Underfloor insulation

[Feeby100]

Hi I am ready to put the base floor down after furtan today 

can I put kingspan straight on to the metal ? 
then the ply on top ? 
thanks pic inclosed 

[Tracy D'arth]

Put some plastic pipe or strips under the Kingspan so that there is a continuous air space between steel and insulation.

[PCSB]

Should there be ballast first?

[Tracy D'arth]

These days I would use sheet steel ballast on top of the insulation so that it is accessible to adjust trim. You can arrange extra ballast under cupboards etc.

[David Mack]

I would fit longitudinal timbers 2x2 or 2x3 laid flat to the top of those angle stiffeners. And attach the ply floor panels to those. Longitudinal rather than transverse will allow air movement below the floor, whereas transverse will result in a series of more or less completely closed cells.

If you are going to insulate the floor (and this is not normally done) then put a layer of insulation on the ply with another ply layer above.

[Feeby100]

31 minutes ago, PCSB said:

Should there be ballast first?

Well there was no ballast there when I lifted it 

the boat is high at rear pic I put up to show the rear out of water 

and when it was craned in water he said it was front heavy.

but the middle won’t make the back go down I need to put more ballast at rear in engine part ir remove slabs from front ? 

9 minutes ago, David Mack said:

I would fit longitudinal timbers 2x2 or 2x3 laid flat to the top of those angle stiffeners. And attach the ply floor panels to those. Longitudinal rather than transverse will allow air movement below the floor, whereas transverse will result in a series of more or less completely closed cells.

If you are going to insulate the floor (and this is not normally done) then put a layer of insulation on the ply with another ply layer above.

Good idea for air flow

45 minutes ago, Tracy D'arth said:

Put some plastic pipe or strips under the Kingspan so that there is a continuous air space between steel and insulation.

Yes good idea

[Robert.80]

On 03/06/2021 at 19:27, David Mack said:

I would fit longitudinal timbers 2x2 or 2x3 laid flat to the top of those angle stiffeners. And attach the ply floor panels to those. Longitudinal rather than transverse will allow air movement below the floor, whereas transverse will result in a series of more or less completely closed cells.

If you are going to insulate the floor (and this is not normally done) then put a layer of insulation on the ply with another ply layer above.

Sorry to drag this up again, but do you mean that insulating the floor is not usually done? I am at a stage where I’m considering lining the underside of my floor with thermal wrap, then overlaying the spray foamed hull, cabin and roof with thermal wrap before lining.. am I mad, will this not offer anything? I figured that if I was wrapping the hull and cabin, i may as well do the underside of the floor too? 
i understand that I won’t be able to tape the seams but I’m thinking that’s the best way to trap as much heat in the winter months and reduce, heating costs and condensation? 
 

Thanks 

[Alan de Enfield]

28 minutes ago, Robert.80 said:

Sorry to drag this up again, but do you mean that insulating the floor is not usually done? I am at a stage where I’m considering lining the underside of my floor with thermal wrap, then overlaying the spray foamed hull, cabin and roof with thermal wrap before lining.. am I mad, will this not offer anything? I figured that if I was wrapping the hull and cabin, i may as well do the underside of the floor too? 
i understand that I won’t be able to tape the seams but I’m thinking that’s the best way to trap as much heat in the winter months and reduce, heating costs and condensation? 
 

Thanks 

 

Not it is not done.

 

How will you get the water out that WILL find its way under the floor, be it from a leak in the hull, a leaky water pump, a split pipe / pulled joint in the water supply pipes or drainage pipes, water (rain) leaks around the window frames running down behind the panelling, rain getting in around the mushrooms and getting into the linings, etc etc etc.

 

You need an access hatch in the floor to be able to acess the cabin bilge and pump it out with a wet-vac or bilge pump

Edited July 22, 2021 by Alan de Enfield

[mickp]

Once the stoves  lit you will be looking to remove the excess heat that soon builds up ,I'd allow good air flow in bilge area ,if it gets any water down there it will be easier to dry out.if using laminate or carpet flooring u could fit underlay first 

[BEngo]

You may also want access to the cool air from beneath the floor, either to fit a floor level cool cupboard, or for some fridge fans to assist in cooling the evaporator and reduce the on time of the motor, saving quite a lot of Ah.

Fridge fans also help keep the underfloor well vented and dry.

 

  A cabin bilge full of insulation will make these difficult.

N

[Tracy D'arth]

1 hour ago, BEngo said:

You may also want access to the cool air from beneath the floor, either to fit a floor level cool cupboard, or for some fridge fans to assist in cooling the evaporator and reduce the on time of the motor, saving quite a lot of Ah.

Fridge fans also help keep the underfloor well vented and dry.

 

  A cabin bilge full of insulation will make these difficult.

N

Pedantic note, its the condenser that benefits from extra fan cooling on a compressor fridge.

[BEngo]

You are dead right, and I knew that.  I plead old age.

 

N