Flooring or insulation

[starman]

I'm about to start both and I've seen them done both ways by professional boatfitters - floor laid and then sprayfoam or vice versa. Spraying down to floor level would leave the underfloor as a sealed space which in theory should keep moisture out of the area. Is that true and, if so, is that a good thing?

[MoominPapa]

I have no opinion on the question but I'd like to take this opportunity to encourage you to update your blog.

 

I think it's the least that those in the enviable position of being able to Play With Boats full time can do for us poor wage slaves, stuck in the office and needing our vicarious hits of PWB.

 

 

Please!

 

MP.

[carlt]

I'm about to start both and I've seen them done both ways by professional boatfitters - floor laid and then sprayfoam or vice versa. Spraying down to floor level would leave the underfloor as a sealed space which in theory should keep moisture out of the area. Is that true and, if so, is that a good thing?

Insulate first.

 

Chopping back overspray is bad enough, without having to remove it from floorboards.

[ditchcrawler]

I'm about to start both and I've seen them done both ways by professional boatfitters - floor laid and then sprayfoam or vice versa. Spraying down to floor level would leave the underfloor as a sealed space which in theory should keep moisture out of the area. Is that true and, if so, is that a good thing?

I think after seeing some of the mess I would go for insulation first and then floor. I would not want my floor sealed down, I like to look under there now and again,

[nb Innisfree]

Sprayfoam down to bottom plate, don't leave any part of hull side uninsulated, condensation will form and drain into bilge.

[Steve Goddard]

Speaking to guys who have done 10's of boats about this only yesterday. Floor down first, tape over with polythene or similar then sprayfoam. This way you don't end up trying to get sprayfoam bits out of the bilges, the sprayfoamers can walk around without tripping over the bottom braces and your floor doesn't get trashed.

 

Steve

[nb Innisfree]

Speaking to guys who have done 10's of boats about this only yesterday. Floor down first, tape over with polythene or similar then sprayfoam. This way you don't end up trying to get sprayfoam bits out of the bilges, the sprayfoamers can walk around without tripping over the bottom braces and your floor doesn't get trashed.

 

Steve

 

That's what I did, covered the floor in polythene sheeting and taped cardboard around the edges to meet the hull side, lovely neat clean job, but, when we eventually launched and set sail we found when outside temp dropped to near freezing the bottom 6" of uninsulated hull side started to condense and steadily run down into the bilge, fortunately I had provided means of access and was able to mop up and keep an eye on it. Upshot of this is I am now gradually injecting foam into this area with the help of some shuttering. If OP does blank off the under floor area I would advise him to somehow apply insulation down to the bottom plate before any fit out is started. Picture shows wedge shaped foam addition below floor level.

I don't think boat many fitters are overly concerned about any hidden condensation at a later date, more concerned with

protecting their work. You, the one who has to live with any probs should be concerned.

Edited November 3, 2010 by nb Innisfree

[starman]

I have no opinion on the question but I'd like to take this opportunity to encourage you to update your blog.

 

I think it's the least that those in the enviable position of being able to Play With Boats full time can do for us poor wage slaves, stuck in the office and needing our vicarious hits of PWB.

 

 

Please!

 

MP.

 

Apologies, blog now updated! I'm always surprised and humbled that anyone should be reading my ramblings.

BTW writing a blog can be as frustrating as sitting in an office. Last night, first the 3 Mobile dongle kept disconnecting itself, then the computer crashed twice and then the camera repeatedly froze while trying to download pics - demanding new batteries and then yet another computer restart to resolve.

And I could have just been reading my book!

[carlt]

Speaking to guys who have done 10's of boats about this only yesterday. Floor down first, tape over with polythene or similar then sprayfoam. This way you don't end up trying to get sprayfoam bits out of the bilges, the sprayfoamers can walk around without tripping over the bottom braces and your floor doesn't get trashed.

 

Steve

We used a floor scraper and dustpan and brush, to get overspray out of the bilges.

 

It was not great hardship and there was no 4"+ condensation trap, all around the bottom of the boat, either.

 

I don't see the point in masking something off, when it doesn't have to be there, before the spraying is done.

 

Personally, of course, I'd go for a wooden hull that needs no additional insulation

[MoominPapa]

Apologies, blog now updated! I'm always surprised and humbled that anyone should be reading my ramblings.

BTW writing a blog can be as frustrating as sitting in an office. Last night, first the 3 Mobile dongle kept disconnecting itself, then the computer crashed twice and then the camera repeatedly froze while trying to download pics - demanding new batteries and then yet another computer restart to resolve.

And I could have just been reading my book!

Thanks for the update. In my case work is the worst of all possible worlds, I get to sit in an office and I have three enormous machine rooms full of bolshy computers to oversee, so I still reserve the right to green eyes.

 

MP.

[Denis R]

Speaking to guys who have done 10's of boats about this only yesterday. Floor down first, tape over with polythene or similar then sprayfoam. This way you don't end up trying to get sprayfoam bits out of the bilges, the sprayfoamers can walk around without tripping over the bottom braces and your floor doesn't get trashed.

 

Steve

Just checked the build pictures for 'Whirlwind' and that's exactly how Peter Nicholls did it. There doesn't seem to be a condensation problem beneath the floor - there are plenty of removable sections for inspection and whenever I've checked, including during Winter, it's been dry.

Talking of removable sections, my neighbour re-floored his 60 footer a couple of years back and didn't include one removable section... That seems like storing up trouble for the future to me.

[starman]

Just checked the build pictures for 'Whirlwind' and that's exactly how Peter Nicholls did it. There doesn't seem to be a condensation problem beneath the floor - there are plenty of removable sections for inspection and whenever I've checked, including during Winter, it's been dry.

Talking of removable sections, my neighbour re-floored his 60 footer a couple of years back and didn't include one removable section... That seems like storing up trouble for the future to me.

 

Yes, I'm not sure why the underfloor area should be prone to condensation - it's well below waterline so in theory at a pretty stable temperature year round.

[Biggles]

My bottom baton sat on the base ribs and the foam was sprayed down to that point in full thickness thne behind the baton was a small amount of over spray.

 

See Here

 

Biggles

 

edit to add. The over spray on the base was easily removed with a metal scraper. It didn't stick that well to the bitumen I painted the base with.

Edited November 4, 2010 by Biggles

[nb Innisfree]

Yes, I'm not sure why the underfloor area should be prone to condensation - it's well below waterline so in theory at a pretty stable temperature year round.

 

That's what I thought originally, it all depends on the temp differential between steel and inside air, I noticed it happening at or near outside freezing point, enough to cool the canal down. When we leave the boat for a few days inside temp drops and reduces that differential and leaves everything bone dry. Bottom plate doesn't suffer as condensation can evaporate over a large surface area, it's the sides which are the prob.

[blackrose]

If you have an insulated floor there's no need to have condensation below the floorboards whatever way the sprayfoaming of the sides is done.

Edited November 6, 2010 by blackrose