Site Investigations explained

When planning an extension, loft enlargement, or internal renovation, the foundation of a successful project lies in understanding the existing site conditions. At Alemara Structural Engineers, we prioritize detailed site investigations to ensure every project is grounded in accuracy and safety. In this blog post, we’ll explore the role of site investigations, including trial pits and opening-up works, and how our comprehensive services can streamline your project.

Why Do You Need a Site Investigation Plan?

Before diving into construction, a site investigation plan is crucial to uncover the hidden details of your property. For instance, determining soil conditions, foundation depths, and structural integrity can significantly influence the design and cost of your project.

At Alemara Structural Engineers, we use site investigations to:

• Determine the type and condition of soil to design appropriate foundations.

• Confirm the depth and state of existing footings.

• Identify structural elements behind walls, ceilings, or floors to assess load-bearing capacity.

Case Study: Extension, Loft Enlargement, and Internal Renovations

For a recent project involving an extension, loft enlargement, and internal modifications, Alemara Structural Engineers prepared a detailed Site Investigation Plan. The goal was to ensure that the proposed works could be executed safely while meeting building control requirements.

Scope of Investigation:

1. Trial Pits (TP1 and TP2):

   • Purpose: To assess the depth and condition of existing foundations and evaluate the underlying soil strata.

   • Key Finding: Determining the suitability of the soil to support the proposed extension foundation.

2. Opening-Up Works (L1 to L4):

   • Purpose: To identify structural elements, such as the direction of joists, and verify whether certain walls were load-bearing.

   • Key Areas:

     • Junctions between ceilings and walls in the living and kitchen areas.

     • Locations where hidden structural elements could potentially interfere with the design.

Alemara’s Added Value: A Dedicated Site Team

To maximize efficiency and minimize disruption, Alemara Structural Engineers offers an in-house site investigation team, depending on availability. This eliminates delays often caused by coordinating third-party contractors and ensures that all necessary information is gathered accurately and promptly.

For example, our site team, pending availability are able to:

• Conduct trial pits and opening-up works.

• Provide real-time feedback to our engineers.

• Complete site investigations in a single visit, reducing downtime.

How We Conduct Investigations

1. Preparation: We collaborate with contractors to ensure all health and safety measures are in place. This includes identifying services on-site to prevent accidental damage during trial pits or opening-up works.

2. Execution: Excavations and opening-up works are carefully carried out. For example:

   • Trial Pits: Excavated to a depth up to 1.2 meters to reveal the underside of masonry footings.

   • Opening-Up Works: Carried out in specific junctions to uncover details of floor construction, joist direction, and hidden load-bearing elements.

3. Analysis and Reporting: Once the investigations are complete, our engineers analyse the findings and integrate them into the structural design. For this project, the results informed the foundation design for the extension and confirmed the structural integrity of the loft and internal modifications.

What Happens Next?

Once the investigation is complete, our team at Alemara Structural Engineers:

1. Prepares a detailed site investigation report, including findings and recommendations.

2. Designs foundations and structural elements tailored to your project.

3. Supports you with the next steps, such as submitting plans to building control.

Get in Touch

Are you planning an extension, loft conversion, or renovation? Let Alemara Structural Engineers provide the expertise you need for a seamless project. With our structured approach to site investigations and years of experience in the industry, we’ll ensure your project is built on a solid foundation.

Contact us today to discuss your project or request a quote!

Frequently Asked Questions (FAQs)

1. What is a site investigation, and why is it important?
A site investigation is a detailed assessment of the physical conditions of a site, including soil quality, existing structures, and constraints. It ensures the project is designed and executed safely, efficiently, and in compliance with regulations.

2. What techniques are used during site investigations?
Techniques include trial pits to assess foundations and soil conditions, opening-up works to examine structural elements, and utility surveys to identify underground services.

3. How long does a site investigation typically take?
The duration varies depending on the project's scope and complexity. A standard investigation typically takes a full working day, but larger or more complex projects may require additional time.

4. Can site investigations identify potential risks?
Yes, they help uncover risks such as weak soil conditions, structural deficiencies, or hidden obstructions, allowing these issues to be addressed early in the design phase.

5. Are site investigations required for all construction projects?
While not mandatory for all projects, site investigations are highly recommended for any construction involving structural changes, such as extensions, loft conversions, or renovations, to ensure safety and compliance.

6. How much do site investigation services typically cost?
Costs depend on the project's size, location, and complexity. Alemara Structural Engineers provides tailored quotes to suit your specific project needs.

Key Insights Gained from This Trial Hole:

• Soil Composition: By examining the soil layers visible in the trial hole, our engineers can determine whether the ground has the strength and bearing capacity needed to support the proposed construction. For example, clay-heavy soil might require deeper foundations or reinforcement due to its tendency to expand and contract with moisture levels.

• Existing Foundation Depth: The trial hole revealed the depth and condition of the current foundation, which is essential for designing a compatible and structurally sound extension or modification.

• Hidden Challenges: Trial holes like this also help identify potential issues such as buried pipes, old tree roots, or insufficiently compacted soil that could affect the construction process.

This trial hole exemplifies Alemara’s hands-on approach to site investigations, ensuring that every project is built on a strong and stable foundation. If you’re planning construction or structural modifications, our team can help you understand your site’s conditions and provide expert solutions tailored to your needs.

Understanding Ground Conditions: A Key Step in Structural Engineering

This image shows a trial hole excavated by our Alemara ground works team during a site investigation. The trial hole is an essential part of any construction project, providing valuable insights into the soil and foundation conditions before design and construction begin.

For this project, the trial hole was carefully dug to expose the ground layers and evaluate the depth and state of the existing foundations. The findings from this investigation will play a crucial role in designing a foundation system that ensures the new structure’s stability and long-term performance.