Large workshop, very cold, mulling over what might work

[S2D2]

14 minutes ago, Roger440 said:

Realistically, I need to close it up. As per my earlier drivel, ideally I'd like it at 10 degrees during winter and need humidity to be sub 65%. If I leave it open, I'm not going to achieve either. I can heat myself as you suggest, but everything will still go rusty.

 

While there will be cars, this is not a professional workshop/business, just a hobby shed. A big one. I'm installing a 3 ft diameter extract fan, so if I need to, I can change the air really quickly.

 

Over roofing isn't going to happen. I have a tame commercial building roofer/builder. He reckons it's north of £20k to over roof. The building is 3000sqft, but the roof is 4000ft as there is a 1000ft covered yard at the front. Whilst it clearly doesn't need insulating, it would look properly shit if it was two different roofs and hieghts! 

 

So, hopefully you can see, insulating from the inside on a DIY basis is realistically my only option.

 

Question is how????

 

I can't just bang rockwool up there as fibres will forever be dropping down. The yanks seem to fix the issue with a plastic sheet  covered system, but it just doesn't exist in the uk. Hence trying to semi replicate with bagged rockwool 

 

Good to get clarification that insulating the building is the way forward, sorry if I missed that in an earlier post. I don't think I'm being clear about leaving the eaves ventilation open, I'm talking about something like the left hand side of this picture:

So the room is closed to the eaves but the roof is not. How you would achieve that with the kind of spans involved in that roof I have no idea but removing all ventilation from roof level will inevitably lead to condensation on the roof as it has nowhere else to go. Breathable roofing felt would be a suggestion to stop fibres dropping, but again how you make that practical is an open question. Might be worth getting a quote for spray foam and a quote to install a flat ceiling with new steels that you could pile rockwool on top of but again the scale is your enemy for keeping prices down. You're probably looking at north of £2k in rockwool just for 200mm then fixtures, felt etc. on top.

 

Hey, at least the walls are easy!

[Roger440]

5 minutes ago, S2D2 said:

 

Good to get clarification that insulating the building is the way forward, sorry if I missed that in an earlier post. I don't think I'm being clear about leaving the eaves ventilation open, I'm talking about something like the left hand side of this picture:

So the room is closed to the eaves but the roof is not. How you would achieve that with the kind of spans involved in that roof I have no idea but removing all ventilation from roof level will inevitably lead to condensation on the roof as it has nowhere else to go. Breathable roofing felt would be a suggestion to stop fibres dropping, but again how you make that practical is an open question. Might be worth getting a quote for spray foam and a quote to install a flat ceiling with new steels that you could pile rockwool on top of but again the scale is your enemy for keeping prices down. You're probably looking at north of £2k in rockwool just for 200mm then fixtures, felt etc. on top.

 

Hey, at least the walls are easy!

 

I'm unclear why we need any airflow?

 

On my last garage, I used composite steel cladding on walls and roof. 100% airtight. Zero condensation. 

 

Condensation only happens when warm air meets cold roof. If we insulate the roof itself, then problem fixed. Otherwise known as a warm roof I believe. In housing terms. Even if this is an industrial building.

 

2k of rockwool is fine. But how to keep it up there, and prevent falling fibres 

 

Spray foam is 10-15k. Not really diy-able, and even if I did, the bulk of the cost is the foam . I guess this is my fall back option and I'll just have to pay. But a rockwool based solution will be much cheaper as the material is cheap, but labour intensive to fit. But my labour is free. 

[SteamyTea]

10 minutes ago, Roger440 said:

Condensation only happens when warm air meets cold roof.

Well almost, it is when it meets something below the dewpoint temperature, or the pressure changes.

That is how clouds/mist/fog form, and they are pretty damp, and no roof involved.

12 minutes ago, Roger440 said:

2k of rockwool is fine. But how to keep it up there, and prevent falling fibres 

You can bag it into breathable bags, something like weed control membrane is cheaper than proper wall wrapping material like Tyvek.

https://www.screwfix.com/p/apollo-heavy-duty-weed-control-fabric-14-x-1m/93943

[Ferdinand]

What are the dimensions of the roof?

