# Forum Home Renovation Pergolas, Gazebos, Strombellas & Rotundas  Verandah Rafter Dimensioning

## laan

Hi, 
I'm planning to build a verandah with a roof rafter span of 4.8 meters, with rafters spaced at 900mm. The estimated roof load is < 10kg/m2 (thin metal sheeting + battens). I'm assuming wind classification N1/N2 (Suburban Canberra). 
I've been trying to figure out the required dimension of the various beams required, with the roof rafters probably being the most critical aspect due to the long span. I've initially tried to figure out appropriate dimensions assuming that I'll be using treaded F7 pine, but I'm open to using other types of woods, LVL etc. Here's what I've managed to dig up so far for the rafters:   AS.1684.2.Supp2 (F7), Table 29  =>      170x35 (4900 max span, 1000 max O/H)  http://www.demak.com.au/wp-content/u...Span-Table.pdf (F7) =>     190x35 (5100 max span) Treated pine Pergola span details (F7) =>     190x45 (4800 max span) http://www.pinewoodproducts.com.au/P...IY_pergola.pdf (F7) =>     190x35 (4800 max span) http://www.bretts.com.au/_cmsFiles/h...20Carports.pdf (F7) =>     190x35 (4900 max span) 
I'm a bit confused by the large difference in dimensions suggested by the "standard" AS 1684.2 (170x35) and the various pergola DIY articles linked above. 
The safe bet here seems to go for 190x45 for the rafters... or should I trust the standard and assume that 170x35 will be enough?  
I'd be very interested in finding out why the recommendation in AS 1684 is so much smaller... Is Table 29 not applicable to a verandah roof? 
Also, any tips in general regarding suitable dimensions and materials for verandah rafters spanning 4.8m would be greatly appreciated. 
Thanks, 
Lars

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## phild01

Do as you are thinking 190x45.  170mm timber is not a common available size.

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## laan

> Do as you are thinking 190x45.  170mm timber is not a common available size.

  Ok, you reckon that's the reason they're recommending 190 in most pergola design articles, even though 170 might be enough, as stated by the AS 1684 span tables?

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## phild01

> Ok, you reckon that's the reason they're recommending 190 in most pergola design articles, even though 170 might be enough, as stated by the AS 1684 span tables?

  Table values aren't absolute and generally the least acceptable values.  Available timber sizes generally skip 120, 170, 220 etc so you just use the next available sizes of 140, 190, 240 etc.

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## METRIX

> Hi, 
> I'm planning to build a verandah with a roof rafter span of 4.8 meters, with rafters spaced at 900mm. The estimated roof load is < 10kg/m2 (thin metal sheeting + battens). I'm assuming wind classification N1/N2 (Suburban Canberra). 
> I've been trying to figure out the required dimension of the various beams required, with the roof rafters probably being the most critical aspect due to the long span. I've initially tried to figure out appropriate dimensions assuming that I'll be using treaded F7 pine, but I'm open to using other types of woods, LVL etc. Here's what I've managed to dig up so far for the rafters:   AS.1684.2.Supp2 (F7), Table 29  =>      170x35 (4900 max span, 1000 max O/H)  http://www.demak.com.au/wp-content/u...Span-Table.pdf (F7) =>     190x35 (5100 max span) Treated pine Pergola span details (F7) =>     190x45 (4800 max span) http://www.pinewoodproducts.com.au/P...IY_pergola.pdf (F7) =>     190x35 (4800 max span) http://www.bretts.com.au/_cmsFiles/h...20Carports.pdf (F7) =>     190x35 (4900 max span) 
> I'm a bit confused by the large difference in dimensions suggested by the "standard" AS 1684.2 (170x35) and the various pergola DIY articles linked above. 
> The safe bet here seems to go for 190x45 for the rafters... or should I trust the standard and assume that 170x35 will be enough?  
> I'd be very interested in finding out why the recommendation in AS 1684 is so much smaller... Is Table 29 not applicable to a verandah roof? 
> Also, any tips in general regarding suitable dimensions and materials for verandah rafters spanning 4.8m would be greatly appreciated. 
> Thanks, 
> Lars

