So why do you need a Structural Engineer?

In coming to Bricks & Pieces you will almost certainly have decided that you wish to alter your present house to create additional accommodation either by the addition of an extension or by a loft or cellar conversion or by a combination of these.

Inevitably this will involve alterations to the original construction which could affect its  stability.  With a traditional pitched roof property a Structural Engineer will normally start at the top and assess the loadings from the ridge down through the rafters to the purlins and onto the eaves and the gable wall, internal walls and party wall if applicable.

All buildings are designed to support their own weight which is commonly referred to as the Dead Load.  In addition they have to support a Superimposed Load which varies in accordance with the usage of the building and is commonly referred to as the Live Load.

Where an opening is created in a building, support has to be provided for the loading above and this is normally catered for by the introduction of a beam which in residential properties is commonly of steel.  This will be designed to resist bending, shear, torsion and deflection.

The beam itself needs to be adequately supported on adjacent walls and often the introduction of piers or steel posts is required to accommodate the concentration of loading created by the alteration.

In the case of more complex alterations a series of steel beams may have to be introduced.

In the case of external walls it is necessary to introduce lintels to support the construction above door and window openings.

Where alterations could adversely affect overall stability it is sometimes necessary to introduce a steel goal post arrangement to restore stability and this can be mechanically connected to adjacent masonry.

All loadings have to be checked through to foundation level and, where original foundations are significantly affected, trial holes are required to ascertain their size and depth and the condition of the bearing strata to assess if any strengthening is required.

The Structural Engineer will advise on the most economic foundation solution either by the introduction of a larger foundation or by underpinning an existing foundation.  The solution will take into account the nature of the site i.e. if it is level or sloping and the proximity of drainage, trees or other structures.

Many alteration schemes include for the removal of existing chimney breasts within the accommodation area to create additional usable space.  However, if the chimney stacks are not to be taken down, the remaining chimney breast brickwork within the loft has to be mechanically supported either by the introduction of steel beams or by the introduction of steel gallows brackets bolted to the chimney breast wall just above ceiling level.

In the case of semi-detached or terrace houses, the chimney breasts may be back to back with those in an adjacent property and therefore the removal of the stack is not possible and the stability of the party wall has to be considered.

As with all alteration work of a structural nature, chimney breast removal is subject to The Party Wall Act and owners need to be aware of their liabilities under the Act.

In some instances buildings may have suffered from previous movement frequently due to wall tie failure, lack of lateral restraint or foundation subsidence which can result in downwards movement and sometime rotational movement.  In these cases an appraisal of the overall stability should be made prior to the preparation of any alteration or extension scheme being formulated.

As part of the appraisal the Structural Engineer will be able to advise if the movement is of an on-going nature and covered by The Building Insurance Policy and if a claim can successfully be made.

Prior to purchasing a property a similar Structural appraisal of movement can be carried out to assess the viability of the purchase.  If foundation subsidence is evident it is frequently very difficult to obtain Building Insurance cover as many Insurers are reluctant to provide cover even when remedial work has previously been carried out with Structural Engineering supervision and Building Regulations approval.

Without Building Insurance it is very difficult to obtain a mortgage and the marketability of the property can be considerably compromised.

Why not contact Bricks and Pieces for more information toda