Insulating underneath caravan

[missionblue22]

Originally Posted by treetopper

Must admit we have slipper socks ,we have loads of vents in dining,kitchen area so the vinyl bonded flooring feels cold even with our good insulation...

as our van is only open march to december, at this time i do not think that the cost / work is beneficial for us, but Gerry is spot on to use the foam board and then the foil bubble to do the job properly, the foil is a great buy ( i had looked before ) at prices etc and method, we use lots of them dust mat carpets, as we have dogs, 3 plus 2 guest dogs so tend to lay lots of the rugs down, plus a hall runner down the bedroom corridor,
this does for us and we have collected lots over the years, so always swapping / jet washing and moving around, stops wet paws quickly and also covers the vinyl flooring up helping with the cold foot scenario,
roll on march, sat here with the first cold spell wishing i was at the van but thinking its warm here at home, so yes if van was open then i would insulate, but as its closed then its not for me, but if i have 5 minutes in summer i may just put the bubble foil on, but thats not really insulation not a proper job so to speak, just a 1/4 measure is all....

[Springtime]

Originally Posted by Gerry1964

Coming from a construction background i may use some of this...



For 25mm thick it works out at £17.00 a sheet which is 1200mm X 2400mm (8ft x 4ft)

Then cut it to fit into the gaps between the joists, Nice and tight but flush to the bottom to leave a small air pocket,

I have also in my Van In the Kitchen under the fridge, 2 air Round vents which means i will need to extend this to exit below the insulation, A nice piece of plastic soil pipe would do well here.

Once fitted flush with the bottom, i'll be able to get some foil bubblewrap https://www.amazon.co.uk/Biard-Doubl...W4VVR2GEA&th=1

and staple this to the underside to stop any wind or draughts or the foam board falling out. But it definitely looks like a job for the summer.

My thoughts exactly. Much more efficient insulation, light and easy to fix.

[Peter.R]

Daft as it may sound but a couple of years ago we had our caravan fitted out with new wool carpet and made sure we got the best underlay !!! We noticed a real difference in the winter !!

[treetopper]

Originally Posted by Peter.R

Daft as it may sound but a couple of years ago we had our caravan fitted out with new wool carpet and made sure we got the best underlay !!! We noticed a real difference in the winter !!

Not daft....I put a runner my side of bed,definitely makes a difference...wonder how many vans have underlay?

[Peter.R]

I think the original quality of caravan standard fitted carpet and underlay is probably very basic ?

[Mosquito]

Originally Posted by Gerry1964

Being down the Caravan this weekend and i've noticed how cold the floor is when your walking without your shoes on.

I've been fitting my Trace heating and have seen that i too have an uninsulated floor, i'm guessing this might be a job for the summer for me

How did you get on with your Trace Heating? We have only had one day when the temperature got below zero. I decided to turn on the cold water to see if the heating had worked. The water that initially came through the tap was tepid which signified that all was well and it was working. Obviously I was pleased with the result.

[Mosquito]

Originally Posted by Gerry1964

Coming from a construction background i may use some of this...



For 25mm thick it works out at £17.00 a sheet which is 1200mm X 2400mm (8ft x 4ft)

Then cut it to fit into the gaps between the joists, Nice and tight but flush to the bottom to leave a small air pocket,

I have also in my Van In the Kitchen under the fridge, 2 air Round vents which means i will need to extend this to exit below the insulation, A nice piece of plastic soil pipe would do well here.

Once fitted flush with the bottom, i'll be able to get some foil bubblewrap https://www.amazon.co.uk/Biard-Doubl...W4VVR2GEA&th=1

and staple this to the underside to stop any wind or draughts or the foam board falling out. But it definitely looks like a job for the summer.

I would need to check the depth of the metal beams that the flooring is fitted to on our van. I would then need to take a look at what depth of insulation the we already have under the van. It might be possible to just add the board and leave the initial insulation where it is. I think there may have to be an air pocket between the floor and the insulation, although when fitting new power point in the boiler cupboard for the trace heating, the insulation in the walls was butting directly up to the plaster board which forms the inside walls of the van. Beyond that is a gap and then a plastic membrane before the outside PVC boards are fitted.