 

Is it a simple oblong building?

[S2D2]

1 hour ago, Roger440 said:

 

I'm unclear why we need any airflow?

 

On my last garage, I used composite steel cladding on walls and roof. 100% airtight. Zero condensation. 

 

Condensation only happens when warm air meets cold roof. If we insulate the roof itself, then problem fixed. Otherwise known as a warm roof I believe. In housing terms. Even if this is an industrial building.

 

2k of rockwool is fine. But how to keep it up there, and prevent falling fibres 

 

Spray foam is 10-15k. Not really diy-able, and even if I did, the bulk of the cost is the foam . I guess this is my fall back option and I'll just have to pay. But a rockwool based solution will be much cheaper as the material is cheap, but labour intensive to fit. But my labour is free. 

If you can provide a 100% airtight seal to stop any internal air meeting the underside of the tin then yes, you will not require ventilation. This is likely to be very time consuming and expensive to achieve, airflow is usually a much easier win to counter condensation, but it's entirely your decision. I am biased because I've had severe condensation issues in the past (resolved by ventilation) as outside humidity is usually >80% around here. 

[Ferdinand]

Might a dehumidifier be a suitable solution to any humidity problems - personally I would ventilate the roof / seal the insulation as well as practicable (rockwool is good for that), and then see.

 

I've been putting my thinking cap on on this project, and will do a separate post.

 

F

[TonyT]

What about a false ceiling, with insulation above?

 

reduce the room volume and insulate at the same time.

[Nickfromwales]

Spray foam insulation has to be the clear winner here?

A thin layer of closed cell to detail all the gaps and seal from moisture travel, there a good 100-150mm of open cell atop that.

The fabric improvements will be completely and utterly decimated by ventilation losses here though, so unless you go to forced heated air input, as well as the  foam and beads, plus plugging every gap you find ( very well ) this will just be a losing battle imho.

You’ll need the heated air input to keep an acceptable ACH for air quality / managing internal humidity etc, even if that’s then very small.

+1 to not having any airflow, as that’s the cause of the condensation, just go tight to the corrugated panels with the closed cell foam, and lose the gaps 100%.

This is a big, “thermally unfriendly” building in which to achieve what you’re looking for, so either all in or don’t bother starting afaic  Pointless putting good money and effort in to not move forwards, or make it worse.

The space blanket is a waste of space…….blanket.

 

Looking at the height of the roller shutter, even a mezzanine with storage may be an option, doubling the floor space for storage, dependant on whether, as a petrol-head, you’ll be installing a lift or 2 of course? 

 

You may be able to DIY the foam, but I’d just bite the bullet and get it separated by a company set up to do this quickly and efficiently. DIY kits will probably work out expensive over this volume.

[Roger440]

10 hours ago, Ferdinand said:

What are the dimensions of the roof?

 

Is it a simple oblong building?

 

22.5 x 12 x approx 5.5m high. So yes, just a simple box.

[Roger440]

9 hours ago, S2D2 said:

If you can provide a 100% airtight seal to stop any internal air meeting the underside of the tin then yes, you will not require ventilation. This is likely to be very time consuming and expensive to achieve, airflow is usually a much easier win to counter condensation, but it's entirely your decision. I am biased because I've had severe condensation issues in the past (resolved by ventilation) as outside humidity is usually >80% around here. 

 

It is an easy way to counter condensation, but in doing so humidity will be whatever it is outside. That's not conducive to the stuff inside sadly. Or retaining any heat.

[Roger440]

9 hours ago, Ferdinand said:

Might a dehumidifier be a suitable solution to any humidity problems - personally I would ventilate the roof / seal the insulation as well as practicable (rockwool is good for that), and then see.

 

I've been putting my thinking cap on on this project, and will do a separate post.