  Rating your roof load at 10kg/m2 is vey low, I would rate it at 20kg/m2 or preferably 25kg/m2, this allows you some engineering space for later on if you want to install insulation and gyprock.
4.8m is a long span, you didn't mention the angle the roof is on, I will asume a 5 deg roof pitch (yes the angle does make a difference) 
At 10kg/m2 a 190x45 F7 will be rated to 87% capacity and have a 17mm deflection, I would not use this for the purpose you want, the deflection and capacity is too high IMO.
10Kg/m2 a 190x45 MGP10 will be rated to 68% with 13mm deflection, at 20kg/m2 76% loaded, 13mm deflection, at 25kg/m2 91% 15mm deflection, reating is ok at 10 or 20kg/ms but deflection is too high IMO. 
If you really want to go with 190x45, I would decrease your rafter spacing to 600, then at 25kg/m2 a 190x45 MGP10 will give you a 66% load with 12mm deflection,  a 190x45 F7 will be 80% with 15mm deflection, for your situation I would go for MGP10 over F7. 
If I was building what you want with 900 spacing, I would choose 240x45, rated at 25kg/m2 gives you a 48% capacity and 8mm deflection, this will give you a much sturdier roof, and one I would feel comfortable walking on, I would not feel comfortable walking on a 190x45 with 4.8m spans.

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## shauck

> If you really want to go with 190x45, I would decrease your rafter spacing to 600, then at 25kg/m2 a 190x45 MGP10 will give you a 66% load with 12mm deflection,  a 190x45 F7 will be 80% with 15mm deflection, for your situation I would go for MGP10 over F7.

  Closing up the rafter spacings to 600 will also allow a ceiling product to be attached directly to the rafters in future as 600 would be the max span of some products (some only 450). You may not want to make these changes but someone else might (if you sell).

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## laan

> Rating your roof load at 10kg/m2 is vey low, I would rate it at 20kg/m2 or preferably 25kg/m2, this allows you some engineering space for later on if you want to install insulation and gyprock.
> 4.8m is a long span, you didn't mention the angle the roof is on, I will asume a 5 deg roof pitch (yes the angle does make a difference)

  Thank's Metrix, that's very useful info. Yes, the roof will have a pitch of 5 degrees, or even slightly less if I can get away with it in order to not make the lower end too low. 
We're planning to cover the roof with about 50% metal sheeting and the other half in some transparent plastic sheeting, and the verandah will have no walls, so it's unlikely we'll want to add insulation or gyprock. That said, I do want a sturdy roof that wont end up in the neighbour's backyard one stormy night.   

> At 10kg/m2 a 190x45 F7 will be rated to 87% capacity and have a 17mm deflection, I would not use this for the purpose you want, the deflection and capacity is too high IMO.
> 10Kg/m2 a 190x45 MGP10 will be rated to 68% with 13mm deflection, at 20kg/m2 76% loaded, 13mm deflection, at 25kg/m2 91% 15mm deflection, reating is ok at 10 or 20kg/ms but deflection is too high IMO.

  Interesting figures. Were/how do you get these numbers? I agree 17mm deflection sounds a bit worrisome. How is x% of capacity defined? Are beams allowed to simply snap at %100 capacity given a specific grade?   

> If you really want to go with 190x45, I would decrease your rafter spacing to 600, then at 25kg/m2 a 190x45 MGP10 will give you a 66% load with 12mm deflection,  a 190x45 F7 will be 80% with 15mm deflection, for your situation I would go for MGP10 over F7.

  I'm surprised your numbers show that MGP10 is quite a bit stronger than F7. My understanding was that MGP10 can replace F5, MGP12 can replace F8. (About grading: http://www.renovateforum.com/f76/mgp...-timber-74539/ ) Happy to go with MPG though, which seems almost easier to get hold of than F7. 
What puzzles me most here is the big difference between what is recommended by the tables in AS.1684.2, and what seems to be common practice. For my design (4.8m span, 900 spacing, F7), AS.1684 says: 
AS1684.2.Supp2 (F7), Table 29  => 170x35 (4900 max span, 1000 max overhang) 
This is very different from the 240x45 beams you recommend, or even the 190x45 that seems to be common practice assuming very lightweight roofing. I'm I reading these tables wrong?   

