epsilonGreedy

Different materials layered for loft insulation.

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The background to this question is a motivation to move into my self build as soon as it is humanly possible. According to my current plan, occupancy could start in October prior to a working central heating system and with incomplete electrics or ducting in the attic.

 

I think I should install a 50% layer of insulation in the attic to survive the first winter but which insulation material would cause least inconvenience when work resumes?

 

My hunch is that polystyrene beads between the roof joists would be sensible and then prior to final Build Control sign off inspection I would then raise the loft insulation up to standard with rolls of some woven Rockwool type insulation laid over and across the joists. Would I be correct in thinking it would be preferable to sweep beads aside in the loft when work resumes v. dealing with woven rolls and the fibres my lungs could ingest?

Edited by epsilonGreedy

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Beads are poor for situations such as that - is this just a flat ceiling and traditional cold roof space .? Insulation is cheap - putting 3-400mm down to start with is a day or two job at most. The hardest bit is the stuff between the rafters, the rest just rolls out in big 1200mm swathes. 

 

What shape is your new house ..?

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19 minutes ago, PeterW said:

What shape is your new house ..?

 

L-shape. We will be spending the first winter living in one 2-story rectangle (900 sq ft) with another 2-story wing of the house (600 sq ft) incomplete with just stud wall frames and bare block walls.

 

19 minutes ago, PeterW said:

is this just a flat ceiling and traditional cold roof space .?

 

Yes a traditional brick and block 2-story house.

Edited by epsilonGreedy

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I have some beads in my loft space - unintentional from when I was filling the wall cavities. They tend to do their own thing and any little movement of air will disperse them. So laying loft roll over the top of them will be a PIA. They will fly every where. And fitting light fixtures in ceiling could also be interesting even if you have swept them to one side to start off, the draft you have created with that new hole could lead up to a spectacular vortex waterfall of beads into the room below!

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12 hours ago, PeterW said:

Beads are poor for situations such as that - is this just a flat ceiling and traditional cold roof space .? Insulation is cheap - putting 3-400mm down to start with is a day or two job at most. The hardest bit is the stuff between the rafters, the rest just rolls out in big 1200mm swathes. 

 

What shape is your new house ..?

 

Plus modern loft fluff (recycled plastic?) is so easy to work with, not itchy or irritating that you shouldn’t let it put you off.

 

Suitable job even for completes novices, like me. Disposable mask, gloves and covered up is sensibly adequate with no worries about getting fibres up you sleeves or worse...

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I think you need to decide on the best insulant for the loft and go from there. I don't understand what you mean by "inconvenience" - all I know is that loose EPS bead will be very messy and probably leave you picking them out of your garden for the next decade or so.

 

What are the target U values for the loft?

 

Blown cellulose?

 

Mineral wool would probably give best value in most cases, but it depends on your overall design.

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If you have somewhere to store it and have a current property, then there are some good offers via the sheds currently on the eco roll stuff. 3 for 2 and a 10% card etc will certainly get it close if not under the BM prices. 

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13 hours ago, epsilonGreedy said:

L-shape. We will be spending the first winter living in one 2-story rectangle (900 sq ft) with another 2-story wing of the house (600 sq ft) incomplete with just stud wall frames and bare block walls.

 

Yes a traditional brick and block 2-story house.

 

Based on the size, that’s 6 rolls per layer of standard 100mm insulation which is about 14sqm / roll for your first bit. 

 

24 rolls, that’s half a day to do the inbetween bits and then the remainder of the two days will be the other rolls to get you to your 4 layers. 

 

As @daiking says, this is an easy DIY job. 

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Ok based on what you are all saying, time for a new approach.

 

The beads idea came into my head because:

  1. I was focused on the hassle of removing insulation the following Spring in order to complete wiring, plumbing or ducting jobs in the loft space.
  2. I recall working in my parent's loft in the 1970's and the irritation caused by the layered wool like insulation.
  3. The loft space of my previous year 2000 vintage Bryant Homes house resembled a back garden after 1ft of snowfall and I could not imagine deconstructing such a maze of criss cross insulation layers to access the ceiling.

I now reckon I should roll out insulation between the rafters over the occupied 70% section of the house to provide 100mm or 200mm of insulation for the first winter. Based on the feedback here, I am led to believe that when needing access the following year it should not be a distasteful task to remove a single layer of a few rolled insulation sections.

Edited by epsilonGreedy

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1 hour ago, gravelld said:

What are the target U values for the loft?

 

 

Something between legal and probably way short of the passive house standards that many here design to. My detailed planning permission mandates 15 wooden Georgian windows including 10 sash windows with boxed counter weights so Jane Austen will feel right at home with the designer drafts.

 

If I do go the extra insulation mile anywhere I am leaning towards lining the inner block wall with foam backed plasterboard which will be fixed with sticky foam glue. I think @jsharris mentioned that dry lining is more effective when convection channels are eliminated by avoiding cement dot and dab techniques and instead applying sticky foam in a grid pattern with contiguous perimeters.

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9 minutes ago, epsilonGreedy said:

 

Something between legal and probably way short of the passive house standards that many here design to. My detailed planning permission mandates 15 wooden Georgian windows including 10 sash windows with boxed counter weights so Jane Austen will feel right at home with the designer drafts.

 

If I do go the extra insulation mile anywhere I am leaning towards lining the inner block wall with foam backed plasterboard which will be fixed with sticky foam glue. I think @jsharris mentioned that dry lining is more effective when convection channels are eliminated by avoiding cement dot and dab techniques and instead applying sticky foam in a grid pattern with contiguous perimeters.

 

My joiner re-makes sash windows and to be honest they are as good as anything with a normal set of seals. Wooden windows made properly can be done to very high standards. 

 

We have battened and insulated with 25mm insulation and then boarded as it’s quicker and cheaper to do and have just as good results. That’s on top of 150mm blown bead cavity. 

 

I would seriously consider a top down approach and get the loft finished first and then you never have to touch it again. 

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12 minutes ago, PeterW said:

We have battened and insulated with 25mm insulation and then boarded as it’s quicker and cheaper to do and have just as good results.

 

 

I should consider this method as well but I am mindful of loosing internal floor area. My 1500 sq ft L-shaped house penalizes such insulation driven encroachment of the external walls... time for me to prove this numerically.

 

I imagine your method is less prone uneven results

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19 minutes ago, epsilonGreedy said:

 

I should consider this method as well but I am mindful of loosing internal floor area. My 1500 sq ft L-shaped house penalizes such insulation driven encroachment of the external walls... time for me to prove this numerically.

 

I imagine your method is less prone uneven results

 

Its the same floor loss - you batten at 600 centres and then infil with insulation cut to size. total loss is only 25mm per wall.

 

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5 hours ago, PeterW said:

My joiner re-makes sash windows and to be honest they are as good as anything with a normal set of seals. Wooden windows made properly can be done to very high standards. 

 

 

This sounds promising. I have an offer to visit the production facility of a nearby sash window manufacturing facility and will report back.

 

The salesman is warning me about cheap Polish stuff on eBay

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