Wrong size fixings used on roof extenda brackets Hi all!
I’m doing a pergola over my deck atm and am using the roof extenda brackets. The house is double brick inside and out.
However, after fitting the brackets and sika flexing the flashings over the tiles, I have realised I used the wrong size bolts to fix into the top plate, and through the rafter.
The holes/instructions allow for m10s into the top plate, and m12s into the rafter. However I have used m8 coach screws into the top plate and m10 cup heads through the rafter.
It’s only a small pergola (about 2.7m x 4.5m). Will the roof rip off in a gust of wind if I don’t change those bolts? Just concerned about what happens re: insurance if it damages not just my own house, but also the neighbours :s
I’m guessing it wouldn’t hurt, also, to put some sort of fixing to secure the top plate to the brick wall it sits on top of (the house was built in the 1940s, not sure how well the roof is tied to the wall plates.
Ideally I’d prefer not to have to pull apart the tiles and redo the extenda brackets, as it will be a pain getting all the dried sika off the tiles to redo them, but if it’s a matter of saving myself the headache of the roof ripping off, then I’ll do it.
Any thoughts of advice would be much appreciated! Thanks everybody!
Per your other thread, it sounds like you have decided to put a roof on the structure. If so, it's not a pergola. It's a roof, a verandah, a fly-over, a patio cover etc... Just not a pergola.
I don't think anyone is going to tell you not to make it right, per instructions. Your concern about the tie-down to the bricks is also valid, so best you attend to that too. Don't be as concerned about insurance as about someone getting hurt, or worse...
Wrong size fixings used on roof extenda brackets You might be ok, it depends on roof area per bracket, wind classification, rafter timber hardwood or pine etc, most of it is in AS1684 but it will take some working though, about half as long as redoing it…
How many brackets have you used?
"A big boy did it and ran away"
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The roof will be about 2.5m wide (x 4.5 long). So there are 3 brackets over the 2.5m span , pretty much one every 2nd rafter, with about 200mm counter lever on one side (over the box gutter).Originally Posted by Moondog55
The rafters in the existing roof are definitely hardwood. It’s an old house
Even if there is some way I can tie it down more at a later date. I just think it will be a bit of a nightmare pulling up the sika-flexed flashings around the brackets. Will prob have to end up getting replacement tiles and replacement bracket flashings if so. But obviously if there is a risk that the whole thing will fly off, then I guess I gotta do what I gotta do.
Would it be simpler and cheaper to just add two more brackets with the correct bolts?
We had access to the inner walls when we did our flyover which made things a lot easier but these are supposed to be fixed to the full frame of a stud wall which then connects to the ground.
"A big boy did it and ran away"
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Yeah this thought did cross my mind after I finished building all the frame work this arvo 🤦@♂️ . I might try and see if it’s not too much of a nightmare to still put two more brackets in with the correct bolts. Then it will have a bracket on every truss/rafter of the existing roof.
And yes I did have a bit of a look to try work out how the top plate was tied to the brick wall that it sits on top of. I only had a quick look but couldn’t see any straps or anything. But surely it can’t just be sitting there without sone sort of fixing. I wonder if there’s a way I can put some dyna screws or something into the brick work without splitting the bricks. And surely the weight of the tiles would hold a lot of the roof down?
I think I’ll give the extenda bracket people a call, perhaps they can help me with the specifics. I realise that the instructions say what size fixings for a reasons, but I’m here now and if I can avoid pulling it apart that would be ideal. Given that it’s only a 12sqm roof with laser light on it in inner suburbs melb, hopefully that means it might be ok.
Thanks guys for the input so far!
That's a good idea. Explaining the wood is aged hardwood might work in your favour
Thanks mate
If it helps we used short bugle headed batten screws with washers on ours rather than 10mm coach screws, the hold down rating is about the same; either is so much stronger than the couple of old skew nails that are holding the rafter to the top plate in old construction, we predrilled too in 80YO hardwood
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This is a interesting topic.
I had to go through many years of study / practical to be legally allowed to build structures that are not only fit for purpose but are safe for the clients to use.
So many times I see on here and in real life situations where a DIY'R will build an inadequate structure that is not fit for purpose, some are still useable many need extra work and increasingly a lot are downright dangerous.
DIY quite often are not following the recommendations as set out by the manufactured product (such as this topic) because of inexperience, not reading the recommendations of the manufacturer or seeking advice from anther DIY'R who is considered an "expert" because they have built something.
Inevitably they build something wrong and then desperately look for a way to hobble it back together to make it safe without undoing something they have done wrong to correct it.
I am all for DIY to give it a go, but there are limitations where something structural such as a raised deck / pergola or any roof structure should really be left to someone who knows what they are doing as these things can end up collapsing or coming off in a storm, either damaging your own property or neighbours, or worse injure a person.
I find it amazing that the general thoughts of DIY'R is you can build whatever you want without the knowledge of how it should be built.
Quite the opposite in electrical or plumbing, you are not legally allowed to even replace a light switch with a new one (which is ridiculous IMO), even though it's very easy to isolate it and make it safe to replace, and there are only 4 small screws to do the complete operation.
Or you are not allowed to change an outdoor tap with a new one, again even though it's very easy to isolate the water, and remove / replace the tap, same as the switch, this is ridiculous rules.
