What Is A Padstone In Construction?
What Is A Padstone In Construction?
A padstone is a simple type of building foundation consisting of a stone that spreads the weight of a wooden building out on the ground and keeps the wood off of the ground.
It is typically used to support the end of a beam, such as steel or timber, and spread its concentrated load over a wider area to reduce pressure.
The size of the padstone depends on the amount of load, the area of the beam bearing on the wall, and its compressive strength. Padstones are usually made from engineering bricks, dense concrete blocks, or other materials with higher strength than that of the wall below.
In some cases, padstones may not be necessary if the combination of loads and wall strength means that they would not be over-stressed.
Pile foundations are another type of deep foundation that can also be used to transfer heavy loads from structures to hard rock strata much deeper below ground level.
What Is The Purpose Of A Padstone?
The purpose of a padstone is to spread the concentrated load from the beam over a wider area of masonry below, reducing pressure and preventing overstressing.
The size of the padstone depends on the amount of load, the area of the beam bearing on the wall, and the compressive strength.
Padstones are not always necessary; if the combination of loads and wall strength means that the wall would not be over-stressed, then there is no need for a padstone.
Engineering bricks, dense concrete blocks, and precast concrete padstones are common choices for padstones. Padstones should be placed on top of and in line with supporting walls, not bridging the cavity, with the RSJ bearing fully on the area of the padstone.
When Should A Padstone Be Used?
A padstone is a block made from stone or concrete that is used to distribute a point load evenly into a structure. Padstones are typically used to support the end of a beam, such as steel or timber beams.
The size of the padstone depends on the amount of load, the area of the beam which is bearing on the wall, and on the compressive strength of the material.
Padstones are not always necessary; if the combination of loads and wall strength mean that the wall would not be over-stressed, then there is no need for a padstone.
Padstones can be used in modern buildings to distribute loads evenly at points where beams and lintels are built into a structure.
In traditional timber-framed construction, foundations in the modern sense would not usually be provided. For a cruck-framed building, padstones can be used to transfer point loads into the soil and are usually placed at shallow depths.
In modern masonry, padstones made from more dense concrete blocks may be used to withstand point loads; without this, standard blocks could crack causing structural damage.
Shims may also be used in conjunction with padstones to level beams carried on them. These shims may be installed in advance of the beam being placed, thus avoiding any need for further vertical adjustment.
In summary, padstones should be used when needed to support beams and distribute point loads safely to supporting structures without undue movement or deflection, taking into account factors such as load size and compressive strength.
How Much Weight Can A Padstone Hold?
A padstone made of 3.5N blocks can carry 0.35kg per sq/mm, meaning a beam end measuring 102mm x 100mm can safely support a load of up to 10.5 tonnes.
