Fire check damaged 2

[rowingengineer]

Due to recent event water penetration to the roof space is a common problem. In one particular house I have a fire check ceiling that is 2 layers of 16mm fire check. This ceiling has extensive mould growing on the top side.

I am wondering if anyone knows of a possible solution other than removing this completely.I was thinking of trying to install additional fire board above the ceiling but the top-hats and trusses are in the way. Possibly a spray fire check could also be used, but again the same problem exists.

I have spoken to the local reps for these products and they all believe it should be removed unless I can get the second fire check in place, just looking to see if anyone else has solved the problem before by another method.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[hokie66]

The mold is a BIG health hazard. It should be removed by specialist demolishers, similar to asbestos abatement.

 

[Ron]

Assuming your term "fire check" means a fire resistive gypsum board.....

First, I agree with hokie66...the mold has to be removed in its entirety.

Second, water intrusion has also increased the moisture content of the gypsum board, thus reducing its fire resistance and increasing its weight. This is likely a localized occurrence, but nonetheless an issue. Higher moisture content will also cause fastener corrosion and compromise, as well as reduce the pull-through capacity of the board, thus compromising its attachment. In my experience, when this happens and pull through occurs, the collapse of the gypsum board is sudden and can severely damage property and people if below.

Before you make the decision, consider the following:

What is the moisture content of the board as compared to "dry" board?
What is the fastening pattern of the board and do the nails/screws, since it is in 2 layers, penetrate the support structure adequately?
Can the mold be removed in-situ, and if so, will it compromise the integrity of the board?
Will the addition of a spray-applied fireproofing add too much weight to (a) the structure or (b) the board (further compromising attachment)?
Will mold that is not visible be trapped between the spray applied fireproofing and the existing board, only to flourish again under the hot, humid conditions likely in the attic space?

Good luck, RE.

 

[rowingengineer]

Hokie and Ron,
Thank you for your comments. The mould while being massive can be dealt with by a specialised contractor, this has happened as a matter of course for this type of project.

The fire resistive gypsum board has been load tested 3 months after the wetting event and passed. The board was only wet by spry from the rain, so it is uncontrolled mould build up like you would get in your bathroom if you allowed spray from the shower on the floor and never cleaned it up. From some cores we took on-site the moisture penetration is about 6% of depth (these weren’t in the best position but gave an idea of the situation we don’t expect the moisture ingress to get above 10%).

I am concerned about the way the fire resistive gypsum board get cleaned; my understanding is they need to scrap down the top of the board. This will remove fire resistance and reduce strength. We can reinforce the existing ceiling in these positions for extra strength, but I can’t think of any solutions for maintaining the fire resistance.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[Ron]

RE...as long as your attachment and board integrity are good, you could consider a fibrous (non-cementitious) spray applied fireproofing such as CAFCO Blazeshield or similar.

 

[hokie66]

If it were mine, the gypsum board would come out. I don't believe you can remove mold from gypsum board. Specialist contractors may say they can, but they are not mold experts. This is based on experience with large "sick building" projects.

 

[rowingengineer]

Thanks for the advice; I shall go for the complete removal option.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”