Quote:
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.