# Forum Home Renovation Pergolas, Gazebos, Strombellas & Rotundas  How to attach bearers to pergola posts?

## LuckyDip

G'day,
First time user occasional reader.
I am building a pergola and attaching a deck as well.
I have dug and concreted my footing pads for the pergola/deck for dyna bolted stirrups. I planned to install 3x125x125 TP posts. One at each outside corner and one in the middle, spaced 3m apart.  I plan to run 2x90x45 TP laminated for bearers between the posts.  I have footing pads between each post, so all up on the oustide I have 5 concrete footings .  How do i attach the bearers to the posts?  Do i notch into the posts, or bolt through the posts, or use hangers, or a combination of notching and bolts? 
Please help!   :Confused:

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## ringtail

> G'day,
> First time user occasional reader.
> I am building a pergola and attaching a deck as well.
> I have dug and concreted my footing pads for the pergola/deck for dyna bolted stirrups. I planned to install 3x125x125 TP posts. One at each outside corner and one in the middle, spaced 3m apart.  I plan to run 2x90x45 TP laminated for bearers between the posts.  I have footing pads between each post, so all up on the oustide I have 5 concrete footings .  How do i attach the bearers to the posts?  Do i notch into the posts, or bolt through the posts, or use hangers, or a combination of notching and bolts? 
> Please help!

  
Yes, use a combination of notching with bolts. Take 45 mm out of your posts.

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## METRIX

Hi LuckyDip, can you tell me the spec of the pergola, I have done a few calculations and 90x45 laminated may not be strong enough for the spans you want, [this depends on the depth of the pergola and roofing material] 
Can you answer the following and I can give you a timber recommendation, FYI using a single larger beam is easier than using 2 smaller ones laminated. 
firstly are you referring to the bearers for the deck ?, or are you referring to the main beam to hold the pergola up ? on the posts 
The below questions are relating to Pergola, if this is what you are referring to. 
The total length is 6m ?, [so 3m between posts] 
What type of roofing are you putting on it  ? 
What distance is it from the house , ie: what is the depth of the pergola. 
What will the rafter spacing be ? 
How are you attaching it to the house 
Do you have a sketch you can upload 
Also what sized footings did you make

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## LuckyDip

The pergola and deck is 6800mm accross the back of the house and 3600mm perpendicular to the house.  The roofing will be laserlite or corrugated iron.  For the rafters i was going to use 190x45x3600 KD, spaced at 900, coming off a ledger beam attached to the house with hangers, but have been advised to use treated pine.  What do you think?  Not quite sure as to the size of the beam that the rafters will sit on that is between the outer posts.  The outer posts are 3000 apart fitting in stirups on concrete pads that are 400 dia x 600 deep.
Any suggestions welcome.  Refer to sketchSketch.pdfSketch.pdfSketch.pdf

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## LuckyDip

Sorry for the multiple sketches.  They are all the same, copied 3 times.

