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Ted Stubbersfield Timber Consulting

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23.01.2022 My latest book, External Timber Furniture, is now available from Amazon and Kindle. Search under Edgar Stubbersfield. The book can't teach you creativity but it can show you how to detail timber furniture so it doesn't fail prematurely.

23.01.2022 How to control gaps in timber floors My last newsletter available at https://www.deckwood.com.au//timber-technology-newsletter- explained how to control gaps in timber floors. Expecting wide boards not to expand and contract with changes in moisture, especially with air-conditioning is unrealistic. Narrow boards, in my opinion, look better and when in conjunction with expansion gaps avoid all the problems. ... The first image shows a 60 year old floor made from ex 52 mm boards. The second shows gapping in front of glass doors and the third shows a wall that has been pushed out by expanding boards. These two images courtesy of Colin Mackenzie) Follow the link and read the full article. Don't forget to sign up for the newsletter.

21.01.2022 These are landscaping projects I have supplied and been involved with the design to different degrees. This is a very small sampler of my work.

21.01.2022 One of my regular readers shared some images with me of the third commercial plastic deck that their company is replacing with spotted gum. This one was grooved to take a side concealed fixing and it failed there. The third image is from a different deck they replaced. I am here to help you bring in an exceptional deck that will age gracefully and with minimum maintenance. Before you believe the hype ask for my university testing of composites, it will shock you. Have you subscribed to my newsletter yet? Here is the link:- https://www.deckwood.com.au/external-timber-newsletter.php

20.01.2022 Decking - Generic Timber or a Product? When designing a timber roof truss, probably all you have to consider is how strong the timber is and how well it holds a nail plate. Timber decking is treated by many in much the same way. Mention a couple of Australian Standards and that is all there is to specifying decking. But this could not be further from the truth. While decking may be structural, its requirements go far beyond those areas considered in Standards. I believ...e decking should be considered as a product in its own right rather than just timber. There are over 200 hardwoods milled commercially in Australia but only a few are suited to the rigors of weather exposed applications. Yet even when one of the most durable timbers is asked for, frequently the grade specified is inadequate. The permitted defects in structural timber can be very generous and when exposed horizontally to the weather they deteriorate rapidly. This degrade of the decking is further compounded by using a dressed face which at the same time means that you cannot achieve the required grip needed for public safety. Rough sawn and oiled achieves a slip resistance rating of R12. Unlike structural members, the width to thickness ratio of decking is critical. While you might be able to use a 6 to 1 ratio for a structural member, the better hardwoods cannot go over 3.5 to 1 when used as decking. The different moisture between the front and back causes cupping. Other factors to be considered are:- Controlling the gaps Avoiding trip hazards developing from untreated sapwood Using profiles that allow rapid drying Avoiding trip hazards resulting from sawing tolerances. Timber that addresses all these issues cannot be achieved by just mentioning an F rating but requires a detailed specification that goes far beyond the Standards. The factors that make up successful decking are expanded upon in my two books:- Deck and Boardwalk Design Essentials & Grading Hardwood Purchase these at https://www.deckwood.com.au/timber-technical-design-guides. Or contact me via email or phone to discuss how to get your decking right.

19.01.2022 Here is a selection of boardwalks I supplied and had varying degrees of input into the design

19.01.2022 Have you signed up for my new training course on Footbridge Fundamentals? The training will enable design professionals to specify footbridges well, identify where shortcuts are made and perform inspections. Module 1 - Footbridge Fundamentals - How to Avoid Problems with Your Footbridges and Bike-ways ... - Grading Hardwood - How to Inspect a Footbridge Module 2 - Case histories - London Millennium Bridge, Berrinba Wetlands (Brisbane), South East Queensland examples and other horror stories... Approximately 4 hours. CPD certificates available. Contact me for a quote to deliver this invaluable training at your office.

