Diagonal Bracing

[Boulder Block]

Hi everybody! I've enjoyed lurking here for a while but now I'm ready to add a question. I'm about to re-clad a very old tin roof. The section I'm working on is the steep-pitched part of an old miner's hut, it's above the two main rooms that made up the original house.

I'm all set to do the job but I've noted a lack of bracing. At either end of this roof there are gables with queen posts, everything else has no kind of bracing between the top and bottom chords. There is one timber diagonal brace running from one end of the roof to the other. So a few questions arise:

Is this adequate?

Would there have only ever been one diagonal brace?

If bracing needs to be improved would it make sense to add something like strapping or speedbrace for diagonal bracing at this re-cladding stage, rather than timber inside the roof later?

About the roof:
1919 Miner's Hut
100 year old jarrah framing
Wind Class - N1
Span - 3.77m
Length - ~8m
Pitch - 40 degrees
3ft between 1 3/4" thick rafters

If this is a bit too specific and technical for a forum, does anyone know where I could get some advice? I'd be especially interested in advice specific to old homes.

I'm looking at buying the NCC volume 2, but I'm not sure I'll get the answers I need out of it anyway.

[rambunctious]

Is what you have adequate ?, yes, by the standards of yesteryear but not by today's standards, which seem to change at the whim of the public service (govmint)
And fwiw I have not looked at standards in a lot of years.
Strap it for your own peace of mind.
But be warned, at some point while screwing the roof you will hit the strap and have fun getting the screw through.
Best to drill a hole in the strap (should you be so unlucky to hit it) to get the screw through.
Hope you are using an insulation blanket under the sheets, well worth it.

[r3nov8or]

Yes, you should add bracing. It's cheap insurance. It needs to be attached to rafters, so run it under the battens and you won't have any hassle hitting it with roofing screws. You may need to lift the batten where it crosses a rafter here and there, but choose a run which minimises that hassle. Fix the brace at each rafter crossing.

[Boulder Block]

Thanks for the advice guys. Yes, I will be adding some insulation to bring that up to scratch. Also yes, I would be putting the bracing under the battens, since I need to replace the battens anyway, some are pretty tired. Cheers! :2tsup:

[jack620]

I would be putting the bracing under the battens, since I need to replace the battens anyway…

In that case I’d be using speedbrace. Just a moment... (https://www.bunnings.com.au/carlray-5-0m-tension-roof-brace_p1095561)

[Boulder Block]

Yes, I was looking at a different brand of the same thing. I'd have to get whatever the local building place stocks, Bunnings don't stock anything suitable here.

[ian]

Boulder Block
A number of questions for you:

is the 1919 miner's hut heritage listed?

do you have a requirement to bring the roof of the building up to the current building code?
If yes, it would pay to know what the current code requirements for the roof are before you begin working on it.

will the building you are working on be insured for risks that a roof not up to code would result in the insurance being voided?

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Yeah, I know PITA type questions

[Boulder Block]

Thank you for the PITA questions Ian, they are the exact sorts of things I've been thinking about.


No heritage listing on this property. I've recently discovered it's probably a fair bit older than 1919, but there are so many old properties in our charming time-capsule of a town the heritage folk are spoiled for choice and this example is not flash.


What I want to achieve is to replace old roofing iron with Colourbond (it's so old some of it is literally iron, not steel). I've read the following and it's pretty straightforward:


https://www.commerce.wa.gov.au/sites/default/files/atoms/files/217163_changing_your_roof_cover_web_0_1.pdf


https://www.commerce.wa.gov.au/sites/default/files/atoms/files/ib_053_roof_cladding_1_0.pdf


What is less clear to me is what my opportunities might be at this stage to improve things to prevent future problems.

So to answer the question, no I don't have any particular reason to bring the roof up to code. Only the new covering has to be installed to current standards.



My overall goal for the house is improvement, not perfection. She's a very cheap house that has already been vandalized by previous owners (and squatters on meth!). Some of it I can undo, some of it I'll have to put up with, and some of it I'm unsure about.

[ian]

Thank you for the PITA questions Ian, they are the exact sorts of things I've been thinking about.

No heritage listing on this property. I've recently discovered it's probably a fair bit older than 1919, but there are so many old properties in our charming time-capsule of a town the heritage folk are spoiled for choice and this example is not flash.

What I want to achieve is to replace old roofing iron with Colourbond (it's so old some of it is literally iron, not steel).
given that steel making was industrialised in the 1860s, I would be more than most surprised if the original "wriggly tin" roofing was NOT originally galvanised steel.


