Cutting out windows, skylights. Before or after insulation and boarding . . ?

[Longboard]

Just can't make my mind up ...
I'd like to get stuck into my self-build by insulating the floor and walls and boarding it out.
What's bugging me is - will I be able to use drills and a jig-saw to cut through the steel body and ply lining with the fibreglass insulation between?
Will it clog or jam the drill bit and saw blade?
It would make aligning inner and outer apertures a heck of a lot simpler if I can work this way, I'm guessing.
Anyone have experience of this situation out there folks?

 

[sparrks]

Just can't make my mind up ...
I'd like to get stuck into my self-build by insulating the floor and walls and boarding it out.
What's bugging me is - will I be able to use drills and a jig-saw to cut through the steel body and ply lining with the fibreglass insulation between?
Will it clog or jam the drill bit and saw blade?
It would make aligning inner and outer apertures a heck of a lot simpler if I can work this way, I'm guessing.
Anyone have experience of this situation out there folks?

Fibreglass wool will bind on drill bits and most likely on jigsaw blades.

 

[hextal]

I'd cut first then sort the insulation once you've framed out the window appature.

 

[Polar Bear]

Hi.
Have you thought about cutting the outside apertures first, you can then reinforce the gaps between where the board will be and body and then fitting insulation - then boarding inside?
You can cut insulation from outside and then drill in corners to get the boarding holes lined up.
I use an oscillating saw but an angle grinder with a cutting disk will do for the tin-work.

 

[Debs]

I used Seitz S4 windows, and you need to cut the holes first, then frame the body to get the correct thickness for the window depth. If your total wall thickness exceeds the max for the window, you then have to inset the inner window frame, which is what I did, because I wanted an extremely well insulated van. Once you've done one, you will wonder what you were worrying about. :idea-007: :wacko:

 

[Longboard]

Thanks!

Thanks for all those advices, everyone. ( :
I suspected fibreglass wool would clog cutting tools - so my fears are confirmed.
My problem is that I haven't yet sourced the correct slit windows, fridge vents, skylight etc that I want - so they're holding me back.
One compromise has occurred to me - knowing the rough areas they will be fitted, I could leave those spots uninsulated - then stuff with glass wool via the apertures once they have been cut?

 

[sparrks]

Thanks for all those advices, everyone. ( :
I suspected fibreglass wool would clog cutting tools - so my fears are confirmed.
My problem is that I haven't yet sourced the correct slit windows, fridge vents, skylight etc that I want - so they're holding me back.
One compromise has occurred to me - knowing the rough areas they will be fitted, I could leave those spots uninsulated - then stuff with glass wool via the apertures once they have been cut?

Why not stick the insulation in (don't compress the fibreglass as it relies on the air for insulation) and then cut and fix the wall panels, but only with a few screws, and carry on with the build, thus when you cut the windows out you have an easily removable panel.

 

[hextal]

Possibly a bit late in the day but have you considered kingspan or similar insulation boards rather than the loft type insulation. Easier to work with and won't settle and create voids after lots of driving round.

 

[Polar Bear]

If you use a angle grinder to cut holes you should have little problem with it picking up.

 

[sparrks]

I use a powered nibbler which is great but hard to get straight cut.

 

[n brown]

a few tips
the easiest way i have found to fit a window or rooflight is to make a timber frame to fit the window and glue it to the metal-----then insulate and panel the walls and ceilings--------then drill a half inch hole in the panelling covering the aperture ----insert edge trimming router blade with end bearing and use router to cut out the hole ---perfect !

now drill a small hole through the metal in each corner of the timber frame and go outside and draw a line between the 4 holes-----mask up all round where you need to cut with cardboard or cloth and cut out with a angle grinder with a 1mm blade

if it's a seitz window don't bother drawing the radius corners ,too little to count,and you can surface mount the inner frame on any thickness wall,just use longer screws. finishing off between the frames isn't hard,but i can't face describing it at the mo !

retro fitting these things is a total PITA,i've done loads, you can't see where wires,pipes,metal beams etc are hiding,then you have to get the insulation out the way and try to scribe in a timber frame--- but if you can't wait ..................

 

[Longboard]

Nibblers and Squeakers.

