Every crack in a facade tells you where it comes from
We repair the facades of houses and apartment buildings in the province of Málaga: hairline cracks, cracks, spalling, balcony edges and damaged single-coat render. Before touching anything, the defect has to be read, and here we show you how: what shape each one takes, how to tell whether it is still moving and how it is repaired once you know what it is.
The same crack does not mean the same thing in single-coat render as in exposed brick. First, find out what your facade is made of.
Six defects, six different causes
A crack is not just a line: its direction, its shape and where it appears tell you what opened it. These are the ones seen most often on facades along the coast, each shown where it usually appears.
Where each one appears
One facade, six defects
A horizontal line at the level of each floor
It marks the edge of the floor slab. The concrete of the slab and the brick of the wall expand differently with heat and moisture, and the render cracks right where they meet. It opens and closes with the seasons.
We repair it
Running diagonally from the corner of a window
The corners of openings concentrate the stresses in the wall, and any movement shows there first. If it is fine and not moving, it is in the render. If it widens, or appears at several windows at once, it points to something moving further down.
Depends on how it develops
A web of fine cracks in every direction
Shrinkage: the mortar or the paint contracted as it dried, often because it dried too fast, in sun or wind. It stays on the surface and does not go through the render.
We repair it
A stepped crack, wider at one end
It follows the brick joints and runs across the wall. It is the classic signature of settlement: one part of the building has dropped relative to another. It is not fixed with mortar or paint until you know why it moved.
A surveyor first
Spalled concrete with the steel showing
On balcony edges and slab fronts. The reinforcing steel rusts, swells as it rusts and pushes off the concrete that covered it. There is usually an earlier warning: a rust stain running down the wall.
We repair it
An area that sounds hollow when tapped
The render has come away from the wall even though it is still in place: damp behind it, mortar that never bonded or years of expansion. You find it by tapping with your knuckles, except on a facade with external insulation, which sounds hollow anyway.
We repair it
Why the fifth is so common near the sea, and what it has to do with the inspection of buildings, we explain in our article on the ITE building inspection in Málaga.
How to tell whether a crack is still moving
It is the question that decides everything else. A dead crack is repaired and forgotten; a live one comes back through whatever you put over it. You find out with patience and with three tools of differing precision.
A pencil line and a date
With a pencil, make a short mark exactly where the crack ends at each end, and write the date next to it. If after a few weeks the crack has gone past the mark, it is growing. It is the first thing you can do, and it costs nothing.
The plaster tell-tale
A pad of plaster placed across the crack, firmly stuck to both sides. Plaster is rigid and brittle: if the wall moves, even slightly, the pad breaks along the line of the crack. If it stays whole week after week, that crack is not moving, at least for now.
Graduated crack monitors
These are what a surveyor uses: two overlapping pieces, one on each side of the crack, with a scale that shows how much it has opened or closed between one visit and the next. When things look serious, they provide the figure the decision is based on.
You have to give it time, ideally through a change of season. A crack that opens in the heat and closes in the cold is not the same as one that only grows: the first breathes with the facade and is treated as a joint; the second has a cause that is not on the surface.
How each case is repaired
Once you know what each defect is, the repair almost follows by itself. There are four different jobs, and none of them consists of covering it up with paint.
Sealing what is superficialCrazing and fine cracks that are not moving
They are opened up slightly with a tool to clean them and let the material in, then filled and levelled with the rest. If the crazing covers a whole section, it is given a coat of render with a fibre mesh embedded in it, which spreads the stress and stops the web of cracks from reappearing. Then comes the paint.
Treating what moves as a jointThe line along the edge of the floor slab
A crack that opens in summer and closes in winter is not fixed by filling it with mortar: mortar is rigid, and within a few months it splits again in the same place. It is treated as what it is, a joint between two materials: an elastic sealant that moves with it, and mesh in the render along the junction.
Making good what sounds hollowHacking off back to sound material
The render that has come away is removed completely, tapping around it until the wall sounds solid again, because the edge of the hollow area is always further out than it looks. The substrate is cleaned, given a bonding agent and the mortar is built back up in layers, matching the texture of the rest so that the patch does not show against the light.
Rebuilding the concrete around the steelBalcony edges and slab fronts
The concrete is broken out until the reinforcement is exposed all the way round, the rust is cleaned back to bare metal, the steel is protected with a passivating coat and the edge is rebuilt with a concrete repair mortar. If, once exposed, the reinforcement has lost a lot of its cross-section, or many balconies are in that state, the decision is no longer ours: it is for a surveyor.
Repair is always followed by paint: it evens out the colour and the texture and protects what has been put in new.
What to bear in mind before repairing your facade
Repair and paint in the same job
Reaching the facade is what costs most, and if you repair now and paint next year you pay for it twice. Besides, an unpainted repair shows: the new mortar has neither the colour nor the texture of the old. The sensible thing is for both to go in the same quote and use the same access equipment.
It should say what each crack is
“Crack repair” on a single line says nothing. A quote you can compare says what defect each one is, how it will be repaired and how it is measured: linear metres of sealed crack, square metres of render hacked off and replaced, balcony edges per unit. And what happens to the price if, once the hacking off starts, there turns out to be more than could be seen.
What could fall cannot wait
A piece of hollow render above a pavement or a patio is a danger to anyone walking underneath. Anything loose is made safe as soon as it is spotted, even if the full repair is done later. And if the crack is one of those that needs a surveyor, the finish waits for their report: repairing the skin before knowing what is going on underneath is throwing the work away.
How each facade is reached, and how much that weighs in the total, we explain in the cost of painting a facade.
What people ask when a crack appears
How do I know if a crack in the facade is serious?
How do I know if a crack in the facade is serious?
By what it does more than by its size. It is a concern if it grows from one week to the next, if it is wider at one end than the other, if it steps along the brickwork or if it can also be seen inside the house, especially if at the same time a door has started to stick. In any of those cases, before a painter, it needs to be seen by an architect or an aparejador (a building surveyor).
Will filler and a coat of paint do?
Will filler and a coat of paint do?
For a fine crack that is not moving, with the right filler, yes. For one that moves, no: a rigid filler cracks along with it, and ordinary paint splits over it as soon as the wall flexes. That is why the first step is not choosing the filler but finding out whether the crack is live.
What is the difference between a hairline crack and a crack?
What is the difference between a hairline crack and a crack?
In the trade, a fisura (hairline crack) is the fine opening that stays within the render, and a grieta (crack) is wider and can go right through the wall. The word matters little; what matters is whether it affects only the skin of the facade or the wall behind it, because that changes who has to repair it.
Can single-coat render be repaired without it showing?
Can single-coat render be repaired without it showing?
Completely, hardly ever. Single-coat render carries its colour in the mix, but the render on your facade has had years of sun and the one in the new bag has not. What works best is to cut the patch back to the panel joints, which act as a frame and disguise the change, or to accept that the whole facade will be painted, and then the repair no longer shows.
How much does it cost to repair a crack in the facade?
How much does it cost to repair a crack in the facade?
It depends on what defect it is, how many metres it runs and, above all, how it is reached: a crack three metres off the ground and the same crack on a sixth floor are not the same job. That is why we do not give a price without seeing it. What we do is measure it in metres of crack or square metres of render made good, so that you can compare.
Send us a photo of each crack
With a coin or a tape measure next to it so we can see the size, another of the whole facade so we know where it is, and tell us how long you have been seeing it and whether it has grown. With that we know whether it is a job for us or whether a surveyor needs to see it first, and we will tell you plainly.