I've read the following and it's pretty straightforward:

https://www.commerce.wa.gov.au/sites/default/files/atoms/files/217163_changing_your_roof_cover_web_0_1.pdf

What is less clear to me is what my opportunities might be at this stage to improve things to prevent future problems.

So to answer the question, no I don't have any particular reason to bring the roof up to code. Only the new covering has to be installed to current standards.
as I read that "changing your roof cover reference, what you must do with the old building is
1. ensure the roof is tied down to the building frame in accordance with the requirements of the current building codes, and
2. ensure the building frame is properly tied down to the building's foundations in accordance with the requirements of the current building codes. Doing the later might require the construction of new foundations, or the driving of ground anchors strong enough to resist the building being plucked off its foundations in code specified winds.

[jack620]

Doing the later might require the construction of new foundations, or the driving of ground anchors strong enough to resist the building being plucked off its foundations in code specified winds.

As if anyone is going to do that for a resheet of the roof of a 100+ year old miner’s hut.

[Boulder Block]

I see things like straps tying rafters down, and I'm unsure how old they are. There has been a time where some professional-looking roof replacement has been done on a portion of the roof, so it's possible there were some upgrades then. That's the sort of thing I need an engineer/builder to have a look at in person. It's also another reason why I don't want to change anything like weight, pitch, profile, etc.
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There is quite a story behind the wriggly tin, if you are interested...

I went to see the council to find any information about my house. They had 1919 as a date for the building and nothing else. The councils of Kalgoorlie and Boulder amalgamated in 1989, and they lost all the records for Boulder in the process. I've since found the original homeowners advertised a boarding situation at that address in a 1901 newspaper. With that, and other observations, I think the original home was two-rooms (and a verandah or two) built between 1899-1901, and had an iron roof and hessian walls, like many at the time. I think 1919 could have been the year it was clad with fibro and extended.

The oldest-looking iron on the roof has a Redcliffe trademark on it. A researcher who has written about the history of the brand has identified different versions of the trademark stamp. The version on my roof corresponds to corrugated iron manufactured between 1881-1895 at the Redcliffe Crown Corrugated Iron Company in Bristol. This company sourced its materials from iron mills with the same owner.

The owner of these companies, Joseph Tinn, was focused on expansion by buying up and leasing old iron mills in spite of the impact of emerging steel technology. From 1893-1895 there was a depression, and at the same time, 1884-1885, the sheet trade transitioned to steel. Without enough capital left to modernize he was forced to file for bankruptcy in 1895. When assets were sold off, only the goodwill and trademark of Redcliffe was purchased by John Lysaght Ltd. in 1895. They had no interest in buying any of the physical assets since they were old ironworks, and they'd already invested in a state-of-the-art facility at Newport, which opened that year. They manufactured corrugated sheeting, marketing Orb as the premium, and Redcliffe Crown as the economical second choice. Although the newer product is a different one the Redcliffe stamp they used looks very similar to the old ones, so it looks like the same thing at first glance.

If anyone is interested in the paper I got all the information from it's available to download here:
Just a moment... (https://www.researchgate.net/publication/287533307_Redcliffe_Crown_Corrugated_Iron_in_Australasia_A_survey_of_its_history_marketing_and_distribution_1875-1921)

[ian]

as I read that "changing your roof cover reference, what you must do with the old building is
1. ensure the roof is tied down to the building frame in accordance with the requirements of the current building codes, and
2. ensure the building frame is properly tied down to the building's foundations in accordance with the requirements of the current building codes. Doing the later might require the construction of new foundations, or the driving of ground anchors strong enough to resist the building being plucked off its foundations in code specified winds.

As if anyone is going to do that for a resheet of the roof of a 100+ year old miner’s hut.
Boulder Block essentially asked what he needs to do to when replacing the sheeting on his miner's cottage.
The reference BB supplied requires that when replacing the roof material, the person doing the resheeting must ensure that the roof structure (rafters and such) is tied to the building frame in accordance with the current building code.

My recollection is that the current building code (post 2020) require that not only the roof structure be tied down to the building's frame, but the building fame itself be tied down to the building's foundations [and that the foundations themselves be structurally sound].
This requirement -- tying down to a structurally sound foundation -- is to prevent the building being lifted off its foundations in the design wind.
Doing this later bit, tying down to the foundation, often requires a number of ground anchors be installed.


The difficulty of doing all that is a major reason why old buildings like Boulder Block's miner's hut typically fall down through neglect or are demolished rather than restored.

[ian]

I see things like straps tying rafters down, and I'm unsure how old they are. There has been a time where some professional-looking roof replacement has been done on a portion of the roof, so it's possible there were some upgrades then. That's the sort of thing I need an engineer/builder to have a look at in person. It's also another reason why I don't want to change anything like weight, pitch, profile, etc.
good thinking.

