Space Blanket Not Wide Enough

[planemad]

I have got some space blanket for my loft. (Loft has NO current insulation)
I put a few rolls up there this evening and have found that my joist spacing are 60mm bigger which leaves me with a uninsulated gap.

I will be laying the 200mm one way and then go over the top another way so will eventually end up with 400mm of insulation.

Does anyone have any tips or advice for filling the gap or shall I just leave it.

 

[dextrous]

Why not put the first layer at right angles to the joists, butted together, and the second layer at right angles to that?

 

[planemad]

I don't think that would work as the will always be a cold air (draft) under the void.

 

[dextrous]

No, there will be warm air under the void, since the heat will be prevented from escaping by the blanket.

 

[planemad]

The cold air coming in through my soffit grilles will fill that void for sure.

 

[dextrous]

No more than leaving 60mm wide gaps along it

 

[planemad]

Exactly my point, what I might do tomorrow is buy some 100mm rolls of insulation to put between the rafters then put the 200mm space blanket on top.

 

[freddiemercurystwin]

The cold air coming in through my soffit grilles will fill that void for sure.

Your soffit ventilation needs to be directed above the insulation, you must not block the vents up or you will have condensation problems.

 

[dextrous]

Good idea. Get the 1.2m wide rolls - they're not as itchy as they used to be, and have already been partially cut to allow for a variety of joist spacings.

 

[planemad]

I will install over the wall plate but NOT into the eves, this should give me good ventilation.