 

F

 

I currently rent a workshop that's very similar. Same roof. But smaller. With a lower roof. As it's not mine, spending big on insulation wasn't happening, thought I did seal it up, so I installed two dehumidifiers that ran 24/7. Fixed the humidity issue. However, rent covers unlimited electricity! Power consumption was a continuous 5.6kw.

 

By volume this building is at least 50% larger.

 

Look forward to your thought.

[SteamyTea]

PU spray it.

 

https://www.alibaba.com/product-detail/Two-Component-Pu-Epoxy-Insulation-Injection_60493130972.html

[Roger440]

1 hour ago, Nickfromwales said:

Spray foam insulation has to be the clear winner here?

A thin layer of closed cell to detail all the gaps and seal from moisture travel, there a good 100-150mm of open cell atop that.

The fabric improvements will be completely and utterly decimated by ventilation losses here though, so unless you go to forced heated air input, as well as the  foam and beads, plus plugging every gap you find ( very well ) this will just be a losing battle imho.

You’ll need the heated air input to keep an acceptable ACH for air quality / managing internal humidity etc, even if that’s then very small.

+1 to not having any airflow, as that’s the cause of the condensation, just go tight to the corrugated panels with the closed cell foam, and lose the gaps 100%.

This is a big, “thermally unfriendly” building in which to achieve what you’re looking for, so either all in or don’t bother starting afaic  Pointless putting good money and effort in to not move forwards, or make it worse.

The space blanket is a waste of space…….blanket.

 

Looking at the height of the roller shutter, even a mezzanine with storage may be an option, doubling the floor space for storage, dependant on whether, as a petrol-head, you’ll be installing a lift or 2 of course? 

 

You may be able to DIY the foam, but I’d just bite the bullet and get it separated by a company set up to do this quickly and efficiently. DIY kits will probably work out expensive over this volume.

 

I think you are probably right on the spray foam front. Just clutching at cheaper straws!

 

Of course, the best starting point is a brand new modern composite panel building. 

 

Sadly, however, getting planning for such in a domestic setting is nigh on impossible. The only practical solution is to buy something that's already there, and even that's not easy on a strictly limited budget. So here we are. With a pretty reasonable building, but needs some improvements.

 

Yes, there will be a lift or two, plus a limited mezzanine area with enclosed workshop below 

[Onoff]

Is a building(s) within a building an option? Say you have a 2/4 post lift and most of your work uses that. Build a tall, insulated garage. 

 

Then maybe a small, seperate welding booth.

 

Poly tunnel for spraying.

 

Storage of cars etc just goes in the cold, main envelope. In Carcoons if needed.

 

Perhaps a garden shed as the tea room etc.

 

The main building shell then just acts as a first line of defence.

[Ferdinand]

OK, breakfast having gone down and teeth polished, it is time to earn the full value of the money I am not being paid 🙂. This is a bit of a brain dump, so pull things out. Let me first be sure I understand the problem.

 

The core problem here is 1 how inexpensively to insulate a 300-350 sqm roof on an ~4-4.5m sloping up to 5.5m 'tin' roof, with a subsidiary of 2 how the duck to attach insulation to steel joists, and 3 how to be sure of an ability to manage humidity. All for not very many £££.

 

I think one thing not mentioned that needs a passing thought is potential fire hazard. Another is whether particular activities need particular temperatures or RHs (eg does doing X to a car require the temperature to be Y for the process to work? - you know about that), and do T and RH therefore need to be controllable? Also it is not clear where you are on aesthetics - can it be ugly?

 

I think that Rockwool is the correct material if possible, or something similar but less prone to releasing fibres. I had not met the space blanket water bubble issue, though it does obvs prevent fibre shedding, but I have never used space blanket. I also note that unwrapped rockwool is ~1/2 (?) the cost of space blanket.