[jack620]

My recollection is that the current building code (post 2020) require that not only the roof structure be tied down to the building's frame, but the building fame itself be tied down to the building's foundations [and that the foundations themselves be structurally sound].


That's not just a requirement of the current edition of the National Construction Code, it was required in the old BCA for decades. That's not in dispute.



Doing this later bit, tying down to the foundation, often requires a number of ground anchors be installed.


My reading of the documents Boulder linked is you are only required to obtain a building permit and upgrade the roof tie-down (in WA) if you are changing the type of roof cladding. Replacing metal with metal should not require this. A call to the local planning authority will clarify that. Of course, it would be prudent to upgrade the tie-downs where feasible, but with a metal-for-metal replacement, I don't believe it's a requirement.

[r3nov8or]

My reading of the documents Boulder linked is you are only required to obtain a building permit and upgrade the roof tie-down (in WA) if you are changing the type of roof cladding. Replacing metal with metal should not require this. A call to the local planning authority will clarify that. Of course, it would be prudent to upgrade the tie-downs where feasible, but with a metal-for-metal replacement, I don't believe it's a requirement.
The documents also says...

Even if you are replacing an aged roof covering with a like-for-like material, it is important to check the roof condition.

Need to remember that the metal sheet today is thinner, so lighter, than what it is replacing, and the screws, will provide far better hold than (presumably) the original capped nails, all leading to a greater possibly of losing the whole roof, rather than a sheet or two. The tie down starts at the battens, which may simply have been skewed nails in the old days.

[Beardy]

The building has already stood the test of time regardless of what current documentation says, when I started in the building trade we used a hammer and nails to build structures that are still standing today but now the same style of structure requires triple grips and screws etc to stop it falling down these days according to a piece of paper.

By all means add any additional support you think is necessary and check the condition of existing fixings like nails that may have rusted out but I would be reluctant to fit any modern products that will be visible to ruin the original appearance of the building.

[BMKal]

Our place was reportedly built in 1910 - we're on the opposite side of town to you, close to the hospital. I have replaced the sheeting on some parts of the roof. I found that the original jarrah was pretty strong and did not need any additional support / bracing, but it is impossible to drive a nail into it. You can't even drive roofing screws into the stuff without pre-drilling a pilot hole for every screw.

Ours was probably originally a miner's house too, with two bedrooms and a loungeroom in the front half of the house, with small kitchen / dining room at the back - outside laundry and toilet. The external cladding was originally the very fine flute corrugated iron - there is still some of it behind the gyprock cladding that has been installed over it where the verandah's were enclosed and turned into bedrooms. The outside of the house has since been clad with some sort of fibre cement boards with a fake "wood grain" finish, which is pretty common on houses around here. We also still have a very high pressed tin ceiling in the old part of the house, though it now has a more modern suspended ceiling below it. The house is now 5 bedroom with two inside bathroom / toilets, one of which also has a spa. The original verandah has been enclosed at the front and up the sides of the house, and the back of the house has been extended at least twice by previous owners (we have been in it since 1991). Biggest problem we have had has been re-stumping some areas of the floors and lifting the front / side bedroom floors to make level as they originally sloped away from the house when they were only verandahs.

I've found over the years that there are very few people around town who have any knowledge of past building methods and materials. Probably the most knowledgeable are the people at Kalgoorlie Salvage & Demolition located at the end of East Street up behind what was Ian Diffen tyre place on Boulder Road. They helped us a lot when we had to replace the asbestos sheeting roof on my son's house down near the racecourse. On that house, we had to attach a lot of additional battens as the number originally installed under the asbestos wasn't enough to support the colorbond we replaced it with.

[Boulder Block]

Yes I'm impressed with the workmanship and the wood they used. So many of these homes have survived for so long, including many that have been seriously neglected for maintenance.


We occasionally get damaging storms. In 2017 we had a storm with gusts over 100km/h, trees were blown over, some were as old as the town. The power lines were trashed so badly multiple crews had to be sent to work here and it took about a week to get power back on. All that has happened to my roof is a batten on the edge has worked loose, and from what I can tell it's because it needs replacing, nothing to do with the way it was installed.

[Boulder Block]

Thank you so much for that, I've been wanting to go and see them anyhow, good to know they are knowledgeable about these old houses.

Your house sounds a lot like mine, even down to the sorts of renovations and extensions it's had. I've often admired the older homes near the hospital as I've walked past. There is one right next to the hospital that has some lovely decoration, window hoods and the like.

