In its most basic form, a foundation is the lowest section of a building which is used to transfer the load of that building into the ground below.
The size and type of foundation depends on many factors including but not limited to: the age of the building, the type of building, the ground the property has been constructed on, the proximity of the property to other properties, rivers, roads etc.
Foundation Types
The most common type of Victorian construction foundations were brick spreader footings. This is where the wall is thickened out using the same masonry in which it is constructed to spread the load over a wider area at the base.
An example of this is identified below (Taken from Modern House Construction 1909) :
In some instances a small amount of concrete was used beneath the brick spreader footing but this generally would be no deeper than 300 to 400 mm.
Following the London Building Act 1930 concrete foundations became a requirement to be at least twice the width of the wall. This was then increase at a later date to be three times the thickness with a depth not less than the width.
Soils and Ground Conditions
Foundation types have since progressed following understanding and knowledge around ground conditions.
Soils which are affected by moisture such as clay can lead to movement dependent on the weather conditions and season in buildings with shallower foundations and therefore the building regulations has progressively deepened foundations to appoint where the shrinkable soils are not affected by seasonal changes except in extreme circumstances.
On difficult ground conditions it is possible to use alternative foundation types such as piles; columns of concrete usually excavated with an augured pile machine. This type of foundation is also regularly used with larger projects.
There are other foundation types such as Sheet Piles, Load Bearing Piles, End Bearing Piles, Friction Piles and Soil Compactor Piles. There use, advantages and disadvantages range on a number of different variants. They will all be discussed in more detail throughout our upcoming blog posts.
Common problems
Foundation problems are normally seen in older buildings with shallow foundations.
The most common problems include issues with ground movement due to (Subsidence caused by numerous different reasons such as water damage or nearby trees).
It is not always easy to correctly identify issues without making assumptions based on experience as foundations are below ground.
In some instances it will be necessary to excavate to look at the foundations in detail. This is commonly known as a trial pit. This can be arranged with a structural engineer through our company. It is normally only required if there is substantial cracking and movement in the property that is causing concern.
If you believe you may have an issue with your home or property that may be caused by failure of foundations talk to one of our team today. We can inspect, advice and arrange not only a building survey but trial pits and structural engineer involvement to help. Our company provides building surveying services throughout the UK but predominantly around Rochdale, Manchester and the North West of England.