Friday, May 6, 2011

External Stairs from Recycled Timber.

Aahh!... another set of stairs...   Amid all the different types of woodwork I do, what I enjoy about building stairs is the brain challenge they provide - particularly in the planning and setting out phase. One of my latest jobs has been to build a set of external stairs for a client. The task was to plan and build a set of stairs which would fit into a particular space on an existing building which was undergoing significant renovations. The stairs would comply with the Building Code of Australia, and made primarily from recycled jarrah.
That's the space available to build the stairs ... in front of the red brick wall.
View from the top looking down. The structure would have to keep 1.5m off the fence line.

Planning the job.
Having taken measurements on site, it was then down to the planning stage - which always involves doing scale drawings on my trusty drawing board. I have never got into CAD drawing on the computer. I still like the old "Technical Drawing" techniques using a T-Square and pencils on a drawing board.
The first place to start with planning a set of stairs is to know the total Rise - the distance from the top floor level to the bottom ground level. In this case, allowing for the new ground level which will be built up to the same height of the underside of the back door sill, the total rise will be 2.5m. This divides readily into 15 steps, each with a rise of 166.67 mm. That rise fits within ergonomic convention. The next thing to determine is the "Going" - the horizontal depth of each step from nosing to nosing. The accepted rule is: (2 x Rise) + Going = 585 (or up to 625mm.)   I decided to have a Going of 260mm, which fits within the range OK.
With the Total Rise, the number of steps, the Rise and Going all established, the length of the flights can be determined. Drawing this to scale would give me the angle of the stringers and help me to visualise how it will fit within the space. A landing will need to be included, as this divides and separates it into two flights going in opposite directions. There also had to be the required minimum standard headroom where the lower flight approached the ground while coming under the top balcony.
After a lot of drawing, calculating, brain-waves coming in the dead of night, meetings with the client and 3 drawing versions later, I believed we had hit on the answer of how to make it fit in the space available and my client was happy too.

Gathering the timber and starting the construction. 
The treads would be easy. Three sticks of timber dressed to 90 x 45 (and nearly 900 long), with gaps of 8mm between, would give a stair tread of  286. With a 260mm Going, there would be a 26mm overhang of the nosing over the back of the tread below. Nice. These sticks would be ex 4"x2" jarrah. In domestic buildings these were normally used for floor joists, rafters and often ceiling joists. Much of the 4"x2"s I had in my stocks came from a house built in 1930. After seasoning for 80 years, this stuff is dry!

4" x2" material cleaned up and ready to be machined to size.
  As much as possible, gum veins were avoided in the selection process, the timber docked just overlength, de-nailed, scanned with a metal detector, scrubbed down with a wire brush, straightened and squared over the buzzer, and machined to the required 90 x 45 through the thicknesser. Three of these per stair tread.

The stringers were a problem. After searching round the salvage yards, I would be unable to find the jarrah suitable to make the stringers. (Stringers have the treads housed into them and make up the sides of the stairs). So I had to buy the material new. The required 10" x 2" jarrah I purchased was pre-dressed and what they call prime grade. Scary stuff really, as I had to pay over $650 for the 4 sticks I would need in order to make the 2 pairs of stringers! Ouch!

The decking would be easy. By ripping 4"x2" jarrah sticks down the middle, the two halves are each machined to 90 x 20mm.  A number of these I was able to make at 3.2m long, enough to go the full length of the decking. The arrisses were shot off with a block plane, and the decking boards pre-coated with oil.

A 4"x2" piece of jarrah ripped down the middle and opened out. Fantastic colours and interesting nail holes coming in from the edges. It will be machined into beautiful recycled jarrah decking. 
  The top plate or apron of the landing would be ex 8"x2" jarrah, dressed to about 45 x 190mm, and the landing floor joists were ex 6"x2" jarrah from salvage. The landing would be supported by 6 galvanised steel legs set in concrete, and the jarrah posts above would be machined to 100x100mm. These took a lot of hunting down - from salvage yards and other sources. I was fortunate to get 4 posts from an old 6"x6" jarrah power pole! The 120 x45mm handrails would also be obtained from the 6"x2"s.
All nails and other fixings used would be Hot Dipped Galvanised. The finish to be applied to the finished timber would be Cabot's Natural Decking Oil.