I've had the experience with drilling holes in jarrah, I've never attempted nailing it. I've heard a few stories about that. One that it's do-able if you have a good enough gun and a bit of beeswax or oil. But I've also been told that if you do nail old dry jarrah the nails don't hold well. Not sure on the reasoning, but that came from a roofer. I don't think he was just making excuses. It was a heritage job and they were required to have nails to maintain the look. He offered to nail it so it could pass inspection, and then come back later and put screws in to make sure it all stays put.

[BMKal]

Some of the building methods (and materials) around this area are pretty unique. The last extension to the back of our place (back verandah which goes out from the house and covers the old laundry and outside dunny) was built with a drill-rod and second-hand jarrah beam frame. It is solid, but the drill-rod uprights were not physically connected to the cross members (also drill rods) by the original installer. We nearly lost the entire thing in a bad storm years ago when it started to lift in the wind. I have since welded it more solidly and installed some steel gussets and it hasn't moved since. I also picked up a truckload of drill-rods from a mate over in King Street Boulder and have used these to build what is now the wife's greenhouse between the back of the laundry and my big shed up the back. I remember when I first moved here seeing some old houses clad in flattened out cyanide drums - they were a popular building material for walls and occasionally roof sheeting back in the day - but haven't seen that for some time now.

I remember the storm you mentioned in 2017. I'm in Varden Street and some of the big salmon gum trees along our side of the street were blown over. The next door neighbour and I spent most of the next couple of days helping the council workers move some of the trees, especially those that were on top of a couple of cars. I forget how many trailer loads of firewood we stacked away for use in a couple of years - but the chainsaws got a good workout. Another large storm since then saw us without power for 5 days. Fortunately the neighbour and I both have generators, so our two houses were lit up at night and fridges etc still working in an otherwise dark street, and at a time when a lot of people and businesses in town lost a lot of food. We still managed to have cold beer when even the local pubs (Piccadilly and Tower) lost their refrigeration.

[Boulder Block]

I've been thinking about the weight of the sheet metal, because I wasn't sure about it. I have felt old corrugated iron that was significantly heavier before, but the stuff on my roof isn't like that.
I have a portion of a sheet of the original covering and it feels pretty light and similar in weight to modern corrugated. I was not sure if it had been reduced in weight by corrosion though, that could have made it a lot thinner, so I did a bit of work to figure it out.

The weight of Redcliffe Crown sheets is recorded in historical documentation. It was available in thicknesses from 18 to 28 gauge, with 26 gauge being by far the most popular. In 1875, 8-foot 26-gauge sheets were reported as weighing 10 cwt 10 lb per 68 sheets. If the width of my sheets is the same as what they are referring to then this converts to 4.51 kg/m2.

Using the Weight Calculator at Steelselect I found:
Fielders S-rib in .42BMT with Colorbond finish is 4.42 kg/m2;
Lysaght Custom Orb in .42BMT with Colorbond is 4.35 kg/m2;
Metroll Corodek in .42BMT with Colorbond is 4.30 kg/m2.

So the largest difference in sheet metal weight would be almost 5% lighter if Corodek was used as the replacement. If any was chosen in .48BMT then they would all be > 8% heavier.

[Mobyturns]

The building has already stood the test of time regardless of what current documentation says, when I started in the building trade we used a hammer and nails to build structures that are still standing today but now the same style of structure requires triple grips and screws etc to stop it falling down these days according to a piece of paper.

By all means add any additional support you think is necessary and check the condition of existing fixings like nails that may have rusted out but I would be reluctant to fit any modern products that will be visible to ruin the original appearance of the building.

That may well be true, however those "nailed" connections may fail over time due to a number of reasons, including corrosion, mechanical failure, and "working" where repeated loadings loosen the nail in the joints. It is prudent to test at least some of the mechanical fastenings (i.e. nailed connections) to ensure that they are still sound.

There are plenty of "Queenslanders" still standing after 120+ years that have weathered cyclones, but will they withstand the next one?

Dad was a builder in Cairns for many decades up to the early 1980's and saw a range of issues when renovating older homes. There are never any guarantees as we've seen almost complete and total failures of a specific connection type i.e. batten to rafter nailed connection due to corrosion of the nails, yet other homes of a similar age in the same area are OK. Why? Perhaps a range of issues, timber species, nail supplier ...

Be prudent, get advice on the requirements to upgrade the chain of connections from roof sheeting to foundation, as retro fixing non-compliant work can get expensive.