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## METRIX

Hi LuckyDip, the sketches look good. 
If you don't mind I have a few suggestions after looking at them, firstly I would remove the guttering from the old roof and put a flashing in here and allow the water from the old roof to flow onto the new roof, and put a fascia and gutter on the new roof, its not always a good idea to have gutters half way between roofs in case of overflow etc, this is a simple job to ensure waterproofing. 
If you cant or don't want to do it this way, then ensure your battens are low enough on the new roof to allow the new corrugated sheets to sit tightly under the gutter, a flashing which goes from the old fascia onto the new roof would be a good idea as well. 
Another alternate is keep the level of the new roof in line with the old roof, put the new sheets directly under the old ones and move the gutter to the end of the new roof. 
For Timber, the figures below would be suitable for Wind Speed N2 and Region A&B, and a roof Dead load of 30kg/m2, this will allow enough structural strength for corrugated roof, and if you decide to insulate and put 10mm gyprock on at a later stage it will still be good for that. 
Figures based on sizes specified, 6800 long with three posts spaced at 3400, distance from wall of 3000 [RLW of 1500] You said you would be using 3600 timbers, I would allow around 400 overhang and attach your new gutter to this, or just let the rain run off if this is what you are after, but I would still allow around 400 overhang. 
I have decreased the rafter spacing to 760 because if you decide to use Poly roof such as Laserlite, spacing them at around 760-780 allows you to disguise the joins in the sheets on top of the rafters. 
At 900 spacing you would need 9 rafters at 844 centres including the end ones, at around 760 spacing you require 10 rafters at around 750 centres. 
Timber for Veranda Beam [Single span because 6800 is too long for stock timber and as you will need to join it at the middle post] 
For 760mm Rafter Spacing
MGP10 TP 190x45 7mm deflection, 85% load capacity
MGP10 TP 240x35 5mm deflection, 57% load capacity
MGP10 TP 240x45 4mm deflection, 45% load capacity
Smart GL18c 150x65 2mm Deflection, 22% load capacity [you can do this in one continuous length] 
For 900mm Rafter spacing
MGP10 TP 190x45 7mm deflection, 86% load capacity
MGP10 TP 240x35 5mm deflection, 66% load capacity
MGP10 TP 240x45 4mm deflection, 52% load capacity
Smart GL18c 150x65 2mm Deflection, 22% load capacity [you can do this in one continuous length]  
Timber for rafters [based on 3000 span and a 5Deg roof pitch, Wind Speed N2 and Region A&B, and a roof Dead load of 30kg/m] 
Rafter Spacing 760mm
MGP10 TP 140x35 7mm deflection, 69% load capacity,
MGP10 TP 120x45 9mm deflection, 86% load capacity 
Either timber is perfectly within the standards but I would choose the bigger sized timber. 
Rafter Spacing 900mm
MGP10 TP 140x35 8mm deflection, 78% load capacity
MGP10 TP 120x45 10mm deflection, 97% load capacity [don't use this as it's too close to its limit]. 
If I was building it I would go for 140x45 for the rafters again because 45mm timber takes to skew nailing better than 35mm, and price difference is not much, 
Rafter Spacing 760mm
MGP10 TP 140x45 5mm deflection, 54% load capacity 
Rafter Spacing 900mm
MGP10 TP 140x45 6mm deflection, 62% load capacity 
I hope the above figures give you an idea of which timber to choose, at the end of the day it depends on your needs and budget, we always over engineer the timbers in our pergolas / decks to be safe. 
A few extra notes, You will need to put a row of solid blocking down the guts of the rafters to stop any twisting of them, keep these in a straight line for aesthetics [see picture below] 
When you use the Joist hangers, skew nail the rafters into the ledger FIRST from both sides, then attach your hangers afterwards, and ensure you use PRYDA Timber Connector Nails and not ordinary clouts to attach these, ordinary clouts can snap their heads off if pushed to their limit. 
To join the timber to the posts, notch out 45mm [or 35mm if you choose the 35mm beam] from the post for the height of the chosen beam, so the beam sits tightly in the notch and use M12 gal cup head bolts with washers on the backs to join them. 
If you have any further questions relation to the above or other please ask away.

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## LuckyDip

Thanks Metrix, 
A lot to digest.  I will consider the options and let you know which way im going.  Im sure there will be more questions. 
Thanks again,
LuckyDip

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## LuckyDip

I like the idea of running the new roof under the old roof but am concerned with the total roof area being collected into the one gutter.  Is there a standard or way of calculating the total roof area for the amount of guttering and downpipes? 
You listed the verandah beam could be "Smart GL18c 150x65".  Can you explain what this is.  I am not familiar with this. 
Also you list the differents size timbers with deflections at a specific load capacity.  Eg. "MGP10 TP 190x45 7mm deflection, 86% load capacity"  Can you give an explanation to this and why is it not calculated at 100% load capacity.  My thinking, which seems wrong is if for "MGP10 TP 240x45 4mm deflection, 45% load capacity", if you double the load capacity to 90% you would get double the deflection (8mm.).  This seems very close to the 190x45 MGP10 TP.   
Im trying to get a better understanding of what it all means. 
Thanks,
LuckyDip

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## shauck

> I like the idea of running the new roof under the old roof but am concerned with the total roof area being collected into the one gutter.  Is there a standard or way of calculating the total roof area for the amount of guttering and downpipes?

