Insulation (yes, again, and I have searched, honest...)

[cambournepete]

My workshop is a 10 year old tandem garage, 30ft long and 9ft wide, with rafters every 60cm.
Would I benefit from insulating the roof?
I'm thinking of using the foil bubble wrap type insulation up and down the rafters, probably taping the seams.
I'd not fill the gap above the insulation - approx 3", and I'd probably leave the underside bare - no OSB, no plasterboard...
Is this worth the effort?
Would my garage be warmer?
Would I be wasting my time?

Currently the garage is not heated - not much point with just felt and reconstituted slate tiles between inside and the sky...

There's too much stuff already on the walls to insulate them (and it narrow anyway), so I can't realistically do anything with them.

And I really did do a search ...

 

[StevieB]

Any insulation is better than none. Some insulations are better than others. If the garage is not usually heated your primary benefit from any insulation will be a decrease in 'heat escape' when you do heat it, and a possible decrease in condensation on the inside of the felt/tiles after you have heated it and the rising hot air cools. Only you can decide if the expense is worth it, depending on how often and how long you heat the garage for. As you have searched you will know some poeple like the foil bubble stuff, some people say its not tried and tested.

Probably not the yes do it / no don't answer you wanted, but with insulation there is no such question in the first place that gives those kind of answers I find!

Steve

 

[RogerS]

For a definitive answer, hopefully Mike G will be along soon.

For my two-pennorth, as Steve says, the jury is out on Trioso type insulation. I could be wrong but I think that recent tests showed that they did not live up to expectation. Certainly many Building Control departments don't like it. What's putting you off going with Kingspan type stuff?

Installing the foil is not as easy as they'd have you believe. You have to lay one lot of battens down first - that gives a gap for the foil to expand into in a roofwards direction. Then lay the foil. Then lay another load of battens on top to allow for space for the foil to expand roomwards. Then your plasterboard goes on top of those battens. OK...I know that you're not intending to do the plasterboard bit so you can maybe skip the second lot of battens.

Roger

 

[MikeG.]

Both of the answers you have received are spot on.......and I don't ever use any of the "Thinsulants". As Roger said, they take almost 3 inches of thickness, and their performance claims are controversial. I would rather use the 3 inches with something that I know works.

I would also caution against leaving one of the foil-type insulants exposed, so that owuld mean battening out and then boarding over.

Have you considered insulating at joist (ceiling) level? It is usually so much easier.

Mike

 

[treeturner123]

Mike

For what it’s worth, I insulated my shed using normal fibreglass which is held in place by sheets of hardboard. This is easy to cut to size, light-weight to hold and easy to fix with screws or nails.

Phil

 

[cambournepete]

Thanks for the responses - sorry it's taken a while to reply, but I had a family engagement...

Anyway, with the thin foil on the underside of the rafters, why would I need battens?
The 600mm wide foil fits nicely on the rafters, with loads of room above.
Couldn't I just staple it on the rafters?
Why can't I leave it exposed - is it very delicate stuff?

I agree I could put up OSB or hard boards on the underside of the joists and use ordinary insulation above, but I use the loft space to store stuff - maybe having to clear the loft space would help me get rid of some rubbish...

 

[RogerS]

Pete..you seem set on this stuff - even yhough the jury is out on its' performance - so go with.

Let us know how you fare and also how easy it is to repair when you snag it with a corner of an 8x4 sheet of ply.

 

[MikeG.]

Why can't I leave it exposed - is it very delicate stuff?

Yes, which is why I reckon you will end up battening out below it and sheeting over it with OSB or ply. As you know, that will be a really awkward job.........imagine trying to manouvre the sheets into position through the joists.

Mike

 

[Chris By The River]

Hi Pete,

If it is of any use to you I sell Home Offices that are insulated with Airtec (tin foil bubble wrap) and it DOES work so if you fancy having a look send me a PM - My show site is not far from you.

Chris

 

[Digit]

This is the stuff that was developed for the Apollo programme is it not?

Roy.

 

[barkwindjammer]

I would like to insulate my wooden shed
constructed of 2x2 stud frame clad with ship-lap boards
I was going to use glass wool type
Q:if I used vapour barrier/building paper, would it go between the ship-lap and glass wool, or glass wool then paper?

I would eventualy be covering the inside with ply possibly

 

[MikeG.]

Oh NO.....not again!!!!!!!

I must do a sticky! Vapour barrier and/or ply, which is highly resistant to the passage of moisture, should be on the warm side (ie the insde) of the insulation.

Mike

 

[barkwindjammer]

maybe you could add a sketchup too