summer, close in winter.
So if I fill them. If you fill them with a rigid
filler in the winter when they're widest, come summer, the
wall tries to expand back, but now the crack is plugged with
hard cement. The wall can't close so it
cracks somewhere else or it crushes the filler and pops it
out. It's a ratchet effect.
You're actually making it worse by fixing it wrong.
Precisely. Yeah.
This is why understanding the source is more important than
just hiding the symptom. If you treat a thermal crack
like a structural crack, you'll just end up with more cracks.
So we have gravity, age and weather thermal.
Then there's the third villain, the DIY extension.
Yes, alterations. Sikorsky highlights this as a
major source of homeowner anxiety.
This is where you bolt a new kitchen extension onto the back
of a Victorian house. Correct.
And you have to remember the Victorian house finished
settling 100 years ago. It's done the new extension,
it's just starting. It's heavy, it's on fresh
concrete footings, maybe on slightly different soil it will
sink slightly relative to the main house.
It's unavoidable. So you get a crack right at the
joint where the old meets the new.
Almost inevitably, unless the builder used a specialized
movement joint that allows the two parts to slide past each
other, if they just plastered over the joint to make it look
seamless, it's going to crack. OK.
Sikorsky points this out to say this isn't necessarily
structural failure, it's just physics.
The new part is settling. It doesn't mean the extension is
falling off, it means it's finding its feet.
OK, so we've got the categories, but I'm still the guy standing
in the hallway with my coffee. How do I actually look at the
crack? The book is a visual guide.
I need you to teach me how to see.
Yes. What are the specific visual
clues that tell me this is fine versus run?
This is the real diagnostic part.
Sikorsky gives us a few specific shapes to look for.
First, look at the taper. Taper.
So is it the same width all the way down?
Exactly. If a crack is a hairline from
top to bottom uniform width, it's usually thermal or
shrinkage to uniform pull. But if a crack is V shaped, say
it's 5mm wide at the top near the ceiling, and tapers to
nothing at the bottom, that tells you something specific
about rotation. What does it tell me?
It tells you one part of the wall has dropped or rotated away
from the other. Imagine holding a chocolate bar
and snapping it. The crack opens at the top first
as you bend it down right. A tapered crack points to
movement in the foundation or the support.
That's a check this out sign. OK, V shape equals potential
movement. What about the direction of the
line? Diagonal cracks are the classic
subsidence sphere. If you see a stepped crack looks
a staircase following the mortar lines moving diagonally down
toward a corner, that suggests that specific corner might be
sinking. OK, that sounds scary.
That sounds like the house is tipping over.
It can be, but Sikorsky adds a very important nuance here.
If the crack follows the mortar, that jagged stepped line, it
means the bond between the bricks broke.
That's the path of least resistance.
It takes relatively low energy to break mortar, however, if you
see a vertical crack that snaps straight through the middle of
the bricks themselves. Like it ignored the mortar and
just broke the solid clay. Exactly like a laser cut
straight down that requires a lot more force, A crack through
the brick itself is generally more concerning than a crack
that zigzags through the mortar. It implies a higher level of
stress. OK, so tapered is meaningful,
through the brick is intense, through the mortar is common.
And what about width? Is there a magic number?
There is. In the UK we have BRE ratings
for cracks. Category 0 is hairline.
Category 2 is up to 5mm. Sigorsky notes that anything
under one 2mm is almost always considered aesthetic or
cosmetic. Wait, 2mm?
Actually pretty visible. That's like the width of a coin.
It is, and that's what freaks people out.
You can fit a pound coin in it, but structurally the wall is
still doing its job. It's still holding up the roof,
right? The house isn't falling, it's
just untidy. But it feels wrong.
I feel like if I can put a coin in my wall I should call the
army. And that's the emotional
reaction Sikorsky is trying to retrain.
He wants you to ask, is the wall unstable or is it just ugly?
Because those are two very different problems.
So let's assume I've done the diagnostic.
I see a crack, it's maybe 2mm. It's stepping through the
mortar. I'm nervous.
I want to monitor it. The book has a tool kit section.
It does. My instinct is to just stare at
it every day and maybe take a photo with my phone.
Which is bad for your mental health and scientifically
useless, right? Sagorsky is very clear on
monitoring. You need data, not vibes.
Photos are tricky because angles change, lighting changes.
You can't rely on them for millimeter precision.
So how do we get data? He suggests using Tell tales.
What are those? They are little plastic gauges
you can buy online for a few pounds.
You screw or glue 1/2 to the left of the crack and the other
half to the right. They overlap and have a grid
printed on them with crosshairs. Now I've seen those.
If the wall moves, the crosshairs shift on the grid.
You can read exactly how much it moved .5 millimeter, 1mm up or
down, left or right. OK, that makes sense.
It's subjective. It removes the guesswork, but if
you don't want to buy a plastic gadget and screw it to your
living room wall, there is a lofi method.
Give me the lofi method. The pencil method.
Draw a horizontal line across the crack, mark the ends, write
the date next to it. Come back in a month.
If the lines no longer match up, it moved.
Simple. But here's the critical
question. How long do I have to do this?
A week? 2 weeks.
This is where Sikorsky drops the bomb that no inpatient homeowner
wants to hear. You really need to monitor for a
year A. Year.
Are you kidding me? I have to look at this ugly
crack for 12 months. If you want the truth, yes,
Think about what we said earlier.
Thermal movement, soil moisture. Buildings move seasonally.
