Roof build up insulation ideas.

[Russell griffiths]

evening. The other day I posted this up and had some good responses, ( thank you everyone) however most of the answers where regarding the actual fitment of the metal roofing and whether I should fit a counter batten and air gap or not. 

 

What i would be interested in is people’s opinions on the insulation side of things, is it enough?

would you go for method A B C. 

 

 

a couple of things please don’t suggest cutting lots of kingspan to fit snugly between those I joists as I may climb through the computer screen and strangle you. 

 

any thoughts mr @JSHarris

Apart from that I am open to any suggestions. Cheers russ. 

Edited August 6, 2018 by Russell griffiths
Change of heading.

[ProDave]

Shouldn't there be battens on which to fix the standing seam roof, and to create an air flow under the SS roof?

 

For insulation type, I would recommend Knauf Earthwool Frametherm 35. It's less nasty to handle than most glass fibre type insulation, and stiff enough to stay put when pushed up between the rafters so it stays there while you board over the underside.

 

I used Protect Barriair as my air tightness / vapour layer.

[Russell griffiths]

The specifications for the sheet roofing is that it must be fitted to a flat solid surface, minimum 18mm thick for fixing purchases, no battens as you would distort the sheets 

being completly flat with just the standing seam used as a joint, without a full flat fixing surface I think you would notice every ripple and wobble as it dipped and humped over the battens. 

[Mr Punter]

I have used a membrane underneath zinc that has a plastic layer on top a bit like Scotchbrite so if there is condensation under the zinc it won't sit in a puddle.

[Russell griffiths]

19 minutes ago, Mr Punter said:

I have used a membrane underneath zinc that has a plastic layer on top a bit like Scotchbrite so if there is condensation under the zinc it won't sit in a puddle.

 

I have seen this type of membrane, 

did you like it ?

did it seem to do what it said it would. 

@Mr Punter

[Mr Punter]

The membrane was supplied and installed by the zinc contractor.  It seemed strong and the curly plastic strand layer supported the zinc about 8mm above the membrane. I am not sure what happens if the zinc is left in water but I assume not good. I can't recall the name of the membrane.

[Alexphd1]

What type of metal are you using. We have a 50mm air gap below ours. Will draw a sketch later.

[Russell griffiths]

2 hours ago, Alexphd1 said:

What type of metal are you using. We have a 50mm air gap below ours. Will draw a sketch later.

 

Sketch please

 

we have looked at the tata(catnic) steel standing seam

but are also looking at importing a product from either the states or Australia. 

[Alexphd1]

Will get a sketch tomorrow but basically double sarked the roof with a 50mm batten in between to create a air gap with a vent in soffit and ridge. We have struggled to get exact information as when people know we are DIY'n the roof they become less generous with info.

Different metals need different breathing requirements even some zinc needs the fancy membrane or air cavity and some other zinc with special treatment needs only standard roof membrane. 

We have chosen stainless steel with being on the coast and needs less breathing requirement but have done a extra air gap as extra protection.  

Edited August 4, 2018 by Alexphd1

[Russdl]

17 hours ago, Russell griffiths said:

we have looked at the tata(catnic) steel standing seam

but are also looking at importing a product from either the states or Australia. 

 

We are planning on using Tata, MBC say it should be laid on OSB and the OSB should be on battens for the air gap.

 

Can you give me a link to the Aussie/US stuff?

[Russell griffiths]

  @Russdl

have a look at stratco highland tray.   Australian company, we had all our roofing off them for a house we built in oz. 

lots of American companies doing standing seam no links at the mo just having a search around. 

[Alexphd1]

Are you planning on doing this yourself?

[Russell griffiths]

6 minutes ago, Alexphd1 said:

Are you planning on doing this yourself?

 

Yes 99% of the house will be done by me. @Alexphd1

when you say double sarked you mean Scottish terms so sarked as in solid boarding

 

if we need a solid board under the sheets for rigidity and fixing, could the lower board be replaced with just a membrane. 

 

Double 18 mm osb is a lot of weight and money. 

 

Your joist depth is not that high, what form of insulation did you use. 

[Alexphd1]

Yes double sarking is over kill, below board could be a membrane.Our orignally plan was all slate then changed to half slate half steel. I wasnt away to remove the sarking. 

