Replacing polystyrene lining - condensation issue.

[pbuk]

Hello All,

 

I'm a prospective boat buyer that is very close to making my first offer on a boat that my wife and I really like a great deal. However I have come across what I think could be a problem and wanted to know how best to rectify it and what might be the costs.

 

The boat's cabin is lined with polystyrene and I think that it is causing a good deal of condensation as warm air gets around the polystyrene and comes into contact with the steel. The current owner keeps mentioning condensation and that it needs to be mopped up occasionally from the bilges at the stern of the boat.

 

Anyway, the impression I'm getting from him is that condensation could be a bit of an issue. I know it is present on a good deal of boats but it is something I really would prefer to live without. It could be a deal breaker for me which is a real shame, as after looking for a while it seemed that this boat was 'the one'.

 

I think the only thing that would give me peace of mind was if the whole boat was re-lined with spray foam but I'm guessing that would mean completely stripping the boat out and starting again..? I'm not sure. The boat is beautifully panelled with 9mm cherry ply and oak beams and is fully fitted with a characterful bathroom and kitchen, no bedroom to speak of just an open-plan saloon/bedroom and of course an engine room and boatman's cabin at the stern.

 

I can't think of any other way to sort out this problem but if anybody on these forums knows an alternative, please do let me know. Having to remove all the furniture, fittings and panelling to spray foam, then putting everything back again would be quite an undertaking I imagine and would negate a purchase, unless the vendor dropped his price a great deal.

 

Any advice is gratefully received. Thank you.

 

PB

[GoodGurl]

There is no easy way, the way you suggest is the only way you will be able to sprayfoam the boat and at great cost.

[Phil Ambrose]

Doesn't have to be a deal breaker because there are quite a few boats with polystyrene insulation, the issue with condensation would, I suspect be just a job which you would need to add to your routine maintenance list. With a decent access point at the stern it would not take too long to suck it out with a wet n dry vac, afterall there are plenty of boats that were built with wet bilges.

I would use the issue to knock the price down.

Phil

[OldGoldy]

Make sure that it IS condensate that he is mopping up and not canal water!!

 

How old is the boat? ..................Have you had a hull survey?

[Tony Brooks]

Make sure that it IS condensate that he is mopping up and not canal water!!

 

How old is the boat? ..................Have you had a hull survey?

 

My thoughts exactly - distraction technique.

 

My boat has the same insulation and it does not get significant condensation in the bilge but then it has comparatively little use in the winter.

[Keeping Up]

Or it may be rainwater leaks, from around the windows etc, which can travel behind a long way the polystyrene and make it look as if there has been condensation.

 

Our boat too is insulated with poly, and in the winter there are no condensation problems if we either stay on board or stay away, the only time we get any condensation is during the first 24 hours if we try and warm it up too quickly from cold after we haven't been on board for a while. We've never had any in the bilge, it's confined to a few drips from the roof telling us that we should either turn the stove down a bit or else open a window or two.

[Ex- Member]

If this boat is several years old and has been condensating all that time, I would really wonder as to the state of the steel work internally, especially in the bilges.

[pbuk]

I'm pretty sure it is condensate and yes I'm concerned about how it is effecting the steel work internally. The original hull is iron and now has a steel baseplate and a steel cabin that I think was added in 1998 - so it could have been going on for a long time or after the poly came away from the steel, whenever that might have happened.

 

I think the boat has a tremendous vibe and some really beautiful features but this problem seems a fairly serious one and I don't want to have to be thinking about condensation all the time on what will be a full live-aboard.

 

Ideally I'd like to fix this problem by removing the panelling, re-lining then putting everything back but the cost will probably be prohibitive.

 

I am right in thinking that not all boats have condensation issues? I know a lot do, but I have a feeling it is pretty severe on this boat.

 

No I haven't had a survey done yet...was just doing loads of research and asking questions before preparing an initial offer...but now I feel like I'd want too much of a discount for the seller to be interested and for me to be happy... :-(

[Grace and Favour]

I think it's fair to say that not all boats have condensation issues.

 

We spend a deal of time on ours in cool winter conditions - - and we do not have a condensation problem at all.

 

(But ours is well insulated)

 

I know of many boats that do not have condensation issues either.

[Ex- Member]

I'm pretty sure it is condensate and yes I'm concerned about how it is effecting the steel work internally. The original hull is iron and now has a steel baseplate and a steel cabin that I think was added in 1998 - so it could have been going on for a long time or after the poly came away from the steel, whenever that might have happened.

 

I think the boat has a tremendous vibe and some really beautiful features but this problem seems a fairly serious one and I don't want to have to be thinking about condensation all the time on what will be a full live-aboard.