> If I was building what you want with 900 spacing, I would choose 240x45, rated at 25kg/m2 gives you a 48% capacity and 8mm deflection, this will give you a much sturdier roof, and one I would feel comfortable walking on, I would not feel comfortable walking on a 190x45 with 4.8m spans.

  I will definitively consider that. This leads me to another question... Most verandah designs I've seen simply hook up the roof rafters to the fascias. The fascias of our house is (50+ years old) 90x35 pine or similar, nailed to truss rafters looking like they'd be 140x45 or so (only guessing, haven't measured yet). Hooking up a 4.8m x 4.5m roof supported by heavy 240/190x45 rafters to this seems pretty dodgy to me!  I'd like to avoid this for two reasons. Firstly, because it seems dodgy. Secondly, because of the wanted level of the decking floor and the required 4-5 degree pitch of roof, hooking up the verandah rafters to the fascia under the current gutter will simply make the roof too low.  
My current plan is to simply remove the whole gutter/fascia/eaves business and let the verandah rafters rest directly on the brick wall, while also being attached to the roof trusses for horizontal support.This would probably require some sort of custom gutter sitting between the house and verandah roofs, and it does seem pretty complicated. The house is an old single brick veneer house with cement tile roof, built in the mid 60's.  
Any thoughts or tips regarding how to attach the verandah roof to this house?

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## laan

> Closing up the rafter spacings to 600 will also allow a ceiling product to be attached directly to the rafters in future as 600 would be the max span of some products (some only 450). You may not want to make these changes but someone else might (if you sell).

  That's a good point. I was worried that 600mm spacing would block a bit too much sunlight, but I can obviously fix that by using more transparent plastic and less metal sheeting for the roof.  
Also, while considering attaching this roof to my old fascia (see my previous post), I was worried 600mm spacing would make the roof even heavier, but if I get rid of the fascia/eaves and let the verandah rafters rest directly on the house brick wall, that's probably not an issue either. Do you have any experience with that sort of attachment? It doesn't seem to be very common, but there must be some upper limit for what you can safely attach to the fascia of an old house!  :Smilie:

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## METRIX

> That's a good point. I was worried that 600mm spacing would block a bit too much sunlight, but I can obviously fix that by using more transparent plastic and less metal sheeting for the roof.  
> Also, while considering attaching this roof to my old fascia (see my previous post), I was worried 600mm spacing would make the roof even heavier, but if I get rid of the fascia/eaves and let the verandah rafters rest directly on the house brick wall, that's probably not an issue either. Do you have any experience with that sort of attachment? It doesn't seem to be very common, but there must be some upper limit for what you can safely attach to the fascia of an old house!

  You wouldnt attach anything directly to the fascia except a hanging potplant. 
The fascia is only for decoration, you need to attach a bracket through the fascia directly to the rafters then you can attach a timber to these and hang your rafters off that. Dunnings 22° Galvanised Extended Fascia Bracket I/N 1076113 | Bunnings Warehouse 
I would go for roof extenda brackets,  Roof Extenda Bracket - Roof Extenda Pty Ltd

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## DuckCommander

As soon as you attach additional load to existing rafters at the end of an overhang for which they have not been designed for, it has gone beyond it's design intention. Therefore the whole arrangement needs to be re-engineered. It may stay upright for a while but if something happens you will be left high and dry. These rafter brackets are not a holistic solution. From my experience, adding point loads to the tail of a rafter overhang will require engineering input which will include strengthening of the original rafter (more than likely a full length scab member), upgrades to tie down capacity, and depending on circumstances upgrades to stud work and subsequent tie down to footing. 
My opinion of the roof extender brackets are similar... they're just a component of a system that has to be properly engineered. By themselves they provide zero lateral capacity, which will have to be accounted for by other means.

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## phild01

> My opinion of the roof extender brackets are similar... they're just a component of a system that has to be properly engineered. By themselves they provide zero lateral capacity, which will have to be accounted for by other means.

  To my mind these would work best by adding an all steel support/roof structure, which in itself would offer better inherent bracing.