 

You have got 2 routes for a DIY standing seam roof either to go to likes of tata and buy a pre formed complete kit which is pretty straight forward on a DIY effort but pretty expensive on £m2 cost for what it actually is but saves a lot with no labour  or buy a rolls of metal and form it on site (which is what your hiland tray is) which is pretty skilled job but also DIY if you are very good hands on type of preson. The machinery for this is pretty expensive new cheapest form is £8k and electric closer is £3k. We are renting the form and bought a second hand electric closer on german ebay but this can also be rented. Plus you will need a few specialised hand tools approx another £1k. We have a local metal fabricator with a 4m electric folder which has been a major help for fascia boards, valleys etc.

 

Tata offered a free day course on the standing seam which would be a good start, also there is a company who offers training on forming the metal yourself which is pretty expensive but is usually on a one to basis. If you go dow this route I would recommend doing the tata first, and treat is a intro.

 

this is a good link for material 

https://www.roofing-tools.com/home.htm

 

 

Edited August 5, 2018 by Alexphd1

[Jeremy Harris]

Pumped cellulose might be a good option.  Relatively high decrement delay, tends to fill every nook and cranny well, the only downside is needing the machine to pump it in.

[Russell griffiths]

9 hours ago, JSHarris said:

Pumped cellulose might be a good option.  Relatively high decrement delay, tends to fill every nook and cranny well, the only downside is needing the machine to pump it in.

 

I had thought of this, has anybody done any cost comparison compared with a roll type insulation. 

[Jeremy Harris]

1 hour ago, Russell griffiths said:

 

I had thought of this, has anybody done any cost comparison compared with a roll type insulation. 

 

Depends on the volume, as much of the cost is the installation.  I believe that warmcell and the like as materials are comparable in cost with rock wool, but it's the installation that pushes the cost up.  Having said that, I believe that cellulose is far better for a roof, in particular, as the higher decrement delay over rock wool is a very definite advantage.  If we're going to have more weather like that we've been having recently, then I reckon a lot more people are going to focus on decrement delay than overall U value. 

 

Right now I'm exceptionally thankful we went for cellulose.  We were over working on some fencing yesterday and the house stayed below 21.5 deg C all day, with no cooling on at all, and the outside temperature peaking at around 30 deg C in the early afternoon.  That's almost entirely down to the long thermal time constant of the house, and a fair bit of that is down to the relatively long decrement delay of the cellulose insulation.

[ProDave]

On 04 August 2018 at 11:39, Russell griffiths said:

The specifications for the sheet roofing is that it must be fitted to a flat solid surface, minimum 18mm thick for fixing purchases, no battens as you would distort the sheets 

being completly flat with just the standing seam used as a joint, without a full flat fixing surface I think you would notice every ripple and wobble as it dipped and humped over the battens. 

If you are wanting to mainly DIY I question is standing seam is really what you want?

 

How about box profile steel instead, that can (mine does) span between battens, and is all 100% DIY if you want to.

[Russell griffiths]

9 hours ago, ProDave said:

If you are wanting to mainly DIY I question is standing seam is really what you want?

 

How about box profile steel instead, that can (mine does) span between battens, and is all 100% DIY if you want to.

 

I would love to use box profile, however at the moment I don’t think it would look right

the house (hopefully) will be very angular and sharp and I think the box profile just won’t look right. 

 

I will I’ll however buy a couple of sheets when we get to that stage and chuck them up and have a look. 

 

Price wise I hope I can use box profile. 

[bissoejosh]

1 minute ago, Russell griffiths said:

 

I would love to use box profile, however at the moment I don’t think it would look right

the house (hopefully) will be very angular and sharp and I think the box profile just won’t look right. 

 

 I will I’ll however buy a couple of sheets when we get to that stage and chuck them up and have a look. 

  

Price wise I hope I can use box profile. 

 

We were initially going for standing seam but have switched to either corrugated or box profile on grounds of cost. SS is much cheaper abroad I can't understand why it isn't available more readily in the UK!

 

One of the box profiles I've seen has fairly wide flat sections compared to most between the ridges and might look pretty similar to a standing seam? Most are spaced around 120-150mm and this one is 270mm so quite a lot more.