o/t - garage insulation

[Asterix]

Dear all,

as well as other jobs, am increasing the use of insulation for the garage. I am intending to use Jabfloor polystyrene slabs (of suitable width) on the inside of the garage.

I'm going to cut to size and bond (or even just wedge in) to the inside of the external fascia in the gaps between ceiling and tops of walls (these are gaps created because of the void necessary for the flat roof joists that sit on top of the garage wall).

I was toying with the idea of bonding the same under the ceiling in the void between ceiling and the twin unguarded striplight installs (which sit between most roof joists).

Problem is, Jabfloor appears to be flammable and would need a heat resistant coating for this application. I’m looking for something simple, so want to install and go, not install, paint and go (or paint, install and go).

I doubt whether the striplights will generate enough heat for the Jabfloor to react but then there’s the risk incurred by the new electric cabling running through the centre of the joists.

So, I can still use Jabfloor for the void between wall tops and ceiling, but what could I use to insulate the ceiling? Am looking for something very easy to install (bonding only because of the flat roof), preferably light or reflective in colour.

Or maybe I'm worrying about nothing, maybe Jabfloor would be perfectly adequate for this kind of application - would be interested to hear if it is.

Any advice gratefully appreciated.

Note that I have other gaps to go for (garage door seal, window to brick seal, etc) but I’m happy with a plan for those.

And lastly, I'm doing this because I am the neshest man on neshday in neshland.

[John Loudon - Sponsorship Liaison]

Peter - polystyrene sheets from Wickes. Cut to width and wedge between the rafters. Cheap as chips

[Hammy]

Are you intending to work in said garage over the winter ?  if not I wouldn't bother a cold dry garage with good ventiliation is better than a warm one for storing cars  IMO (rate of rusting increases with temperature and humidity. Keeping a warm garage with dry air is impossible). Other opinions are available.

I've insulated mine on one side (to keep the heat in the house !) with secondhand commercial freezer panels at zero cost - 4" thick, powercoated steel finish.  I would not use anything combustible for insulation - but thought some of the polystyrene sheet you could buy was treated to stop it burning    ( e.g as prev post) you might find alternative cheap materials

[Mark (smokey mow)]

John, Jabfloor is essentially a EPS polystyrene the same as the stuff sold in Wickes so the queries raised in his post would still be relavent.

Asterix, I'll have a look through the Tech literature for Jabfloor and get back in a little while.  It's been so long since I've seen it used I forget it's fire classification.

[John Loudon - Sponsorship Liaison]

Yes but dont forget the wooden rafters are also fllamable  

[RedditchJay]

i plasterboarded my roof area.............. cut down storage space BUT made it much lower ceiling height and warmer............. just got the drafts around the garge door to solve next..........

[Mark (smokey mow)]

Yes but dont forget the wooden rafters are also fllamable  

indeed, but.... Their ignition temperatures and the flame propergation charactoristics are somewhat different.  

A Class D material such as untreated timber would require exposure to a flame for a considerable amount longer than a Class F product such as EPS polystyrene.  This will have almost instantainious ignition and then rapid propergation of flame across it's surface.

Fire resistance and surface flame spread are very different and not to be confused.  Going slightly off topic here a product can achieve a level of fire reistance whist still being combustable in it's self.  For example a oak beam of a suitable size whist being combustable could if correctly sized be capable of holding up a floor above a burning room for +30 minutes.  However a non-combustable steal beam in the same situation would fail much sooner than the oak unless it is suitably clad to insulate it from heat.

Flame spread classification defines how well the surface of the material behaves when exposed to a naked flame.  A class A product under test conditions would have no notable ignition of the surface of the material and any flame would extinguish almost immediately.   In comparison a class F material would have rapid growth of the fire across the surface and alow the spread of the fire to other adjacent surfaces.

Back on topic again my personal reccomendation is not to use exposed EPS insulation in close proximity to any sources of heat or ignition.  A hot spark thrown from a grinder would also be sufficient to cause ignition.  

For the method of insulating you describe I would reccomend a PIR insulation such as Celotex FR4000 which achieves a European Class B. However in relaity all insulations should be covered by plasterboard etc and not left exposed.  Certain products are not UV stable and therefore would need to be covered from sunlight to ensure they don't breakdown with age.

Also depending on how much insulation you're putting in and the postion of the electrical cables it may be necessary to de-rate the cables burried in the insulation.

Edit to add: if you put a ceiling in then go for rockwool.

[Mark Stanton]

and do be careful of  blocking up all the holes / draughts     condensation and lack of air circulation has its own set of long term problems  

[Trevori]

Asterix,

You could try spray applied Urethane foam. Can be applied to walls, roofs etc and has a BS fire rating. Obviously good for irregular surfaces and filling gaps.

Not a DIY job but suprisingly cheap and very effective.

I just had a  40ft x 23 ft garage roof (pitched) done for less than £1200.

Google for a contractor in your area.

[Mark (smokey mow)]

A word of warning on spray applied insulation.  They only achieve the fire classification quoted by the manufacturers if installed strictly in accordance with their Agrément Certificates.  In majority of cases this means that the foam must be covered by a fire resistant ceiling.

I've checked several installations carrier out by some of these so called specialist companies and none have been done correctly and the insulation has been left exposed.

Be aware also that once applied it's never going to come off again so any maintenance to the roof down the line will likely result in you needing a new roof.

[slater]

Asterix,

QUOTE

You could try spray applied Urethane foam. Can be applied to walls, roofs etc and has a BS fire rating. Obviously good for irregular surfaces and filling gaps.

Not a DIY job but suprisingly cheap and very effective.

I just had a  40ft x 23 ft garage roof (pitched) done for less than £1200.

I would never recommend the use of spray on insulation within a roof void, any damage to the exterior tiles/slates can not be remedied without major aggravation. If the roof is slate the slates need to breath,  if they are covered in foam they rot so does the tile batten not so much a problem with concrete tiles but clay tiles will react the same as slate.

Lewis

[Trevori]

Mine is applied directly onto corrugated compressed asbestos cement sheets, and like most garages, mine does not have a suspended cieling so no roof void. Works for me, and has a health benefit, but wont suit every situation.

[Asterix]

just got the drafts around the garge door to solve next..........

am looking at this for 25% of that

[Asterix]

and do be careful of  blocking up all the holes / draughts     condensation and lack of air circulation has its own set of long term problems  

well Mark, the garage is currently as draughty as a checkerboard and the damp is terrible (no heating on in the last 2 weeks, yet tools in bag are wet).

Am thinking that a dehumidifier, though expensive to run, is the only way (well, it's the way I'm going to go).

[slater]

QUOTE

Am thinking that a dehumidifier, though expensive to run, is the only way (well, it's the way I'm going to go).

problem with that is you will be emptying it every five minutes. Its condensation that is the problem cold air and even colder walls etc. probably be cheaper to try and bring the temperature up a little.

Lewis