The construction process started with making a set-out board of the stringers, giving me the angles and dimensions of the tricky ends of the stringers. This info was then transfered on to the stringer material and the two pairs of stringers were then made at my workshop and pre-finished with a couple of coats of oil.
The Stringers were laid out in pairs, marked out, and the tread housings cut.
The treads were then all made and cut to size ready. The two flights would be too heavy to lift if assembled, so I decided to do the assembly on site. With the flight components made and the landing materials organised, I moved to the site to build the landing. When the setting out on site was completed, the holes were dug for the steel posts. Using lots of big cramps and big sticks of timber, all the prepared posts were suspended in their holes, plumbed and held in the right positions. My son Ben was giving me a hand that day, and it was a big day! Ben operated the electric cement mixer and we did the concreting job. Six posts, rock solid. The following day I would do the concreting of the final two, supporting the base of the lower flight.

One of the steel posts suspended and cramped in position in its hole, awaiting the concrete.

The top stringers were also suspended/supported  in place to ensure the landing position was correct. While working from the drawings, sometimes it is good to check "in the flesh". 

The lower flight stringers fixed in place, with metal spiggots at the base set in concrete. The concrete will later all be buried under sand and brick paving.
 Completing the landing.
With the steel posts set in concrete and the landing apron or top plate being bolted to the steel as the jarrah posts were inserted into them, the floor joists were then added. These in place, the decking was then nailed down.

Decking nailed down and completed. That's a cake of soap on the stair tread - to lubricate the 4" galvanised nails used in landing construction.

Top flight treads fitted in place. Handrails and balustrading still to be added.

Landing done. Stringers in place, most treads installed. Time to cut posts to height and add balustrading. 
The jarrah posts were installed "over-long", so that they could be cut to a finish height after the transitions had been worked out - ie. where the flight handrails meet the landing handrails at the newel posts. These transitions would be calculated and modified ensuring a smooth transition as well as compliance with the minimum requirements under the Building Code of Australia (except for the lack of infill under the balastrading, which someone else would be doing.) While the scale drawings would give a good indication, the measuring and marking of the real thing in place would be most accurate. 

Making and Fitting the Handrails.
With the landing decking completed, it was time to get on with the handrails. The customer hadn't quite decided what balustrading to have - but will probably have stainless steel horizontal wires. That's someone else's job. Other than the posts below, I don't do steel. Out of interest, to comply with the BCA, balustrading must not be able to have a 125mm (5") sphere pass through any part of it. Horizontal handraisl must be a minimum of 1000mm high, etc. At the commencement of the job we had agreed I would only to install the newel posts and handrails, so that was what I was doing. I had made the handrails from ex 6"x2" jarrah ceiling joists. Nice straight sticks too, which I had machined into 120 x45mm. This gives a 10mm overhang on each side of the 100mm posts.
One of the newel posts at the transition from landing to top flight. That's the tenon on top awaiting the handrail which will be housed onto it.
The posts were cut to length with tenons on top, and the corresponding housings cut in the underside of the the hand rails. The interesting part was the angled corners of the landing handrails. In one of these brainwaves I have in the dead of night, I resolved how to do the joint... a beautiful mortice and tenon joint. In fact, a stub tenon with a haunched tenon either side of it. And it worked a treat!. All this was done on site. My trusty tenon saw cut the tenons on top of the all the posts, and the tenons on the ends of the handrail returns on the landing. Good to see a saw live up to it's name. I was going to take photos of the joint components before I glued it up and fitted it to the posts ... but once again I was so hooked into what I was doing that I forgot and just assembled and glued the joint. Sorry about that...  Love that glue - Titebond III.

Nice mortice and tenon joint! 27 degrees off 90. There's a long haunch and a stub tenon in there.

That's the other corner. Another very tidy joint, the same as the other end.
Anyway, I was very pleased. The haunch mortice was cut with a slot cutter in the router, and the deeper mortice for the stub tenon was chopped by hand. The tenons were all cut by hand. It was a winner.

Job completed.
When I had completed construction, I brushed the whole structure down and gave it one more final coat of the oil finish. It looked like a million dollars. I then gathered up my tools, cleaned up the site, took a few pics, and drove away. Satisfaction is such a nice warm feeling. Here's a few pics:


View from the top looking down and across.

View down the top flight.

View of the bottom flight from above.

The ground level is yet to be built up and brick paved. The height of the bottom step allows for this. 

This pic puts the stairway in context. Soon there will be a swimming pool in the foreground!

View from the ground level back door.The galvanised steel legs will be painted a colour similar to the jarrah. 
On the joys of jarrah.
Jarrah is such a beautiful timber, and I am lucky that I have been working with it all my life. Jarrah (Eucalyptus marginata) is only found naturally in the southwest of western Australia. I understand there is only about 6% of the original forest remaining. Such a significant timber since European colonisation began here 1829. Until a couple of decades ago, in Western Australia just about every part of a timber framed house from the stumps to the ridge piece were all made from jarrah. It is a is very strong structural timber, very durable in the weather and in the ground, and a very high quality furniture material. Beautiful grain and rich reddish brown colours. The all round dream timber. Yep, I love the stuff.

