pergola fascia fixing - newbie

Hi everyone, im just a newbie to all of this and would like some info on putting up a pergola. basically the pergola is going to be roughly 3m by 7-8 mrts in measurement with a pitch roof and is going to covered with some sort of laserlite. I have colourbond fascias currently and have noticed that when i lift the roof tiles, that there is a gap between the end of the roof rafter and the fascia. I have bought the pergola design book from bunnings which helps and have researched also. My questions are:

1. Fixing of the pitch roof to the fascia - someone has suggested simply popriveting the joist hangers into the fascia and that would be safe as houses. I am not sure about that!. Could i simply attach a piece of timber onto the end of the rafter in the roof to get it touching the fascia so then i could attach a ledger timber beam onto the fascia which then i could attach the pitched roof onto? Is that the best way to go for me?

2. Since i am putting the posts up against the existing colourbond posts of my fence so it looks neater i have had to dig up around the old post as far as i can go, but depth wise im only 250mm deep but 350mm in lenght and width. Been told to simply fill the hole with concrete and put a post bracket onto it, instead of using a post stirrup and stickm that into the wet concrete.

Any advise would be of great assistance. Sorry if i seem a little on the amateur side.

Welcome to the madhouse. Ozizu.

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Originally Posted by ozizu

2. Since i am putting the posts up against the existing colourbond posts of my fence so it looks neater i have had to dig up around the old post as far as i can go, but depth wise im only 250mm deep but 350mm in lenght and width. Been told to simply fill the hole with concrete and put a post bracket onto it, instead of using a post stirrup and stickm that into the wet concrete.

Any advise would be of great assistance. Sorry if i seem a little on the amateur side.

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Before you worry about the facia lets start at the bottom. Your footing size is way too small. Minium specs would be 450X450X450 and 500 depth to bottom of hole

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Originally Posted by Tool-Horder

Before you worry about the facia lets start at the bottom. Your footing size is way too small. Minium specs would be 450X450X450 and 500 depth to bottom of hole

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i agree its the little on the shallow side but the mitre10 pergola brochure quotes a post footing dimension of 300*300 and 300 deep. But other internet resources quote anything from 250 to 900. Also want to go for the 90*90 posts since they look a little more smaller since my backyard is very small to say the least

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Originally Posted by ozizu

i agree its the little on the shallow side but the mitre10 pergola brochure quotes a post footing dimension of 300*300 and 300 deep.

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I just love a lot of these 'how to' brochures put out by various companies. I havn't read the brochure but by any chance are they talking about a true pergola with timber rafters only or rafters and batterns with no roof sheeting? Two majorly different structures as far as stresses and windloads go.

I dont know what your council requirements are down that way but a structure that size up here would require council approval and to meet the BCA regs. The footing is not just there to support the weight of the structure but in a situation like yours it is more to stop it flying away in the wind. Your neighbour may or maynot be happy when it lands in his yard .... guess it depends if it lands the right way up just where he needs it!:D

I've got to agree with Tool Horder on this. A pergola is a structure that has just beams and rafters with no roofing materials on it.

When it has a roof on it, it becomes a patio roof and comes under different stresses such as wind download and upload pressures and requires substantially larger footings. I don't know about Victoria but in NSW different councils have different requirements under their LEP's for exempt structures varying from 0m2 to 20m2.

You will need a building permit my friend.

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Originally Posted by Tool-Horder

I just love a lot of these 'how to' brochures put out by various companies. I havn't read the brochure but by any chance are they talking about a true pergola with timber rafters only or rafters and batterns with no roof sheeting? Two majorly different structures as far as stresses and windloads go.

I dont know what your council requirements are down that way but a structure that size up here would require council approval and to meet the BCA regs. The footing is not just there to support the weight of the structure but in a situation like yours it is more to stop it flying away in the wind. Your neighbour may or maynot be happy when it lands in his yard .... guess it depends if it lands the right way up just where he needs it!:D

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I agree i will need a permit. Also the mitro10 brochure gives out dimensions for the post footings if later on down the track i cover it up with laserlite etc so I assume there pergola is safe and strong enough for coverage later on down the track.

