Problem Constructions

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There are 4 main types of construction especially prone to structural problems.

Timber Frame

English half-timbered terraced house

Timber frame buildings are relatively common. Unfortunately so is cement render on timber frame. This traps damp in the frame, and sometimes leads to rot of the frame. (ref) Repair can be costly. Prevention consists of using only lime or earth based renders on the building, and only lime or earth based porous paints. Cement renders and modern impermeable paints should be avoided.

Earth Buildings

The citadel of Arg-é Bam: The world's largest adobe structure, dating to at least 500 BCE

Known variously as cob, earth, adobe and other names, earth buildings are part of Britains historic housing stock. While these work well enough as designed, common modern alterations can lead to significant structural problems. Cement render tends to cause damp walls, and when the cob reaches a certain level of water content, it loses its strength and can collapse. Although not common, there have been cases where the cement render had become structural due to failure of the cob, caused by the cement render.

Cement rendered earth should generally have its render removed, and be rerendered with lime, which is porous enough to permit any damp in the wall to evaporate out. Precautions are needed in doing this, as it could in rare cases cause collapse if done wrongly.

Replacement roofs can sometimes be an issue with earth buildings, as these buildings require generous roof overhangs to remain in good health, and these are not normally provided on modern roofs.

Reinforced Concrete Buildings

Reinforced concrete buildings suffer from rusting and consequent expansion of the reinforcing steel, which breaks the concrete apart. Most of the compressive strength of the building material is thus lost. These are known as a defective building type, and obtaining mortgages is difficult if not impossible.

Steel Frame

Steel Frames rust, and houses may have frames that are impossible or impractical to inspect, thus the condition of the frame can not be determined.

Mortgage Companies

Abbey and Halifax lend on steel frame.

Ecology building Society lend on a minority of derelict houses, but only with a low income multiplier. ref

See Also

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