Hi guys me again, need some loft insulation advice!!
Ok so.....
Few years back I insulated the attic with space roll, you know the stuff with orange plastic on the bottom and perforated silver over the top of it, well I rolled that out between the joists, then I got the big blanket version of it and put this 90 deg over the first layer

This quickly developed drips of moisture everywhere , like someone had been up there with a hose pipe! And this was dripping off the roof onto the insulation ,

So I installed those white plastic roof felt spacers into the overlaps of roofing felt, about 50 of them! This cleared the problem up in a few days, along with sealing cables and pipes and holes with foam and sealant.

Well anyways, just been up the loft to sort the insulation out because it’s a bit of a mess and been disturbed, and whilst everything looks dry and a million times better than it was I stuck my hand on the silver insulation at bottom of the pile and it felt damp and cold, so I opened the silver perforated layer and stuck my hand in, and yep it’s wet!

If I had to give it a description I’d say it’s 95% dry and just the top most 5mm is slightly damp

So what do I do now? I was going to put the second layer back over it but thought I’d ask the experts first!
It’s an old stone house, with big standard plasterboard nailed to the ceiling, with pink plaster and white emulsion
I pulled the bag of insulation out of the gap and the plasterboard is bone dry, the rafters it sits in Look dry, the felt above it looks dry, the bags weren’t stuffed into the eaves really but I’ve looked down the eave and that’s all dry, my house doesn’t have eaves

So my thinking.... cannot be dissipating through the ceiling because the apace roll has the orane vapour plastic on the bottom, so either it’s still damp from before when I had the damp issue (4 years ago?) or ??

Any help gladly appreciated guys, before I mess it up again and have brown stains all over the ceiling cheers!!

Just made a discovery!! The silver perforated top side of the loft roll is not actually perforated, it looks like it is covered with millions of pin holes but I just put a piece of it over my mouth and blew like a madman and no air comes out! Should I take all the plastic off the insulation rolls ?

This insulation has a supposed perforated orange bottom and silver top, it’s definitely been through the perforating machine at the factory but I’ve put the orange and silver over my mouth and tried to blow through it, if it is perforated it’s not very good!

I could cut the silver topside off easy with it scissors as it sits in place! And I could leave the orange plastic on the bottom, or warm side as you call it!

But once the first layer is done and I want to apply a 2nd layer, which is the huge space quilts , should I also take the plastic off this?

I had a decent dig around when I was up there, the 2nd layer had been pulled out of the way, and likely been like it for years, so the wet section was in the first layer, it was only very slightly damp , checked all around it, it was the only thing wet, the rolls to the left and right and the plasterboard below it were all dusty and dry

It’s called knauf space blanket, it’s just normal mineral wool 200mm thick but in an orange and silver bag, think it’s mainly for easy diy, to stop bits going everywhere, the orange bottom plastic , the top silver plastic, all sides have millions of pin holes, or so it seems!

So my layers are, plasterboard, then orange plastic, then 200mm insulation , then silver plastic. Then 2nd layer on top is orange plastic, 200mm insulation, silver plastic

The orange and silver definitely have the perforated markings, but you can’t blow through it, I remember a few years back when I had mega condensation there were small pools of water sitting on top of the silver, if you hold it towards the light bulb you can’t see through the holes even if you stretch it, but hey ho, everything else around it does feel dry, cold but dry, this wet section wasn’t direct water contact, when you put your hand inside the bag it was as if the whole piece had been slightly misted with water , when I dragged this bag out the plasterboard is dry and dusty , just the top 5mm of the wool felt wet

Maybe it still is wet from a few years back

The light cable and switch cable is still sealed , checked that

I’ll attack it with a fresh head tomorrow, charge the FLIR up and see what’s what, I did discover a slight crack in the coving to ceiling in bedroom below , only looks like paint pulling away from the caulk but I’ll check it

Don’t think it’s condensation, didn’t see a drip anywhere, and the wet patch is inside the bag and all over, I’ll have another look later today

<blockquote><cite>Posted By: GreenPaddy</cite>From what you've described it's a local issue, for what ever reason. I would slice that damp bag open on one side, and fold the foil back. Leave it for a few days till nice and dry. (This cold dry snap might help with that. If it doesn't dry, then there is likely another moisture source close to it. You can then investigate that.)

Once dry, fold foil back over, replace the top blanket, and inspect it once a week over the winter. You need to inspect it regularly over a longish period, so that you can build a base line, from which change will be obvious. Also, it could well be something affecting that one area, and you'll then have a better idea as to what has changed around that area (rain, cold, lots more showers/baths, whatever), to give any resulting change in damp inside the bag.

