Author: jay

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Foundation movement can affect the serviceability of a building. This may include water penetration through cracks and sloping floors. It can also result in distortion of door and window frames. This can be as an indirect result of movement in the external walls or directly through movement of the internal walls. 

Such movement can take the form of ‘wracking’ where the frame loses its squareness (if that’s a word) and is demonstrated by tapered widening at one end of the gaps and a narrowing at the others. This results in the door jamming. The most common cause of doors jamming in older properties is normally temperature and moisture variations during the year.

This door frame in Cork City is about 20mm out of level!!!

But, interpretation of movement needs careful consideration. In this instance, it is evident that the top rail of the door and architrave have been significantly altered over a long period of time and this is disproportional to the cracking. This would suggest that the initial movement began quite some time ago, maybe when the building was constructed, and adjustments were made from or at that point.

Nonetheless, movement was rejuvenated for another reason thereafter and the result was a development of the original movement. This is demonstrated in the cracking. The weak points in the superstructure created during the settlement period will normally be the first to be compromised.

Therefore, it could be argued that the distortion in this situation represents both settlement and subsidence.

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Cracking in walls is the most common sign of foundation movement and may form within or between components. Despite the width of any crack, a key aspect of any subsidence investigation is to determine if movement is ongoing or not.

When an extension begins to move away from a building, a vertical crack will usually form at the interface of the building and extension. This crack will be wider at the top as the extension rotates away from the original structure. The corner of the extension will normally act as the pivot point.

In terms of diagnosing progressive movement, there can be simple signs to suggest that the building is still moving e.g. cracks which have been repaired and re-opened can strongly suggest that movement is not historic. This crack in Blarney St was repaired at some point yet has continued to open and is now in the order of nearly 8mm!!!!!!

The building showed other signs of movement internally in the form of cracked floor tiles and ceiling cracking between the function of both buildings.

The remediation scope was a series of small diameter displacement piles known as Grundomat supporting RC ground beams beneath the foundation.

 

Diagnosing subsidence or foundation movement through a simple present condition survey may sometimes prove difficult without further investigation.

The most common sign of foundation movement is cracking. As a foundation moves, the building will become distorted, particularly around openings in walls.

The construction type of the building can also have an influence on how the building will react to such movement. Foundation movement in this conservatory in Co. Cork has resulted in the window frames becoming so distorted that the glass has cracked!!!!