 

Now - analogies. In the past the cheapest insulated roof I did was for a conservatory (with 7" deep wooden joists) repurposed as a lounge, where I put a tin roof on top of the joists (over the existing polycarb), and staple-gunned 100mm rockwool just above the bottom level of the joists to leave a ventilated 25-50mm gap, with routes for air circulation in and out. Then wiring was done along the joists, and it was clad with white shiplap (at about £5 per sqm). I would not use plastic shiplap now, as I am unhappy about gases it would potentially put out in a fire situation, but risk is managed. Nearly ten years later it is still solid.

 

The other thing that strikes me as similar is putting insulation under a suspended floor. Again my standard inexpensive was is as much rockwool as possible stapled in place, which comes in at about £1 - £1.50 per sqm per 100mm of thickness.

 

The other one I have been involved in has been renovation of a 6000 sqft mid-height  (20m by 30m ish, prob. 5.5m high walls and a 8-9m ridge height) former warehouse into a gym. We did not try and insulate; we did repaint.

 

Possibilities

 

A How to support rockwool on the pitch?

 

The one that jumps to mind is something like sheep netting (metal or plastic) or even wire mesh. Very inexpensive.

 

Though roofing laths every 1m or so may be more practical.

 

But that leaves...

 

B How to attach to steel . 

Are those modest depth I-beams * or simple rectangular cross-section? If I-beams, can you just wedge roofing laths or something a bit stronger across each ~2m inter-rafter gap, and secure with spray foam?

 

If rectangular section, can you just attach laths using spray foam to keep the rockwool up there? Will it support it? Perhaps a test? Is such a light structure an issue if bits fall down (I'm guessing potentially yes 🙂) ?

 

Or is there a kind of punch nailer that will go into the steels, or bolt through every 2m or so across those 2 to 2.2m inter-joist gaps, or attach clamps and attach roofing laths across? Those feel more tricky except the last, but structural metal-work is not my thing.

 

C How to be sure of an ability to manage humidity
 

I'm with those who say ventilate above the insulation, and making sure there are inlets / outlets at top and bottom, or both ends. I'd say do it by putting rockwool depth in 75-100mm shallower than the depth of your beams, aligned to the bottom, and seal within reason around the edges.

 

With dehumidification as an available Plan B when required.

 

I wonder, is there something to be said for a workshop version of a lowish volume PIV fan as a humidity control, as these are heroically cheap to run. Triggered by humidistat?

 

D Make it a cold loft. @Onoff touched on this. What about a mezzanine or similar structure, or putting sub-buildings inside it? 

 

My wild thought is that could you use a mezzanine partial mezzanine of 3m scaffolding? It's structural, gives you the chance to subdivide cells when you need it, on 2.5m or 3m cells or with larger bridged cells probably suitable for cars, and you can just roll out the insulation on top. I make it about 6 x 10 max cells, so is that doable? Plus you get a structure to subdivide if needed. With scaff you get to take it down and sell it in 20 years, plus the rockwool, and the building is unchanged. Needs a detailed think check, and probably a bankrupt sale.

 

It feels like quite a big chunk to spend, perhaps. But can you build your scaff framework, roll out fencing mesh on top (attached with zip ties), then roll out rockwool on top of that? Needs thought about access - perhaps a run of scaff planks along an edge of each cell?

 

E Make it beautiful

 

I think this should be criteria 27 on the list, and that criteria 1 through 26 should be cost and practicality, but in at least one comment above you imply it matters at least slightly.

 

I think that in that case you are looking more at a modest renovation, and may need to be looking at things like internal cladding beneath your insulation. On that I cannot do better than the plastic shiplap I mentioned, unless you put box section tin on the inside.

That's my random thoughts - I hope there is a spark there somewhere.

 

F

 

(Update: I realised that I have missed the suggestion of using glue to secure the insulation supports to the roof joists, which is really in the same type of idea as supporting it using spray foam.

 

Are there suitable glues around? Which may be expensive - when we glued down 4500 sqft of rubber matting to our gym floor we used £900 worth of the strongest glue from B&Q. But 4 years later the matting is still firmly attached, and the only thing that pulled it up was when the ^&*(())_ landlord insisted on bringing a mini digger or a forklift or something in to do maintenance.