However my situation with the footing is that i already have a partial footing in the hole i want to put the post because of the colourbond post. I have simply dug around it at the front of it to get my 350*350 wdith and length. Half of the hole has got concrete already. The existing concrete in there starts rought 150mm below my concrete level and also takes up half the hole size. So essentially i was hoping this would be helpful to me and would avoid the need to dig somewhere else since there is a stable concrete footing in already. I hope i have made myself clear.I can dig up somewhere else and get a depth of 450mm but i didnt want too many posts in my backyard and was hoping 300deep would do. Could i possible make the depth and width bigger to maybe 450mm to compensate for the lack of depth. Also smy soil is heavy clay which I thought would help me out further.

Also was at bunnings yesterday and seen these fascia brackets which bolt onto the rafter and then come down and turn 90 degrees to be flush witht the fascia. Are these brackets a better alternative to putting a piece of timber at the end of rafter to support a ledger acrooss the fascia?

how big is the gap between the roof tiles and the fascia? if the colourbond fascia is not directly fixed to the trusses then i would not put rafter connections onto it. i have seen metal sheet torn by wind-loads where other members have been fixed. forgive my next question, but i must clarify - you are looking at the fascia, yes? not the gutter?

if you are fixing your patio posts to the fence posts then provided it is done properly, the patio will be structurally tied to the fence & should be sufficiently strong, granted it is a decent run of fence that is. that's not to say that it will meet regs though - in all likelyhood it wont if the fence is a shared boundary. and building right to the boundary, in canberra anyway, will give you grief in some instances with approval if you already have built right up to a different boundary (you can only have one 'zero-setback boundary' and i would say this is the case in other jurisdictions). you are getting approval, right? :U

what are your post spacings? what type of timber are you using? what about for your rafters? where are you in the world? what about the beam supporting the rafters,what type & size of timber is this?

these are the questions you need to be able to answer before a determination can be made as to whether your footings are sufficient.

r's brynk

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someone has suggested simply popriveting the joist hangers into the fascia and that would be safe as houses

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I'd hate to live in their house then. Hopefully they were having a lend of you because if that was a serious suggestion, then they need a good kick up the backside.

Seriously, if someone told you that and you even considered it, then you're out of your depth with this and I'd suggest you pay someone to do it. Honestly...

I wouldn't even be confident fixing through the fascia into the existing rafters, as the eaves overhang is often at the maximum allowable, and isn't rated to carry the extra load of another roof.
Selected rafters could be stiffened by attaching cantilevered steel angles to them before attaching a ledger to pitch the new roof from.

I want to put 5 posts of 350*350 at 300 deep which already have partial concrete in the hole with a post size of 90*90 pine. The post spacings will be 2.4mtres. Like I said earlier I can go wider and make the hole 450*450 and make sure the areas where there isnt that concrete bit is goes 450deep. The current colourbond fence is straight and the posts seem very secure.

The pergola i want to build is a 3metre by roughly 6 metre structure. It will be fully supported by the fascia connection on the 6 metre side. So width is only 3 metres. height to the fascia is about 2.5metres and the same goes for the post heights. The fascia ledger and the rafters were going to be 140*45 and the the main beams to be 190*45.

There is a 45mm gap between the end of the rafters inside the roof and the fascia flush, and yes im not talking about the gutter.

The fixtures I would like to install ontop of the pitch roof are mainly laserlite and any other light structures. I am doing a pitch roof because of my small minute backyard, I dont want a standard straight pergola roof since it will make the area look smaller. But i feel a pitch roof will make it look a little bigger and more roomy, better for air circulation also i hope.

The block has two single storey units with a common driveway for both. The pergola is on the front unit, and the current colourbond fence seperates my backyard and the thin landscaping and driveway. I know i will need permits from council but thats another story.

I think I'd be looking at hanging it off the wall. Or it could be free standing with an extra row of poles on the wall side.

when i did my pergola, i secured extra beams to my rafters using a bunch of bolts.
I then made my own bracket using 3mm steel (i think) that is based on the bunnings right angled one but was 3 times longer
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i then pulled the metal facia off and secured a beam of wood against the rafters and then put the facia back on.
The tin facia is not a structural part of the house so it must be reinforced. (this method was approved by my council)

the other way you can do it is those brackets that extend past the facia and gutter and create a mounting point for a new strutural facia for your pergola.