If you monitor for three weeks in July, you'll learn nothing.
You only know what the house does in July.
You need to see how the house behaves through a wet autumn, a
freezing winter and a hot summer.
You need the. Full cycle.
Exactly. You are looking for one specific
thing. Is the movement cyclic or
progressive? Break this down.
Cyclic means it opens and closes, opens and closes, it
breathes. That's usually fine.
It's annoying but it's stable. Progressive means it opens 1mm,
then 2mm, then 3mm and it never goes back.
It just keeps getting wide. It's a one way trip.
That is when you call the engineer.
That is when you worry if it's cyclic.
You just need to manage. It which leads us to the repair
section, because my instinct, and I think everyone's instinct
is to grab the polyphylla, slap it in there, paint over it and
pretend it never happened. This is what we call the
polyphylla paradox. You know.
What if the crack is cyclic moving with the seasons and you
use a rigid filler like standard polyphylla or cement?
You are fighting physics right? As we said, the wall moves, the
filler doesn't. It will crack again, it's
guaranteed. So what's the alternative?
Leaving it open. No.
You use a flexible repair. You use mastic decorators,
caulk, or specialized flexible mortars that have a bit of
rubber you give to them. You have to work with the
building's movement, not fight it.
You're essentially creating an expansion joint.
So sometimes the repair is actually just hiding it better.
Or managing it. Sikorsky emphasizes that we need
to determine if a repair is even appropriate.
Sometimes doing nothing is the best engineering decision.
If a crack is historical, it happened 20 years ago and hasn't
moved since. You don't need to structurally
repair it, you just fill it for looks.
That adds so much credibility to the source.
It's not trying to sell you a repair service or a product.
In fact, the source mentions that this book was reviewed by a
group of fellow surveyors. Yes, that peer review is
crucial. It ensures the advice is
factual, balanced and grounded in real surveying experience
rather than theory alone. It's not just one guy's opinion,
it's a consensus of professional practice in the UK.
Now for the people listening who are thinking this sounds great,
but I still want a simple answer.
I don't want to become a surveyor, I just want to know if
I'm safe, right? The book actually has a feature
specifically for them. The decision guide.
I love a good flow chart. It's basically a logic tree for
your anxiety. It's a very practical tool.
At the end of the book it asks simple binary questions to route
you to the right action. Questions like is the crack new?
Is it wider than 5mm? Is it near a door frame?
And here's a big one. Is it visible on the outside and
the inside? Oh, that's a good one, seeing
daylight. If you can see daylight through
your wall, or if you can stick a ruler through from the lounge to
the garden, the flow chart sends you straight to call a
professional. Yeah, that is not a DIY fix.
That feels like common sense, but when you're panicking,
common sense goes out the window.
Exactly the guide leads you to one of three conclusions.
Monitor cosmetic repair or consult surveyor.
And we should be clear, and Secorski's very clear, reading
this book does not make you a surveyor.
Not at all. I can't just wave the book at my
house and expect it to be certified safe.
No, please don't cancel your home insurance because you read
A50 page guide. This book is a tool for triage.
It helps you decide if you need a professional and crucially, it
helps you have a better conversation when they arrive.
Right. So instead of standing there
trembling, asking is my house dying, you can say I've noticed
a tapered crack on the South elevation.
It looks like thermal movement. What do you think?
Exactly. It changes the power dynamic.
You're not a victim of your house.
You're an active participant in its maintenance.
You have agency. I really like that it's about
taking control back from the fear.
It is. The FAQ section in the book
reinforces this too. It addresses the most common
worries raised by buyers and owners.
It's almost like a greatest hits of homeowner anxiety.
Debunked 1 by 1. So as we wrap up this deep dive
into cracks in residential buildings, what is the big
picture here? We started with panic in the
hallway, holding our coffee, convinced the roof was caving
in. Where do we end up?
We end up with perspective. The main message is that
uncertainty drives fear. When you don't know what a crack
is, it's a monster. When you understand that
buildings move, shrink, age and settle, the panic dissipates.
It's about normalizing the imperfections.
Yes, Sikorsky's work reminds us that the goal isn't a flawless
plastic house that doesn't exist.
The goal is a stable, safe home. Knowledge leads to better
decisions and fewer unnecessary worries.
The aim is clarity, not complexity.
It reminds me of that Japanese concept Kitsugi, you know, where
they repair break and pottery with gold lacquer to highlight
the cracks rather than hide them.
They see the break as part of the object's history.
A beautiful comparison. Maybe we shouldn't be filling
our wall cracks with gold, that might be a bit expensive, but we
should certainly view them with a bit more respect.
They aren't always failures, they are adaptations.
Here's a thought to leave you with listener.
We usually look at a crack as a flaw, a mistake, something that
needs to be erased or hidden immediately.
But if we take the lessons from the source material, cracks are
just a building's way of responding to its environment
and its history. They are evidence of existence.
Exactly. So perhaps we should stop
looking at them as defects and start seeing them as data
points. That line in your wall is
telling you a story, right? Maybe it's a story about that
really hot summer three years ago.
Maybe it's a story about the soil shifting after a rainy
season. Or maybe it's just the house
settling into its old age, getting comfortable like.
Laugh lines on a face. Like laugh lines.
So next time you see a crack, before you panic, ask yourself,
what is my house trying to tell me about the seasons, the soil,
or the history of where I live? And then maybe check the flow
chart just to be sure. And then check the flow chart.
Thanks for listening to the deep dive.
Until next time.