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  • Green Oak for a car port?
  • Mowgli
    Member

    I’d like to replace the tatty car port on the side of our house, and have always fancied having a go at green oak framing. The posts would be 100×100 and the beams probably 150×50 x 3.5m long. I’m wondering if these timbers are too small to be used green and might warp horribly? I would guess that with bigger frames for buildings, the beams are large enough that they don’t warp or twist too much as they dry. Anyone got any tips or experience of this sort of thing?
    Thanks!

    rydster
    Member

    No direct experience but it shouldn’t warp or split as much as a wet softwood. The question is does the car port need to stay absolutely square? I’d suggest probably not in contrast to say a door or window frame, but it’s up to you.

    Premier Icon hamishthecat
    Subscriber

    Check out some green oak builders’ websites. it’s quite a popular material for new build traditional timber frame houses, barn conversions etc.

    Some info here

    dyna-ti
    Member

    They’ve used green oak in just about every building in the 18th century back to the earliest times. A car port in oak would look smashing. Be nice if you used joining and pegs instead of steel bolts(Iron incidentally reacts with oak to produce black staining around them. A bit unsightly so if you do use metal fixings, check out some of the house building forums etc for examples of non staining fixings. Probably stainless steel or such

    Are you cobbling this together yourself ?. On the shelf ive “Timber Building In Britain by R.W.Brunskill”(1985).
    Mainly dealing with construction methods of all timber framed homes, barns et all across the heyday of carpentry 14th century through to late when stone started to really take over.
    Some great examples of really technical roofs and supports. As well as giving the reader an understanding of the theory and practice of framing timber.

    We’ve got a big 3 bay garage with an upper floor which is green oak framed. It’s been in place over 3 years. The timbers do shrink across their width but not along their length. They also develop longitudinal cracks (called ‘shakes’ apparently) which are normal. They don’t seem to warp but some of the longer unsupported lengths have sagged I’m the middle very slightly.

    Premier Icon kayak23
    Subscriber

    I would guess that with bigger frames for buildings, the beams are large enough that they don’t warp or twist too much as they dry.

    Nah, she’ll be reet 😉

    Premier Icon spooky_b329
    Subscriber

    Presumably it won’t shrink as much as a new build house because it’s outside and unheated. It should dry slower and more evenly than a sealed, centrally heated house

    Premier Icon Murray
    Subscriber

    My brother in law did his porch in green oak with stainless steel fixings. He drilled larger holes part way so that the heads were below the surface and then hammered in frozen sausages oak pegs to look authentic but be strong and easy.

    Premier Icon slackalice
    Subscriber

    Yup, I’ve done quite a bit of oak framing, design and build.

    Your dimensions for posts and rafters (which I presume are your ‘beams’?) are okay but there’s a good chance they’ll be awkward to lay out, scribe and cut your mortise and tenons due to their lightness. They will dry out perfectly as it’s outside but depending upon where the 2” section stuff is taken from the tree, what tension it holds, will have more bearing on whether it twists as it seasons.

    If I were using 2”x6” softwood rafters/ beams, I would fit one or more courses of noggins to help control the behaviour of the timber. Noggins in a framed construction are not required.

    Wall plate? I’ve no idea what your current car port looks like, it’s size or the material used for the roof, more specifically it’s weight.

    Racking? What bracing have you considered? Curved beam stock is available from a decent saw mill, ask around.

    It’s all about proportions and what looks and feels ‘right’ as much as it is about the dimensions of the beam stock able to take and support loads. Personally, with the caveat as above, 4”x4” posts will look light, lighter still if you set a stop chamfer on each corner. This in itself could work if you wanted to hide the car port, but I get the sense that you kinda want to make a statement.

    Think about the size of the post as having to accommodate both the wall plate and a primary rafter. Jointing is quite straightforward so long as you scribe and mark everything correctly. Look up English Medieval Tie Joint, or Post Joint – I cant remember, sorry.

    Guaranteed, even with one long wall, if you just throw it up and bolt it together it’ll look naff and probably not square, or true. But that doesn’t stop anyone having a go, so my advice would be to do some research.

    I’ve no idea of your skill set and relevant experience but it’ll be a fun project and one I’m sure you’ll get great satisfaction from as you research, design, and build it. Done properly, it’ll outlast your house!

    HTH

    Premier Icon timber
    Subscriber

    4″x4″ is visually a little skinny and gives less space for joints if your carpentry is rather more agricultural like mine. Smaller sizes like this are also more likely to come from the outer of a log nearer the sapwood that isn’t as durable.
    By going up to 6″x6″ the timber is more likely to come from closer to the heartwood.
    You could also increase spacings, so less to do and less posts in the way of doors.
    Probably 6″x3″ for the beams for the visual and extra material to work with.

    Mowgli
    Member

    Thanks all, some helpful tips there. I’ve done a reasonable amount of diy carpentry/joinery but nothing on green wood before. Happy cutting joints etc. I was aiming for as light a structure as I could get away with, rather than having something big and chunky, but I do want it to stay straight!
    Cheers,

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