As for the fence posts If you want to do it aesthetically pleasing and what not and you want to do it right, can't you remove the section of fence around the posts (please say you don't have a good neighbour fence), remove the post, crack the concrete off with a sledge hammer, make the hole bigger and then cement both fence post and pergola post in the same enlagrened hole to the proper specfications. the work required to do this by yourself would only add a day overall to your schedule of erecting the pergola.
this was my facia support plans i submitted:
http://i139.photobucket.com/albums/q...oofsupport.jpg
this was my footing details i submitted:
http://i139.photobucket.com/albums/q...tingdetail.jpg

note this may or may not be over engineered as i did not use an engineer to design my pergola, i designed it myself and thought if i designed it to maximum specs then it should be fine to be approved (it was).
the general dimensions were 5 metres by 6 metres pitch roof in RHS steel.

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Originally Posted by silentC

I think I'd be looking at hanging it off the wall. Or it could be free standing with an extra row of poles on the wall side.

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I thought the external wall wasn't structural either....(although a damn sight stronger than the eaves i guess given it is already a downward force acting on it.)

What you are effectively doing (assuming you put a roof on it, which I gather is the intention) is altering the roof load width as it applies to the existing wall. If it's a truss roof, the existing roof load width is equal to half the length of the sloping part of the truss between the wall and the ridge plus the overhang. If it's a framed roof, well who knows without actually looking at it.

When you add this 'pergola' - which is really a verandah because a pergola doesn't have a roof - you are increasing the roof load width on the existing wall by 1/2 the length of your verandah rafters - in your case 1500mm. So the question is, does your existing frame support this new load width? Perhaps it does, perhaps it does not. If it's double brick, you're OK. If it's timber frame then you might be pushing the limit.

But they probably don't mention things like that in the Mitre 10 brochure :wink:

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I thought the external wall wasn't structural either.

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I know sod all about brick houses. I presume if it was brick veneer, then what you say is correct, in which case the rafters would be a better fixing point perhaps? Not sure.

For timber frame, the wall has to carry the weight either way, I just feel it would be a better fixing than the ends of the rafters. It's only a layman's opinion though.

good post barned01 - a stout design. a consideration is the concrete-set timber post will be a durability issue because the conc shrinks and leaves a gap around the post which creates a water trap. you must allow for suitable drainage at the bottom of the post otherwise the rot will set in at the base of your posts. alternatively you can use some post-anchors.

i think you should be able to enlarge the fence footing without disturbing the existing concrete as long as it is not 'crumbly' - just dig around and enlarge, also go deeper underneath - it will pay to put some large gluts under the bottom rail of the fence to keep it in place while the new footing goes off & you dig the soil back in. be sure to tamp the earth at the base of the footing well with something heavy, to minimise movement. maybe even jack the fence up slightly to allow for settling.

something else to consider - if you are fixing your posts to the fence then the rafter joint to rafter-support beam or rafter to house-rafter or truss must allow for some movement or it will resolve itself along the fenceline by pulling/pushing it toward/away from the house. your situation will determine whether this is an issue or not - i guess it depends on how much of a feature your fence is :roll:

silentc raises some good points about fixing to the wall & roof frame - certainly the code demands the span of the verandah be considered when designing the wall. it probably wouldnt be an issue for the wall itself - the issue will arise with openings in the wall. as the roof-frame is supported above openings by lintels, this will be your area of biggest concern; considering this and the above, you may be better off overall building a free standing structure that doesn't attach to the house or the fence.

r's brynk

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the issue will arise with openings in the wall

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I originally said "if you have windows or doors under the new roof" but I took it out, because even bearers are subject to RLW calculations. Again, if it's double brick, it's probably moot.

However if the existing RLW is within 1500mm of the maximum RLW used to determine any part of the structure, you could put the structure under-spec by adding a verandah roof to it. The point is, people do these things without considering the wider implications.

Just some extra piece of info regarding the proposal.

Soil is heavy clay, i can go wider to 450*450 post footing and go a little deeper to maybe 400 around the area the concrete base already is. Posts will be 90*90 treated pine at 2.4mt spacing. I specifically do not want to take out the existing colourbond posts and start from scratch since i have developped landscaping plants on the other side and in another area there is stencil concrete driveway. Too much work for my liking but still thanks for the idea.

