Underpinning is a method used to increase foundation depth or to repair faulty foundations, often used when planning add stories to an existing structure or when the foundation is damaged. Underpinning may be necessary for a variety of reasons including if it is found that the original foundation is not strong or stable enough, the usage of the structure has changed, the properties of the soil supporting the foundation has changed through subsidence, the construction of nearby structures necessitates the excavation of the soil supporting existing foundations, to support the addition of another storey to the building, or if earthquake, flood, drought, fire, explosion or other damage have caused the structure to move, requiring stabilisation of foundation.
Underpinning to strengthen and stabilise the foundation of an existing building involves increasing the depth of the foundations to a building being increased, normally done in phases by evacuating the existing soil and replacing it with concrete. Underpinning may be necessary for a variety of reason and maintenance on foundations generally does not require planning permission. However if you live in a listed building or designated conservation area, you should double check with your local planning authority before any work. Most companies offering underpinning services can do this on your behalf as they normally have their own architectural designer who can liaise with the council and keep you up to date with procedures and information.
However, if you need to underpin the foundations of your building, Building Regulations will apply and appropriate measures must be carried out to ensure the underpinning stabilises the movement of the building, with particular given to any sewers and drains near the work. Underpinning specialists can provide a site survey, free quotation, engineering drawings using autocad and complete project management from planning to completion.
Underpinning can be used to strengthen foundations for a number of reasons such as strengthening the foundations if you’re planning an extension above an existing room, if the building’s use has changed and there is more pressure being placed on the property, if there is movement or subsidence beneath your property, or if there’s a new development nearby which is having an effect on your property. Often people seek advice from builders and contractors when they see cracks appearing or walls bowing out, but before repairing a crack you need to know that the movement that caused it, has stopped, or the repair is a waste of money.
Arresting movement often requires underpinning and it can cost between £8,000 and £16,000 to get a house underpinned. Stopping a wall bowing may require tying in on an older property or the replacement of wall ties in a newer property, this could cost an additional £5,000. In addition, price of underpinning a house to stop the movement in a wall does not usually include returning the wall to it’s original position, to do so will incur additional costs of around £5,000. Underpinning is labour intensive and therefore expensive work, the prices may be eye watering but there are no cheaper alternatives.
MyJobQuote provides a free service to gather quotes from reliable local builders near you which is recommended by many satisfied users. But before you employ a builder to carry out underpinning work on your foundations, you should ask the builder to take you to see work that they have recently finished and introduce you to previous customers, don't simply accept written references as these can easily be faked. Check builder qualifications and make sure your builder can demonstrate awareness of health and safety issues and note any trader scheme memberships.
Always ask to see a copy of their insurance certificate and make sure there is cover for public liability insurance in case someone gets hurt on your site, cover in case there is damage to your property, plus cover in case the builder goes bust or has an accident and cannot finish the job. reputable builders will guarantee the work for a period of time in writing.
Always create a contract detailing what work the builder is going do, the payment stages and what happens if there is any dispute. Finally never pay for all building work upfront, you should release money only when each stage of the work is finished to the specification in the contract and to your satisfaction.