19.01.2022 Here is a selection of bridges I supplied and had varying degrees of input into the design.

19.01.2022 The annoying thing about footbridges, boardwalks and decks is that most of their life they are simply supporting their own weight and the usual design loads of 5 kPA and 4.5 kN can seem onerous. Then, maybe once in the structures life, it actually has to carry the intended load and, when it does, you need to make sure the details are right. The image is from the Gatton railway overpass bridge on Anzac Day and it simply couldn't take another person. So, the lesson is to take the design loads seriously.

17.01.2022 This collection of images show decks I supplied and was involved with the design to varying degrees.

16.01.2022 Joist Width on Commercial Decks For years I have been advocating that designing for durability, i.e. what this structure will be like in 25 years time, should be the primary consideration of all professionals. The use of narrow joists (50 mm and even 38 mm) is an example of a weather exposed structure that is only designed for their strength on the day of construction The deck in the images below illustrate my perspective. With its screws in a straight line it looks like... any other until you get on your hands and knees and look closely at the narrow (50 mm) joists. The image of the split joist was taken twelve months after completion. To get some perspective of the size of the split, the head of the screw measures 16 mm. The joists were split 5 mm before the builder left the site! It is not rocket science. The consequences of moisture entering spit joists are that it promotes decay and the screws themselves also work out and can be a trip hazard. If I had been the asset owner I would have insisted that it be repaired! Then the fight would begin about who is responsible. Designers persist in specifying 50 mm joists and builders keep trying to make them work. In the example in one of the images below the builder has understood the need to stagger the screwline and has done so while still using a 50 mm joist. But this arrangement cannot be made to approach anything like the edge clearance requirements of the codes. It is primary school mathematics. The shank diameter of a 14# batten screw measures 6.3 mm. We have found that the screw must be in at least 4 diameters from the edge i.e. 24 mm. This means that you can only stagger 2 mm on a 50 mm joist but you need to stagger at least 16mm (more if you can) meaning that a 75 mm joist is the smallest that can be used with a 14# screw. Another image illustrates a correct joist width and screw line. A further argument for a wider joist can be seen in in the images where we can see that the screw alignment is hopeless. Few will take the trouble to straighten the joists. The eventual failure of split joists is seen in Figure 6. So, to maximise the life of your structure through using best practice you just cannot avoid using a joist at least a 75 mm wide.

16.01.2022 NEW Training Course Available - 'Footbridge Inspections'. The course covers how to purchase well, what to look for when inspecting, how to grade hardwood and several case studies. If your organisation has need of this course, or any other timber training - contact me!

13.01.2022 Importance of predrilling, decking selection and decking installation Check the image of newly laid high quality decking and compare it to that of low quality decking. I have been involved with a consultancy where a large deck needs to be replaced prematurely. When the original decking was removed, and the top of the joists were finally visible, they were split, but, not down the centre as usual. Instead there were two splits along the line of the where the screws were stagge...red. Batten screws are brilliant fasteners and you can just force them into the joist without predrilling and this will be what happened. The timber shrinks, and, when doing so, the joist splits along the screw line. (Remember that you cannot purchase dry 75 mm wide timber so you have no choice other than working with green.) The only good timber was up the centre! It is not enough to specify that the joists are predrilled full depth, you have to ensure that the lowest priced tenderer actually does it. Fortunately the timber was not decayed so a liberal coat of CN emulsion was worked into the splits and a high quality dampcourse used. This is why predrilling joists for screws is critical! Look at the quality of the decking in the lead image. It did not happen by accident but through careful selection of the species, the specification and then confirmation grading. You will notice that the timber is laid with a small gap when I usually say to butt up tight so you do not get an excessive gap after seasoning. Again there is a good reason for this. The timber was dried to 25% prior to treatment to ensure that H4 could actually be achieved which meant that some seasoning and therefore shrinkage had already occurred. Look at the join in the decking. This is how it should be done. No moisture gets into the end grain which causes decay, but it requires set length decking and taking thought over the joist layout. I explain how to do this in detail in my book Deck and Boardwalk design Essentials. Order at https://www.deckwood.com.au/timber-technical-design-guides.