The beams will be 190*45 and the rafters and ledger beam that attaches to the fascia with the use of a angled rafter bracket(i seen them at bunnings dont know the exact name) will be 140*45. Wishing to use laserlite on top of the pitched roof. There is a current 45mm gap between the fascia and the end of the rafter in the roof, which that bracket would fix by reinforcing the rafter so i can attach a ledger beam onto it. The brackets I assume would go on every rafter every 600mm i think. Also house is double brick.

The current colourbond fence islocated on the boundary so i know i must get a permit regardless which is another issue. Area is melbourne Hume city council.

Just wondering shall i use rapid set concrete bags or shall i make my own concrete mixture etc? Also as for the post brackets, since i cant fully deep in some areas, would it be wiser to concrete the hole and then fix different brakets (the ones that dont have a stirrup) onto the concrete with blue tip concrete bolts (not dynabolts bad experience). I know that the bottom of the post shall be protected from rust but these brackets elevate the post slightly which avoids that problem.

Hope thats some more info.

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Also house is double brick

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Good oh, ignore everything I've said then. Except the bit about the pop-rivets - that's just stupid :)

that 45mm gap between facia and rafter is the same gap i had, which just so happened to coincide with a statndard peice of 45mm thick pine that you see on all the building sites. if you can get that in thereand use those brackets to attach to the rafter and the peice of wood, then there is your reinforcing of the facia (i will see if i have a 3d picture of what i mean.....)
http://i139.photobucket.com/albums/q...ciasupport.jpg
i pretty much replicated that for every rafter i came to in the roof which i think was 7 in total, the theory being the load of the pergola would then be spread along all of them...note this was by far and a way the worst job of building the pergola.
if you didn't want to put the piece of wood behind the facia, there is another style of bracket bunnings have (although the version from olympic industries is better as it is sooooo much more longer) that allows you to put a new facia onto the house just past your gutters. this is an easier bracket to install and you don't have to fiddle around getting that piece of wood behind your facia....but then you have 2 facias and a void to fill between them, but that is how most pergolas are constructed if you look at a lot of pergolas already out there
http://i139.photobucket.com/albums/q...rgolasetup.jpg

and there is yet another bracket that goes above your structural wall and pops out through your roof, kind of like a stirrup to allow you to create a pergola that sits slightly above the existing roof but i can't remember how that one looks.

I personally am against rapid set concrete especially for something structural. if it was good stuff why wouldn't it just be called standard set concrete and the slow set stuff be taken out of the market completely.
Concrete cures over the space of several months and gets harder with each passing month. To have it set in 15 minutes plays against my understanding of concrete. sure it is harder to make everything square while you wait for it to set, but you feel good knowing you didn't use the 15 minute stuff :)
And if you go to the same section the anchor bolts are in you should find a set of chem set bolts which come with a test tube style system of setting compound.
Drill your hole in the concrete, place tube in hole, screw the bolt int othe hole effectively crushing the tube already inside, wait half an hour and you have a bolt that will be stronger than either a dyna bolt or anka bolt.

ps. Im not a builder but am just drawing on experience when i did mine and my house was brick veneer with truss style roofing.

Great info barned01. Answered most of my issues well. Definitely now going to not use rapidset concrete. Also the bracket you used from olympic industries, im assuming that wasnt from a bunnings store. The one i seen at bunnings is a pryda bracket for around $10. I have roughly 10-11 rafters to put these brackets on but hey, its better to be safe than sorry.

Im probably made my mind up about the post footing at 450*450 and digging down as far as i can go probably till 400mm. fill with hand made concrete, attach above ground post brackets with the post elevated. I basically got this idea from a chap who done his work http://jaw.iinet.net.au/projects/pergola.html

Even though his backyard is much bigger, there are some similarities with the colourbond fence and green posts and pitched roof. Especially the green lattice he used.

