Tag Archive for: basement lowering|underpinning

What is Basement Underpinning Used For?

Underpinning job in Toronto homeIn theory, houses are built on solid foundations that are strong enough to bear their full weight and more. Unfortunately this is not always the case. Foundations may subside and even disintegrate for structural reasons. They can also be affected by flooding, shifting earth and heaving clay.

When this happens there are two solutions. Either you have to reinforce the faulty foundations by adding bulk beneath them, or you have to demolish the house and start again. The former, which builders call underpinning (or basement lowering), is obviously the preferred alternative. While the practice of Underpinning is used to repair a faulty foundation, it’s sometimes  done for other reasons.

Increasing Basement Height

Some basements are little more than crawl-space cellars, having been built for the sole purpose of raising the ground floor level of the house. This could be to achieve a view, level the main structure across a slope, or create a defense against flooding.

Excavating a cellar without first adding support can be a recipe for disaster. You could remove foundation lateral support and cause it to start sliding into the excavation with inevitable results. The only way to avoid this happening is to create more bulk beneath the existing foundation as you dig down. For practical reasons this is done in sections.

Other Reasons to Underpin Foundations

Warning signs are cracks appearing in walls, especially in relatively weak places like corners. You might also notice:

  • A slight tilt to the house
  • Floors moving out of level
  • Cracks in wall and floor tiles
  • Windows and doors that are hard to close
  • Gaps around doors and windows
  • An opening between the roofline and the upper walls

The first step involves digging trenches to establish whether the root cause is foundation failure, or inadequate structures built on top of it It’s also essential to determine what compromised the structure in the first place.

The Underpinning Process

The purpose of an underpinning job determines the extent of its scope. If you are excavating out a basement to increase head height, then the entire foundation needs to be progressively underpinned in sequence. However if you’re repairing a cracked, eroded or subsided foundation you may only need to reinforce the relevant part.

In either instance it’s important to dig down to at least the point where moisture levels are consistent, and to install jacks until the new concrete has dried fully. You can check ground moisture with a meter obtainable from a garden store, as you don’t require a high degree of accuracy.  Bear in mind that this involves the work of a structural engineer and construction experts experienced with basement underpinning.

Repairs to Brickwork

After you have repaired a damaged foundation you would remove and repoint loosened mortar between the bricks above. This is not only for cosmetic reasons. You will also be adding a modicum of strength to the wall itself.

The Value of a Specialist

This is not an easy job (as you can see). The work is dirty, arduous and time-consuming. The time and costs involved are also something to consider.  If you’ll be in your home for the long haul, and would like full living use of your basement, it may be worth looking into adding another level of living space to your home.

 

How To to Find Extra Space in Your Home

Many older homes have a basement or cellar but the likelihood is that this isn’t being used for anything other than storage, if it’s being used at all. Yet in cities, where space to expand is at a premium (like in The Bay Area), converting your cellar can give you useful extra space and add value to your property with relatively little disruption. The advantage of a cellar conversion over converting your loft is that it’s usually nearer to other living areas of the house. This makes it ideal for things like games rooms, gyms, studies or home cinemas.

The key to a successful project is to find an experience renovation contractor.  When I searched for a home addition contractor near me, I found several good ones but the one I ultimately chose was the highest rated on Google.

Converting a cellar or basement into habitable space is a relatively rare task people take on in the UK due to moist air and land. It doesn’t have to be a scarce home improvement though. In most cases a conversion won’t need planning permission as you’re not changing the external appearance of the property. The exceptions are if you’re creating a completely separate living unit, a basement flat say or you’re excavating a new basement from scratch. Building regulations of course will always apply with regards to things like escape routes, ventilation, damp proofing, electrics and so on.

Is My House Suitable?

If you have an existing cellar then the answer is almost certainly yes. You’ll probably need to carry out some remedial work like water proofing and fitting a better staircase but otherwise it should be a relatively painless process.

The modern trend is to add new basements to properties that don’t already have them. Most older properties have a suspended timber floor which means that disruption to the house is minimized because most of the work can be carried out from the outside. However, some older homes have relatively shallow foundations so you may need to underpin the walls before work can commence. It’s important to get a professional to advise you here.

The biggest problem with any below ground conversion is likely to be water and how to keep it out. Rainwater may seep from the outside boundaries of the property or from blocked gutters and drains down towards the basement. Because it doesn’t get direct sunlight it can be difficult to get damp to dry up, leading to mildew and other problems. The most common solution to dealing with rainwater problems is to lay drainage pipes around the base of the outside walls so that the water is carried away before it seeps down.

Groundwater seeping into the cellar may also present a problem. In these cases the best solution is to install a lining membrane behind a secondary wall; this allows water to collect in a sump from where it can be pumped away to the outside. This is more effective than the older technique of tanking with a cement lining and works even in locations where the water table is high. Before undertaking any kind of conversion you should check if your area is liable to flooding.

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Other Things to Think About

If your house is terraced or semi-detached then you’ll need to consider the neighbors. They’re entitled to inquire about the possibility of subsidence and request a report at your expense. A good architect or surveyor should be able to advise you here but it’s still worth having a chat to your neighbors before you start work.

Your cellar conversion will also need services like electricity, plumbing and heating so it’s important to work out how you’re going to provide these. Depending on the use you intend to put it to you may also need phone and TV points. To ensure safety it’s a good idea to have a smoke detector and a carbon monoxide alarm too.

If there’s a wooden floor above you’ll need to pay attention to soundproofing so that you’re not disturbed by people moving about upstairs. Don’t make it too soundproof though, you still need to hear the phone and the doorbell!

Because there’s likely to be little natural light you’ll need to pay particular attention to lighting in your cellar. The use of halogen spot lights can produce a bright, white light and they can be embedded discreetly in ceilings or walls. The décor can help here too, opting for lighter colours can help to give the whole thing an airier feel.

There are lots of uses to which you can put a converted cellar, you’ll find plenty of inspiration online if you’re stuck for ideas. Whatever you want to use it for a cellar conversion can enhance your lifestyle by allowing you to utilize an under-appreciated resource in your home. It can also add significantly to the value of your property.