[ian]

I've been thinking about the weight of the sheet metal, because I wasn't sure about it. I have felt old corrugated iron that was significantly heavier before, but the stuff on my roof isn't like that.
I have a portion of a sheet of the original covering and it feels pretty light and similar in weight to modern corrugated. I was not sure if it had been reduced in weight by corrosion though, that could have made it a lot thinner, so I did a bit of work to figure it out.

The weight of Redcliffe Crown sheets is recorded in historical documentation. It was available in thicknesses from 18 to 28 gauge, with 26 gauge being by far the most popular. In 1875, 8-foot 26-gauge sheets were reported as weighing 10 cwt 10 lb per 68 sheets. If the width of my sheets is the same as what they are referring to then this converts to 4.51 kg/m2.

Using the Weight Calculator at Steelselect I found:
Fielders S-rib in .42BMT with Colorbond finish is 4.42 kg/m2;
Lysaght Custom Orb in .42BMT with Colorbond is 4.35 kg/m2;
Metroll Corodek in .42BMT with Colorbond is 4.30 kg/m2.

So the largest difference in sheet metal weight would be almost 5% lighter if Corodek was used as the replacement. If any was chosen in .48BMT then they would all be > 8% heavier.Boulder Block,
these sorts of comparisons are in reality meaningless.

Your roof structure has to support the weight of the person installing the replacement sheeting, weights much greater than the weight of the sheeting itself.


Then there's the wind loading -- which again, is many orders of magnitude greater (perhaps as many as 4 or 5 orders of magnitude) than the weight of the sheeting.

[Boulder Block]

This was something specific to address the folk who think new sheeting is significantly different to old sheeting. That's all. I'm not trying to say anything else with it.

[ian]

This was something specific to address the folk who think new sheeting is significantly different to old sheeting. That's all. I'm not trying to say anything else with it.
sorry, I misunderstood.


My reading of this thread is that installation of the new sheeting will involve
1. pre-drilling the sheets with the supplied (recommended?) self-driving screws;
2. once the self-driving screw contacts the hardwood (Jarrah?) purlins, switch tools to a drill and predrill a hole to a depth slightly greater than the length of the self-driving screw;
3. switch back to the nut driver and drive the self-driving screw home. (I don't know if the same self-driving screw can be used to drill multiple holes through the sheeting, or if driving the screw through the sheeting once "blunts" it sufficiently to make drilling multiple holes pointless.)

So, in practice doing the re-roofing will require two drills, ideally one of which has a long (low resistance) tail.
Though the hardwood purlins might require that both drivers have low resistance tails.

[rwbuild]

sorry, I misunderstood.




So, in practice doing the re-roofing will require two drills, ideally one of which has a long (low resistance) tail.
Though the hardwood purlins might require that both drivers have low resistance tails.

:?:?

[rwbuild]

sorry, I misunderstood.




So, in practice doing the re-roofing will require two drills, ideally one of which has a long (low resistance) tail.
Though the hardwood purlins might require that both drivers have low resistance tails.

:?:?

[ian]

Originally Posted by ianhttps://www.woodworkforums.com/images/buttons/viewpost-right.png (https://www.woodworkforums.com/f345/diagonal-bracing-256047-post2315669#post2315669)So, in practice doing the re-roofing will require two drills, ideally one of which has a long (low resistance) tail.
Though the hardwood purlins might require that both drivers have low resistance tails.
:?:?
I'm thinking that the 120 or so old roofing timbers will be hardwood -- Jarrah, if Boulder Block is lucky, but more likely a locally sourced hardwood which after all this time will be almost impossible to drill into.
Hence the suggestion that the drill making the pilot holes might require a long low resistance tail.


US based woodworkers -- not that Boulder Blok is US based -- are almost universally surprised by how hard and abrasive Australia hardwoods are.

[jack620]

I suspect rwbuild is confused, as am I, about what a “low resistance tail” drill bit is. I’ve never heard of one, and Google isn’t offering anything.

[ian]

I suspect rwbuild is confused, as am I, about what a “low resistance tail” drill bit is. I’ve never heard of one, and Google isn’t offering anything.
should I apologise for the confusion ?


A heavy duty extension cable is what I am referring to when I say "a long low resistance tail"


Given the likely length of the extension lead, using a medium or light duty extension lead risks cooking the drill at the far end.

[jack620]

Have you forgotten we use 240V here? :)

I’ve used a 2300W 9” angle grinder on a very long extension lead with no problems.

[rwbuild]

should I apologise for the confusion ?


A heavy duty extension cable is what I am referring to when I say "a long low resistance tail"


Given the likely length of the extension lead, using a medium or light duty extension lead risks cooking the drill at the far end.

I have been in the building industry since 1966 and power tools are either corded or cordless, everything else is arm-strong powered :D