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Case Study (Floor Sag)

Updated: Dec 24, 2023

November 2020

Sagging Floor
Pittsburgh Design & Engineering Services- Floor Sag

I was recently consulted to assess a sag in a single-family house located in the South Hills area of Pittsburgh. Here’s the situation:

The first-level wooden floor exhibited a noticeable sag, approximately 1 inch over a 4-foot span when measured with a bubble level. Upon further examination, it became evident that a previous homeowner had made modifications to a load-bearing beam. These modifications, likely made without a full understanding of the consequences, were the root cause of the sag and had compromised the structural integrity of the house.

What’s the next course of action?

To restore the structural integrity of the support system, it will be necessary to replace the compromised beam with a new, structurally sound one, likely an LVL (Laminated Veneer Lumber) beam. The selection of the LVL beam will involve calculations based on its span and the tributary load it needs to bear. In some cases, a steel beam could be a suitable alternative, provided logistical challenges are addressed.

Proper installation of the LVL beam requires leveling, which may entail raising the floor joists accordingly. A licensed and competent contractor should be well-equipped to handle this task with ease.

It’s worth noting that such deficiencies are becoming increasingly common, especially in flipped houses. This often occurs due to improperly removed load-bearing walls or the removal of such walls without consulting a professional.

If you’re considering removing a wall in your home and are unsure if it’s load-bearing or not, or if you need guidance on sizing an LVL beam for replacement, please don’t hesitate to contact us. Additionally, it’s essential to be aware that most jurisdictions require permits for any structural modifications, including the removal of load-bearing walls.

Your safety and the structural integrity of your home are our top priorities. We’re here to assist you in making informed decisions and ensuring that any modifications are done correctly and in compliance with local regulations.

Picture below shows the improperly modified beam:

built up beam-not proper
"built up beam"

Written by Firas Abdelahad, P.E.

Firas Abdelahad has been a practicing structural engineer since 2005, collaborating with a diverse range of professionals, including consultants, architects, investors, homeowners, contractors, and subcontractors. Together, they tackle the various challenges that can arise during the design and construction phases of projects.


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