  Check out this PDF. May have answers for you.

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## METRIX

Hi Luckydip. 
The idea of running the new sheets under the existing sheets is a much tidier idea, if you read the document shauck put up there it will explain it for you. 
Basically the amount of downpipes you need are determined by where you are located [annual rainfall and 100 year max rainfall], and the amount of roof area etc, this determines if you need 1, 2 or three downpipes. 
Re the timbers you asked about, Smart GL18 is part of Tillings SmartLam product range, the is a type of manufactured or "Engineered" timber, GL18 is basically small pieces of Hardwood glued together to form a very strong and perfectly straight beam, which for it's dimensional size is stronger than an equivalent solid timber usually used in pergola / deck construction, GL18 is actually stronger than the commonly available LVL15. 
I mainly put these in just for a comparison and for most normal designs GL18 is overkill, usually a correct sized MGP10 TP will do the job perfectly well. 
We tend to use GL18 when clients want large openings and don't want supporting poles obstructing their view, as a GL18 can span much further than say a piece of MGP10 of equivalent or larger size, you can space the poles further apart, GL is also Dressed and primed ready for painting, See below file for more information. 
Re the different sized timbers, Load capacity and deflection I mentioned, The Load capacity is what the timber is able to safely support with a particular load on top of it, As an example I mentioned the figures given were based on the following,  *Timber for rafters [based on 3000 span and a 5Deg roof pitch, Wind Speed N2 and Region A&B, and a roof Dead load of 30kg/m]*
What this all means is the rafter span is 3m in length, The roof is at a 5 degree pitch [usually for skillion 5 deg is normal], Wind speed is N2 and for Region A&B, you need to determine how strong your structure needs to be depending on your location in Australia so it will resist being blown away by the winds your area is expected to have. 
The more you move North the higher the expected wind speed is due to entering cyclonic regions etc, this goes towards determining the sized of timbers you need to use, and the type of hold down fixing your required to fit, to ensure the structure will stay where you put it, and not end up falling down. 
A lot of people don't take these things into consideration when designing a Pergola or deck etc and may under engineer these structures which can pose a danger to yourself or family if something fails.   
We build a lot of these structures and all are required to have Construction Certificates, issued by the local council or independent certifier, all our designs are scrutinised by the certifier / Engineer BEFORE we can commence building it, this way it has been checked to be strong enough for the intended purpose. 
 Anyway that is the official process, but many people will just build them without approval or certification, this is not a problem as long as you build it to code and is it engineered to do the job intended and not pose a safety hazard, but this can be hard if you don;t actually know what to look for when designing such a structure. 
The Figures you asked about for Deflection and capacity, Eg, To determine the deflection figure for the Veranda Beam you need to know the length of the rafters which will be resting on it, the angle these are coming into the beam, what type of roofing material you have [both internal and external], this will all add up to a particular load rated in kg/m2. 
So when you complete your structure and load it up with roofing material, internal ceilings etc, your beam will deflect downwards by the figure, obviously the lower the figure the better and the more rigid the structure will be, say you had a beam which had a deflection of 25mm when loaded, this is a fair amount of deflection and I would rethink the design and keep the deflection to around 5-10mm. 
The rating for "Capacity" is when the structure is fully loaded eg, with roof material etc, this is the amount of capacity [or holding strength] you wil have reached for that particular timber size, with this less is better, say you design a pergola and you have reached 98% holding capacity for the particular sized timbers, as long as this is within the Minimum Australian Standards, then there is no problem, but again when you build these for other people you would never design anything to be at minimum, for us we would usually choose timbers based on 60-70% capacity, this leaves you with a lot of extra strength in case needed for the future. 
Example, I can design a structure to minimum standards to have a poly carbonate roof and choose timbers to be at around 95% capacity and this is perfectly ok, if it abides by AS codes, problem is, the client may sell the house in a few years, and the new buyers hate the polycarbonate roofing, and decide to replace it with Colorbond and insulate the ceiling, then put up some gyprock internally, all of a suden you have exceeded the "Safe" capacity of the timber and things will start to go wrong soon enough. 
This is why I designed yours with a 30kg/ms, this allows you to fit an internal ceiling and insulate [lightweight insulation] at a later stage and you will still be safe knowing the structure is still within design capabilities of the timbers. 
I hope this explains some of the figures given, As I said in the post at the end of the day, it's your choice of how you want to design the structure, as long as it abides by Minimum AU Standards, and is suitable for the job then this is ok,   
The cost of timber is relatively cheap to go up to the next size and "over engineer" the structure, this is a lot safer than having it fall down and cause many $$ of damage, or worse still hurt someone.
If you still have question please ask. 
Regards