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## METRIX

The two available options above were offered as proprietary connection methods to the OP concern about connecting the structure directly to the fascia. 
It goes without saying the OP should be seeking independent advice from a local Engineer or Builder rather than just relying on information provided on a forum, as I have said many times on here. 
It also goes without saying the OP should be seeking council approval for the structure rather than just building something and hoping for the best, as I have also said many times on here. 
FWIW, I have used the roof extender's on many structures over the years and have found them to be a surprisingly strong unit, if implemented as per manufacturers engineering / limitation / design recommendations you should not have any concerns, but like anything if you don't follow the manufacturer's recommendations then the possibility of failure is high. 
I and other builders I know have not had any structures fail or otherwise where these have been used, for my own projects I know there has been a lot of shear and uplift forces put on these structures by the high winds we get in Sydney at times, and they have held up without a problem.

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## laan

Metrix, I don't know if you saw my initial answer and follow up questions to your first reply, it had to go through moderation for some reason and took a while to pop up, but it's there now... Thanks for the useful info!

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## phild01

I have a need for this type of roof and thinking of using roof extenders but I have an lvl in lieu of a top-plate so I would be concerned that the plate fixing offered will not be good enough.  The plate fixing would be a coach screw wouldn't it?  Bolting would mean removing the wall lining. 
As for getting council consent , it is bothersome the feel of entitlement Councils have for grabbing a fistful of dollars for all their simple 'okays', and still deny any level of responsibility if anything goes wrong!

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## DuckCommander

> The two available options above were offered as proprietary connection methods to the OP concern about connecting the structure directly to the fascia. 
> It goes without saying the OP should be seeking independent advice from a local Engineer or Builder rather than just relying on information provided on a forum, as I have said many times on here. 
> It also goes without saying the OP should be seeking council approval for the structure rather than just building something and hoping for the best, as I have also said many times on here. 
> FWIW, I have used the roof extender's on many structures over the years and have found them to be a surprisingly strong unit, if implemented as per manufacturers engineering / limitation / design recommendations you should not have any concerns, but like anything if you don't follow the manufacturer's recommendations then the possibility of failure is high. 
> I and other builders I know have not had any structures fail or otherwise where these have been used, for my own projects I know there has been a lot of shear and uplift forces put on these structures by the high winds we get in Sydney at times, and they have held up without a problem.

  I don't disagree METRIX. The products IMO do not stress their limitations enough hence why the goes without sayings are probably not stressed enough. The whole engineering spec of the roof extenders reads like one large caveat. It's like saying one M24 bolt will make my house stand up in high winds, which it may be strong enough to to resist the loads, but unless it is a part of a holistic design by itself it's just a bolt. 
I have seen dozens of rafter extensions and roof extender type apparatus fail under wind loads in the range of upper design limits. While the product itself satisfies criteria they were not part of a fully engineered solution. No offence intended to the posters of this forum but even builders contracted from southern states generally were found to not understand the different requirements of cyclonic conditions.

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## DuckCommander

> I have a need for this type of roof and thinking of using roof extenders but I have an lvl in lieu of a top-plate so I would be concerned that the plate fixing offered will not be good enough.  The plate fixing would be a coach screw wouldn't it?  Bolting would mean removing the wall lining. 
> As for getting council consent , it is bothersome the feel of entitlement Councils have for grabbing a fistful of dollars for all their simple 'okays', and still deny any level of responsibility if anything goes wrong!

  Is the LVL above an opening? The engineering report for them has caveats for such an instance. 
Wholly agree about council consent.