 

But if it does the job satisfactorily, it would be worth it.)

[S2D2]

11 hours ago, Roger440 said:

 

It is an easy way to counter condensation, but in doing so humidity will be whatever it is outside. That's not conducive to the stuff inside sadly. Or retaining any heat.

No, the ventilation is underneath the tin roof, above the insulation and so the heated envelope below is practically unaffected by it, other than a small increase in heat loss from the upper surface of the insulation. The diagram I linked should hopefully demonstrate this. You then condition the air inside the heated envelope as appropriate as it no longer flows freely to outside, the relative humidity of which will be reduced as you have heated it.

[Onoff]

16 hours ago, S2D2 said:

No, the ventilation is underneath the tin roof, above the insulation and so the heated envelope below is practically unaffected by it, other than a small increase in heat loss from the upper surface of the insulation. The diagram I linked should hopefully demonstrate this. You then condition the air inside the heated envelope as appropriate as it no longer flows freely to outside, the relative humidity of which will be reduced as you have heated it.

 

@zoothorn should read this comment.

[SteamyTea]

39 minutes ago, Onoff said:

 

@zoothorn should read this comment.

You wicked man.

 

[Roger440]

On 13/10/2022 at 20:48, S2D2 said:

No, the ventilation is underneath the tin roof, above the insulation and so the heated envelope below is practically unaffected by it, other than a small increase in heat loss from the upper surface of the insulation. The diagram I linked should hopefully demonstrate this. You then condition the air inside the heated envelope as appropriate as it no longer flows freely to outside, the relative humidity of which will be reduced as you have heated it.

 

I understand what you are saying.

 

However, what i dont understand is what the nenefit is to constructing an additional internal ceiling/roof structure to carry the insulation and then leave a void above it.

 

If there was a structure, sure. But there isnt. Well there is, it the existing roof. So leaving aside the exact process, why would i not just insulate that? And the whole building is then the heated envelope. What do i gain from your suggestion?

[Roger440]

On 13/10/2022 at 09:40, Onoff said:

Is a building(s) within a building an option? Say you have a 2/4 post lift and most of your work uses that. Build a tall, insulated garage. 

 

Then maybe a small, seperate welding booth.

 

Poly tunnel for spraying.

 

Storage of cars etc just goes in the cold, main envelope. In Carcoons if needed.

 

Perhaps a garden shed as the tea room etc.

 

The main building shell then just acts as a first line of defence.

 

Im sort of partially doing that, or plan too. At the back, under the exsisting mez thats got rooms on it, i will close off as a workshop to do stuff like engine builing etc. Easy to heat, warm and dry. I also intend to have another similar area for one car that will be for welding, spraying and other properly messy jobs. 

 

But i keen for the remaining area not to be come too divided up. That restricts what you can use the space for as each "seperation" becomes a room dedicated to a particular task, which takes that space out of use for any other use.

 

There will be 2 ramps so, along with enough room to work and sufficent height, its starting to get quite big. Plus wall create issues with approach angles etc. 

 

But your theory is sound.

 

If i build that many "rooms" the cost will likely be quite high at which point i might just as well insulate the roof and walls anyway.

 

[Onoff]

5 minutes ago, Roger440 said:

If i build that many "rooms" the cost will likely be quite high at which point i might just as well insulate the roof and walls anyway.

 

Look for a free garden shed, that's your tea room / changing area. Or build one from pallets.

[S2D2]

50 minutes ago, Roger440 said:

 

I understand what you are saying.

 

However, what i dont understand is what the nenefit is to constructing an additional internal ceiling/roof structure to carry the insulation and then leave a void above it.

 

If there was a structure, sure. But there isnt. Well there is, it the existing roof. So leaving aside the exact process, why would i not just insulate that? And the whole building is then the heated envelope. What do i gain from your suggestion?