Once again thankyou Barned01

Your total uplift area on the posts is approx 9m2.
Work out the uplift per post i.e the end posts will have half the uplift load of the internal posts. Don't quote me [ it varies depending upon the designated wind gust speed ] but a 450*450*450 deep pad will cope with around 5m2 uplift.
the founding depth for load should be around 500mm - 800mm depending on the clay type. This is strictly speaking in regards to a house structure etc but I don't know of any 'leeway' in the reg's for a small verandah.
If the roof slope is to the boundary, the gutter has to be inside the fence line.
Termite treatment around the posts.

that facia bracket in the first picture is a piece of 2mm steel about 20cm long and bent to the right angle if you were to buy it from bunnings as you have seen (that pryda bracket you speak of).
This looked woefully underspecced so i just went down to my metal merchant and got a peice of 65mmx3mm (i think...could have been 5mm) thick strap.
i then got a hole cutting firm to punch some holes in it (50 cents a hole) and i welded the facing plate to the front of it.
So in all i ended up with 50 cm long strap with more holes than the bunnings one and also more rigid (by far). And funnily enough i think it came out to be cheaper than buying the equivalent number of straps from bunnings.

the second one (with the slight curve in it and a hole on each end of the facing plate) is the one you gan get from olympic industries...they are about 1.5 metres long at olympic but only around 45cm long at bunnings.
without seeing better pictures, these are the sorts of brackets i think that that person in the link you supplied would have used.

You have to consider all the forces acting on your existing eaves overhang.
barned01's diagrams don't completely address the fact that the eaves overhang is considered as a cantilever, and is usually allowed to be no more than 900mm depending on the specific circumstances. It could be as little as 450mm or less.
There are span tables here which give maximum eaves overhangs, and they don't make allowances for whacking an extra 3 metres of roof framing supported by the end of the eaves overhang.

This is what could happen if you're not careful by using a long and strong reinforcement method that cantilevers over and back past the load bearing wall which will eventually carry the loads from your new roof as well as the existing roof:

http://i7.photobucket.com/albums/y26...cated-01-4.jpg http://i7.photobucket.com/albums/y26...-Duplicate.jpg

The existing rafter may already be weakened by a birdsmouth cut out above the load bearing wall, and there could be significant additional tensional stresses applied at the top of the rafter at the same point, which could lead to failure if it's not considered in the design of any stiffening.

pawnhead:
the stiffening beams i placed in the roof go back past that point of the structural wall and fulcrum point (you can see the size and specifications i used on the first picture on the first page, 45mm thick x 90mm wide x 1.6metres long, although i ended up using 2 metre long beams instead and the wood was standard mgp10 or 15 that you find on a building site rather than F8...whether this was good enough, i guess time will tell).
i did that as because as you alluded to, i looked in the roof and thought that would be the weak point (my rafters had that cutout you speak of also).
so combining that with spreading the load over multiple rafters (connected via the hidden facia beam installed behind the aesthetic tin one) then the load share should have reduced sufficiently and pulled the stress point further inside the roof cavity (again this is using my own logic, i am not a builder, i did not get an engineers report, but my council did approve the plans as i submitted it to them and they do have an engineer on board to assess these things.)
also on one of my corners i did even install that triangulating beam as well using a piece of angle iron i had lying around. Although it wasn't on my council plans, i just did it for my own peace of mind.
but ozizu's is a solid brick home, so i don't know if that luxury exists in this instance of installing a triangulating beam. And i don't know if the external brick facia is considered structural or not to triangulate from that, when i did mine, i took it as it wasn't structural so left it alone.
also notethat those the new facia brackets i mentioned from olympic industries also extend past that fulcrum point which is why i recommended them over the bunnings ones which are a lot shorter and commonly don't extend deep enough into the roof cavity (i think they were 1.5metres long from memory of 5mm thick steel).

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Originally Posted by barned01

pawnhead:
the stiffening beams i placed in the roof go back past that point of the structural wall and fulcrum point

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I can see on your second diagram that it's stiffened by an extra piece of timber, and having this treatment on every rafter would be sufficient I'd say (but I'm a builder, not an engineer). I was merely pointing out that this point of weakness must be considered since it hadn't been mentioned anywhere. Those short Bunnings stiffeners wouldn't be up to the task IMO, and neither would those short stirrup type brackets unless there was no eaves overhang or the eaves support timbers form a solid triangle which braces the overhang horizontally back to the load bearing wall. But even in this case, I would at least nail some hoop iron strapping on top of the rafter, extending from the end of the rafter, well past the load bearing wall. This would help take up the additional tension placed on this weak point.

