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4 Things to Consider Before Underpinning Your Home

(May 25, 2024)

When the ground beneath a structure begins to weaken, it becomes unstable. This then causes the building that sits on top to shift and become warped and damaged. It can be a daunting prospect as a homeowner to come across signs that your house needs to be underpinned. 

However, there are some things that you’ll need to consider before employing the help of an underpinning professional. Aside from having a subsidence survey carried out, here are four things you’ll need to know before committing to underpinning services from us here at Geobear. 

 

1. Understand what ‘underpinning’ means

It’s imperative that you understand what underpinning is, what it involves and why it’s needed. There are a few different methods that are used to carry out underpinning services. The most popular and least disruptive one being the resin injection method. This is the method used by us here at Geobear. An alternative underpinning method is ‘mass concrete underpinning’. It requires excavation of all the soil beneath the foundations and the pouring of concrete in the exposed areas. Mass concrete underpinning takes weeks or months to accomplish.

Geobear uses a fast resin injection method whereby we inject the affected area with resin that fills the voids in the ground and hardens as it goes, therefore strengthening the soil. It achieves the same results as traditional underpinning services to rectify subsidence problems, only it’s less messy and is completely non-disruptive. 

This is what underpinning means; it restores the grounds’ strength, therefore giving it the ability to carry the structure, without hindrance, once again. However, now we’ve covered what underpinning is, it’s important that you know the signs of subsidence so that you can know whether or not underpinning is really necessary. Here are the signs of subsidence:

  • Cracks appearing in walls that are 3mm (or more) wide
  • Cracks in walls that present themselves in a zigzag pattern
  • A diagonal crack that is wider at the top than it is at the bottom
  • The same cracks is visible both inside and outside
  • Cracks that appear around windows and doors
  • Cracks spreading under the damp-proof course
  • Wallpaper creasing at the joins or where the ceiling meets the walls
  • Doors and windows that become jammed
  • Doors and windows that cannot be closed
  • A house extension coming away from the rest of the house

 

2. Research around building regulations & planning permission

You will need to check with the Local Authority before having mass concrete underpinning services carried out. This is because it will need to be done to current building regulations. Usually, this includes the submission of a structural design that’s done by an engineer as a result of an onsite investigation. 

The same design will also have to include a description of the process that is due to be carried out. However, you do not need to submit a planning application if it involves underpinning alone, unless you’re changing the appearance of the house. If you’re still unclear about your responsibilities when it comes to building regulations and planning permission, then contact your local council for further advice and guidance.

Geobear resin injection method does not require any consent or approval from outside parties.

 

3. Be aware of the different underpinning methods that are used

There are several different methods that are used to underpin a house or a structure of any kind. Here at Geobear, we use the resin injection method, which is one of the least disruptive and most tidy ways of carrying out underpinning services. 

If you need underpinning to be carried out, then it’s important, however, that you familiarise yourself with the different underpinning methods that are used so as to ensure you’re undertaking the right method for you. 

You should discuss this with the underpinning firm you have enlisted, asking for their advice before work is carried out. As experienced professionals, our dedicated team here at Geobear have worked on many different buildings, each varying in the severity of subsidence. 

Therefore, we are able to impart specialist and expert guidance to our clients, giving them absolute peace of mind that the correct method for their situation is being used. As an overview, here are the different methods that are used to carry out underpinning services:

  • Underpinning to walls
  • Mass concrete underpinning
  • Underpinning by cantilever needle beam method
  • Pynfored underpinning
  • Mini piled underpinning
  • Pit method
  • Grout
  • Resin
  • Pile method of underpinning
  • Beam and base method
  • Angle piling

 

4. Know the circumstances in which underpinning is needed

Underpinning isn’t something that needs to be carried out if you spot a hairline crack in the walls. There are times when you might think that subsidence is at play when it’s actually something that you needn’t worry about. Where we have already discussed what subsidence is, together with the sure signs of it, there are some things that you might experience in and around the home that can be mistaken for subsidence. So when is subsidence not subsidence?

 

Cracks in walls that are less than 2mm wide

Cracks are commonplace in any home, no matter its age, and they don’t always point towards subsidence. If they appear in walls, floors and ceilings can occur in and around the home for a variety of different reasons, including:

  • Settlement cracks – most common in newbuild properties or where new plastering work has been carried out
  • Hairline cracks – these can be seasonal, expanding and contracting with the changes in temperatures
  • Several cracks in new plaster – cracks in plaster is common where the plaster or skimming is new. If you’ve recently had work done, then new cracks appearing shouldn’t be cause for alarm
  • Some cracks due to traffic – cracks can form in walls if you live on the main road, caused by the vibrations that ripple through the road and along the floor of the house
  •  A few cracks due to lintel failure – when lintels above doors and windows fail, it can cause bricks to slump and, therefore, crack. Lintel failure cracks can be mistaken for subsidence as they often present themselves in a zigzag pattern, much like subsidence cracks

 

Sinking floors

Far more common in older houses, it’s commonplace for floors to slope and bow, especially if the floor is made of wood or stone. In addition, it might also be a sign that some underpinning work has been carried out in the past. However, you should not panic if this is the case. Underpinning is a highly-effective subsidence solution that will last for many decades. Although, if you’re looking for peace of mind, then book a subsidence survey with Geobear today. We will be able to confirm or deny subsidence problems.

 

The extension coming away from the rest of the house

We have already listed this as one of the sure signs of subsidence. However, there are times when this particular sign doesn’t spell subsidence. If you live in a Victorian or Edwardian house and have had a new extension built onto it, then it’s likely that your extension is coming away because the main house has been built on shallow foundations, whereas the new extension would have been built on deeper foundations. 

In addition, the materials used to build the house and to build the extension are different. Old houses use far more flexible materials in comparison to brand new structures. When those materials come together, it can cause an incompatibility. If this situation rings true for your individual circumstances, then it may not be subsidence that is at play.

 

Goebear is pleased to offer underpinning solutions that are able to seamlessly rectify subsidence problems. From domestic houses to commercial properties, we are highly-experienced, making no project too big or too small for our dedicated team. If you would like further information, get in touch with a member of our friendly, knowledgeable team today – we’re always pleased to hear from you.

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