13.01.2022 On June 5, 2018 I delivered a continued professional development session at Guymer Bailey Architects in Brisbane. It was entitled External Timber 101. It the first part of a two part programme. The second part deals with detailing external timber structures. When are you going to order your CPD session? For the full range of sessions see https://www.deckwood.com.au/continuing-professional-develop

12.01.2022 Prior to 1997, I supplied the design and material for a boardwalk at Toohey Forest Park in Brisbane. Recent images show the boardwalk is as good now as the day it was installed. If you want to build timber structures that last a long time and age gracefully, you need me as your consultant. It makes a difference! For more images of and information on this structure follow the link:- https://www.deckwood.com.au//timber-technology-newsletter-

11.01.2022 Sawn Timber Joists Alternatives Increasingly builders and designers want to substitute new and improved materials in lieu of traditional hardwood or treated pine joists. Is this wise? ~Steel Joists... Bluescope will not certify their steel joists when used with decking (Bluescope Technical Bulletin CTB13) due to the acidity of the timber and the increased corrosion potential from the new preservatives. One Steel's guide permits the use of steel joists with timber but requires protection between the joist and the decking and this can be expensive if you use an effective one. Neither One Steel or Bluescope permit decking to be screwed to their joists but require fixing with hardened steel nails. The likelihood of the instructions being followed are very low. So as a substitute for timber, C and Z sections along with light box sections are sadly lacking. On top the galvanised coating thickness is light. ~LVL Joists The decayed H3 treated LVL joist illustrated was only in service for 18 months! The LVLs may be available with either individual laminates treated before gluing or treated after gluing. The former is more expensive and invariably looses out to the treated after manufacturing option. As well, the amount of chemical used varies considerably. The screws can split the laminates and allow water in so decay follows rapidly. In this case the LVLs were replaced with solid treated pine. ~Fibre Composite Joists The thin wall of the Fibre composite joist causes trouble as screws easily strip out, especially when trying to install decking that is not perfectly straight. As these joists should outlast up to four decks the top will look like Swiss cheese with sections breaking out between close screw holes. This can be rectified by inserting a H4 pine up the centre of the FC Joist and screwing into that and not relying on the thin joist. So while there are alternatives, they are not free of problems, these problems probably outweigh any benefit than can be gained from using them. The issues with timber are well known and can be designed around. By substituting different joists the designer is taking on a different set of less understood problems. You are hard pressed to get better joist performance than with one of our durable hardwoods. Contact me if you want to discuss this further. Subscribe to my timber newsletters at https://www.deckwood.com.au/external-timber-newsletter.php

09.01.2022 Trip Hazard Warning! When one of my regular readers went out for a run his day was spoiled when he tripped as he went over a footbridge. The trip hazard was on the narrow deck where the boards spanned across between the two girders. One board had bowed upwards and one downwards. Unfortunately, when the council installed a new deck two years later it was worse than before and now there is up to an 11 mm difference in levels between some boards. To avoid trip hazards on your d...eck contact me for expert advice. If you are designing a footbridge with any timber elements you need my two books - Timber Footbridges and Light Bridge Manual. Order at https://www.deckwood.com.au/timber-technical-design-guides. My free Deckwood Selection Guide contains useful information on spans and decking sizes. Have you subscribed to my newsletter yet? Here is the link: - https://www.deckwood.com.au/external-timber-newsletter.php

08.01.2022 Coming soonmy new book on External Timber Furniture. It will be available on Amazon search Edgar Stubbersfield. All books available at https://www.deckwood.com.au/timber-technical-design-guides.

