Crazy Paving, Anybody ?

[Bob the welder]

No underfloor insulation for me, I can't see its really needed?

 

And since I tightened my stern gland up, there's no water down there... just a sh*t load of coppers which drop out of my pant pockets each night on my return from the pub

CASH. rich man . more beer

[blackrose]

I'm currently doing my barge up and have one room basically back to the hull + sprayfoam, the baseplate doesn't get condensation but on the side the exposed metal studs are dripping with condensation.

 

Yes, well heat rises so any exposed metal on the sides will 'sweat'

 

No underfloor insulation for me, I can't see its really needed?:

Before I put down underlay and carpet tiles my marineply floor was freezing in winter. It definitely needed some insulation down there.

[nb Innisfree]

I'm not curious because I know it's nonsense! . I've had large sections of my floor uo and it's bone dry too, so condensation on the baseplate is certainly avoidable...

 

I'm not saying that others haven't found condensation on their baseplates, but I wonder if they've just had a leak at some point and what they see as condensation is actually the remaining water that they neglected to dry out.

 

When I lifted our floor panel up in a cold spell the BP was dry but as warm air came into contact with it I saw the condensation starting to form on BP, having said that it was very warm inside (probably +28c) Thing is if there is enough temperature differential, condensation must form. Why it doesn't is, I guess, because air in contact with BP isn't warm enough due to being covered hence my suggestion of insulating under floor panels to further prevent heat escaping downwards into air space and warming it.

 

In answer to Alan perhaps thin sheets of kingspan stuck to underside of floor panels between crossmembers?

[Guest]

Bricks are neater, but why better?

Because they cost more

[Ray]

Ours was built with something tht may be roofing felt under the concrete slab ballast. Everywhere seems to stay dry except when we have a leak.

 

Alan - I think you can get 1.5in thick slabs so you could probably squeeze more in if you wanted to.

[churchward]

I have just been completing our winter job which is fitting a full size shower cubicle (760mm tray) in our bathroom to get rid of the curtained 500mm tray unit we used to have. for a chap like me it was like showering inside a plastic bag!

 

Any how this also allowed some access to the underfloor and was also pleased to find no real corrosion or dampness. The ballast is much the same as Alan's in that it is broken paving. I had to take some out to trim the boat this time though as the shower cubicle and tray is much heavier than the equipment it replaced.

 

Elsewhere in the boat though I have changed round the ballast to get a better balance front to back and side to side with some very dense old storage radiator bricks I had from when I removed some from our house and fitted a central heating system years ago. These things don't really take in water and are very heavy compared to the same size of concrete paving slab. If I had to put some extra ballast in a small space then I would look for some scrap iron/steel to get good size to weight ratio.

Edited February 15, 2010 by churchward

[blackrose]

Bricks are neater, but why better?

 

If they are the right sort of engineering bricks then they won't absorb water like concrete slabs do. I'm not sure about ordinary bricks?

 

Ideally any ballast should be raised about 5mm off the baseplate to allow water to run through and eventually evaporate, but not many builders do this. I've had a couple of water leaks and cut a series of inspection hatches to see what was going on and clear up the mess.

 

I have 2 layers of broken concrete ballast laying on bitumen soaked cloth and the bottom layer of slabs tends to soak up the water. Also, because the ballast is resting on the cloth/baseplate the water can't evaporate easily. The cloth just makes matters worse in my opinion if water gets under it. I believe that it's there to prevent a reaction between the lime in the concrete and the steel.

 

The first time I got water down there I pulled a load of ballast out of 4 big inspection hatches to dry it all out. The broken slabs needed to be dried out too. The second time it happened I couldn't be bothered - I just took the ballast out of one section. When I checked the next section about a year later I found it had dried out by itself, so it does dry out eventually. The leaks that tend to rust hulls from the inside are the slow drips from showers or baths that remain undetected for years.

Edited February 15, 2010 by blackrose

[ChrisPy]

I have 2 layers of broken concrete ballast laying on bitumen soaked cloth and the bottom layer of slabs tends to soak up the water. Also, because the ballast is resting on the cloth/baseplate the water can't evaporate easily. The cloth just makes matters worse in my opinion if water gets under it. I believe that it's there to prevent a reaction between the lime in the concrete and the steel.

not sure about that, Mike, because lime/cement actually passivates steel.... as in cement wash used in water tanks.

surely the cloth is used as waterproof tanking and probably helps to repel any water that gets close to the baseplate?

[nb Innisfree]

I used strips of foofing felt folded repeatedly till it formed a 25mm sq pad approx 10mm thick placed on plenty of blacking and rested slabs on those. Hopefully will allow air circulation under slabs.

[blackrose]

not sure about that, Mike, because lime/cement actually passivates steel.... as in cement wash used in water tanks.

surely the cloth is used as waterproof tanking and probably helps to repel any water that gets close to the baseplate?

 

Well all I know is that when the water gets under unadhered parts of the cloth it's a bastard to get it out because the rest of the cloth is stuck to the baseplate with bitumen.

 

The only positive thing I can think about having cloth and slabs (or bricks) on the baseplate is that if it's just a small amount of standing water (that isn't being added to every day from a leaky shower), then it will contain a finite amount of oxygen. That being the case, if you get the bulk of it out eventually the remnants will evaporate and rusting of the baseplate will be minimal.

