DIY Stable Renovation: Need Your Advice and Ideas!

ThisIsWeird

Section62 said:

The point is that even if the roof void is left draughty and uninsulated, condensation on the underside of the steel sheets will still be a problem. It is just the nature of a sheet steel roof - it needs something directly underneath it to deal with the problem.  Anti-condensation felt is one option, the other is to insulate it.  But the insulating layer(s) have to be in close contact with the steel - the important thing here is it is the steel which needs to be insulated, not the room/space below. The aim is to increase the thermal mass of the roof.
Not a good idea to use crawling boards on coated steel sheet (although from a safety POV better than walking on them if the installation was bodged without enough support for the sheeting).  The surface finish is prone to damage, and if it gets damaged it will be the start of rusting and/or debonding of the finish. Humping crawling boards around a roof is hassle vs doing the job properly in the first place.  On a fragile roof (e.g. asbestos-cement) crawling boards are necessary because excess point-load will fracture the sheet - the crawling board spreads the load.  But properly supported steel sheeting doesn't require their use.

If the steel is fitted direct to purlins (note: not noggins) without using a membrane then the inevitable condensation will drip onto the timber roof structure, and the 'ceiling', and that would be a potential cause of rot.

I wonder if cond forming on the underside of these sheets will be a problem here? Where would the moisture come from - the building below will be isolated and insulated from the roof void, which will be thoroughly ventilated.

Crawling or dragging boards over coated sheet metal is not ideal, granted, but this would have to be the case regardless of whether OSB was first fitted; you wouldn't be stepping or placing your knees on these sheets whilst reaching over to screw them down in any case - you'd need a board of some sort either way?

FreeBear

ThisIsWeird said: I wonder if cond forming on the underside of these sheets will be a problem here? Where would the moisture come from - the building below will be isolated and insulated from the roof void, which will be thoroughly ventilated.

Ever looked at a can of paint (or any other metal item) stored in a dry shed on a cold day ?

On certain cold days of the year, any cold metal surface in my garage & shed will have a thin film of condensation on it.

Section62

ThisIsWeird said:

I wonder if cond forming on the underside of these sheets will be a problem here?

I can't say with certainty... but I'd estimate the chance of condensation at about 99.99%, given typical UK conditions.

ThisIsWeird said:

Where would the moisture come from - the building below will be isolated and insulated from the roof void, which will be thoroughly ventilated.

For a start, there will be moisture in the air ventilating the roof void (if sujsuj goes with that option).  That's regardless of how isolated the room below is from the void.

If sujsuj is using thin plywood as the ceiling then in reality the void won't be isolated - to achieve that would require impermeable sheeting (e.g. vapourcheck plasterboard) with the joints all taped.  Using the space as a home gym would also mean there's likely to be more moisture in the air than if the space were being used for storage or as a garage - so the condensation risk is likely to be at the higher end of the scale.

ThisIsWeird said:

Crawling or dragging boards over coated sheet metal is not ideal, granted, but this would have to be the case regardless of whether OSB was first fitted; you wouldn't be stepping or placing your knees on these sheets whilst reaching over to screw them down in any case - you'd need a board of some sort either way?

*The following is NOT a recommendation*

As a DIY project the level of risk taken is largely a personal choice.  My personal choice based on a personal risk assessment is that I'd rather be on the top of the roof - being conscious of the slip/trip/fall risks at all times - rather than standing on a ladder leaning over trying to reach a fixing point which could be up to a metre away (on the assumption I've been able to position the ladder as close as possible for each fixing).  And fixing the ridge capping+filler simply can't be done from a ladder, whatever method you try.

As soon as a [properly supported] steel roofing sheet is fixed top and bottom I would personally assess the risk of walking on it to be lower than working at height from a ladder - but with the following provisos -

1) The sheet is completely dry and clean*

2) The pitch is not excessive

3) I'm wearing non-slip footwear

4) Trip hazards are minimised (which includes not having crawling boards laying about)

5) I've not been drinking before or during the work

6) Other stuff, such as what I might hit on the ground below if I did slip/fall

(*The 'clean' bit also means sweeping any drill swarf off the sheet before standing/kneeling on it - so it doesn't get pushed into the sheet coating)

The emphasis should be on 'properly supported' though.

Personally I would consider 18mm OSB3 sufficient to support my weight - although the roof structure might need beefing up for 18mm, I think it would be worth doing.  In terms of cost (using Wickes as a guide) 18mm OSB3 works out at £8.05/sqm vs £7.38/sqm for 11mm, and £6.60/sqm for 9mm.  Paying £1.45/sqm extra seems like good value to me if it means the roof is more solid.  Worrying about paying 67p/sqm extra isn't worth the time or effort for a smallish shed.

sujsuj

ThisIsWeird said:

sujsuj said:

Only just seen this pic. Ok, so the roof rafters are currently covered in sarking boards? I just can't see any reason to add OSB to that. But I'm happy to be corrected.

