Structural Engineer Advice Needed: Severe Subfloor Rot or Just Water Damage?

Question

Hi!!! (photos in the link)

An ongoing water leak beneath an upstairs shower has caused moisture damage and wood rot in the subfloor.

Two licensed contractors inspected the same area but provided different findings:

• Contractor 1 $25k : Reported severely rotted subflooring and warned of possible floor collapse. replace bathroom and flooring.

Contractor 1 $25k : Reported severely rotted subflooring and warned of possible floor collapse. replace bathroom and flooring.

• Contractor 2 $3900: Recommended water damage mitigation but did not mention structural deterioration or any potential collapse risk.

Contractor 2 $3900: Recommended water damage mitigation but did not mention structural deterioration or any potential collapse risk.

We have photographs of the exposed subfloor and bathroom.

Could you please advise:

• Can you determine whether the wood is simply wet or severely rotted and structurally compromised?
• Is an on-site inspection necessary to determine whether the subfloor and joists need replacement?

Can you determine whether the wood is simply wet or severely rotted and structurally compromised?

Is an on-site inspection necessary to determine whether the subfloor and joists need replacement?

Thank you!!! mike

here is the pictures:

https://www.dropbox.com/scl/fi/gcl0pwtjlm415um20cynp/shower-bathroom.pdf?rlkey=wwb4gcyh1uwjo07fq395p1x70&st=xou2xc7m&dl=0

Richard F. · Answer

"Collapse" is pretty dramatic...probably just enough to scare you into the $25K job. Of course, I have no idea of your local pricing, but really, as is often the case, it looks to me like you are just wasting time stressing. The tile work needs to be demo'ed out, completely replace Hardi board backing, supply and shower head risers, waste line and trap, brass faucet assembly; properly install and test a new shower pan; grout and seal properly and you are good for the next 30 years. Oh, yes, you probably will need to replace a small area of subfloor, and possibly "sister" a floor joist, too hard to tell for sure from the pics.

If the $4K guy is licensed and has commercial liability insurance, approve him to demo, evaluate what is uncovered, and give you a price to finish based on your tile selection.

Matthew Morrow · Answer

@Mike Young those estimates may be pricing two different jobs rather than disagreeing about the same repair. With one contractor raising a collapse concern, I'd have an independent structural engineer inspect it in person before anyone treats it as a simple drying job. Then get both contractors to price the same written repair scope, including fixing the leak and putting the bathroom back together. I wouldn't use the room until the safety concern has been assessed. Photos aren't enough for me to judge that.

Alexandra Kemp · Answer

Looking at these photos, I’d be curious how far the moisture damage extends beyond what’s visible, especially with the staining on the framing. It’s hard to determine the full extent from pictures alone. Has the source of the moisture been identified, and is there a plan to assess the affected areas before moving forward with repairs?

Mike Young · Answer

https://www.dropbox.com/scl/fi/gcl0pwtjlm415um20cynp/shower-bathroom.pdf?rlkey=wwb4gcyh1uwjo07fq395p1x70&st=xou2xc7m&dl=0

here is the pictures.

Structural Engineer Advice Needed: Severe Subfloor Rot or Just Water Damage?

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