Foundation knowledge base

Stepped cracks, cracks wider than ± 2 mm and cracks that keep growing often point to subsidence. Hairline cracks in plaster are usually harmless. →

Not before you know where it comes from. A filled crack comes back as long as the cause remains, and you can no longer see whether it grows. →

That depends on the cause and your policy. A subsidence survey report helps you in the discussion with your insurer. →

Usually, yes. With push piers down to firm ground we stop the subsidence, and often we can lift the foundation back in a controlled way. →

No. We usually work from the outside, without vibrations. Count on a few days per façade. →

After a first conversation with photos we come on site. Where needed we monitor the cracks for a while with crack gauges. →

Much of Flanders and Wallonia has clay that shrinks in drought. After dry summers we see more cracks. Leaking drains and trees often play a part too. →

Have the drains checked by camera, keep trees and large shrubs away from the façade and monitor cracks with a crack gauge. →

In Flanders you can check the DOV database (theme: plastic soils), in Wallonia Geoportail. A CPT sounding on site gives certainty. →

Not necessarily. Many cracks are stable or can be repaired well. If in doubt, have a subsidence survey done before you sign. →

Send us photos and the address. We take a look and plan a site visit. →

Yes. After the survey you get advice with the recommended technique and a quote. →

Often, yes. A sunken concrete floor is lifted with expanding resin (Slab Lift). If the foundation is subsiding, we stabilise it with push piers and lift it back where possible. →

No. Damp and temperature play a part too. If cracks appear as well or the problem grows, have it surveyed. →

Do not wait until cracks are wider than a few millimetres: the earlier you act, the more limited the repair. →

Usually not. We stabilise its foundation and lift it back where possible. →

Only once the movement has stopped. Monitor the crack with a crack gauge first. →

Yes. Screw piles down to bearing ground prevent a new extension from settling differently from the house. →

Have it inspected by camera by a drainage company. It shows cracks, displaced joints and root ingress. →

It stops the cause. If soil has already washed away or the foundation has settled, the ground or foundation also needs repair. →

Our resin is free of CFCs and formaldehyde and is even allowed in water catchment areas. →

That depends on the situation and the insurance. A condition survey beforehand and measurements afterwards help to show the cause. →

No. Screw piles are screwed in and push piers pushed hydraulically, without pile driving. →

Yes, a simple crack gauge is available in shops. With serious damage, have a professional survey done. →

There is no single best method. If bearing ground lies deep, push piers are often the right choice. If the weak ground is shallow, resin may be enough. Sometimes we combine both. →

With push piers often yes, in a controlled way and as far as the walls and finishes allow. →

For push piers, locally down to ± 1 m next to the foundation. For Deep Lift and Slab Lift only small drill holes. →

Yes. We record the installation torque and depth of every pile and give you an installation report. →

No. It is an installation check. The design is based on the soil and the loads, in consultation with your engineer. →

We screw the pile deeper, choose a larger helix or another pile, until the required torque is reached. →

A CPT measures resistance continuously and so shows the layers. A borehole brings up soil samples, on which a lab can determine, for example, the plasticity of clay. For damage from shrinking clay, Buildwise combines both. →

As deep as needed to find the bearing layer, often several metres below the planned pile tip. →

A specialist site investigation firm. We start from the result to choose the pile and the depth. →

A screw pile is chosen for the load and the soil and screwed to the required depth. We check the capacity of every pile through torque. →

Yes. Screw piles are generally accepted wherever a concrete foundation is allowed. The design is made with your engineer. →

Yes, piles can always be added. They can also be removed and reused. →

In undisturbed ground corrosion is slow. With fluctuating groundwater or aggressive soil such as peat we choose a thicker wall or extra protection. →

The steel is dipped in a bath of molten zinc, and the zinc layer protects it. The standard is ISO 1461. →

The manufacturer of our screw piles guarantees the steel for up to 100 years. →

Yes, but below the zone that moves with the seasons. With screw piles we go below that zone or down to a bearing layer. →

Then we screw through it down to the bearing layer underneath, with extensions if needed. A CPT shows how thick the peat is. →

Yes. Dense sand is often an excellent layer for the helix. →

For a shed that must not move, at least below frost depth. Our ground screws go 1.2 m or more for that in practice. →

Not if it is deep enough. The thread then sits in ground that does not freeze. →

Often, yes, because clay also moves with drought, down to about 1.5 m. →

Because the price depends mainly on the number of piles, their length and access. You get a fixed price after a short request or a site visit. →

You get a fixed price in advance. If you then let us carry out the repair, the survey is deducted. →

We reply to your request within two working days. →

At least below frost depth, and further until the helix sits in a layer that can carry the load. For homes or soft ground that can be 6, 10 or even 15 m. →

During installation we measure the torque, which is directly related to the capacity. For larger projects we also start from a CPT sounding. →

Decades. The manufacturer guarantees the steel for up to 100 years, and we account for corrosion according to EN 1993-5. →

For buildings and structures that must not move, at least below frost depth, in practice 1.2 m or more. Short 0.8 m screws are only used for light applications such as fences. →

Yes. You simply unscrew it, and it can be reused. No concrete is left in your garden. →

Yes. In soft ground we choose a longer or extendable screw. On a slope the adjustable head brings everything back to level. →

That depends on the size and weight. The pile calculator gives you an indication in one minute. →

For structures that must not move, at least below frost depth, in practice 1.2 m or more. →

Yes. By screwing deeper or shallower, all head plates end up at the same height. →

That depends on the size and the timber section of your bearers. The pile calculator gives you an indication and a plan in one minute. →

Yes. We screw the piles in at the edge and in the pond, without dewatering and with no concrete in the water. →

For a timber terrace, screw piles or ground screws are almost always faster and cleaner: no digging, no curing and no waste. →

That depends on the structure itself, not on the foundation. Screw piles are generally accepted wherever a concrete foundation is allowed. If in doubt, check with your local council. →

That depends on the size, the weight and the soil. The pile calculator gives you an indication in one minute. →

Often that works: with hand-held machines we also get through a narrow passage. →

That depends on the structure and the location, not on the foundation. Check with your local council. →

Yes. We unscrew the piles and they can be reused. →

That depends on the weight, the size and the soil. The pile calculator gives you an indication in one minute. →

Usually one per post. The pile calculator gives you an indication for your dimensions. →

Wind can pull a carport upwards. Ground screws are strong in tension, and we take it into account in your quote. →

Yes. By screwing deeper or shallower and with the head plate, all posts end up at the same height. →

Blocks have to be heavy enough to resist the wind and are left behind as waste. A helical pile holds the frame through the soil above the helix, without concrete. →

That depends on the soil and the wind load. In our project a 1.2 m helical pile with a 15 cm helix was enough. →

Yes. They are simply unscrewed, with no concrete left in the ground. →

A slab needs excavation, formwork and curing. Screw piles can be loaded at once and disappear completely when the units leave. →

Yes. The piles are chosen for the loads per support, also for several levels. →

With levelling plates on the pile heads we align to within 1 to 2 mm. →