Much of this stairway was made from recycled jarrah. This material had come from an assortment of buildings and other uses, much of it from a house which was built 80 years ago. All over it, there are the echoes of the former lives of this timber. Rows of nail holes along a tread nosing, testifying to a past life as a floor joist, with the nail holes even showing the width of the old floorboards which were once nailed to it. A couple of old checks in the side of a newel post, speaking of a former life as a verandah post on a building. The residual jaw marks from an old pair of floor cramps, telling of the time that piece of stair tread was once a floor joist. Other pieces were once rafters or ceiling joists, and the spacing of nail holes can often speak of these former lives. It is the echoes of the former lives of this timber which is so fascinating in something made from recycled timber. It is also why I don't fill the old nail holes. Let them speak.

Working with pre-worked timber also gets me thinking about the tradesmen who worked this timber when it was green. That's how these building were always constructed. Green jarrah, while heavier, is easier to work with - and easier to nail. No need to pre-drill the nail holes like I had to! These guys built the houses only with hand tools. There were no power tools. Most of the saw mills were steam driven, and life was different. Simpler times, moving at a slower pace, when tradesmen took pride in their tools and their work. It wasn't just about money and having a job - it was a vocation. An identity. A way of life.

I tip my hat to those guys, and hope I did them proud in the way I re-used the timber they first worked.

5 comments:

  1. What did the customer think of the stairs? Ah, who cares it is totally beautiful, from what I can tell you did it for yourself. What a joy to read your blog and share in your passion for your work. You are certainly lucky to get to work with such beautiful wood. It really makes me happy too that you appreciate the material and know how to respect its history as you give it a new piece of history in your work. Keep up the great work, I have added your blog to my rss and I will take my time and enjoy going back in time for you reading your older posts. But this one was so nice I though you just needed to know that a guy from San Jose is appreciating your work. -- Cyrus

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  2. Thanks, Cyrus. Nice to know there's a guy from San Jose appreciating my work and ramblings! There is a lot of talk about better management of forests, etc - but no talk about how we manage and utilise the enormous and fantasic resource of wood which is already with us. Instead we just waste it, every day. Totally crazy, and not good for the planet either. Such a wonderful natural material which requires so little energy to produce, wood is full of stored carbon, will last for centuries (so long as it does not rot), and can be re-used and recycled endlessly.
    I figure that recycling timber like this is good stewardship as well as an absolute joy to do. I like the idea of being part of a chain of craftsmen who work the same piece of timber many times and for many uses - and in doing so give honour to the tree from which the timber came. The echoes of the life of that tree are always reflected in the figure and grain of the wood. Wood is surely a beautiful gift from the trees.

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  3. I’m amazed, I have to admit. Seldom do I encounter a blog that’s both educative and amusing, and let me
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  4. Hi Greg, I came across your blog while searching the internet for information on timber to steel transitions. I love what you have done with the recycled jarrah, the stairs look amazing and I am sure your client must have been very happy with them. I am curious as to how you joined the timber handrail posts to the steel posts. From your description am I correct in thinking that you reduced the timber post at the base so that it fitted inside the steel post, sort of like a timber plug into the top of the steel? I also saw your link to fundacao lafaek diak, which caught my eye as I am currently working in Timor Leste, but heading back to Oz soon after 2 years here. I enjoyed reading your blog.

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  5. Gidday, Mark.
    You are right about the transition. The external size of the square galvanised steel was 100mm. The jarrah posts were machined to 100mm square, and then reduced down with big fat tenons for insertion into the steel post. The transition was behind the 200mm outer joists, which were bolted onto the outside of the posts, so that visually the steel came out below the joist and the wooden posts came out on the top side of the outer joists. Very clean and tidy. The posts ere inserted deep enough that those bolts through the outer joists passed through both steel and the timber posts within them. Nice. A flush joint on the posts where the timber and steel transitioned one to the other.

    I have been to Timor Leste about 5 times, (several weeks at a time) each time supporting Fundaceo Lafaek Diak on a range of projects. Lucky you to got to hang around in that wonderful country for a couple of years! FLD are based in the village of Triloka, just out of Baucau. Make sure you check them out before you leave the country! Please tell my old friend Senor Constantino Pinto (President of FLD) that I sent you!

    It's really time I went back again...

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