08.01.2022 LIFE THREATENING DECKS In 2004 Archicentre issued a press release urging all home owners with timber decks to have them inspected. Their concern was that decks were being built, often without any approvals and design, with inappropriate timber and poor workmanship. Archicentre statistics indicated that approximately 6% of Australian homes have a timber balcony or deck and that about 2% of these were potentially fatal. This worked out to 8,000 life threatening (not subst...Continue reading

06.01.2022 Is Recycled Timber Seasoned? The short answer to the question about whether recycled timber is seasoned is, "You would not want to trust your professional indemnity to it." Take, for example, the 300x150 jarrah I inspected that had been in a wharf for over 50 years. The moisture content was constantly about 25% and timber does not start to shrink until it reaches this point and, as would be expected, they are still almost full size. The timber is simply too large to dry. If... you took these pieces as is, gave them a wire brushing and then used them in some architectural feature they will give no problem. But if you re-sawed them into 300x50 mm planks they would behave like green off saw timber and shrink the full 7.5% or almost 22 mm. This will cause problems when used for some structural purposes e.g. floor joists. Conversely, if you take a 50 mm floor joist from a building, even just a couple of years old, and recycle it you will have no problems as far as shrinkage. (Serviceability is another matter though, it may have been in the building for 100 years but that does not mean it is a durable species that can be used externally.) But take timber from the larger sizes, re-saw it into say 25mm boards and produce dressed products from it and prepare yourself a claim. An image below shows recycled spotted gum which has shrunk so badly it that the shiplap is no longer lapping and you can see the insulation underneath. So, proceed with caution. Specify and check your moisture contents when shrinkage is going to be an issue as with flooring, decking and cladding particularly.

05.01.2022 Decking - Generic Timber or a 'Product'? When designing a timber roof truss, probably all you have to consider is how strong the timber is and how well it holds a nail plate. Timber decking is treated by many in much the same way. Mention a couple of Australian Standards and that is all there is to specifying decking. But this could not be further from the truth. While decking may be structural, its requirements go far beyond those areas considered in Standards. I believ...e decking should be considered as a product in its own right rather than just timber. There are over 200 hardwoods milled commercially in Australia but only a few are suited to the rigors of weather exposed applications. Yet even when one of the most durable timbers is asked for, frequently the grade specified is inadequate. The permitted defects in structural timber can be very generous and when exposed horizontally to the weather they deteriorate rapidly. This degrade of the decking is further compounded by using a dressed face which at the same time means that you cannot achieve the required grip needed for public safety. Rough sawn and oiled achieves a slip resistance rating of R12. Unlike structural members, the width to thickness ratio of decking is critical. While you might be able to use a 6 to 1 ratio for a structural member, the better hardwoods cannot go over 3.5 to 1 when used as decking. The different moisture between the front and back causes cupping. Other factors to be considered are:- Controlling the gaps Avoiding trip hazards developing from untreated sapwood Using profiles that allow rapid drying Avoiding trip hazards resulting from sawing tolerances. Timber that addresses all these issues cannot be achieved by just mentioning an F rating but requires a detailed specification that goes far beyond the Standards. The factors that make up successful decking are expanded upon in my two books:- Deck and Boardwalk Design Essentials & Grading Hardwood Purchase these at https://www.deckwood.com.au/timber-technical-design-guides. Or contact me via email or phone to discuss how to get your decking right.

02.01.2022 My book on external timber furniture is almost complete however I need help with some images. Do you have examples of: - Decay under film finish - Decayed sapwood - Failed glue joints - Problems with edges of round tables... - Corner details See more

01.01.2022 NEW Training Course Available - Footbridge Inspections. The course covers how to purchase well, what to look for when inspecting, how to grade hardwood and several case studies. If your organisation has need of this course, or any other timber training - contact me!

01.01.2022 Here are 17 of my 20 guides on external timber. They are going to Kurata Co in Japan. I also have a book on 'Timber Fences' and two books that contain 8 years of my technical timber newsletters. Contact me to order an entire set of PDF files for $440. You can also order hard copies through Amazon - search 'Edgar Stubbersfield'. Further details at https://www.deckwood.com.au/timber-technical-design-guides.