Hybris between rafters insulation

Hypericum

Hello, I had Hybris insulation installed between the rafters in the loft two years ago. (1960's house, brick wall, tile roof) The installation was checked by an independent company recently, for free (cold call so-say linked to the Govt Warm Home  Scheme).  The chap said the felt under the Hybris is wet.  Anyone any experience of this type of insulation and is it likely to cause damp?  I thought I was doing the right thing but threads on here suggest if loft floor insulation is sufficient, the extra rafters insulation is surplus to requirements.  The Hybris has fallen out in places so company is willing to rectify but should I just have it taken out altogether?  Thanks.  (Pensioner widow but fairly compus mentus!)

FreeBear

Hypericum said:

Hello, I had Hybris insulation installed between the rafters in the loft two years ago. (1960's house, brick wall, tile roof) The installation was checked by an independent company recently, for free (cold call so-say linked to the Govt Warm Home  Scheme).  The chap said the felt under the Hybris is wet.

Not familiar with Hybris, but it appears to be a multifoil with a polyethylene core. I would imagine condensation forms on the underside as moist air percolates through the ceiling. Probably not a good thing...

My experience of these cold calls offering "free loft insulation surveys" are a prelude to a sales pitch for spray foam insulation - Instantly down valuing your property and adding a bunch of new problems.

If you can get more traditional fibreglass or rockwool insulation fitted under an ECO4 grant, I'd recommend going for it. It would solve any damp problems, and be a world ahead of any spray foam crap.

ComicGeek

If the loft is unheated, and you have sufficient insulation in the loft floor below, then you shouldn't have this rafter insulation at all. With both sets of insulation, you have a high risk of condensation forming on the underside of the rafter insulation, which it sounds like you (might) do. Ask someone you trust to check the loft for moisture under the Hybris slabs - personally I wouldn't trust a single word these cowboys say. 

I would take it all out - it might make a marginal difference in terms of keeping the house warmer, but the risk of creating condensation is too high. Even breathable insulation like fibreglass/Rockwool isn't appropriate for this, it just isn't needed. Loft should be draughty, dry and cold - insulated at floor level only.

ThisIsWeird

Hypericum said:

Hello, I had Hybris insulation installed between the rafters in the loft two years ago. (1960's house, brick wall, tile roof) The installation was checked by an independent company recently, for free (cold call so-say linked to the Govt Warm Home  Scheme).  The chap said the felt under the Hybris is wet.  Anyone any experience of this type of insulation and is it likely to cause damp?  I thought I was doing the right thing but threads on here suggest if loft floor insulation is sufficient, the extra rafters insulation is surplus to requirements.  The Hybris has fallen out in places so company is willing to rectify but should I just have it taken out altogether?  Thanks.  (Pensioner widow but fairly compus mentus!)

No idea what this stuff is - any chance of a photo, Hyper?
And, how was it 'sold' to you - as 'house insulation'? 'Cut your energy bills'? 'Make your house easier to heat'?

Hypericum

Many thanks to you all for your speedy and helpful replies.  Hybris is a honeycomb strip with reflective foil on the side facing into the attic (it has its ' own website).  My intention is to get it removed and view it as an expensive lesson learned!!  Yes, it was sold as being good extra insulation. (I had it installed privately, not via a Govt grant).  Thank goodness I didn't have foam - recent reports have highlighted the problems with that, and I'm told there was small print which exonerated the Govt Green Scheme from rectifying the resulting problems?

ThisIsWeird

Hypericum said:

Many thanks to you all for your speedy and helpful replies.  Hybris is a honeycomb strip with reflective foil on the side facing into the attic (it has its ' own website).  My intention is to get it removed and view it as an expensive lesson learned!!  Yes, it was sold as being good extra insulation. (I had it installed privately, not via a Govt grant).  Thank goodness I didn't have foam - recent reports have highlighted the problems with that, and I'm told there was small print which exonerated the Govt Green Scheme from rectifying the resulting problems?

So, it was effectively mis-sold to you. Sold as house insulation that can actually have next to zero benefit, and possibly cause condensation issues and rot to your roof structure.
You clearly understand what you have 'up there'; you have the actual house 'shell' - floor, walls, and ceiling. That's the bit you heat, and adding insulation there obviously makes complete sense. For the ceiling, you add loft insulation to the other side, a good 300-odd mm is good.
Above this is the 'loft'. The loft is actually ventilated to the outside via gaps, often grilles, in the eaves and soffits. Hence it's draughty up there, and that's exactly how it should be; that breeze keeps the woodwork nice and dry.
In summer, it can cook up there, in winter, freeze. That doesn't matter, since the house itself is insulated from this by the lagged ceiling.
So, the Q is - how can adding insulation to the rafters help to insulate the house below, when there's a howling draught running through the loft space between them? The answer is, it doesn't. It cannot.
I liken it to your head, outside on a cold and wet day. What do you use to keep your brains warm and dry? For 'dry', you use a brolly - you hold it above your head, it keeps the rain off; it is a roof. But does it keep your head warm? No, 'cos the cold air still circulates around yer 'ead, just as it does through the loft. So, how do you keep your head warm? By pulling on a wooly bunnet. That's your loft insulation. 
So, what did these shysters sell you? A layer of insulation that you added to the underside of your brolly = pointless.
I'd be tempted to sue them. It's an outrage. 

Grandad2b

ThisIsWeird said:

So, it was effectively mis-sold to you. Sold as house insulation that can actually have next to zero benefit, and possibly cause condensation issues and rot to your roof structure.
You clearly understand what you have 'up there'; you have the actual house 'shell' - floor, walls, and ceiling. That's the bit you heat, and adding insulation there obviously makes complete sense. For the ceiling, you add loft insulation to the other side, a good 300-odd mm is good.
Above this is the 'loft'. The loft is actually ventilated to the outside via gaps, often grilles, in the eaves and soffits. Hence it's draughty up there, and that's exactly how it should be; that breeze keeps the woodwork nice and dry.
In summer, it can cook up there, in winter, freeze. That doesn't matter, since the house itself is insulated from this by the lagged ceiling.
So, the Q is - how can adding insulation to the rafters help to insulate the house below, when there's a howling draught running through the loft space between them? The answer is, it doesn't. It cannot.
I liken it to your head, outside on a cold and wet day. What do you use to keep your brains warm and dry? For 'dry', you use a brolly - you hold it above your head, it keeps the rain off; it is a roof. But does it keep your head warm? No, 'cos the cold air still circulates around yer 'ead, just as it does through the loft. So, how do you keep your head warm? By pulling on a wooly bunnet. That's your loft insulation. 
So, what did these shysters sell you? A layer of insulation that you added to the underside of your brolly = pointless.
I'd be tempted to sue them. It's an outrage. 

Excellent analogy!