Narrowboat insulation

[nb12]

Hi,

I've got a problem with what appears to be moisture coming through the walls on my narrowboat (see attached pics). This issue appears to be happening in all of the major panels around the boat, and all of those walls have spray foam insulation behind them.

I know that it's normal to get condensation forming on the inner steel of the boat, especially during the winter months - but is it supposed to come through to the interior like this?

Having looked around the internet, I can't seem to find any pictures of any other narrowboat that looks like this. So what I'd really like to know is:

1. How common is this sort of thing?

2. What do you think is the most likely cause?

3. What, if anything, can be done to fix this?


Many thanks,


Nick

 

[Oletimer]

That's a problem you have. I have experienced foam insulated walls 'sweating' and causing mould growth but you seem to have a deeper problem.
Can you get any moving air behind the panels?
If you can, (and it doesn't need to a lot of air movement) it with help to deal with the condensation but it won't cure it completely. Sadly, I can add nothing of benefit to your situation except ventilation is key to you finding a cure.
George

 

[coopec]

Here are some links

https://www.canalworld.net/forums/index.php?/topic/95188-advice-please-damp-patches-on-ceiling/

https://www.canalworld.net/forums/index.php?/topic/94998-condensation/

https://www.youtube.com/watch?v=gV5448EkuZ0

Preventing Condensation - Frequently Asked Questions - Canal World
https://www.canalworld.net › Boating › Frequently Asked Questions

Dec 20, 2009 - They will be dripping with condensation if unlagged and are a large contributor to low level moisture. The dripping water will be absorbed into the surrounding woodwork and anything near them, giving mould, mildew and leading to rot. ... Cut down on production of moisture, by only boiling as much water as you need.
Condensation - Boat Building & Maintenance 6 Feb 2018
How to tackle the damp???? Any ideas??? Thanx - New to Boating ...
3 Jan 2018
Damp issues - General Boating 21 Jan 2014
Condensation in the hull - Boat Building & Maintenance 2 Jan 2009

 

[Tammany]

Spray foam insulation soaks up moisture like a sponge so this is your problem. It's probably permanently wet. The only way your going to get rid is to dig it out I'm afraid. I used silver foil backed neoprene on mine with no issues so far. Polystyrene sheets would be a cheap alternative. Only a few pounds for a 8x4 sheet from travis perkins.

 

[blan321]

Closed cell spray foam is waterproof but open cell is not, so it depends on what you have. Are you able to contact boat builder to find out?
It looks like panels lining hull are worst, could water from "bilges" be wicking upwards?
Inserting circular soffit vents along top of hull sides lining panels would be relatively easy and may help ventilate, and also look at managing vapour production in boat as much as you can, +/- dehumidifier?

 

[PCUK]

As said earlier you may be able to relieve the worst of the problem by fitting small permanently open vents in the lining throughout the boat. I suspect that the other problem is the inner side of the lining is not protected with sealer or paint. A problem with most production boats.

 

[lw395]

The root cause is the water content of the cabin.
If there is excess water in the boat, it will condense on the coldest surface.

Where is the water coming from? Rain leaks? Cooking? people breathing with inadequate ventillation?

IMHO you have a choice. Either a dehumidifier and limited ventillation when it's cold and/or humid outside, or heating and ventillation.
You can start by getting and keeping the bilges as dry as a bonio. And being sure no rain is getting in.
I'd suggest getting a hygrometer and keeping an eye on the cabin humidity.
But personally I'd close the hatches and turn up the dehumidifier, maybe with a small heater, while I wasn't aboard. If the dehumidifier can't get the interior dry, you have a problem!
While I'm aboard, I prefer plenty of air and a bit of heating to lose the humidity.

 

[nb12]

OK, thanks very much for your replies. The links are very helpful too. I don't think it's a ventilation issue, as I've tried both heating the place 24/7 and also leaving all my windows open, 2 dehumidifers, etc. On a cold winter's night I can feel the wall behind me is wet, the bed clothes are wet down the side against the wall, and when you switch the lights on I can see the wall itself is wet.

I know you get significant moisture in the air just from your own breath, the cooker, etc, but I'm only finding this happens on the lower wall panels, most of the woodwork in the surrounding areas is bone dry.

I already have a moisture monitor on board. It spends most of it's time at 60%+ moisture/humidity, but I've seen it go up to 81% just in the last week alone. It was 79% when I returned home last night, and only reduced down to 77% even with my windows open and the dehumidifier on.

It's closed cell foam as far as I'm aware, and the staining usually starts from around 2/3 of the way up the panels, so I'm inclined to not think it's bilge water rising upwards.

Nick

 

[nb12]

Sorry, double post. Please see above.

 

[lw395]

There is no point having the dehumidifier on and the windows open. You can't dry the great outdoors, especially near a canal.If it's warm and dry outside, or you're cooking, open the windows.
Otherwise shut the windows etc and crank up the dehumidifier.
If you have water trapped in the structure it will take time to dry.
Temperature is important too, there is a lot more water in air at 20degC than 10 degC for a given % humidity. So, some heat helps.
When boats get very wet inside, it doesn't matter very much whether the insulation is closed cell or not. The issue with open cell is that you will get condensation on the inside of the steel hull even when the interior is low humidity, if there is no moisture barrier between the interior and the insulation.
Some office desk fans can help a lot.
Also, if you lift the cabin sole (floor boards), the bilge is probably uninsulated and will work as dehumidifier? Just keep drying it.
But then you need to identify and fix the source of the water.

 

[Keith 66]

Closed cell spray foam is waterproof but open cell is not, so it depends on what you have. Are you able to contact boat builder to find out?

Spray foam is most definately not waterproof, Despite what builders will tell you. If its in contact with bilge water it will soak it up eventually. Ask any boatbuilder who has ever had to dig out waterlogged foam from any boat or from rudders etc. Dell quay dories were foam filled & that was supposed to be waterproof, they often weigh twice what they should!

 

[lw395]

Spray foam is most definately not waterproof, Despite what builders will tell you. If its in contact with bilge water it will soak it up eventually. Ask any boatbuilder who has ever had to dig out waterlogged foam from any boat or from rudders etc. Dell quay dories were foam filled & that was supposed to be waterproof, they often weigh twice what they should!

Those soggy dories go back to what, the 70s?
There are spray foams around these days which achieve high levels of cell closure.
But I don't think that's the key to this problem.
There is basically just far too much water in the cabin for too long.