Rockwool is breathable, so (relatively) warm humid air will rise through it (slowly). If your tin roof is below the dew point of that air you will get condensation on the underside of the tin. You are already seeing this overnight on your pictures. The ventilation air current mixes with the warmer moist air to carry the moisture to outside, keeping the tin and insulation dry. This is what you gain.

 

Spray foam solves the problem because it is not breathable, so the warm air does not meet a surface below it's dew point.

 

A dehumidifier solves the problem by decreasing the dew point, again preventing the air from meeting a surface below it's dew point.

[Roger440]

On 13/10/2022 at 12:21, Ferdinand said:

OK, breakfast having gone down and teeth polished, it is time to earn the full value of the money I am not being paid 🙂. This is a bit of a brain dump, so pull things out. Let me first be sure I understand the problem.

 

The core problem here is 1 how inexpensively to insulate a 300-350 sqm roof on an ~4-4.5m sloping up to 5.5m 'tin' roof, with a subsidiary of 2 how the duck to attach insulation to steel joists, and 3 how to be sure of an ability to manage humidity. All for not very many £££.

 

I think one thing not mentioned that needs a passing thought is potential fire hazard. Another is whether particular activities need particular temperatures or RHs (eg does doing X to a car require the temperature to be Y for the process to work? - you know about that), and do T and RH therefore need to be controllable? Also it is not clear where you are on aesthetics - can it be ugly?

 

I think that Rockwool is the correct material if possible, or something similar but less prone to releasing fibres. I had not met the space blanket water bubble issue, though it does obvs prevent fibre shedding, but I have never used space blanket. I also note that unwrapped rockwool is ~1/2 (?) the cost of space blanket.

 

Now - analogies. In the past the cheapest insulated roof I did was for a conservatory (with 7" deep wooden joists) repurposed as a lounge, where I put a tin roof on top of the joists (over the existing polycarb), and staple-gunned 100mm rockwool just above the bottom level of the joists to leave a ventilated 25-50mm gap, with routes for air circulation in and out. Then wiring was done along the joists, and it was clad with white shiplap (at about £5 per sqm). I would not use plastic shiplap now, as I am unhappy about gases it would potentially put out in a fire situation, but risk is managed. Nearly ten years later it is still solid.

 

The other thing that strikes me as similar is putting insulation under a suspended floor. Again my standard inexpensive was is as much rockwool as possible stapled in place, which comes in at about £1 - £1.50 per sqm per 100mm of thickness.

 

The other one I have been involved in has been renovation of a 6000 sqft mid-height  (20m by 30m ish, prob. 5.5m high walls and a 8-9m ridge height) former warehouse into a gym. We did not try and insulate; we did repaint.

 

Possibilities

 

A How to support rockwool on the pitch?

 

The one that jumps to mind is something like sheep netting (metal or plastic) or even wire mesh. Very inexpensive.

 

Though roofing laths every 1m or so may be more practical.

 

But that leaves...

 

B How to attach to steel . 

Are those modest depth I-beams * or simple rectangular cross-section? If I-beams, can you just wedge roofing laths or something a bit stronger across each ~2m inter-rafter gap, and secure with spray foam?

 

If rectangular section, can you just attach laths using spray foam to keep the rockwool up there? Will it support it? Perhaps a test? Is such a light structure an issue if bits fall down (I'm guessing potentially yes 🙂) ?

 

Or is there a kind of punch nailer that will go into the steels, or bolt through every 2m or so across those 2 to 2.2m inter-joist gaps, or attach clamps and attach roofing laths across? Those feel more tricky except the last, but structural metal-work is not my thing.

 

C How to be sure of an ability to manage humidity
 

I'm with those who say ventilate above the insulation, and making sure there are inlets / outlets at top and bottom, or both ends. I'd say do it by putting rockwool depth in 75-100mm shallower than the depth of your beams, aligned to the bottom, and seal within reason around the edges.

 

With dehumidification as an available Plan B when required.

 

I wonder, is there something to be said for a workshop version of a lowish volume PIV fan as a humidity control, as these are heroically cheap to run. Triggered by humidistat?

