How Do Buildings Decay?

So as many of you know, EDS was my first explore. I've seen pictures of the building from 2007 to the ones I took. A lot has changed. I understand there are robbers and metal thieves, but aside from that fact, how do buildings fall in disrepair (i.e. collapsing in on themselves, etc.)

Once water gets into the building through the roof on a continual basis a building is doomed. Woodwork starts to rot and any rusting metal work starts to expand because of the corrosion products produced. Many older buildings were not that well built - I have seen a Georgian mansion that had every floor joist in a large (30ft long) 1st floor reception room made from two 17ft lengths of timber joined by a nailed 12ins lap joint. The collapsing lath and plaster ceiling caused the majority of the joints to fail. The very common lath and plaster interior walls and ceilings are very prone to shedding their plaster coat when water penetrates the lath work, this then leads to the weakened and often rotten floors to collapse onto the ground floor.

There is a saying that the best way to destroy a barn is to cut a 2ft hole in the roof and wait a year.

Just to mirror what DS says, water kills all materials which were never designed to be in such an exposed environment. When they fail they often take large bits of not-that-decayed matter with them.

Pripyat is mainly concrete frame, and 99% of buildings are absolutely sound structurally. They've now endured 28 winters down to -40C and summers up to +35C.

I went to explore a fishing village inside the Arctic Circle this year. I knew they were concrete framed, and had only been abandoned 35 years. The weather there is a lot, lot more consistent than Ukraine, so I thought they would be in fairly good condition... but they were ruined beyond most 300 year old UK ruins!

Water ingress, as others have said, basically means disaster for any building. Often it starts with a blocked gutter, a leaky skylight, a broken window or a missing tile. In an occupied building you'd get this seen to ASAP, but in an empty building that rarely happens.

Also, it's worth remembering that without people regularly coming and going, turning on heating, opening windows etc, the atmosphere in a building will change - it becomes colder, damper and air flow is reduced. Over time that can do a surprising amount of damage.

Two things, water ingress and visible damage.

Water is self explanatory and well explained by Dirius, but the other is visible damage. Once that occurs it's like a beacon to every kid and scrote around that the building is fair game to be picked apart.

soon as buildings lose their heating / lack of maintenance its a downward spiral into decay
water gets in through either theft of lead or damage

Leave an old car outside for a few years and study it's fall in decay

I'd say that social media and thus people have contributed to pushing the decay of buildings along that bit further. Seems to have gotten to a point where it's not even a case of google fu anymore, but merely checking out a few public facebook groups to find good places to smash up.

The initial cause of any (sound) structures collapse is the establishment of plant growth, usually starts within a year of maintenance ceasing.

Vandalism may accelerate the early stages.

it is surprising how quickly a building gets what I call "building cancer". As soon as the heat of central heating, and just people being inside it ceases; as soon as the air circulations tops because of this and as soon as people stop fixing the little problems, little weaknesses start to show. And then before long the structure will simply shut down and be overtaken by the damp and elements.

Engineer said:

The initial cause of any (sound) structures collapse is the establishment of plant growth, usually starts within a year of maintenance ceasing.

Vandalism may accelerate the early stages.

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This isn't true at all.

SlimJim said:

I'd say that social media and thus people have contributed to pushing the decay of buildings along that bit further. Seems to have gotten to a point where it's not even a case of google fu anymore, but merely checking out a few public facebook groups to find good places to smash up.

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Sadly, I think the above is certainly a major factor when considering the 'speed of decay' seen in some structures these days.

Vegetation certainly can appear to cause decay - but one must realise that if one encounters a building full of greenery, then the wet and damp were certainly there first to allow the plant life to gain a foothold. Our common invasive plants here in the UK do not thrive well under arid conditions.

Quoted for truth:

MD said:

soon as buildings lose their heating / lack of maintenance its a downward spiral into decay
water gets in through either theft of lead or damage

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Lack of heating and ventilation over the winter is how decay begins. Heat drives moisture out of the building fabric, ventilation removes moisture from the air inside buildings. When both are switched off, the relative humidity of the air, and moisture content of internal finishes increases, which affects paint, plaster, timber and so on. They expand and begin to swell and delaminate so paint flakes, carpet tiles lift, fabrics rot, timber warps etc etc.

After a few years, lack of maintenance to the external envelope of buildings means that flashings lift, slates and tiles are pulled off in storms and so on, letting moisture in. Over the winter, the moisture freezes and expands, which forces open joints and perpends in masonry, thus letting in more rain and show. It's a vicious circle. If you don't clean the gutters, plants grow in them then when they overflow, the water finds its way into the wallhead and percolates down, which is what ultimately destroys masonry wall constructions. If you want to preserve a wall, keep it covered with a roof, a flashing or a coping.

The mechanisms of decay are well understood, and if you're really interested you can look up BRE (Building Research Establishment) reports … or study architectural conservation.

When a building's roof starts to fall apart that's the being of the end. When the rain gets in the ceilings fall in followed by the floors seen it so many times over the years. A building like for example Oakhurst house in Derbyshire was abandoned in the late 1970s now in 2014 its merely a shell and beyond economic repair the last time I was there the brickwork has started to fall in give it another ten years it will be just rubble on the ground. A derelict building can be salvaged up to 16 years after its abandonment depending on condition and willingness to spend the money to return the building back to a reasonable state.

ironsky said:

A derelict building can be salvaged up to 16 years after its abandonment depending on condition and willingness to spend the money to return the building back to a reasonable state.

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It is actually impossible to state how long a derelict building will remain in a 'cost effective salvageable state' - there are far too many factors involved. Type of construction. materials used and even the overall yearly climate can drastically alter the life of a derelict property.