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## LuckyDip

Thanks for all the info. 
I have decided on running the roofing sheets under the guttering off the existing house.  It would be difficult to run another downpipe off the pergola as there is no fall and the guttering and down pipe has already been replaced on the house.
I have been able to source 140x45x3600 KD hardwood and will use them for the rafters spaced at 900mm.  Do i use the same size timber for the ledger board on the house, or larger piece, or pine??  I also need a ledger for along the house for the decking.  Is that the same scenario, size and type? 
thanks,
LuckyDip

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## METRIX

Hi LuckyDip; 
Do you know the "F" Rating for hardwood you can source ?, as this makes a big difference if it is suitable, hardwood is rated in F numbers, Pine is rated by MGP numbers, Pine also has a "F" rating but the norm is to quote the MGP rating for pine. 
Figures below are given for your scenario of length 6800, depth 3600, Rafter spacing 900, overhang of 400 per side, Roof load 30kg/m2, remember the roof load is based on what you are actually putting on the roof both internal and external, . 
30kg/ms will allow you to have 0.75mm Steel roofing sheets, up to 13mm gyprock and insulation, if you are only ever intending to have polycarbonate then you can drop the roof load to around 10kg/m2, but it is better to look to future requirements rather than minimum requirements. 
Bear in mind HW weighs a lot more than TP, so if you are using HW rafters there will be a lot more weight on the ledger and veranda beam even before you install any roofing material, in comparison to using TP rafters, so the figures may not be accurate, Choosing HW rafters could easily add another 10kg/m2 weight in comparison to using TP. 
I will provide you figures for 30kg/m2 roof load. 
 KD HWD 140x45 *F11*, load to around 70% but if I up this to 40kg/m2 to theoretically allow for HWD Rafters then the load capacity goes to 91%
 KD HWD 140x45 *F17*, loaded to around 52%, at 40kg/ms 68%. 
 If you go up to a F11 170x35 KD HWD, at 30kg/m2 loaded to 50% and at 40kg/m2 loaded to 65%. 
If you want to use TP as the ledger, then a piece of MGP10 190x35 is suitable and rated to 76%, again using HW rafters the extra weight could be 10kg/m2 more so the same piece of TP with a Roof Load of 40kg/m2 is loaded to 92%.  
As you can see you need to know exactly what timber you are intending to use, with dimensional sizes and either F or MGP ratings, and what you are actually intending on putting as the roofing, and future needs, these all tie in to give you the correct timber members to use. 
Unless you have a specific need for HW, or it is a lot cheaper than TP, I would just recommend to stick to TP as it is an easier wood to work with for a novice [as a general rule], but if you are after a particular look, possibly dressed HW to be stained or oiled, then by all means go for the HW, bearing in mind the extra weight of the timber will affect the ledger sizes to use. 
In regards to your deck ledger, do you have a design of the deck, as this is altogether another ball game. 
Type of timber [HW or TP for sub structure] length, depth, design you want to use, [Deep joist or joist and bearer], bearer spacing, post spacing, if you can provide more details I will see what i can work out.

