Flat roof profile - how to proceed?

[theflyingpig]

Hi all. I'm about to start an outbuilding that will have a flat roof and can't decide how to tackle the roof profile...

Building off a concrete slab, approx 6m x 6m. Walls are 4*2 stud. Roof will be on posi joists, furrings (though just reducing height timber screwed through onto top of posi joist), 18mm osb, 100mm celotex. 18mm osb, epdm...

I'd like roof to overhang walls by aporix 200mm to give cladding a bit of protection, but am unsure how to achieve this...

As in this sketch, option 1 - running the posi joists long will create a ridiculously deep roof profile. Option 3 - shooting the 'furring' out long - fine, but what about at back where furrings or nothing? Option 4? Just overhanging deck?

All input appreciated!

 

[freddiemercurystwin]

Option 4. If you did option 3 the height of the fascia will vary.

What is your wall construction? In any case the (wall) finish will obviously need to run up the outside of the joists to meet the underside of the lower deck.

 

[theflyingpig]

Thanks, wall is to be 4*2 stud, osb, wrap, battens, cladding (prob vertical treated 4*1)... I plan to run the cladding up to soffit, leaving a 10mm gap at top to allow ventilation behind cladding .... Some sort of bee/wasp proof grill here (and at bottom) would be good...

 

[freddiemercurystwin]

So if doing vertical cladding you need your studs + osb + breather membrane + vertical battens + horizontal battens + cladding.

 

[noseall]

Hi all. I'm about to start an outbuilding that will have a flat roof and can't decide how to tackle the roof profile...

Building off a concrete slab, approx 6m x 6m. Walls are 4*2 stud. Roof will be on posi joists, furrings (though just reducing height timber screwed through onto top of posi joist), 18mm osb, 100mm celotex. 18mm osb, epdm...

I'd like roof to overhang walls by aporix 200mm to give cladding a bit of protection, but am unsure how to achieve this...

As in this sketch, option 1 - running the posi joists long will create a ridiculously deep roof profile. Option 3 - shooting the 'furring' out long - fine, but what about at back where furrings or nothing? Option 4? Just overhanging deck?

All input appreciated!

Bulky, in-you-face flat roof edge details are BIG these days, especially with larger span flatties and the latest insulation Reg's. I see a few designers are stepping the fascia detail in order to take your eye away from one broad slab of an edge.

We did one a few years ago where we stepped the insulation etc...

Untitled

• noseall
• 3 Nov 2014
• 2

Untitled

• noseall
• 3 Nov 2014
• 2

Untitled

• noseall
• 5 Nov 2014
• 1

Untitled

• noseall
• 5 Nov 2014
• 1

Untitled

• noseall
• 20 Nov 2014
• 2

Untitled

• noseall
• 20 Nov 2014
• 1

 

[theflyingpig]

So if doing vertical cladding you need your studs + osb + breather membrane + vertical battens + horizontal battens + cladding.

Couldn't I just do horizontal battens and fix cladding to those? Then again, I guess 25mm batten isn't much to fix into...

 

[theflyingpig]

Bulky, in-you-face flat roof edge details are BIG these days, especially with larger span flatties and the latest insulation Reg's. I see a few designers are stepping the fascia detail in order to take your eye away from one broad slab of an edge.

We did one a few years ago where we stepped the insulation etc...

Untitled

• noseall
• 3 Nov 2014
• 2

Untitled

• noseall
• 3 Nov 2014
• 2

Untitled

• noseall
• 5 Nov 2014
• 1

Untitled

• noseall
• 5 Nov 2014
• 1

Untitled

• noseall
• 20 Nov 2014
• 2

Untitled

• noseall
• 20 Nov 2014
• 1

Yikes! I don't much like the look of that stepped roof! Alot of flaff for what?

 

[noseall]

Yikes! I don't much like the look of that stepped roof! Alot of flaff for what?

Massive faff.

As I said previously, you can actually have dual fascia stepped overhang. It takes your eye off one big barge board.