solarguard loft insulation

[Jemstone]

Hi, I'm wondering if anyone has any experience of solarguard as suitable insulation for a loft. A company has recommended we take out our current insulation (approx 1m high!), replace with solarguard and board the loft (we want the loft boarding, they didn't recommend we do it). The roof space is very limited, the current insulation goes up to the rafters so to be able to store anything up there it would have to be reduced. Does anyone know if this will give us decent insulation, and what questions I should be asking? Thank you.

[Jemstone]

Anyone?

[Homebird8]

Ask them what the r-value of the insulation they are recommending is.

And what is the type of insulation you have at the moment? Is it glass fibre (the fluffy itchy stuff). It might be in a plastic/foil bag.

What are you hoping for? That you can get the same insulation level in less space so you can board the loft for storage. Did I read you right?

[Homebird8]

Oh, and you want the r-value in SI units m2.K/W (not American imperial hr.ft2.degF/Btu)

It's good stuff but not magic and it'd take quite a lot of insulation to match 1m thick of glass fibre.

[Jemstone]

Thank you homebird, I will ask them about the r value. What kind of value should they be aiming for? I accept it probably won't be as good as what we have now but given it's a detached house with solid walks and single glazed windows I'm not sure if having a hugely insulated loft counts for much.

[Homebird8]

Insulating an old house is always an issue. You've probably got somewhere around the 12ish mark now assuming a sloping roof and 500mm thick. I know you said 1m but it'll be less than that at the eaves and insulation is very dependent on it being fitted well. Gaps and creases and squashed bits mean big losses in effectiveness.

Putting all that together with the solid walled, single glazed house and the probable construction then...

You need to either go for a warm roof space with a product like solar guard on the sloping parts and the roof treated as indoor space so heated from below. It important not to let warm moist air from the house into an unventilated roof space at a cooler temperature though because you're likely to get condensation. A wet roof space is a very bad thing.

Or, lay the insulation of whichever type directly over the rafters holding the ceiling up (the floor of the roof space), have your boarding over that, and maintain the roof ventilation. This would mean a cold roof space and whatever you want to store there being able to deal with this.

As far as the r-value is concerned, it is important to stop all your house heat rising and getting expensively lost through your roof. You're right in thinking there will be a lot of loss through the walls and windows though. Stopping draughts is very important too. I'd look into whether you can insulate your walls using a product like Celotex or Kingspan on the outside and render over it. Would that spoil the look of the place. It's very effective, and then you needn't worry so much about a reduced insulation in the loft.