But it seems accepted you can build a roof structure or a raised deck that has hundreds of areas for potential failure if not done correctly, much more potential to kill someone than either replacing a light switch or outdoor tap does.
I stopped offering regular advice to DIY'R some time ago, as I found most of the time you offer advice and they tend to ignore it, or they don't think you are being serious about what they need to do to rectify the problems.
Mieux vaut prévenir que guérir
I tend to agree Metrix, luckily I have a qualified mate to double check my work for me and I did buy the requisite manuals etc.
Re the bugles the advice is that for this purpose they are functional equivalents.
Regarding the OPs query; how are top plates on a double brick wall secured or is the weight of a tiled roof "enough" to stop uplift given the extra load an attached fly-over roof will place on the existing structure?
"A big boy did it and ran away"
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Definitely not just sitting there with the weight of the roof enough to hold it down, this would result in a lot of I have "misplaced my roof" problems during bad weather.
The basic system is with steel straps that are embedded into the masonry wall typically a minimum 900mm down the wall, these are then attached to the top plate with nails at given distances, typically every 1200mm.
It all depends on the N wind rating, the roof spans, the type of roof frame etc, heavy duty systems would be rods that are embedded into the slab then run up the cavity and attach to the top plate with an angle type bracket.
For something like a roof extenda, this is an "Engineered" solution, this means the system is guaranteed to perform as expected when installed to the engineering requirements of fixing sizes, weight limits, spans etc, if you don't follow the recommendations and an issue arises you won't have a leg to stand on because you didn't follow the manufacturers requirements.
For this one, does it matter the wrong fixings were used, I would say yes, because they are not the ones set out by the manufacturer, should they be replaced, I would say yes, but that's entirely up to the person who built it, if it's a hassle to undo Sika then there is the answer and most likely won't be rectified.
Undoing a mistake is a common lesson you learn when you DIY stuff you probably shouldn't be DIY, if you don't want to undo something that's wrong for whatever reason then you shouldn't start the job.
Will this one fail, I doubt it but I can't offer any advice as I'm not the person who installed it, I don't know the house, or the condition / construction of the house, so it's all arbitrary as every situation is different, hence why I don't agree with DIY'R building roof structures.
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Brings up another issue then. If the posts supporting the existing structure aren't set deep enough then that alone might make the roofing of this area unviable.
To the OP
When we had our roof done we had to go down a minimum of 1000mm in a 450*450 hole to satisfy the building inspector, needed to be this deep to resist upload; do your existing posts meet the minimum uplift requirements?
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And that depth depends on the situation, the type of soil, etc, I believe Melbourne is built on reclaimed wetlands ie Swamp.
So requirements to go deeper are not surprising, I believe it's what contributed to the flooding in the suburbs around the raceway recently, as much as everyone want's to blame the raceway for putting up a wall, the inherent problem is not the wall but the underlying natural watercourses before non indigenous interfered with this and started building low lying housing on it.
Most of Sydney is on Sandstone, that's where the old saying Sydney is built on Sandstone comes from, because there's so much of it, they have measured it up to 6km deep in various areas, that's a lot of sandstone.
So requirements here would be different to Melbourne.
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Yes to that if you live in the Western suburbs, especially around the racecourse area, some parts of Melbourne still have exposed basalt, it depends on what side of the river you are.
Only way to tell really is to get a geologist out and have a proper soil test done; not cheap sometimes, I can't remember what we had to pay.
"A big boy did it and ran away"
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Hey Metrix thanks for your detailed input. I agree with you completely on all of this.
For the record, I am a qualified carpenter, not a DIYr. Trust me, I am all for doing things right the first time round and as per engineering spec - prevention is better than a cure.
The mistake I made in this instance is that I had a mate helping me - who is also a qualified carpenter. I was busy doing the lap joints on the front posts, so I put him in charge of getting the brackets and fixings from Bunnings, and installing the brackets. However, after he had installed them (weather seal and all), I was looking at the receipt and the instructions on the back of the bracket packaging, and realised he had used m8 coach screws, and m10 bolts through the rafter. I asked him why and he said he thought the instructions said to use m8s and m10s. However obviously this is not the case.
And as I’m on my last weekend of Holidays before going back to work, I wanted to push on to get it ready for the roof plumber to come in, as I’ll be tied up with work till Easter.
However, after much thought, I think I have decided to leave it without the roof on until Easter when I can pull it apart and fix with the correct fixings: and also see if I can find a way to tied the top plate to the bricks better. Not sure how, as it’s a double skin brick wall. There might be a small cavity between the two brick skins, but no way I can fix hoop iron to both sides. If there is no way to do hoop iron, I’m hoping that doesn’t mean too bad roof extendas can only be used on stud walls or new build brick structures when there is still access to the bricks to be able to fix on both sides.
Yeah I built the deck with all the relevant council and building permits, and engineering requirements, when I renovated the house last year. The post holes had to be 1500 x 450x450 (500 mm concrete footing, post concreted in remaining 1m), as a result of the soil report test results. So with a bit of luck the posts ain’t going anywhere.
Given the size of (greater) Melbourne, "almost none" is an accurate estimate of how much began as swamp. "Inner West" basically covers it
The hoop iron should already be in there when the house was built, there is no way in hell you would ever get down the cavity to fix anything.
The hoop iron is embedded in the mortar as the walls are going up.
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