Thread: MGP10 90x45 replacing

The plans state that I use 38 x 50 f8 for roof battens(600cntr) finding the stuff hard to get does anyone see the problem of using MGp10 90x45 ?

More info needed,roof type truss etc and color bond vs tile and distance of rafter

Originally Posted by barney118

More info needed,roof type truss etc and color bond vs tile and distance of rafter

Colorbond Roof LVL rafters 190x43 spacing of 900 Span of 5 m skillon roof

Hope that helps

Can you rip? Cut the 90 * 45 down the guts and use half each 45*45.
I think they are functional equivalents

I use Hyne T3 90 x 45 mgp 12 when spanning 900 but 70 x 45 mgp 12 would do the job also from memory

Originally Posted by Moondog55

Can you rip? Cut the 90 * 45 down the guts and use half each 45*45.
I think they are functional equivalents

What about F8 35 x 25 hardwood

Not meaty enough

i used 90 x 45 MGP12 which is easy to get and spans 900 as ringtail says. The existing house was screwed to HW battens and its a right PITA. F8 is not a hardwood recheck your desdign and correct span tables, is a grading system usually for treated pine outdoor use. Use T2 which is used for indoor covered applications for termite protection.

Mgp10 90x45 is good to span1200 on sheet roof at 1200 spacing

I stand corrected there is span tables for the f8 unseasoned. Since when is f8 a hardwood?
A tip for screwing your battens down offset the screws to your rafters so when you screw your sheets down the screw will line up with the centre of the batten and you won't hit your screws.you may even nail to rafters I just went for overkill

What about mgp10 7o x 35

45*70 mgp10 or 35*70 mgp12

I don't know what state your in but most hwds in nsw will go F14 & is used commonly for battens, 50 X 38 is also a common size & readily available.
regards inter

70x35 mgp10 only good for 650 span

Originally Posted by intertd6

I don't know what state your in but most hwds in nsw will go F14 & is used commonly for battens, 50 X 38 is also a common size & readily available.
regards inter

The plans state 50 x 38 f8 (600 spacing)hardwood but finding that hard to get does that seem right ?

You could always use metal top hat like on most new houses. Cheap, light and ultra strong

Think about what you are after here, span means distance between rafter/truss, spacing means number of batten rows needed. The further between spacings reduce total linear metres of material and less labour costs. I find it better to use wood battens on a house as when laying insulation blanket you can get it tight using foil clips.

Originally Posted by ringtail

You could always use metal top hat like on most new houses. Cheap, light and ultra strong

Thanks for that am I still looking at 600 spacing or can go to 900 withe top hat

Funny; I have just finished talking with my builder cousin, he says that a 90*45 MGP12 is fine if cut in half and used as a 45*45 as it is the thickness of the timber that counts most

45*45 doesn't meet the timber framing code

900 with a 65 mm top hat no problem. You will see pro roofers running a batten between the 900's (at 450 ctrs) but it is quite small insection and there only to support the roof blanket and make it harder for them ( roofers) to fall between the trusses as they are working.

Originally Posted by ausdesign

45*45 doesn't meet the timber framing code

What about 40mm will that give me 900

2010 span tables - MGP10 90x45 - spacing at 600 or 900 will both span 1200
- F8 USHW 38x75 - spacing 600 will span 1150 or spacing 900 will span 900

The batten spacing for corrugated iron roofing is a maximum of 1200 on internal runs & 900 spacing at the sheet ends.(0.47 custom orb)
I assume that the colorbond mentioned in your first post refers to corrugated iron. If it is a 'tray deck' then there are differing max. spacings depending upon the product used.
Pine battens are used by many builders as it is generally easier to source than unseasoned hardwood (OB) & is easier to work with as far as straightening & it comes as H2 for termite protection.
A timber product is also easier to fix down RFL which is now standard under steel roofing.
'Top hat' sections are used frequently by steel frame manufacturers as it fits with their system & their 'buying power'.
With a rafter spacing of 900 I would generally nominate 35*70 MGP12 battens at 900 centres.
The calculation in the timber framing code also takes into account the 'uplift' capacity strength of the member. Having said that at an N2 design wind gust speed 35*70 mgp12 will span 1050 & at C4, cyclone rating will span 1000.
As an aside - 35*70 is different to 70*35 etc etc. The first figure relates to height.

Peter where does .47 c/orb as a sheet stated? As the standard for domestic is 0.42mm, 0.47 is used more in a commercial side.

My understanding is that 0.42 is the BMT. 0.47 is the TCT

Originally Posted by ausdesign

My understanding is that 0.42 is the BMT. 0.47 is the TCT

Base metal thickness & total coated thickness

Thanks for the help

I am using 190 x 45 LVL for the rafters and 40 mm top hats at 600mm spacing

Thanks for the help

I am using 190 x 45 LVL for the rafters and 40 mm top hats at 600mm spacing

Also does the foil insulation go on before or after the battens

Before

I have always put insulation on after battens, otherwise how do you support between rafters. The pros use magnets for top hats I believe to keep tight. For me I used foil clips to wood battens which is easier.

If we're talking RFL, then it's better to lay it over the rafters, creating a batten air space to the underside of the roofing iron. With the RFL layed parallel to the guttering & overlapped it acts as a sarking as well.
In a 'blanket' situation (rfl + batt) it is possibly easier to lay the product down the slope of the roof, dished over the battens, but with this application there is always the probability of moisture (condensation) penetrating into the roof space through the overlaps.