Mouldy areas

[Jennifer McM]

In the middle of preparing the bathroom for a repaint. Trimmings have been removed, which has highlighted black mould on wood.  The insulation foam has been cut away to lay cables. Has this caused the condensation problem? I know bathrooms are great for mould to grow. 

 

Should the gap be filled with expanding plumber's foam? Wondering what other's would do.

 

Thanks for help and advice.

 

[BEngo]

Cutting back the insulation probably has encouraged condensation, leading to mould.

I would tape over the cables with aluminium foil duct tape ( in case the cable insulation reacts to the foam), then fill with foam from a can.  It is overhead so gun grade foam will be best.  Treat the mould with some of the Polycell stuff for mould.

 

N

[blackrose]

How are you going to stop the foam from simply falling off the ceiling and down your lining on the cabin sides and onto the floor?

 

If you're intending to drill holes and 'inject' the foam into the cavity be very careful. Without constraint foam expands spherically and although it will travel laterally along a cavity to some degree, it will also push your lining off the ceiling.

[David Mack]

Classic thermal bridging and condensation. Lots of steam in the bathroom, some of which passes through the cabin lining and condenses on the relatively cold wooden framing (which is more conductive than the foam in between), so the mould gets a hold. Ideally you would have a continuous vapour barrier between the lining and the insulation/framing. Some additional insulation over the framing would help also.

Cellotex/Kingspan insulation boards have an aluminium foil surface for just this reason, and all joints between the boards should be taped with aluminium foil tape to maintain the continuity of the vapour barrier. In building construction you would ventilate the space behind the vapour barrier to allow any moisture which has got through to escape, but not easy to do that on a steel narrowboat shell.

In your position it's not that easy to deal with. So either treat the mould then cover it up and forget about it. Or perhaps fit a thin layer of Cellotex over the whole are, and tape the joints, then fit a new lining.

[Ray T]

The Coventry Canal goes through some mouldy areas.

 

[Jennifer McM]

 

2 hours ago, BEngo said:

Cutting back the insulation probably has encouraged condensation, leading to mould.

I would tape over the cables with aluminium foil duct tape ( in case the cable insulation reacts to the foam), then fill with foam from a can.  It is overhead so gun grade foam will be best.  Treat the mould with some of the Polycell stuff for mould.

 

N

Thanks BEngo! We've got some aluminium foil tape onboard, we'll stick that on when the mould killer has dried. 

 

2 hours ago, blackrose said:

How are you going to stop the foam from simply falling off the ceiling and down your lining on the cabin sides and onto the floor?

 

If you're intending to drill holes and 'inject' the foam into the cavity be very careful. Without constraint foam expands spherically and although it will travel laterally along a cavity to some degree, it will also push your lining off the ceiling.

 

The pic doesn't show it, but there's quite a hollow to fill in with new foam. Perhaps rough up the surface of the foam, for the new foam to get a grip? Thanks for the heads up on the foam expanding and pushing off the lining, I never thought of that ?

 

 

1 hour ago, David Mack said:

Classic thermal bridging and condensation. Lots of steam in the bathroom, some of which passes through the cabin lining and condenses on the relatively cold wooden framing (which is more conductive than the foam in between), so the mould gets a hold. Ideally you would have a continuous vapour barrier between the lining and the insulation/framing. Some additional insulation over the framing would help also.

Cellotex/Kingspan insulation boards have an aluminium foil surface for just this reason, and all joints between the boards should be taped with aluminium foil tape to maintain the continuity of the vapour barrier. In building construction you would ventilate the space behind the vapour barrier to allow any moisture which has got through to escape, but not easy to do that on a steel narrowboat shell.

In your position it's not that easy to deal with. So either treat the mould then cover it up and forget about it. Or perhaps fit a thin layer of Cellotex over the whole are, and tape the joints, then fit a new lining.

 

Cellotex is something to research. You've confirmed my thoughts about the mould, it's always a worry when removing a panel on what's underneath. Thanks for your help David.

[Jennifer McM]

32 minutes ago, Ray T said:

The Coventry Canal goes through some mouldy areas.

 

? Sun's out and the mud's drying up! I live in hope ?

[blackrose]

1 hour ago, David Mack said:

 

In your position it's not that easy to deal with. So either treat the mould then cover it up and forget about it. Or perhaps fit a thin layer of Cellotex over the whole are, and tape the joints, then fit a new lining.

 

They do a 12mm thick board which would probably bend a little with the curve of the ceiling. It's either made by celotex or kingspan. If it snaps when bending start again because you'll have lost most of the insulation properties.

Edited March 22, 2021 by blackrose