What's the best way to install metal roofing?

[jamie4321]

Hi,

 

I’m planning to build a music studio in my garden.. I’m 80% there with the design, but need some advice regarding cladding the roof. I’m keeping it small enough that I won’t need to meet building control requirements, but I still want to do the job properly. 

 

The plan is for a pitched roof design and I want to use either box profile or corrugated metal sheeting to clad it.

 

I’m thinking from an acoustic and thermal insulation perspective, to go for a decent thickness of PIR insulation between the rafters, then a layer of (18mm?) OSB on top, then a membrane, but I’m not sure of the correct way to then attach the metal sheeting on top of this. 

 

All the manufacturers guidelines I can find for this type of material suggest attaching it to thick purlins, but they are all aimed at building a barn or workshop roof with no mention of wood sheathing or insulation below. I have found several videos on youtube (all from America), where people are using metal roofing on houses and are laying the metal directly on top of the membrane and are using foam packers at the ends, but I feel like restricting airflow beneath the metal might be an issue..?

 

 

 

Basically my question is:

 

On top of the joists should I go OSB>membrane>metal roofing sheet or OSB>membrane>some sort of battens (or larger purlins)>metal roofing sheet. Or do away with the OSB altogether? 

 

I feel like any sort of horizontal battens will prevent any drips that occur from running downhill, but having no battens might restrict airflow. What’s the proper way to do this?

 

Thanks,

 

Jamie

[elite]

LABC have some details on their site: https://www.labcwarranty.co.uk/technical-blog/fully-supported-single-skin-metal-roofs

 

I'd proboably be tempted by insualted panels - e.g. something like (https://www.colourcladprofiles.com/collections/insulated-panels) - not used so not a recommendation. But I suspect this might help to reduce noise from the tin roof

[Patrick]

Airgap ! For your own peace of mind , please put an airgap into your build-up. The more the merrier. LABC is keen on that as well and doesn't allow warm roofs unless warranted by the system provider .

 

All USA instructions are only partially useful as this all depends a lot on climate zone as well .

[Redbeard]

Don't expect much acoustic performance from PIR. Density is your friend there.

[Nickfromwales]

1 hour ago, Redbeard said:

Don't expect much acoustic performance from PIR. Density is your friend there.

Yup.

 

On 15/05/2023 at 14:32, jamie4321 said:

I’m planning to build a music studio in my garden.. I’m 80% there with the design, but need some advice regarding cladding the roof. I’m keeping it small enough that I won’t need to meet building control requirements, but I still want to do the job properly. 

 

The plan is for a pitched roof design and I want to use either box profile or corrugated metal sheeting to clad it.

 

I’m thinking from an acoustic and thermal insulation perspective, to go for a decent thickness of PIR insulation between the rafters, then a layer of (18mm?) OSB on top, then a membrane, but I’m not sure of the correct way to then attach the metal sheeting on top of this. 

You and I are doing the same thing, just I want to be able to set up my DJ decks / amp / monitors etc and not piss the neighbours off. The walls will be decoupled 3x2 studs x2 with 50mm of acoustic between them so 2x 75mm acoustic infilled in each leaf (75+75+50 = 200mm of acoustic in the walls) and I will probably go nuts and use resilient bars or some other measure for the lower frequency sound, possibly rubber (recycled car tire) mats.

 

However, the roof.......

 

I'd like to use metal profile pre-insulated sheets, for simplicity, and would then overlay (internally) with 100mm of acoustic batts. Still unsure of how this would work, bu tI think I'll be ok if there are no gaps / cavities between the interior metal skin, the batts, and the room airspace.

 

Issue is further compounded by 21 PV panels being destined to go onto the roof and me wanting to go MCS so I can sell excess (and force-discharge), meaning the fixings and structure need to 'comply'.

 

PIR aka SIPs roofs are acoustically "shart" so beware.