Insulation Choices

M

Mr Tayto

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Hi

Im in the middle of insulating our house, its a timber frame so Im having to go with either mineral or rockwool.

As with all things with sales people Im getting conflicting reports as to which one is better. Could any one shead any light on the subject.

Thanks

Mr Tayto.
 
Rockwool is better than mineral fibre.

Rockwool has a heavier physical property thus will keep the dwelling cooler in hot summer days.
Rockwool is made from rock, thus is less likely to be infected by insects, mould, fungus or bacteria.
Rockwool is not hygroscopic but is breathable.
Rockwool has slightly better fire resistance properties than most fibreglass.
 
Am also in the middle of a renovation & extension of a 1.5 storey house and have to make insulation choices too. House is brick built but am trying to achieve A2 energy rating. I realise A2 applies to the entire building fabric and am confident I can reach it everywhere except the roof. Am replacing rear half of the roof to accommodate 2nd floor extension but front half of roof, which stays, has 4 inch rafters. However, as it's a dormer I need to create a 'warm roof'. Even using phenolic foam would require c. 200mm to reach A2 level (u-value 0.12). However, I would prefer to use a natural product such as sheep's wool but this requires even greater quantities of insulation to achieve u-values. Do I have to bite the bullet and compromise or is there anything I can do to achieve A2 value in the roof space?
 
Phil,
although you are to be commened for trying to upgrade your isulation, your terminology is a bit off.

Whilst kingspans latest booklet is a good starting point, it should be noted that insulation is only 1 of about 5-6 different factors that significanlty affect your BER rating, so asking how to achieve an A2 rating is a bit disingenuous, theres so many other factors to be considered.

Believe it or not you cant actually get a BER rating on a renovation. You can only get a BER on a new build or, from next january, on an existing build at point of sale or rent.

My best advice is to hire an architectural technician thats also a BER assessor.
 
Syd,

Have an engineer doing the plans for me who's also BER trained however, have been fighting with him over the amount of insulation I want to put in. He says I'm putting in too much everywhere! Have studied the other BER factors, air tightness, solar panels, HRV etc. so I understand what you're saying. I suppose I am trying where possible to future-proof the house and am more worried about this than the actual BER rating, but the BER is a useful guideline for me and gives me a common denominator to discuss with the builders. However, the weak point seems to be the roof insulation so I am trying to remedy that as best I can.
 
id always be wary of someone saying youre including too much insulation :eek:

to answer your original question, 'do i have to bite the bullet', i woul dsay that you need to design either a breathing roof with a breathable insulation (hemp, wool, fibreboard), or a non breathable roof with non breathable insulation (PU/PIR etc)

the breathable roof is ecologically better, but needs to be thicker to achieve the same performance as a non breathable.
 
Cheers Syd,

I have decided to go the ecological option. However, whilst I can get Thermal Conductivity figures for sheep's wool, I cannot get these figures for Hemp or fibreboard. Also, wondering if these products have IAB/BBA certification as is the case with Sheep's wool? I'd like to make a comparison to see what amounts I'd need to achieve the same u-values.
 
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