A strip foundation is a continuous concrete strip, typically reinforced, used to distribute the weight of load-bearing walls over a floor area. This type of foundation is most commonly used for low-rise domestic buildings on stable ground. It can also be used when a structure needs to support localized loads, which pad footings cannot do.
The width of a strip foundation is predetermined by the soil’s allowed bearing pressure and the building load. Weaker soils and greater loads will require broader foundations to disperse the weight over enough of the ground surface. A table within Approved Document A of the Building Regulations sets out the minimum strip foundation widths for different categories of subsoil and loading.
For strip foundations to be effective they must be excavated at a depth equal to the height of the wall being supported. The foundation trench must then be backfilled with concrete of a strength equal to that of the building and compacted thoroughly before the wall is built on top. If the load-bearing walls are to be erected close to existing trees or other features in the site, then special care must be taken to avoid disrupting them. Ideally, the foundations should be kept away from any tree/s by a distance equal to that of their expected height at maturity.
The advantage of using strip foundations is that they do not need the large machines often needed for pad footings, as they can be constructed by hand. They are also cheaper than solid slab foundations. However, a disadvantage is that they do not have the same level of durability as other types of foundations and may not be resistant to frost or soil chemicals. If you are considering using a strip foundation it is important to consult a structural engineer who will be able to advise you on the best solution based on the soil conditions on your site.
If your site has poor soil conditions you should not use a strip foundation as this could lead to structural problems. A pad or beam foundation is more suitable for your situation. It is important to choose the right foundation for your project, as a mistake here could cost you a lot of money and put the integrity of your building at risk. Our engineers are happy to advise you on the best foundation type for your site. Just get in touch with us for more information or to request a quote.