IF you are ultimately going to be adding a flat ceiling inside, then that's where you place your insulation. Not point at all in adding any to the pitched roof - it's likely to just cause trapped moisture and rot, certainly if you get it wrong.

The basic idea is, your outer roof covering is like an umbrella - it simply stops the rain getting through. Underneath this brolly/roof will be cold, windy, but dry.

So, the roof void should be rainproof but draughty = dry.

Then you insulate the inner shell, from the new ceiling downwards.

This is side wall photo, not roof. I took this pic to show the membrane it got now though disintegrated. 

sujsuj

ThisIsWeird said:

I don't think that light grey will suit it at all.

However, if that stable is in the corner of your plot - is that your boundary behind it? - then no reason at all not to use the stuff on the rear roof slope, and also the back and LH sides, where it won't normally be seen.

Make the front look spesh :-)

Yaa may be, since I have them I have no other option but to use them. Unless I find another way to those sheets. Thanks

sujsuj

Section62 said:

ThisIsWeird said:

sujsuj said:

Only just seen this pic. Ok, so the roof rafters are currently covered in sarking boards? I just can't see any reason to add OSB to that. But I'm happy to be corrected.

Think you are looking at walls rather than the roof there?

The first pictures in the thread show the current roof covering is knackered. sujsuj could do as he did with the garage and replace individual planks, but in terms of time and cost it will be better to strip the roof and redo it with OSB3.

As I said upthread - the steel sheets need something underneath them to deal with the issue of condensation.  12mm OSB3 would be an ideal choice as it has some strength as well as providing a flat surface for the steel sheets to be laid on.  The steel could be fixed direct to the purlins without using OSB3 but then the only strength is from the steel sheeting itself, and it doesn't stand up well to people walking around on it unless the purlin spacing is close enough.  The number of OSB3 sheets needed to cover that roof is small, so the cost is not going to be vast compared to the cost of the steel and all the other materials going into the project.... so really the question ought to be why wouldn't you give the steel the additional support and condensation protection that the OSB3 (or something else) would provide?

Alternatively the OSB3 could be omitted if the steel is laid on 50mm or 75mm Celotex, but for a DIY project it is probably safer to have some kind of timber product in there as well.

sujsuj said:

ThisIsWeird said:

Section62 said:

It needs something under the steel - it is much easier taking whatever it is (e.g. insulation/OSB/polythene) over the purlin and fixing through it, rather than cutting whatever it is to fit between the purlins and then working out a way of fixing it in place.  Continuity over the purlins also helps with keeping the wet on the outside, and looks much neater. (and this is why roofing screws are available in very long lengths).

Ah, good point - so remove old roofing, and then insulate and sheet on top of rafters, then metal roofing?

I suppose the insulation, like Celotex boards or something similar, should be installed from the inside after the roofing is completed, correct?

No. If you re-read my earlier post - the bit TIW quoted above - it is better to put the sheets (insulation/OSB/polythene) on top of the purlins because that way the sheet materials (a) are supported by the purlins with no need for additional support; (b) help to support the steel sheeting; and ( c ) it is much easier to fit them on top of the purlins rather than try cutting them to fit between purlins/rafters.

You want to end up with a sandwich of steel-polythene-insulation-OSB3 because that will be much stiffer (and better at carrying loads) than the steel on its own.

Yes I did garage repair with wood planks which took year for me to complete. I assume OSB3 will be less work & economical option.

So we are talking about 4 layers here now..?

(1) Outermost corrugated metal sheets --> Already bought
(2) Polythene membrane  --> (Damp Proof membrane/ Polythene Sheet)
(3)OSB3 Board --> To be decided on thickness ,12mm suggested
(4)Insulation --> 25mm of celotex as insulation??
All these on top of the purlins..??  or 3 & 4 need to be swapped with OSB just over purlins??

sujsuj

Lots of useful inputs let me see some more Youtube DIY videos over weekend.
I am getting worried about so many layering etc.  My garage roofing was very simple, compared to this now. Thanks

ThisIsWeird

sujsuj said:

Lots of useful inputs let me see some more Youtube DIY videos over weekend.
I am getting worried about so many layering etc.  My garage roofing was very simple, compared to this now. Thanks

Keep it simple.
IF you intend to have a flat ceiling inside that building, then insulate that - it'll be dead easy, and very effective.
Then just OSB and metal-sheet the roof as S62 suggested, to make a strong rain cover - that's it's only job. 
Make sure the eaves are well ventilated - you want a good draught passing through the roof space, above the ceiling.
And an inspection hatch!