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## METRIX

Interesting figures. Were/how do you get these numbers? I agree 17mm deflection sounds a bit worrisome. How is x% of capacity defined? Are beams allowed to simply snap at %100 capacity given a specific grade?  These are generated by a modelling program based on AS standards, and real life specifications for the various timbers, they provide more accurate results based on a given situation than any paper table will give you. 
 I'm surprised your numbers show that MGP10 is quite a bit stronger than F7. My understanding was that MGP10 can replace F5, MGP12 can replace F8. (About grading: http://www.renovateforum.com/f76/mgp...-timber-74539/ ) Happy to go with MPG though, which seems almost easier to get hold of than F7.  Not always, it all depends on what you are asking for, comparing F rated and MGP rated timbers is not as straight forward as you may think, you will find many articles on the web regarding this, but for example,  
 F rated timbers are all bunched under the same unbrella, be it Softwood or Hardwood and the rating is obtained mainly by the flexural strength of the timber but other caracteristics are taken into consideration. 
If you compare the bending strength of a F5 and MGP10 these are around the same at 16 & 16.2 Mpa, but compare the compressive strength and the MGP10 has nearly double the compressive strength of a F5 rated timber, do some searches there are some good articles out there. 
What puzzles me most here is the big difference between what is recommended by the tables in AS.1684.2, and what seems to be common practice. For my design (4.8m span, 900 spacing, F7), AS.1684 says: Define common practice !, no builders I know will go by what the tables say, they now use computer generated results for any given situation because there are many alternative soultions available such as LVL, GL, Smartframe, Hynebeam and many others, the tables will always give you a Maximum rating, but you never want to build to the maximum of any timbers capacity. 
This is very different from the 240x45 beams you recommend, or even the 190x45 that seems to be common practice assuming very lightweight roofing. I'm I reading these tables wrong? Your spans were 4.8m, this is a considerable distance sor a single span, if you wnat the structure to be rigid, and be able to withstand the forces put onto it yo would build it above minimum specifications, minumum is a starting point, it all comed down to how you want the structure to perfom over time..  
I will definitively consider that. This leads me to another question... Most verandah designs I've seen simply hook up the roof rafters to the fascias. The fascias of our house is (50+ years old) 90x35 pine or similar, nailed to truss rafters looking like they'd be 140x45 or so (only guessing, haven't measured yet). Hooking up a 4.8m x 4.5m roof supported by heavy 240/190x45 rafters to this seems pretty dodgy to me!  I'd like to avoid this for two reasons. Firstly, because it seems dodgy. Secondly, because of the wanted level of the decking floor and the required 4-5 degree pitch of roof, hooking up the verandah rafters to the fascia under the current gutter will simply make the roof too low.    This is why you need to seek advice from an Engineer or Builder, they can advice you on what's best for your situation, there is no such thing as one size fits all when it comes to building what you want to do.

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## laan

Regarding council approval etc... I certainly plan to get council approval for the verandah, but I enjoy trying to figure it out and I was thinking I might be able to submit something myself, without consulting a structural engineer. If it's rejected I guess I might have to. I haven't even checked how much it actually costs to have it approved yet though.  
As for attachment to the house, my main problem is that if I attach 24 cm deep roof rafters at the level of the fascia, i.e under the house gutters (assuming that the fascia/eaves/house rafters have been properly reinforced to support the verandah roof), the verandah roof will be a bit too low (less than 2m from deck to roof at the far end, assuming 5 degree pitch). As Metrix suggested, Roof Extenda brackets would to the job and put the veranda up over the eaves, but, mostly for cosmetic reasons, I don't really like to have my old house eaves sticking out under the new verandah roof. I'd rather remove them completely, and let the verandah rafters rest on the brick wall (see my 2nd post in this thread for more info, is needed moderation and was late to pop up and might have been missed).  
Does anyone have experience doing something like this? I can probably post a picture to explain it better if it's unclear what I mean. Cheers.

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## METRIX

> I have a need for this type of roof and thinking of using roof extenders but I have an lvl in lieu of a top-plate so I would be concerned that the plate fixing offered will not be good enough.  The plate fixing would be a coach screw wouldn't it?  Bolting would mean removing the wall lining. 
> As for getting council consent , it is bothersome the feel of entitlement Councils have for grabbing a fistful of dollars for all their simple 'okays', and still deny any level of responsibility if anything goes wrong!

  Bolting can be done, as your external wall does not go all the way to the underside of the rafters it sits lower than the inner walls.