Aah, Manuel Nibbler - didn't he play for Barcelona? ( :
I did consider rigid polyurethane foam insulation sheet (if that's what Kingspan is?) - but even a simple panel like the roof has ribs with some complex pressings which look very difficult to fit to snugly. I've also heard that Kingspan can squeak infuriatingly - so I have gone for glass wool for its mouldability, speed, and price).
The point about sagging, I'm guessing, is more an issue with house walls where the cavity height might cause compression from the weight of the glass above.
The point about not over-compressing fibreglass is interesting - I thought the same, but my builders' merchant tell me that Rockwool comes in various densities, and the most dense has the highest thermal rating. Anyone know why?

 

[Polar Bear]

Aah, Manuel Nibbler - didn't he play for Barcelona? ( :
I did consider rigid polyurethane foam insulation sheet (if that's what Kingspan is?) - but even a simple panel like the roof has ribs with some complex pressings which look very difficult to fit to snugly. I've also heard that Kingspan can squeak infuriatingly - so I have gone for glass wool for its mouldability, speed, and price).
The point about sagging, I'm guessing, is more an issue with house walls where the cavity height might cause compression from the weight of the glass above.
The point about not over-compressing fibreglass is interesting - I thought the same, but my builders' merchant tell me that Rockwool comes in various densities, and the most dense has the highest thermal rating. Anyone know why?

In house building the cavity wall insulation is supported on brick ties. The denser the insulation the less cold that is transferred.

 

[mark61]

I'd be checking that on their data sheets, could be right, but years ago the denser one was for acoustics, or sound insulation. Not they have products for each and both.

 

[Polar Bear]

As we all know water is a good conductor of heat an the idea is to stop heat being conducted or transferred.
We do this by creating a thermal blanket to stop it being transferred.
If we could fill the cavities with argon and get it to stop in, there's a thought.
Insulation prevents cold transfer better than air, the more dense the least transfer.
Heat transfer is measured in 'thermal resistance=R-value' this R-value is measured by applying heat of a know amount and time on one side of the insulation and measuring it on the other.
Cavity wall insulation is pumped in and provides a solid thermal block with no air left in the cavity.
That's why a denser higher R-value insulation can prevent more heat escaping.

 

[Longboard]

Ouch.

Expertise much appreciated!
I'm cutting a tightly radiused learning curve I think!
Hopefully a bit of forward planning will mitigate some of the pain though? I can leave the planned apertures clear of insulation and wiring - so it won't be a total 'retro -fit' situation I hope.

 

[sparrks]

Normally the fibreglass insulation placed in loft spaces is very thick and soft, not dense, and is used for it's thermal properties. Very dense fibreglass slabs that are white faced are used as fire breaks rather than insulation and as have been commented on the wall insulation in houses is high density slabs, so what is best? slab insulation or fibreglass wool? for insulation.

 

[Tbear]

Normally the fibreglass insulation placed in loft spaces is very thick and soft, not dense, and is used for it's thermal properties. Very dense fibreglass slabs that are white faced are used as fire breaks rather than insulation and as have been commented on the wall insulation in houses is high density slabs, so what is best? slab insulation or fibreglass wool? for insulation.

I am guessing that in a van. Its the quality of the fit as much as the materials used. If you end up with gaps or thin areas, may well lead to cold spots and condensation which in turn could lead to water saturation and then you are spiraling downwards. Rust, rot, mould, smells so make sure you have a good moisture barrier which in itself will give you a little insulation. Think secondary double glazing with polythene sheeting.

Richard

 

[mark61]

I too thought insulation was basically about trapping lots of little pockets of air. Rockwool is used as cavity insulation too, it's supplied like ripped up bits of rockwool about the size of a finger nail.

 

[Longboard]

Damn you, expanding foam!

Epic fail at the first hurdle:
Drilled and injected all the structural box sections the walls and roof of my van with aerosol expanding foam.
Extremely messy job, so decided to seal off the holes with tape straight after application - to keep the foam inside.
Next day - all the foam in the cavity has shrunk back to liquid goo. Apparently I should have kept the spaces open to allow air to cure it.
Second attempt next day:
Left the holes open, so the foam could ooze out at will.
Next day - all the foam has shrunk back to liquid goo inside the cavities.
Has anyone succesfully used this stuff in their build? Anyone had the same disaster?
Manufacturers tech dept. says 'try spraying water inside first'. Do I really want my van walls pre-soaked with water?
Nyaaagh!