 

Ideally I'd like to fix this problem by removing the panelling, re-lining then putting everything back but the cost will probably be prohibitive.

 

I am right in thinking that not all boats have condensation issues? I know a lot do, but I have a feeling it is pretty severe on this boat.

 

No I haven't had a survey done yet...was just doing loads of research and asking questions before preparing an initial offer...but now I feel like I'd want too much of a discount for the seller to be interested and for me to be happy... :-(

 

Not all boats, we certainly don't, but then again we did the insulation ourselves. It seems to me that many boat yards consider insulation a job to get out of the way that they leave to private contractors. I've yet to see spray foam insulation applied properly on a boat.

 

Polystyrene was and probably still is a cheap option and there's nothing intrinsically wrong with it. These types of insulation need to fit tight to the hull side though, and every gap crack or crevice filled in, some even adhered the insulation to the hull. Unfortunately though many boats done in poly weren't insulated very well and the Polystyrene comes away from the steel. Some boats I've seen have one inch thick poly in a 2 inch gap.

 

I

[blackrose]

I think it's fair to say that not all boats have condensation issues.

 

We spend a deal of time on ours in cool winter conditions - - and we do not have a condensation problem at all.

 

(But ours is well insulated)

 

I know of many boats that do not have condensation issues either.

 

I don't have any condensation issues and my boat's not even that well insulated.

 

If the problem really is condensation and has been happening for some time, then you should see some tell-tale staining of the wooden lining.

Edited July 24, 2014 by blackrose

[pbuk]

Thanks for all the replies...

 

I think a lot of the panelling is pretty new and some freshly painted, so you wouldn't be able to see any staining yet. The poly is exposed around a couple of roof hatches and by some windows that haven't been finished and looks a bit grey but it does look thick enough at about 2 inches. Of course that's just where I can see, who knows what's going on elsewhere.

 

It seems condensation doesn't have to be an issue and I'd rather it wasn't but I can't yet decide if I'd rather it wasn't on a boat that my wife and I have a bit fallen in love with. I'm hoping we can find a solution and I'm currently writing to the owner to express my concerns.

[pbuk]

I've since read that spray foam isn't necessarily the best kind of insulation so perhaps I could move onto the boat then re-insulate with Kingspan a bit at a time? Would that be practical?

 

PB

[Phil Ambrose]

I can think of no good reason why you can't do exactly that, afterall it is your boat.

Phil

[pbuk]

Thanks Phil,

 

It's not my boat yet...but I'm going to do my best to make a deal with the owner who seems like a reasonable guy, so we can at least feel it's worth taking the boat to be fully surveyed. He mentioned it may need some welding at the chines - I think I'm right in saying that is where the steel base plate meets the iron hull sides? I'm hoping that isn't to do with condensation that has collected in that seam over time - but having restored the boat himself and being extremely handy he said he would do any welding that needed doing at his expense...Fair enough.

 

While I'm on here... and it may be I have to start another topic on this...the boat sits in the water on a slope, high at the bow and low at the stern, which means the bed is on a slope too. The water tank is in the bow and is a pretty big one but of course as it empties the ballast it provides diminishes and the slope will become more pronounced. The current owner props the mattress up with bits of board but that isn't ideal.

 

Is there a way of trimming the boat so the slope is less? I'm guessing use of water tanks, filling up of waste tanks, weight of items on board always effects the trim but I'm just wondering if there is any way of keeping a little bit of consistency amongst a load of changing variables ... :-/ As I write this I'm thinking this is a bit of stupid question... it's just other boats I've seen didn't seem to have beds with mattresses propped up by bits of board to level them out.

 

Thanks again for any advice.

 

PB

[pbuk]

In addition I read elsewhere on the forums someone suggesting polystyrene balls (EPS) that may be able to be blown in between the panelling and the steel without having to remove the panelling but I'm guessing with the old polystyrene still in place, the balls wouldn't be able to get to any gaps between the old poly and the steel...? Don't know if it would work..?

[starman]

Thanks Phil,

 

It's not my boat yet...but I'm going to do my best to make a deal with the owner who seems like a reasonable guy, so we can at least feel it's worth taking the boat to be fully surveyed. He mentioned it may need some welding at the chines - I think I'm right in saying that is where the steel base plate meets the iron hull sides? I'm hoping that isn't to do with condensation that has collected in that seam over time - but having restored the boat himself and being extremely handy he said he would do any welding that needed doing at his expense...Fair enough.

 

While I'm on here... and it may be I have to start another topic on this...the boat sits in the water on a slope, high at the bow and low at the stern, which means the bed is on a slope too. The water tank is in the bow and is a pretty big one but of course as it empties the ballast it provides diminishes and the slope will become more pronounced. The current owner props the mattress up with bits of board but that isn't ideal.

