Second Nature stuff on sale

[Ian Bond]

I suppose it depends on the type of insulation - urethane vs. rockwool or sheeps wool?

And the physical limitations of the structure - If I put more than 2 inches of insulation into my roof slope I need to lose the lath & plaster ceiling. More than 6 inches and the attic ceiling becomes oppressively low.

Then there's the ceiling joists hidden below all that insulation. I can imagine a future owner's foot going through the carefully restored ceiling.....

 

[Nemesis]

Right - is there a difference in u values or whatever, which makes a thinner layer of one type have the same value as a thicker layer of another?

We have a variety of problems (opportunities...) to consider, one of which is insulation between the roof and ceiling, but that's not urgent, at the moment I'm concerned with the area above the original part of the house, in the loft, which currently has a thin and filthy layer of ancient glass fibre. It needs a greater thickness and have not yet decided what to do!

 

[Ian Bond]

I can't bring quite convince myself to install the urethane board insulation, despite its slimline appeal. Or rockwool.

Can't raise the roof (in a terrace).

Won't lower the ceiling (lath and plaster, loss of headroom, depth of roof timbers)

So a few inches of sheepswool between the rafters should be better than nothing. And deeper insulation in other places, where I can do it without causing other problems.

As long as it is affordable, and will pay for itself within a reasonable time period.

 

[Nemesis]

No, totally agree, I just wonder what the u value of sheepswool is versus the recycled bottles or rockwool inch for inch.

I appreciate the problems, as we have similar in some places, such as the barn.

My pressing concern thsi winter is the main part of the house, the loft, and have yest to decide the best course of action.

 

[Penners]

And nice bacon rolls in Colchester B&Q. I sometimes take my lady wife there for a light luncheon.

Nothing's too good for her.

 

[Alastair]

Is the B&Q price really that good? http://www.lowimpact.org/acatalog/thermafleece_sheeps_wool_insulation.html here it is £95 for 27 batts, agreed there is carriage of £45 for up to 4 packs, but you have to get it from B&Q to site anyway, and that costs time and you need a BIG wagon.

 

[Ian Bond]

Nemesis -

The Thermafleece claims 0.039 W/mK

Knauf Crown Rafter Roll (glass mineral wool) claim 0.032 W/mK

How effective these are in practice is another matter. How well would the insulation perform if slightly damp, with a breeze blowing across it?

Then there's the physical limits on what insulation you can squeeze in, the need to manage condensation, and the law of diminishing returns. I'm quite happy to pay for 3 or 4 inches of sheepswool (or an alternative)insulation for over the ceiling joists. But how much more enegy would I save in the long term by doubling the thickness? Would it be worth it even if I could afford it?

Penners - you certainly know how to treat a lady. Screwfix Trade Counters do free tea and coffee (from a machine) while-u-wait. Just FYI

 

[Nemesis]

Penners likes his bacon though. Presumably in big baps (see other thread...).

 

[Penners]

Screwfix Trade Counters do free tea and coffee

Thanks Ian. There's a new Screwfix store in a nearby town, but I haven't been there yet. Do you get the chance to have a look at their woodworking machinery before you buy? I'm considering a table saw.

 

[Penners]

big baps

You see, there you go again. Utter filth. My mum warned me there were women like you.

 

[Nemesis]

And mine warned me about blokes who had only one thing on their mind, and see smut in everything.

xxxx

 

[Ian Bond]

Screwfix Trade Counters do free tea and coffee

Thanks Ian. There's a new Screwfix store in a nearby town, but I haven't been there yet. Do you get the chance to have a look at their woodworking machinery before you buy? I'm considering a table saw.

You could always ring up and ask - if they don't want to let you see or have a demo then they've only lost a potential sale.

The Scr*wF*x counter is just a counter, with a very few things on display. Just take your list to the counter, pay and they fetch it out from the back. Like Arg*s but not as up-market.

Some trade places have suppliers demonstrating products in-store. Free snacks whilst you watch someone weilding the latest shiny new toys. I mean tools.

 

[Mark]

Right - is there a difference in u values or whatever, which makes a thinner layer of one type have the same value as a thicker layer of another?

Yes, absolutely correct.

You need to know the thermal conductivity figures to compare them. think of this as the rate of energy(heat) flow through a material when it has a temperature difference between two sides.

Its a property of the material, so yo can compare different types of inslation. Lower numbers are better from an inslation point of view.

Its confusing because so many sites confuse the measres,they say resistivity rather than conductivity ( these are inverse ie R = 1/C)

the urethane board is a 'better' insulation than the sheepswool. having a conductance of about 0.02 as opposed to about 0.037 for thermafleece and the hemp batts at about 0.04. So you can get the same insulation effect from a thinner layer of kingspan, in fact you would need almost double the depth of wool to give the same inslation effect.

In the real world yo have extra issues about draughts, convection crrents, radiated heat etc, which is what U values are supposed to cover. Thats why many guides talk about taping joints - a nice draghty gap undoes all the point of having the insulation.
Also that doesnt allow for moisture etc - as I understand it the hemp suffers when wet - the thermafleece less so. Also the flexible stff may be much,much easier to install in some cases.

Also environmental cost of prodction etc.

(sorry I mst sort ot the keyboard on this laptop one of these days)

 

[Nemesis]

Ah - more missing u values...

Well, thank you for that.

I think I might just add another vest for the winter.