 

D Make it a cold loft. @Onoff touched on this. What about a mezzanine or similar structure, or putting sub-buildings inside it? 

 

My wild thought is that could you use a mezzanine partial mezzanine of 3m scaffolding? It's structural, gives you the chance to subdivide cells when you need it, on 2.5m or 3m cells or with larger bridged cells probably suitable for cars, and you can just roll out the insulation on top. I make it about 6 x 10 max cells, so is that doable? Plus you get a structure to subdivide if needed. With scaff you get to take it down and sell it in 20 years, plus the rockwool, and the building is unchanged. Needs a detailed think check, and probably a bankrupt sale.

 

It feels like quite a big chunk to spend, perhaps. But can you build your scaff framework, roll out fencing mesh on top (attached with zip ties), then roll out rockwool on top of that? Needs thought about access - perhaps a run of scaff planks along an edge of each cell?

 

E Make it beautiful

 

I think this should be criteria 27 on the list, and that criteria 1 through 26 should be cost and practicality, but in at least one comment above you imply it matters at least slightly.

 

I think that in that case you are looking more at a modest renovation, and may need to be looking at things like internal cladding beneath your insulation. On that I cannot do better than the plastic shiplap I mentioned, unless you put box section tin on the inside.

That's my random thoughts - I hope there is a spark there somewhere.

 

F

 

(Update: I realised that I have missed the suggestion of using glue to secure the insulation supports to the roof joists, which is really in the same type of idea as supporting it using spray foam.

 

Are there suitable glues around? Which may be expensive - when we glued down 4500 sqft of rubber matting to our gym floor we used £900 worth of the strongest glue from B&Q. But 4 years later the matting is still firmly attached, and the only thing that pulled it up was when the ^&*(())_ landlord insisted on bringing a mini digger or a forklift or something in to do maintenance.

 

But if it does the job satisfactorily, it would be worth it.)

 

Thanks for the detailed reply. Much to consider

 

You have correctly identified the core issues.

 

Just to clarify a few points

 

The humidity issue is soley about stopping corrosion. Sub 65% it cant happen. So that is the target. The temp is about being resonably comfortable whilst working there. Its a hobby. I have no desire to be freezing cold whilst engaging in hobby. I'll just sit on the sofa instead!

 

Ref ugly, if its confined to the celing, inside, then i can liuve with it if i have to. Spray foam is truly ugly.

 

I agree, rockwall is the cheapest option. As for holding it up, im not sure. Im yet to get up there to take a proper look, but the galvanised bits look to be pressed steel section, so could be nailed through if need be. However, i still need a covering to prevent fibres falling. This was where i referred to the yanks as per pic. Simply not available here.

 

Good thinking on the PIV. Not thought about that.

 

With regard to "rooms" inside, i replied to onoff on this. Im keen to avoid an excess of this. But clearly its a solution.

 

Yor last bit, E, you mention cladding with tin. his is aneat solution in as much that it would be much easier to retain the insulation, potentially negating all the previous suggestions. But its not an easy task managing big sheets of to upside down. Need to ponder a safe method for that. 

 

Thanks again for your input.

[Roger440]

Following my above musings on using tin to retain rockwool, i then returned to thinking about PIR (or similar).

 

Following Ferdinands suggestion of spay foam to secure, i could stick this to the roof, then add wires between the joists to ensure it definitely cant fall down. 

 

This would then only contact the lowesrt part of each corrugation leaving the rest open for ventilation above the insulation.

 

More expensive than rockwool, much less than spray foam, but a fair bit of work.

 

Hmmmm......................

Edited October 16, 2022 by Roger440

[Nickfromwales]

On 13/10/2022 at 07:39, Nickfromwales said:

The fabric improvements will be completely and utterly decimated by ventilation losses here though, so unless you go to forced heated air input, as well as the  foam and beads, plus plugging every gap you find ( very well ) this will just be a losing battle imho.

PIV  

 

Use the ugly spray foam and just look at the metal beasties vs looking up!?! 🙄