 

Is there a way of trimming the boat so the slope is less? I'm guessing use of water tanks, filling up of waste tanks, weight of items on board always effects the trim but I'm just wondering if there is any way of keeping a little bit of consistency amongst a load of changing variables ... :-/ As I write this I'm thinking this is a bit of stupid question... it's just other boats I've seen didn't seem to have beds with mattresses propped up by bits of board to level them out.

 

Thanks again for any advice.

 

PB

To be honest if you have the head of the bed at the bow end you really won't notice the change in slope so long as your head is above horizontal when the boat is at it's nose-heaviest - we didn't on our last boat which was just the same.

The condensation is a much bigger issue. You need to keep the whole boat warm inside and deal with issues locally (eg cooking steam, cold window glass etc). Stripping out and re-insulating would be a nightmare.

[Machpoint005]

Walk away. There are lots of boats out there.

[John V]

One thing that people seem to miss, when putting in insulation, is that it is necessary to prevent warm moist air getting between gaps in the insulation and reaching the steel.

 

Ideally if the insulation is slabs the seams should be taped to prevent moist air getting through. alternatively after insulating, the whole should then be covered with a vapour barrier.

 

When I re-built my forward cabin I used celotex then battened again and used foil bubble wrap as both extra insulation and as a vapour barrierfwd cabin 043 by mudlarker2, on Flickr' alt='a>, on Flickr'>[/url]fwd cabin 015 by mudlarker2, on Flickr

 

fwd cabin 021 by mudlarker2, on Flickrfwd cabin 015 by mudlarker2, on Flickr

Edited July 25, 2014 by John V

[pbuk]

Yes I agree, there are a lot of boats out there and a lot with hidden problems that you might never know about until you start living on them..so I don't want to walk away too quickly at least I have an informed idea of what I'm getting, if I do go ahead and make a purchase.

 

I've since heard from the owner and apparently all the steel is coated with aqua-seal internally.. There is 50mm poly beneath the gunnels, 25mm above, and 50mm on the ceiling which all sounds OK I think. He says the small amount of water that collects in the back cabin bilges at certain times of the year is unavoidable. I asked about insulation under the floor and there are some 25mm off-cuts laid on the ballast ..the floor itself is 25mm solid oak treated with linseed oil.

 

He said we could Kingspan the boat a bit at a time but it would be costly and we might as well buy a new boat...which is pretty honest of him.

 

I'm going to go and see it again and have as much as a good look around as possible. This time I'll be less wowed by the interior and be thinking more practically so I can ask the right questions.

 

Thanks again to everyone who has taken time to pitch in and John V - that's an impressive insulation job you've done there!

 

PB

[Ex- Member]

There is 50mm poly beneath the gunnels, 25mm above,

 

 

Considering heat would be lost from the higher areas of the boat, that's rather an ass backwards way of insulating a boat LOL

[David Mack]

 

Considering heat would be lost from the higher areas of the boat, that's rather an ass backwards way of insulating a boat LOL

True, but you can afford the loss of width rather more below the gunwales than above (unless you're trying to fit a cross bed in a NB).

[pbuk]

Yes I think he wanted to have height in the boat and he's definitely achieved that. It feels much bigger than other boats I've been on.

 

PB

[Neil Smith]

I think the vapour barrier is very worthwhile as that is what we have to do on new houses now, and a breathable one is even better so that is what I am going to do.

So its 50mm kingspan glued to the steel that I will spray paint first as primer is porous then go round all joints with silicone, then a breathable vapour barrier, then linings,

cant think of much more I can do apart from a 50mm air gap which is not going to happen on a narrowboat but is what is required on houses now.

 

Regards Neil

[Ex- Member]

I think the vapour barrier is very worthwhile as that is what we have to do on new houses now, and a breathable one is even better so that is what I am going to do.

So its 50mm kingspan glued to the steel that I will spray paint first as primer is porous then go round all joints with silicone, then a breathable vapour barrier, then linings,

cant think of much more I can do apart from a 50mm air gap which is not going to happen on a narrowboat but is what is required on houses now.

 

Regards Neil

 

In essence with products like Kingspan Cellotex etc the vapour barrier is the foil.

 

We insulated our boat in Rockwool batts on top of the batts we applied 10cm thick Cellotex over all the rockwool. all the joins were taped over with Aluminium foil. The cavities were exactly 60mm so the Rockwool stays pressed tightly to the steel.

 

Another tip is to fill any ribbing/square tube with tinny spray foam. We drilled a 10mm hole every 18 inches and gave a 1 second squirt in each hole. It will prevent condensation forming in tubes ribbing.