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## METRIX

> Regarding council approval etc... I certainly plan to get council approval for the verandah, but I enjoy trying to figure it out and I was thinking I might be able to submit something myself, without consulting a structural engineer. If it's rejected I guess I might have to. I haven't even checked how much it actually costs to have it approved yet though.  
> As for attachment to the house, my main problem is that if I attach 24 cm deep roof rafters at the level of the fascia, i.e under the house gutters (assuming that the fascia/eaves/house rafters have been properly reinforced to support the verandah roof), the verandah roof will be a bit too low (less than 2m from deck to roof at the far end, assuming 5 degree pitch). As Metrix suggested, Roof Extenda brackets would to the job and put the veranda up over the eaves, but, mostly for cosmetic reasons, I don't really like to have my old house eaves sticking out under the new verandah roof. I'd rather remove them completely, and let the verandah rafters rest on the brick wall (see my 2nd post in this thread for more info, is needed moderation and was late to pop up and might have been missed).  
> Does anyone have experience doing something like this? I can probably post a picture to explain it better if it's unclear what I mean. Cheers.

  If you go through council you will need to supply a set of plans, with specifications relating to connection points, timber sizes, spans, connection methods etc, if you cannot provide adequate information the council will knock it back. 
You can draw these up yourself, it's not too difficult if you cover all the points required, I have done them at various times and had no issues with the council (depends on the coincil).
But bear in mind, if you go outside the AS standards for anything they will require an Engineers sign off for that alternate method. 
For your situation, if you pitch the roof at less than 5 deg you will get water ingres problems, so my advice is don't even consider less than 5, you may nee dto reconsider the length of the roof, if you cannot get enough fall or are having height probles at the low end you may nee dto reduce the roof length, or go on top of the existing roof.

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## phild01

> Is the LVL above an opening? The engineering report for them has caveats for such an instance. 
> Wholly agree about council consent.

  Yes, the lvl is above an opening, actually 2 125x42.  The design is a continuous span and done this way for maximum headroom for a sliding door.  I would have liked to include a top-plate over but insufficient space.  So drilling through for cables is even a concern.  The beam is fully loaded and the predicted deflection hasn't occurred.  I was going to place the extenders over the walled areas.

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## laan

> For your situation, if you pitch the roof at less than 5 deg you will get water ingres problems, so my advice is don't even consider less than 5, you may nee dto reconsider the length of the roof, if you cannot get enough fall or are having height probles at the low end you may nee dto reduce the roof length, or go on top of the existing roof.

  Ok, I will stick with a 5 degree pitch, and I don't really want to make the length less than 4.5-4.8m, so going on top of the existing eave is the only option. Does my plan to simply remove the eave and rest the veranda rafter on top of the brick wall (with additional, mainly lateral, support from attachments to the house roof rafters) make sense at all?

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## METRIX

> I don't disagree METRIX. The products IMO do not stress their limitations enough hence why the goes without sayings are probably not stressed enough. The whole engineering spec of the roof extenders reads like one large caveat. It's like saying one M24 bolt will make my house stand up in high winds, which it may be strong enough to to resist the loads, but unless it is a part of a holistic design by itself it's just a bolt. 
> I have seen dozens of rafter extensions and roof extender type apparatus fail under wind loads in the range of upper design limits. While the product itself satisfies criteria they were not part of a fully engineered solution. No offence intended to the posters of this forum but even builders contracted from southern states generally were found to not understand the different requirements of cyclonic conditions.

  If the bracket has failed under upper design limits because they were used independantly of an engineered solution, this cannot be blamed on the bracket, it was clearly used in a situation where additonal measures should have been implemented, this has to come back to the engineer or builder to take that responsibility not the bracket itself. 
Its the same as putting a set of retreads on a Bugatti and then saying the tyres blew out and caused the car to crash, when these are clearly not designed for such a vehicle, as the correct tyres would be part of an engineered solution to ensure it capabilites were able to be exploited safely. 
No offence taken but as we don't have to build to cyclonic conditions, I would not expect you average non cyclonic builder to understand the cyclonic requirements.
If I was applying for a contracted job in a cyclonic location, I would make it my business to understand what I was expected to know before undertaking any work clearly this was not the case, perhaps the people who contracted them should have done some checks before letting them loose.

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## phild01

> Bolting can be done, as your external wall does not go all the way to the underside of the rafters it sits lower than the inner walls.