It may well be residual moisture from when everywhere was dripping with condensation, and this area happens to have not had the chance to dry out so well (maybe the top blanket was particularly well tucked around it, and so slower to dry out). Could equally be the top blanket is particularly badly tucked around it, and so cold air getting to its top face, and causing condensation at that top face, as moisture rises up through from house below. Hundred guesses...none helpful.

Dry it. Re-lay it. Check it. That's what I'd do.</blockquote>

When I get home tonight I’m gonna pull all the rolls back to centre, inspect cable entries, turn lights on below see if I can see any obvious holes, I’ll fire up the flir camera and see what it’s like with heating off, then heating on, then relay the rolls and check with camera, then relay 2nd layer, I’ll move my lap vents down another step, got more on order, only thing I don’t know what to do is with the eaves, I don’t have any, when I pull the rolls out I can see the plasterboard ceiling edge, and can see down into the eave, it’s empty and dry and just wood rafter sitting on top of stone wall, there isn’t any airflow, think I’ll add something in each eave to vent it like a corrugated plastic, then tuck the insulation right in, that way it’s insulated just past the plasterboard edge and also still vented if there is anything to vent, I don’t think I can add pictures to this forum? Can I?

deniance - sounds like a good approach to get the insulation right out as far over the ceiling edges at the eaves as possible, whilst maintaining the free ventilation of the attic space. Sounds like you're suggesting filling the eaves, over the wall head, by putting corrugated plastic against the felt (between the rafters) to keep a gap from insulation to felt. Can't see any issues with that.

If you do have good ventilation up there, I don't see any issue with water vapour passing from the house into the attic area. That's how these houses were designed to operate, and the plastic on the rolls won't really stop it, as "djh" mentioned before. I only mention this, as I got the impression you were trying to plug every little hole to stop vapour passage, which you won't achieve.

If you do retard vapour from the house going into the attic space and being vented away, there will be an increase in vapour within the house, which you will need to remove. Vapour passing through the ceiling to a vented attic is not a scenario that has to be stopped.

<blockquote><cite>Posted By: GreenPaddy</cite>deniance - sounds like a good approach to get the insulation right out as far over the ceiling edges at the eaves as possible, whilst maintaining the free ventilation of the attic space. Sounds like you're suggesting filling the eaves, over the wall head, by putting corrugated plastic against the felt (between the rafters) to keep a gap from insulation to felt. Can't see any issues with that.

If you do have good ventilation up there, I don't see any issue with water vapour passing from the house into the attic area. That's how these houses were designed to operate, and the plastic on the rolls won't really stop it, as "djh" mentioned before. I only mention this, as I got the impression you were trying to plug every little hole to stop vapour passage, which you won't achieve.

If you do retard vapour from the house going into the attic space and being vented away, there will be an increase in vapour within the house, which you will need to remove. Vapour passing through the ceiling to a vented attic is not a scenario that has to be stopped.</blockquote>
That’s my plan yes, I had mega condensation up there before but think that was because of 3 spotlights on the landing! Closed them off and added felt vents and all was good, just need to find something to go into eave for airflow and then I can tuck insulation up under it

Posted By: deniance

just need to find something to go into eave for airflow and then I can tuck insulation up under it

When fitting the insulation between the rafters over the top of the wall, cut the insulation at a chamfer so its not squashed flat right at the edge. Once the insulation is in place push a length of plastic conduit down the side of each rafter so the conduit sits on top of the insulation and under the felt. If you cut the ends of the conduit at 45 degrees you can put a small screw through the chamfer to hold the tube in place. Do the same on opposite sides of the roof to get a crossflow of air through the roof.

Hope these pictures work

The ventilation gap should be 25mm

What do I do with the gap between rolls, where I’ve tucked each 100mm roll between the joists, they’ve puffed up a bit, should I fill in the gap with some more or just whack the 2nd layer over the top?

<blockquote><cite>Posted By: philedge</cite>Id take out the covered stuff youve got in the picture and put in 75/100mm cut to fit between the joists without bellying up. The put the coverdd stuff over the top at 90 degrees to the new stuff between the joists.

If you put another layer over what youve already fitted, youll have lots of "tunnels" which air can just blow through and take any trapped warm air away.</blockquote>

Yeah I get you, that’s what I was trying to get at, thinking about getting a roll chopped up to fill in the tunnels before the top layer, trying to not spend any money

This image is where I’m up to! Slow going!