corrugated iron roof on a cottage - U values?

[downshifter]

Hi
As part of the renovation project on our cottage we are wanting to re-cover the roof with corrugated /iron/tin (I know its technically steel). It is a pitched roof with ist floor accomodation directly under the slope.We are unsure about how the U values will work with this material and what the best approach for insulation will be. Not wanting to get into a discusssion, at least on this thread about the pros and cons of wriggly tin as a traditional building material (we think it is) does anyone have nay experience or advice they can share on this. The planning officer has already said its ok. but the BCO may need convincing.
Thanks

 

[MdB]

You can completely ignore the steel in any U value calculations. Its contribution to thermal insulation will be close to nill. As it sounds like this will be a new roof, put a sensible amount of celotex underneath it.

 

[robgil]

i was just going to ask , what will be underneath it?

 

[Flyfisher]

Coincidentally, I was in Heydon, Cambridgeshire, recently and I noticed what looks like a fairly new barn conversion with a corrugated metal roof. It looked very much in keeping and, presumably, meets the required regulations.

As for the U-value, I would guess such a material to have essentially zero insulation factor, much like other roofing materials such as slate or pantiles, and would expect the overall roof construction to provide the real insulation required to satisfy BC. So I'd be surprised if the outer covering material is really that significant in the overall thermal construction.

That's purely an amateur view though. An architect should be able to provide a more definitive answer and provide a design that would satisfy BC.

(beaten to the 'submit' button by MdB!)

 

[Feltwell]

I can't see why the BCO would have a problem regarding U values. A "conventional" roof covering doesn't get taken into account when doing the U value calcs - or at least it didn't in my case. If the ceilings are attached directly to the bottom of the rafters, I would insulate between & above the rafters with Kingspan / Celotex or similar - or you can go below rafters and underclad but then you reduce your ceiling height.

Where you may find an issue is I imagine the BCO will not come across many uses of "wriggly tin". "Normal" roof coverings are well documented and researched - so, for example I know that the BCO will accept every 5th row of my plain tiles being nailed down - but (without wishing to insult) as corrugated iron seems to be most often used as the cheapest possible repair for a bad roof on an agricultural building and I would imagine rarely gets viewed by a BCO, what guidance exists in terms of fixing methods etc and perhaps more importantly how much knowledge your BCO have of these will be a factor.

I personally would also use a membrane under the tin - the BCO may insist on this anyway - such as:-

http://www.proctorgroup.com/index.asp?lm=268

I think the first thing to do would be to call the BCO for a chat. My one is very approachable.

Beaten to submit button by Robgil, MdB and Flyfisher!!

 

[downshifter]

Thanks for all the swift responses. Its pretty much as we thought- put everything into the roof structure and insulation and the top covering is neither here nor there.
BTW nice picture of the rolling machine.
cheers

 

[JoceAndChris]

I'm very interested in this thread as I must insulate the chicken's house, rather than use a radiator, this winter. Last winter the radiator's heat was just escaping through the gaps between the wiggly tin and the rafters - such a waste.

By the way, FWIW I think wiggly tin is nice not just on agricultural buildings!

 

[Flyfisher]

A radiator for the chickens? :shock: It'll be a new television for them next. :wink:

Seriously though, I've read that they don't need any heating in the winter, although they don't like drafts. Ours seemed quite happy last winter and their coop seemed quite cosy when opened up in the morning, so they must give off a fair bit of heat. I'd be wary of over-insulating them and waking up to cooked chicken for breakfast.

 

[JoceAndChris]

But your chickens are in a naturally sheltered spot. Last winter there was thick ice and snow everywhere for nearly a month, and someone I know locally said he'd go out to feed his birds and find them frozen solid to the floor.

The lemon millefleur sabelpoots (getting another 8, of show quality, soon) are coming indoors, no question. But I have to find a cheaper way of making sure the blue Orpingtons, and babies, and turquoise egg laying Legbars don't get frostbitten wattles, or have their drinkers frozen solid.

 

[Penners]

I'd be wary of over-insulating them and waking up to cooked chicken for breakfast.

Yum!

 

[Flyfisher]

Sheltered from the wind, yes, but not from the outside temperature. That's why it's important to ensure their coop is draft-free. It's also important for them to be able to roost off the ground. We just have a couple of poles about a foot off the ground, which they happily hop up to at dusk.

Still with a name like lemon millefleur sabelpoots I suppose they expect a bit of molly-coddling. :wink:

 

[robgil]

bet they dont have boiled eggs for breakfast though.

 

[JoceAndChris]

Actually they often do! They love eggs - and chicken. Do you know it's quite normal for a healthy flock of hens, if presented with new hens, to kill and eat the new hens - every last bit. They can be very predatory, they'll hunt and kill a mouse for example. Georgiana trampled one of the chicks I gave Sukey, it died straight away, she'd have eaten it if I hadn't intervened.

Anyway, yes they do need to be draught free, and they aren't at all, so thanks for the recommendations of insulation.

 

[Penners]

Your wuvverly fwuffy chick-chicks are starting to sound like cannibalistic monsters. :shock:

 

[christianb]

u-values are one thing. Insulating against the horrific clattering sound of heavy rain is another. I had the square-section type of stuff on an outbuilding (which I've since slated) and couldn't hear myself think if it even thought about drizzling.

 

[Feltwell]

u-values are one thing. Insulating against the horrific clattering sound of heavy rain is another.

That would be my concern as well - the insulation will help deaden it a bit, but I still reckon it will be damn noisy every time it rains.

 

[TimM]

Surely the sound of rain is the best bit?

 

[Feltwell]

Ohh I love the sound of the rain - I'm the biggest hippy you'll ever find when it comes to rain and storms, I like nothing better than standing watching a good storm, I'm quite happy to get wet! Mrs F thinks I'm completely mad, but nothing new there.

The sound of rain on a tin roof can be very noisy, even I wouldn't want to be woken up by every nightime shower. But then I do live near Wales! :wink:

 

[Feltwell]

I'm very interested in this thread as I must insulate the chicken's house, rather than use a radiator, this winter. Last winter the radiator's heat was just escaping through the gaps between the wiggly tin and the rafters - such a waste.

Joce, do you mean the gap against the eaves? If so then you can get pre-cut "wriggly foam" to fill the gap - or eaves fillers to give them their proper name. Sold for use wth corrugated bitumen roofing, so might not be exactly the same profile, but worth a try.

http://www.roofingsuperstore.co.uk/...n-roof-eaves-fillers-pack-of-6-pack-of-4.html

For toasty chickens why not line your shed, including the roof, with some Kingspan? Seconds and Co often have offers on, the thinner sheets aren't very expensive. 25mm of Kingspan would make a huge difference to how warm the shed would be, it's very easy stuff to cut & fix. 20 to 25mm boards at £6.50 each at the moment for an 8' x 4' sheet.

http://www.secureviewer.co/cgi-bin/main/viewitem.php?groupid=7&productid=18

(I've no connection, other suppliers are available, blah blah blah)

 

[JoceAndChris]

Thanks Feltwell that's perfect! That would make such a difference. And yes I did mean the eaves.

Wonder if you can wallpaper directly onto that stuff?