Roof insulation, Screwfix or Bricodepot

[CeeJay]

I have converted the grenier into a living room with half of it being chopped out to take a roof terrace. The ceiling is quite high and pitched front to back with the voliges showing over the rafters. I would like to insulate the space between the rafters and cover up again with wood and have seen some quite thin aluminium insulation stuff. However the type sold here in France seems to be very different from that sold in UK. I have a Screwfix catalogue and their products seems to be glorified bubble wrap, whereas the BricoDepot stuff seem to be various layers of different materials and appear to be, whilst more expensive, more efficient.

Has anyone experience of the two types and would share their opinion?

[Dick Smith]

It may be glorified bubble wrap to you, matey, but it keeps my shed warm!

I've seen the BD stuff, and it looked a better bet to me, and probably a lot easier to use.

[Cassis]

I've seen the BD stuff, it is NF classed (Normes Francaises) but you really need to know the R-value of the products to make a proper comparison.  This is usually given on the packaging.  BD do several insulations of this type, by the way.

[LEO]

Try this site for technical info Insulation.They are UK based company ,and in addition they, if asked  will help you with SAP calculations (heat loss)

all new build properties in the UK need this calculation before they can get a completion certificate. 

http://www.ybsinsulation.com/

Kind regards,

Leo

[Dave&Olive]

hi

               ok you get what you pay for !!!! that bubble wrap stuff is ok for keeping the dog warm ??

                                     dave

[Cassis]

I guess so.  As long as you leave an airhole.  [:D]

[Coco]

Our builder's opinion of the bubble wrap stuff was that it is just that, bubble wrap! and won't keep you any warmer.  He agrees with Dave and Olive - you get what you pay for and the bubble wrap is just a waste of time putting it up.  And he wasn't trying to flog us any insulation either - just an opinion whilst chatting about something else.  We'vealready used the old-fashioned stuff.

[Cassis]

I agree with St Amour and Dave that the basic bubble sandwich stuff is poor.  There are more sophisticated thin isolating rolls which are equivalent to 200 or 240mm fibreglass or rockwool, but they work out at 2-3 times the price of the thick stuff for the equivalent thermal insulation so I guess they are only worth using if circumstances require it (like you want to leave rafters exposed and you couldn't do this with traditional insulation, or headroom is a premium) or if ease of handling is VERY important.  The traditional stuff also has some acoustic insulating properties, which the thin does not.

[Brilec]

Brico Depot usually have one of their range of isolation products on a special offer. The ones with many layers also contain layers of woll which will have some accoustic effect. They are claimed to have the same thermal insulation as 200mm of rock wool.

Also, given that they are bulky, whay would anyone want to take that sort of thing from England when a bettter and cheaper item is available locally in France?

[cooperlola]

Castorama also have a good offer on the thin metal stuff at the moment.  We used it (for the reasons described above, ie wishing to keep the roof beams exposed and give extra headroom) and it's excellent in the heat insulation department.  Bubble wrap I can't say but doesn't the plastic-y nature of it cause condensation problems - don't know.  You pays your money....

[Cassis]

[quote user="cooperlola"]You pays your money....[/quote]

I think that's what it boils down to, usually.

[Alane]

I've seen it written that the claims about "equivalent to 200mm of rockwool" are dubious but haven't been able to find any verification - does anyone know the truth on this?

My other concern regards the lifespan of this thin insulation - how long before the plastic degrades in the heat of an under roof location for example and will installing a reflective insulation layer under roofing felt make it so hot that it will melt - again if anyone has any information that would be useful as I too am thinking of using this to retain headroom and exposed rafters.

[Cassis]

I don't know, Alane, as I can't find any R values on the adverts for the alu stuff - I wonder if they are printed on the packaging itself?  Many have a 10-year guarantee, which is about as much as you get on anything, so they can't all be rubbish.

[cooperlola]

As it's foil on both sides of the middle layer, I assume that the bit in the middle (which looks more like a thin foam than "plastic") is thus protected from overheating.  Packaging is gone I'm afraid so can't check that.  Suffice it to say that it was recomended by the architect, rather than the builder, for whom additional costs to us are irrelevant (ie, the recommendation made no financial difference to him).

[Cassis]

Plus some of them are made of multiple layers of this, that and the other. 

It's not just bubblewrap in a tinfoil sandwich. [:D]

[cooperlola]

No, certainly not, it's a this that and t'other sani.[:D]

[Iain]

I think the most important thing on using the "layered" stuff is the fitting - ie make sure all the edges are airtight, using batten, and leave a "static" air gap (minimum 20mm I think) between the insulation and the plasterboard. Also be wary of the metallic joining tape - it comes unstuck after a couple of weeks, so really needs a batten along all these joins as well.

With regards to price, it's worth waiting untill it goes on promotion at one of the bricos, when it does seem to be significantly cheaper than elsewhere, whether that's the 9 layer stuff or the 15.

Iain

[littlemouse]

I know its a while ,but I came across some rt values for foil insulation today made by Actis

triso-super9 +   thickness25mm 14 layers Rt =5.6 m2 .K/W

triso-laine+  thickness20 mm 14 layers Rt=6.1 m2.KW

multiproTS250+ thickness25 mm15layersRt =6.5 m2.KW

rt = efficacite thermique mesurée en conditions réelles

[Cassis]

Nice one, Stuart.  Pretty impressive figures!

[Alane]

Thanks Littlemouse

Those figures tie up with the claims made by BricoDepot and others but its the first time I've been able to find R values published.

[Albert the InfoGipsy]

You may want to look here:

http://www.greenbuildingforum.co.uk/forum/index2.php?DATEIN=tpc_wlpssdlpg_1142805843

It's a huge thread, but the general consensus is that the thin stuff isn't worth having.

[gers32]

the multi layer known in uk as super nine or ten its same in brico is the best insulation by far but it is exspensive per mtr square but more comfortable to install and cleaner you must remeber to double batten either external or on top of rafters to keep air flowing a\nd stopping condensation use min 40mm battens as screwing plasterboard up will be a nite mair also any spot lights cannot touch foil hope fully its can be usefull if not email

pete 

[Rodie]

Actis Tri iso the multi layer insulation comes from france so i would say it would work out a bit cheaper

[Fred]

In the wake of the changes to Part L of the UK Building Regs insulation manufacturers are making all sorts of claims and counter-claims about their products - just do a search for "Roof Insulation" Archisearch.co.uk to see what I am talking about.

Some people claimed that the foil type insulations were only effective if they were kept clean to enure that they reamin effective and the BBA held back on issuing certificates for this type of system for some time, however the first certificate has now been issued, see http://www.bbacerts.co.uk/certs/43/4379.html

I'm not greatly reassured by BBA certificates myself (they seem to issue them to anyone who sends them £30,000 these days). However as this type of product has been a hot topic of debate I'd imagine that the'd have done their homework on this one.