I'm simply saying that this point of weakness must be considered before placing any additional roof loads on the end of an existing eaves overhang. :wink:

I have never seen a pergola atached to the fascia cause significant problems to the rafters. I have however seen facias pulled off. I think barned method is well and truly overdesigned ( i am not an engineer either) For timber facias we generally accept a bugle crew to each rafter end and a joist hanger atached to the existing fascia. No rafter strenghthening required. If i saw something that changed my mind i would reconsider this. As you or all aware building surveyors and inspectors that are pioneers in not accepting tried and true methods become very unpopular quickly (not that we are popular in the first place)

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Originally Posted by thebuildingsurv

I have never seen a pergola atached to the fascia cause significant problems to the rafters. I have however seen facias pulled off. I think barned method is well and truly overdesigned ( i am not an engineer either) For timber facias we generally accept a bugle crew to each rafter end and a joist hanger atached to the existing fascia. No rafter strenghthening required. If i saw something that changed my mind i would reconsider this. As you or all aware building surveyors and inspectors that are pioneers in not accepting tried and true methods become very unpopular quickly (not that we are popular in the first place)

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I agree with that.

Spanline have been attaching Patio roofs to the ends of rafters for the last 18 years with Council approvals and have never lost one yet. Certainly not to metal fascia without some support back to the rafters but fixed certainly through timber fascia to the ends of the rafters as thebuildingsurv says. They have 1,000's of extensions all over Australia.

It all depends on how much weight you're going to put on the end of the eaves. I'm guessing that Spanline is a pretty light weight roof.
I wouldn't like to see this type of structure, weighing two tonnes by TEEJAYS estimate being erected without engineering and inspection (and possible strengthening) of existing eaves structure.

In a worst case scenario you may have a situation where a birdsmouth is cut one third of the depth of the rafter. The carpenters may have been slack, and simply overcut with a circular saw instead of stopping short and tidying up with a hand saw or recipro. The rafter would then be effectively reduced from a 90x45 to a 45x45. If they haven't pulled the birdsmouth tight against the load bearing wall, and there's a gap there, then the rafter is free to pivot downwards. If they haven't framed their eaves support back to the framework, but instead simply stopped it above the brickwork and nailed a vertical from the rafter down to the eaves support to hold it down, then there's no triangular support for the end of the rafter overhang and the rafter is free to sag at the end.

If someone doesn't check all of this and proceeds to attach deep long span rafters to a ledger attached through the fascia into the existing rafters, then there's every chance that it will begin to sag, and just keep going until something breaks.

Failures are very rare with the safety margins built in and I'm sure you could remove half the timbers in a house, and double the spans allowable and you still wouldn't have a collapse. It might be a bit springy to walk on, but I've walked on some very springy ceilings before any hangars have been attached.

One thing is for certain. According to the code, and the span tables, you would not be allowed to design a new home with a roof attached to the end of an eaves overhang without engineers approval. And I'm almost certain that he would suggest that the roof should be carried directly by the wall, or he would design extra support for the eaves overhang, above and beyond what the framing code calls for.

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Originally Posted by pawnhead

It all depends on how much weight you're going to put on the end of the eaves. I'm guessing that Spanline is a pretty light weight roof.
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John

That is true that Spanline is a light weight roof and when they construct it all the ends of the rafters are carrying is the roof and not any beams. Any beams that they may have in the structure are usually carried back to the wall such as on a gable in the middle of a skillion roof.

The one thing you have to remember when an engineer designs a roof the dead load is a secondary consideration. What they usually consider most important is the live loads which are created by the upward and downward pressure from the wind which is usually far greater than any dead load.

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What they usually consider most important is the live loads which are created by the upward and downward pressure from the wind which is usually far greater than any dead load.

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That's why I don't understand how they can accept a roof that is attached with hanger brackets and a few screws to the ends of the rafters. They go to great lengths to specify tie-down and then just let you go and do that. It makes no sense at all.

The other thing is that tie-down requirements for a roof are different when there is a verandah attached (what they refer to as Dimension "A" in the framing code). The dimension for tie-down on the external wall is half the span of the rafters on the main roof plus half the span of the verandah for a rafter roof, or half the span of the truss + half the span of the verandah for truss roof.

I suppose the saving grace is that in a big wind storm, that verandah roof would be torn off like the lid off a tin of sardines, leaving the main roof behind.

the biggest problem in this example is alot of weight is being supported on the creeper trusses at the ends that have hardle any (or none) backspan. For something like that i would feel more comfortable with post support. If a descent beam is fixed to the facia this can cantilever to make up the shortfall in the weak creeper trusses at the ends of a hip roof.