  No, my external wall is right at the underside of the rafters.  Eaves follow roof pitch.
Must admit wall linings aren't on yet but wondered how fixings are made with no access to underside of top-plate and reckoned coach screws.
I am hesitant to drill thru the LVL's as it will compromise their design strength, holes being close to lvl edge face.

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## DuckCommander

> Interesting figures. Were/how do you get these numbers? I agree 17mm deflection sounds a bit worrisome. How is x% of capacity defined? Are beams allowed to simply snap at %100 capacity given a specific grade?

  Timber deflection is a very rough calculation. Elastic deflection under immediate load is calculated and then factored by 2 for long term creep effects (from experimental data not because the timber god said so). Deflection can sound bad but there are guidelines within AS codes to run by. Typically if it does not exceed span/250 or max 25mm it would be generally acceptable. 
As far as the capacity ratings in terms of % factors or ratios go they indicate that the worst piece of timber that would be expected of that grade would not fail under 100% loading condition with all relevant factors considered. The timber code is LOADED with redundancy for material variability. There are grade reduction factors (larger for non-machine graded), duration of load factors (from 57% for permanent to 114% for fasteners under wind), partial seasoning factors and temperature factors to name a few. To say that a specific timber will be x loaded and y deflected does not mean a lot other than it is a guide.  
MGP and F grade comparisons that are widely known are only a yardstick for bending stress. Significant upsides are in shear, tension and compression from machine graded sections. This isn't forthcoming in the span tables. 
With brick/veneer the brick is not structural. Can you draw something up like a cross section/plan showing what you're trying to do?

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## DuckCommander

> If the bracket has failed under upper design limits because they were used independantly of an engineered solution, this cannot be blamed on the bracket, it was clearly used in a situation where additonal measures should have been implemented, this has to come back to the engineer or builder to take that responsibility not the bracket itself.

  Yes that is what I mentioned but I also said that the information about the products is not forthcoming for the average user. I doubt many builders delve into the engineering reports of particular products to find out that it may not suit their particular application. At face value they give x capacity under this general condition, which in real terms means your bugatti with retreads will get you around the nurburgring in two hours but not under 10 minutes cause you gonna die when you're wrapped around a tree. 
I mention it because I have seen many a joe blow lose out in a big way because of stuff like this installed correctly. Rarely does this come back to the builder or product manufacturer. 
I wasn't being discriminate about failure of correct installation of these products with cyclonic/non cyclonic builders, it was a blanket comment.

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## laan

> MGP and F grade comparisons that are widely known are only a yardstick for bending stress. Significant upsides are in shear, tension and compression from machine graded sections. This isn't forthcoming in the span tables. 
> With brick/veneer the brick is not structural. Can you draw something up like a cross section/plan showing what you're trying to do?

  
Thanks for that. I realize that the single brick wall couldn't be trusted to support much load in any direction other than down... But my gut feeling is that it would actually be able to support a fair bit of load pushing straight down, while horizontal and uplift forces would need to be handled by attaching the pergola rafters to reinforcements attached to the house rafters. 
A bit tricky to explain, I'll try to draw up a sketch showing the current setup and what I'm trying to do ASAP.

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## DuckCommander

Avoid putting any load through the brick. All the forces need to go through to the timber framing.

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## laan

So here's a side-on view of my planned verandah:  
Ignoring the issues of reinforcing the fascia to properly support this verandah roof, my main problem is that if building the roof as shown in the attached image, the roof height at the far end of the verandah will simply be too low for my liking (just over 1.8m). 
I'd like the roof to be at least 30-40 cm higher, and I'm trying to figure out how to construct the attachment to the house is that case. My original plan was to get rid of the eave all together and attach the verandah rafters somewhere near the top of the brick wall. 
Btw, the house roof rafters are just 90x45, and spaced at 900mm. 
Another option that was suggested to me is to have the verandah roof pitching down towards the house instead (i.e, with the high point of the verandah over the posts). I don't know if I like the look of that, but it would certainly solve the roof height problem.

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## laan

Also, the reason why my verandah floor is 450mm above the ground level is that I wanted it level with an existing concrete extension behind the house, and to keep it mostly level with the internal floors of the house.