Section62

ThisIsWeird said:

sujsuj said:

Lots of useful inputs let me see some more Youtube DIY videos over weekend.
I am getting worried about so many layering etc.  My garage roofing was very simple, compared to this now. Thanks

Keep it simple.
IF you intend to have a flat ceiling inside that building, then insulate that - it'll be dead easy, and very effective.
Then just OSB and metal-sheet the roof as S62 suggested, to make a strong rain cover - that's it's only job. 
Make sure the eaves are well ventilated - you want a good draught passing through the roof space, above the ceiling.
And an inspection hatch!

Sorry TIW, but you keep giving sujsuj bad advice here.  The steel sheeting will generate condensation on the underside and unless something is done to deal with that sujsuj will have problems.  The options are to use a drip-stop fabric, or to insulate the steel sheeting.  That requirement is regardless and independent of anything done to insulate the roomspace to make it more comfortable or cheaper to heat.  The OSB and insulation together will insulate the steel as well as providing the strong rain cover.  Doing it this way means the OSB and insulation are doing two jobs, not one - it is a more economical use of materials.

The simplest, easiest and most effective approach is to lay (whole) sheets of celotex over the top of the OSB, but under the polythene and steel.  The only cutting required is if the length/width of the roof isn't a whole number of sheets.  Contrast that with having to install insulation between parts of the roof structure.  If the insulating layer is above the purlins then the need to allow (cold) air into to the roof space for ventilation is reduced or avoided (the 'warm roof concept') meaning there's no need for the work/materials to create the ventilation path(s) and worrying about whether they are working.

So susjsuj, you were right, except for the order. The OSB goes on first -

(1) Outermost corrugated metal sheets
(2) Polythene membrane  --> (Damp Proof membrane/ Polythene Sheet) [Tape all joints]
[3]Insulation --> 25mm of celotex as insulation?? [thicker if you can afford it]

then

[4]OSB3 Board --> To be decided on thickness ,12mm [minimum] suggested

...all on top of the purlins.

ThisIsWeird

Section62 said:

ThisIsWeird said:

sujsuj said:

Lots of useful inputs let me see some more Youtube DIY videos over weekend.
I am getting worried about so many layering etc.  My garage roofing was very simple, compared to this now. Thanks

Keep it simple.
IF you intend to have a flat ceiling inside that building, then insulate that - it'll be dead easy, and very effective.
Then just OSB and metal-sheet the roof as S62 suggested, to make a strong rain cover - that's it's only job. 
Make sure the eaves are well ventilated - you want a good draught passing through the roof space, above the ceiling.
And an inspection hatch!

Sorry TIW, but you keep giving sujsuj bad advice here.  The steel sheeting will generate condensation on the underside and unless something is done to deal with that sujsuj will have problems.  The options are to use a drip-stop fabric, or to insulate the steel sheeting.  That requirement is regardless and independent of anything done to insulate the roomspace to make it more comfortable or cheaper to heat.  The OSB and insulation together will insulate the steel as well as providing the strong rain cover.  Doing it this way means the OSB and insulation are doing two jobs, not one - it is a more economical use of materials.

The simplest, easiest and most effective approach is to lay (whole) sheets of celotex over the top of the OSB, but under the polythene and steel.  The only cutting required is if the length/width of the roof isn't a whole number of sheets.  Contrast that with having to install insulation between parts of the roof structure.  If the insulating layer is above the purlins then the need to allow (cold) air into to the roof space for ventilation is reduced or avoided (the 'warm roof concept') meaning there's no need for the work/materials to create the ventilation path(s) and worrying about whether they are working.

So susjsuj, you were right, except for the order. The OSB goes on first -

(1) Outermost corrugated metal sheets
(2) Polythene membrane  --> (Damp Proof membrane/ Polythene Sheet) [Tape all joints]
[3]Insulation --> 25mm of celotex as insulation?? [thicker if you can afford it]

then

[4]OSB3 Board --> To be decided on thickness ,12mm [minimum] suggested

...all on top of the purlins.

Oops - I thought I was suggesting what you had recommended? Then just OSB and metal-sheet the roof as S62 suggested?

You are saying the upper roof needs insulating too, in addition to the OSB?! Lawdie.

Ok, this is my final offer, and then I'm shutting up... I would Tyvek over the rafters, horizontal batten as if fitting a slate/tile roof (except at spacings that the sheeting co recommends - say 2'?), and then screw the metal sheets to that. Ensure the roof void is well insulated. Jobbie jobbed.

If that doesn't do the trick, the world's gorn mad.