Gerry, you may be able to advise me on what is required when adding more insulation under the van. Your view would be greatly appreciated.

[Gerry1964]

Originally Posted by Mosquito

Gerry, you may be able to advise me on what is required when adding more insulation under the van. Your view would be greatly appreciated.

Glad to help, Initially i was just going to use Bubblewrap foil, but to be honest by the time you buy enough foil to do the whole van its just a cheap getting these sheets of Cavity Sheets and using these, Not only does it do a better finished job its better rated than just using Bubble foil.

Now when i got under my van i saw that my underfloor was just exposed, Piping and wires were within the runs of joists and the only service i had lower was the waste pipes.

So this is what i would recommend from a beginners point of view

1. Get the right thickness for the size of your floor joists (Thats the Support Timbers running under your van)

2. Make sure you have a gap from the top of the foam board to the underneath of the floor - This is our air pocket, which not only may have pipe runs and wiring, but it allows us to have an area of trapped air which acts as a thermal barrier.

3. So if your Joists are 75mm or 100mm or 3" or 4" in old money, then use this as a guide to get the correct thickness board.

Mine is 75mm so if i use 25mm board i will create a nice warm cavity of 50mm

4. Then you cut the board make sure you cut it nice and tight and make sure the saw is 90 degrees so you get a nice level, upright cut.

5. Push up between joists making sure any drain valves or vents are opened, To do this whilst maintaining the cavity seal you could use a small piece of 4" soil pipe, Just press it into the foam to mark and use a Padsaw or hacksaw blade to cut it round, Then when the board is up you just push the pipe up, until its flash with the bottom, You can use a good quality duct tape (Waterpoof) or the foil tape that you have for sealing the joins to keep it in place.

Another tip to make sure you have a uniform cavity depth is to stick some offcuts of foam to the top of the board before you push it up, then you'll be sure of a nice uniform cavity depth. So for a cavity of 50mm, stick 2 pieces of 25mm board with adhesive mastic.

I'm using the tightness of the boards to hold it in place until i tape up at the end but if your a bit worried that the boards will drop or if you haven't done them tight enough you can stick the spaces to the underneath of your floor with "No more Nails" or any other adhesive mastic type. Please try not to use screw or foam board fixings as you may screw further than the thickness of your floor and into the van itself, so please be careful.

MAKE SURE THE FOAM IS FLUSH WITH THE UNDERSIDE OF THE JOIST, Not only will this make it nice and smooth under your van but will stop any wind resistance that flows under your van, we want it to glide through not get trapped in areas.

6. Once you've done all that, you can start to seal the edges and where the boards join, I would tend to use a Aluminium foil tape as the boards are foil faced and this would stick really well, The bonus is you can buy 4" foil Tape which would do one complete run without going backwards and forwards with small width tape.

Finally sit back and enjoy a nice cold Beer or a Cuppa and admire your work, Not only would you be in your other halfs good books, but look at your neighbours who will be amazed at what you've just achieved

I was thinking of having the bubble wrap as a final layer, but to be honest that would be a waste of money, as the foam is already doing what it does best creating a thermal break between the outside and a nice warm and toast floor for the winter months to come.

IF you can just fit the boards so that they are tight without any fixings then this would help at a later stage if you needed to gain access, for wiring or plumbing
Don't overdue it with the Foam board, Yes you can get 75mm thick boards but then you'll have the wiring and plumbing in the way not to mention the increased cost, which will give you no extra thermal comfort than what a 25mm board will give with an air gap.

Cutting

Cutting should be carried out either by using a fine toothed saw, or by scoring with a sharp knife, snapping the board over a straight edge and then cutting the facing on the other side.
Ensure accurate trimming to achieve close butting joints and continuity of insulation.

I'm sure others may come up with more ideas but i've done it the way i will do mine. using the minimal of material to make the best thermal break possible.