Edited February 15, 2010 by blackrose

[Robbo]

I used strips of foofing felt folded repeatedly till it formed a 25mm sq pad approx 10mm thick placed on plenty of blacking and rested slabs on those. Hopefully will allow air circulation under slabs.

 

I recently got a example decking tile from http://www.versatile-flooring.co.uk, the price seems quite reasonable and is strong enough for heavy ballast as well as providing drainage and airflow.

[blackrose]

I used strips of foofing felt folded repeatedly till it formed a 25mm sq pad approx 10mm thick placed on plenty of blacking and rested slabs on those. Hopefully will allow air circulation under slabs.

 

The only problem with that is if you have leak and those pads are submerged any air pockets will fill with water. If I were doing it myself I'd use plastic strips or cables. (Or decking tiles as Robbo has posted - although a cheaper alternative might be the black rubber mats with holes sold by Wilkinsons. They are cheaper and thinner than many others).

Edited February 15, 2010 by blackrose

[alan_fincher]

We have this amazing ballast on Warrior, small hessian sacks filled with what appears to be small circular stainless discs - washing machine drum punchings. Sensationally heavy, each bag weighs over 1cwt but a bit of a bugger when they split. When we bought Warrior the boat was very front end up even with the water tank full, when we got to Keith Ball's we put over a ton of concrete crusher teeth around the water tank, now is level and low. Chertsey on the other hand might be more of a problem

 

Try something like 20 to 25 tons of house coal!

[nb Innisfree]

The only problem with that is if you have leak and those pads are submerged any air pockets will fill with water. If I were doing it myself I'd use plastic strips or cables. (Or decking tiles as Robbo has posted - although a cheaper alternative might be the black rubber mats with holes sold by Wilkinsons. They are cheaper and thinner than many others).

 

I think you have misunderstood me, I only used 4 pads per slab, nowhere for any air pockets or water to form as the pads are only 25mm or less square, they act like 4 small pillars.

[Robbo]

The only problem with that is if you have leak and those pads are submerged any air pockets will fill with water. If I were doing it myself I'd use plastic strips or cables. (Or decking tiles as Robbo has posted - although a cheaper alternative might be the black rubber mats with holes sold by Wilkinsons. They are cheaper and thinner than many others).

 

I was going to go with the rubber mats from Wilkinsons, but I think they will compress too much to allow a decent airflow underneath.

[Bob the welder]

Because they cost more

£60 for 500 bricks. not to bad ?deliv to my door

[blackrose]

I think you have misunderstood me, I only used 4 pads per slab, nowhere for any air pockets or water to form as the pads are only 25mm or less square, they act like 4 small pillars.

I see, yes I misunderstood.

 

I was going to go with the rubber mats from Wilkinsons, but I think they will compress too much to allow a decent airflow underneath.

 

That's probably true. The little dimples that the rubber mats sit on and allow water to flow would probably compress with the weight of the ballast so that the body of the mat was touching the baseplate.

Edited February 17, 2010 by blackrose

[bristol & argo]

One upmanship strikes again.

 

Phil

 

No that would be by saying that Bristol has slabs stacked 5 high under the floor at the back end, and i think 4 high at the front end, and Mike told me he also found slabs on their side in the wall lining at the front too during his refit.

 

Simon.

[hamishnf]

I have just ordered a load of artifical greengrocers grass, which will go on the baseplate with slab ballast on top. The grass is plastic so cant rot, should allow ventilation under the slabs in the event of water in the bilge, and is latex backed so will prevent scratches to the bilge paint (zinc phosphate then industrial floor paint). Paid £75 for enough to cover rear 2/3 of base plate (I wont ballast the front).

[soldthehouse]

I have just ordered a load of artifical greengrocers grass, which will go on the baseplate with slab ballast on top. The grass is plastic so cant rot, should allow ventilation under the slabs in the event of water in the bilge, and is latex backed so will prevent scratches to the bilge paint (zinc phosphate then industrial floor paint). Paid £75 for enough to cover rear 2/3 of base plate (I wont ballast the front).

What about ventilation under the grass, if you have water in the bilge will it not become trapped under the grass

[casper ghost]

What about ventilation under the grass, if you have water in the bilge will it not become trapped under the grass

 

What soil will you put under the grass... Seems a rather odd idea to me.

[hamishnf]

The Grass backing is a course weave impregnated with latex, it has lots of little holes in apparently, so water should be able to evaporate from between the grass and the baseplate, as well as between the grass and the slabs. If the backing looks a bit too waterproof then I will either cut the grass into strips, to ease evaporation, or simply turn the grass upside down, so the backing is in contact with the slabs, and the short 'grassy' bits are in contact with the baseplate, allowing the baseplate to dry. My main priority is to protect the bilge paint which is a very thick coating, ventilation comes second for me, because with luck the bilge wont be getting wet on a regular basis.

[smileypete]

What about milk carton tops as spacers for ballast slabs?

 

cheers,

Pete.

[steelaway]

I have just ordered a load of artifical greengrocers grass, which will go on the baseplate with slab ballast on top. The grass is plastic so cant rot, should allow ventilation under the slabs in the event of water in the bilge, and is latex backed so will prevent scratches to the bilge paint (zinc phosphate then industrial floor paint). Paid £75 for enough to cover rear 2/3 of base plate (I wont ballast the front).

 

 

Hi

 

Why wont you ballast the front?

 

Alex

[Hairy-Neil]

Hi

 

Why wont you ballast the front?

 

Alex

 

Because a full tank of water and a couple of full gas bottles does a pretty good job of that.....