Box profile roof and insulation

[joeirish]

I am building a garden office and will be using box profile cladding for the external roof covering. I was thinking of putting this over a warm roof but I was wondering if I needed the outer layer of osb or could the cladding be laid directly over the PIR (possibly glued on using something like Soudatherm Roof 250?). Unlikely there would be any foot traffic on the roof. It will be 4m wide by 3.5m deep. The cladding will be a single sheet the full depth of the roof.

 

Thanks

[Iceverge]

I'd do,

 

Metal cladding, sinusoidal profile (I prefer the way you screw through the ridge of the metal rather than on flat)

 

Diagonal 75*25mm battens.

Breather membrane pulled tight and taped at joints. 

Rafters full fill with mineral wool,

Airtight membrane.

Insulated service cavity. 

Plasterboard. 

 

PIR and OSB are expensive. 

 

Alternatively you could buy some insulated panels and do it all in the one shot. 

 

 

 

 

 

[Cpd]

4 minutes ago, Iceverge said:

Alternatively you could buy some insulated panels and do it all in the one shot. 

?….. 

[joeirish]

7 minutes ago, Iceverge said:

I'd do,

 

Metal cladding, sinusoidal profile (I prefer the way you screw through the ridge of the metal rather than on flat)

 

Diagonal 75*25mm battens.

Breather membrane pulled tight and taped at joints. 

Rafters full fill with mineral wool,

Airtight membrane.

Insulated service cavity. 

Plasterboard. 

 

PIR and OSB are expensive. 

 

Alternatively you could buy some insulated panels and do it all in the one shot. 

 

 

 

 

 

Thanks. Unfortunately the lead time on insulated panels is over 2 months (I live in Ireland) or excessive delivery costs if I buy from UK and even then all sorts of potential issues becasue of Brexit. I need to get the roof on in the next couple of weeks to protect the rest from rain. So I was kind of thinking could I just make my own insulated panels. I can get the cladding in the next couple of weeks and the PIR is readily available.

[Iceverge]

Your area pretty small. Have you had a look on donedeal? Might be some on there. 

 

Nothing to stop you making your own! Let us know how you get on

[joeirish]

1 hour ago, Iceverge said:

Your area pretty small. Have you had a look on donedeal? Might be some on there. 

 

Nothing to stop you making your own! Let us know how you get on

Nothing on Donedeal. So any advice on making my own insulated roof panels?

[saveasteading]

47 minutes ago, joeirish said:

making my own insulated roof panels?

2 layers of metal cladding.

firstly lay metal cladding as if it was the weather layer, supported on rails.

Then there is a steel spacer system to provide a raised support.

lay fibreglass to completely fill the space

another layer of steel cladding, screwd through a thermal break layer.

all ends must be completely closed off to keep birds etc out.

 

the height of the spacer system dictates the amount of insulation you put in.

anywhere between 100mm and 400( if you are in Iceland.)

 

The advantage is the low bulk for delivery, and steel/insulation direct from specialists.

Also it is all manageable by hand whereas composite panels are very heavy.

 

This works but whether I advise you to try or not depends on your ambition and skill-set.