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## shauck

> I also need a ledger for along the house for the decking.  Is that the same scenario, size and type? thanks,
> LuckyDip

  There are different span tables for deck subframe. It serves a totally different purpose to a roof. The design is also very different.  
For example Using F17 Seasoned Hardwood 140x45 (20kg/m2) for deck joist spaced at 450mm, maximum span is 3400mm. If you use the same timber for rafters (20kg/m2) spaced at 450mm (not typical spacing for rafters but for comparison), maximum span is 5000mm.

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## LuckyDip

Thanks for all the advice.  All this thinking is keeping me awake at night.  Not good for the health, but enjoying it. 
I've changed plans again.
Ledger and verandah beam 190x45 F7 TP, beam spanning the verandah posts 3m.
Rafters 140x45 F7 TP spaced at 900mm with solid blocking down the middle as suggested (looks good in the pic).
Verandah posts 115x115 Cypress pine, mounted in stirrups, 3 off 1500 apart.
Battons have not been decided but thinking of high enough to run the guttering on top of the rafters and not off the end.  And on the overhang putting a decorative cut on the end of the rafters.
Polycarbonate roofing. 
Decking
I have footings already put in which are spaced at 1500mm.  400 dia and 600 deep. Ref PDF above.
Bearer 1 running parallel to the house 90x45x2 or 90x90 F7 TP running between the outer posts, 3m from the house, notched 45mm into the posts and bolted and supported mid way between the posts, spacing 1500.
Bearer 2 running parallel to the house, 1500 from house, supported on stirrups, 5 off. As above 90x45x2 or 90x90 F7 TP
Bearer/ledger - 3m against a single layer of bricks and 3m not against bricks. The area not against bricks is where the back door and windows are. Bearer to be 90x45x2 or 90x90 F7 TP.  The area along the brick wall to be a ledger, dyna bolted to the single layer of bricks.  
What size should the ledger be?
Joists to be 90x45 F7 TP spaced at 450mm with TP decking on top. 
??
I have a tap and drain against the brick wall.  I do not want to remove the tap and drain but am unsure of how to incorporate the drain into the deck.  I was thinking of putting in a drain sump (maybe incorrectly named) like what you would put at the end of a channel drain across a driveway.  Mounted flat into the decking.
Any suggestions??  
Thanks,
LuckyDip

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## shauck

> ??
> I have a tap and drain against the brick wall.  I do not want to remove the tap and drain but am unsure of how to incorporate the drain into the deck.  I was thinking of putting in a drain sump (maybe incorrectly named) like what you would put at the end of a channel drain across a driveway.  Mounted flat into the decking.
> Any suggestions??  
> Thanks,
> LuckyDip

  Hmmmm. Maybe some kind of sink in a style that suits, set low, so water can't splash up out of the sides and onto the decking. If you can see a way for it not to look too weird. Or an outdoor bbq/kitchen area. Hard to say, without seeing the area or knowing your lifestlye/uses for the area. Just a crazy idea perhaps.

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## LuckyDip

I just had a read of *fascia fix - ?? rafter stiffening* and am now thinking of how i am going to attach the ledger for my pergola to the back of the house.  The wall is blue board and underneath there are 2 lintels that running the majority of the way along the back of the house which i am going to attach the ledger.  One lintel is 230 x 45 x 3600 above back door and windows and another that is 190 x 45 x 3000 above a kitchen window.  I was going to use timber screws 14g x 100 Type 17 to hold the ledger to the rear wall.  After reading the above forum i have doubts if this is ok.  I do not have access to run bolts threw the lintels from the inside unless i remove the newly installed plaster, which i really dont want to do.   
Is the timber screws 14g x 100 Type 17 ok? Or is there and alternative to attaching the lintel? 
Also what length dyna bolts do i need for attaching the post anchor bolts downs (stirrups) to my concrete pads?
What length does the dyna bolt need to go into the bricks for the ledger on the decking? 
Thanks
LuckyDip

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