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## r3nov8or

Have you considered a flyover roof? Benefits for you are that the timber house frame will be the support for the house-side structure, and this will allow you to raise the outer-side structure to a height you are happy with. Also no messing with the existing eave and gutter etc. 
And, as mentioned already, don't rely on the bricks - for anything. 
Edit - flyover diagram -

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## r3nov8or

Another option is to add two more posts and a beam, as below. To keep the height maximised you could use a steel PFC beam. A 180 may span your distance, but you'd have to check the span tables for steel, in the Library last time I checked.   
I did this, and got 'cleats' added to the PFC to bolt the rafters to. 
It's totally functional, but sometimes I wish I'd gone with the flyover design...

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## laan

> Have you considered a flyover roof? Benefits for you are that the timber house frame will be the support for the house-side structure, and this will allow you to raise the outer-side structure to a height you are happy with. Also no messing with the existing eave and gutter etc. 
> And, as mentioned already, don't rely on the bricks - for anything.

  Yep, I've considered a flyover roof. My initial thought was that it'll look neater to get rid of the eave all together if I have to put the verandah roof above it, but if it turns out to be too complicated, a flyover with the eave in place might be the way to go. 
Ok, taking yours and others advice... no load on the bricks!

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## DuckCommander

As renovator mentioned a flyover will get your heights and prevent ripping your eaves apart. Otherwise you could destroy the eaves and support the rafters on the stud wall.
Have you considered using trimdek sheeting? You can go down to 2 degrees slope, which will give you an extra 250mm height at the end of your verandah.

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## laan

> Have you considered using trimdek sheeting? You can go down to 2 degrees slope, which will give you an extra 250mm height at the end of your verandah.

  I didn't know you could use a smaller angle with trimdek. How come? Does water flow off it faster?

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## laan

Thanks for the design suggestions renovator. Adding a couple of extra support posts near the house might be a good idea if the support from the existing frame seems a bit questionable... 
Here's the current setup around the eaves of my house:    
I'm probably overcomplicating things, but ideally, I'd like to build something like this: 
What I'm not quite sure about is how to add a gutter in between the house roof tiles and the verandah roof (we want a gutter here to collect rainwater into a nearby tank) and how to build a waterproof connection between the two roofs. With the house roof tiles being corrugated, it seems quite tricky to make sure water doesn't get into the house roof in windy weather or if the gutter overflows.

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## laan

I'm thinking something like this, where the outer edge of the gutter would be a bit lower so that water flows on to the deck instead of back towards the roof tiles in case of gutter overflow. 
Is this something that can be done with off-she-shelf hardware? 
I'd only remove the eave because I think it looks nicer, not for any technical reasons. A flyover would do the job just as well I think. Am I being silly and would be much better off just leaving the eave in place?

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## phild01

That gutter would have to be formed with flashing integrated and in such a way that prevents wind swept rain running into the framework.

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## r3nov8or

> I didn't know you could use a smaller angle with trimdek. How come? Does water flow off it faster?

  Trimdek has a taller ridge profile than corrie and is therefore less prone to water wicking up under the laps and has less deflection under heavy water load. Also the flats are supposed to be turned down at the low end which increases the angle and prevents wicking back under the sheet end (and turned up at the high end). Kliplok is even more robust and can go down to 1 degree (and is more expensive).

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## r3nov8or

> I'm thinking something like this, where the outer edge of the gutter would be a bit lower so that water flows on to the deck instead of back towards the roof tiles in case of gutter overflow. 
> Is this something that can be done with off-she-shelf hardware? 
> I'd only remove the eave because I think it looks nicer, not for any technical reasons. A flyover would do the job just as well I think. Am I being silly and would be much better off just leaving the eave in place?

  I think you are risking leaks with that design. The seal between the gutter and the green flashing will need to be perfect. If you are really set on this, either get the gutter and flashing formed in one piece if possible, or in two pieces with gutter wrapping over the flashing. This would by a special order at a place like Lysaght, Stramit or Striproll (in my neck of the woods anyway). No need to think "special order" is some sort of magic, tradie-only, place. It's common. Just take your requirements including all dimensions and angles. You WILL get what you ask for  :Smilie:   
Also remember with the gutter on top you will need to get up on the roof to clean it.

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