FLOOR MEMBRANE GOOD OR BAD ?

[gloswood]

Hi there all

I was wondering if anybody had any thoughts on plastic membrane under the floor on a narrow boat, as iam in the throw of a total

refit iv'e lifted the first two floor sheets and noticed the balast was wet not to serious, due to a couple of leakey window and

front doors, part of the problem being that the floor is screwed directly to the baseplate cross members thus making each compartment

fairly well sealed add the plasic membrane to the total length of the floor between the crossmembers and the floor and everything

stays damp.My plan was to lift the floor and place 25mmx50mm galv tophat section steel which i have down the lengh of the floor to

give an air gap, but if i replce the membane it will reseal the copartments when it sags under the floor so my thought was to

leave it out does any one have any thoughts

MARTIN P

[onionbargee]

I am just about to fit ballast and a floor, and it seems common sense to me to drop some DPM underneath, i'm putting a layer of foil covered bubble wrap type underfloor insulation in on top of the ballast, so i wont need DPM sheet on this one. I'm spashing the undersides of the ply sheets with wood preservative gel as well.

Edited April 10, 2013 by onionbargee

[dreadlockpasta]

Insulation and a vapour barrier,sound like a very good idea.I'm going to be doing the same job in a few weeks so have given some thought.

I am going to use a barrier and probbally try glue it the underside of the flooring to stop sagging.

I haven't decided how to tidy job around the inspection hatches yet.What are you thinking of doing?

I have used tophat alot for work,but only on walls and ceilings and it can sqweak and move,and I imagine it could be worsre if you compress it as you walk.I think the idea of ventilatoin (of the floor,without loss of head room) is important.My plan is to put "iso rubber"(used on site under floor screed and boarding) over the steel.

Nic

[The Bagdad Boatman (waits)]

Vapor barriers are very good on the walls, stops condensation. One boat builder used a method of ventilating the bilges by fitting up-stands in the well deck and rear deck so that fresh air would ventilate the under floor and the ends of the ventilation fitting would be above any water ingress at locks etc. I used large round pebbles as ballast so water would drain off and not get trapped. Then if you get a leak you can vacuum or mop the water easily.

[David Mack]

part of the problem being that the floor is screwed directly to the baseplate cross members thus making each compartment

fairly well sealed

 

Better to fit longitudinal 'joists' to the steel cross members and then fix the floor to them. That will allow continuous longitudinal ventilation.

[smileypete]

A vapour barrier should go on the warm side of an insulation layer, otherwise condensation is more likely to occur on the membrane and steadily build up over time. Also if water DOES get into the bilge it needs to be able to get out again somehow!

 

cheers, Pete.

~smpt~

Edited April 11, 2013 by smileypete