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Pete Bannister

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Everything posted by Pete Bannister

  1. Pete Bannister
    Difflock that’s a fair description of its mechanical properties. I was also thinking of its poor natural resistance to decay. I think its formal classification in the BS/ EU scheme for natural durability would be 'perishable'. Codlasher's observation on the durability of preservative treated Sycamore can be attributed to its permeability. ie a suitable preservative can easily be impregnated. However, wood preservatives are not invulnerable to decay. In fact, fungi are used to break them down in recycling applications elsewhere in Europe
  2. Pete Bannister
    But to return to the OP.. for what its worth Stereo, Ive been looking at timber in buildings full time for over 25 yrs. Have yet to see a piece a sycamore that performed well as a construction timber. Sure you can deter decay if you pump enough poison into it. But better to select more suitable species in the first place. Sycamore is good for certain uses but construction is not one of them.
  3. Pete Bannister
    Hi Alec, yes I thought a derail was about to happen there! What you've said however, does illustrate my point about the need to apply more thought than is generally the rule when applying new to old. Clearly you think about it.
  4. Pete Bannister
    Agg221, just looked at the Hipin site. Interesting. What I said above wasn't a comment on Hipin (or any other materials) and certainly not intended as a criticism! I can expand on my concerns ( based on experience in the UK) but this is perhaps not the forum for it.
  5. Pete Bannister
    Farmerjohn, SPAB have published some interesting (although rather partial) research on thermal performance of trad buildings. SPAB: Energy Efficiency You might find it interesting. The way chosen to retro-fit additional thermal insulation into traditional buildings is really important and requires more thought than is generally given to it! There's an obsession these days (which verges on the fetishistic) for thermal insulation and in some of our building stock it just doesn’t make sense.
  6. Pete Bannister
    I'd endorse tuttle's comments. For rock and ice you'll want lightness and as little restriction as possible. You will find any arb harness a significant restriction. Silky is right, regarding equipment design but I cant imagine a fall, even a factor one fall, would be likely to significantly damage any harness in most circumstances if you are using dynamic rope correctly. My first rock climbing was in the early1970's (I was first taught to lead climb at school on local rock outcrops before man-made training walls were common. Somehow I cant see that happening today!). Anyway my first 'out of school' harness was 3" nylon webbing sling; and to this day, I have a disproportionate fear of falling off any route as a result!
  7. Pete Bannister
    I was called in to advise on the failure and on repair. It was sorted by altering the design (inserting raking 'posts') to remove the moment and some serious glue. I'll put a ref list together on grading timber. Im not in my office right now so give me a couple of days and Ill post something up for you. :thumbup1:
  8. Pete Bannister
    Alec, yes hardwoods and softwood may both be visually graded for structural use. Visual graders are licenced and stamp their licence number on the individual timber. Its then a licenced commodity. The EuroCode (B/S) lists common species used in northern Europe for structural use. If you have timber that’s not listed in the 'Code' then it can’t be graded. However, that doesn’t prevent anyone from using it effectively ( or not as the case may be) The slope of grain in the failed rafter was 1:5 it should have been 1:13 or better and had it been so the failure would not have resulted
  9. Pete Bannister
    Farmerjohn, yes it was formally designed and had already gone through Building Control. You're exactly right, the design does stress that joint very highly for the reasons you surmise. However, it would have worked ( in fact it did work in about 8 other trusses in the same building) but for the slope of grain. BTW there's a handy little guide that TRADA publish on using green oak. It provides a grading criteria that is quite well considered and I used it as reference whilst reporting on that failure.
  10. Pete Bannister
    farmerjohn, green timber ( timber above 20% m.c.) cant be graded within the B/S EU standards. So you cant buy graded timber if its above 20% m.c. Allegedly
  11. Pete Bannister
    The roof trusses/ roof was formally designed by a Struct Eng. I reviewed the calcs. Nothing wrong with the design. It would have worked but for the slope of grain issue! Agg, we visually grade softwood and hardwood. Softwood’s easier to do by far. The grading rules for h/w are more complex.
  12. Pete Bannister
    Here's a newish green oak truss roof that didn’t go so well! I’m posting it because the cause of failure was down to the grading of the timber; specifically slope of grain. Oh and yes, the inevitable fissuring that occurs as green oak dries. The raised tie beam result in really rather high bending moment at the connection to the rafter. The very artfully crafted dovetail jointed trusses at the start of this thread have a similarly high tie beam and relatively high moment. However the span of the trusses is very different. Note the pegs haven’t failed in my example. The timber failing along its weakest axis. The eaves distortion resulted at both sides of the building pretty much equally. Oh and the ridge had a nice dip of about 300mm too. The first photo is not a 'before'. its a neighbouring truss at the other end of the roof.
  13. Pete Bannister
    Nice sturdy frame that farmerjohn. Green timber, or dry graded? and what did you make the pegs from? cheers .
  14. Pete Bannister
    A serious challenge met with panache Id say.
  15. Pete Bannister
    Thanks for the helpful link Tony. Woody Paul's question on amputation as a control measure is a very good point. Maybe folks working on the problem in continental Europe will have something to say on that. Where is Gerrit when you need him?
  16. Pete Bannister
    Is 'peoples' a word; or should an apostrophe be used? Just curious. Good luck Tony (with the grammar I mean; the PhD should be a doddle by comparison!).
  17. Pete Bannister
    Brilliant photos!
  18. Pete Bannister
    'I just watched this and wish I hadn't' Wisewood, I saw that sometime last year and it had the same effect! Realy dont think I want to watch it again. Perhaps not the best lesson in 'near balance point rigging' then? Just a thought
  19. Pete Bannister
    Seeing as it's mid-summer; here's some of better weather. First pair are in the High Peak Derbyshire having just missed the mountain hare but being rewarded with the Scots pine. Made that trip on skis Jan 2005! Last one another little ski trip, this time Glenmore forest 2011
  20. Pete Bannister
    Sorry, my previous comment was misplaced. I was refering to Tom D's Edinburgh evening panorama. By way of penance, here's some of my not very good landscapes. First pair are a private house in Shropshire; second pair are at Harlaxton nr Grantham
  21. Pete Bannister
    Crikey, what a great photo! Well done
  22. Pete Bannister
    Very good point well made. Also valid because it adds rope to the system, thereby reducing stress on your weakest link and increasing its life
  23. Pete Bannister
    One of the reasons an incident such as this may go to court is to 'test' it. Court procedures often provide the best means we have at our disposal of revealing evidence, having it clearly expressed considered and discussed by an expert or experts and then judged. Whilst it may not be the case in this instance; it has been known in recent history in cases of serious injury or death for it be necessary to establish 'negligence' in order for insurance to pay out.
  24. Pete Bannister
    with respect b101uk, they dont have similar expansion properties! That's why we use specific joint details when building with these materials. I agree with your sentiment about concrete slabs and timber beams though. Chris, you are right to er on the side of caution. BTW you can submit a Building Notice to your LA and pay a modest fee based on the value of the the building work you are doing. A building inspector is usually your friend in these situations. They are not designers but can often steer you in the right direction.
  25. Pete Bannister
    Top tip Steve! Anti-condensation paints were first developed for the submarine parts of steel ships. They are however, generally pricey. The principle is preferential absorbency. Any hygroscopic material at hand will do the same job. Plasterboard, thin sheets of timber, sawdust, common salt, paper, cotton. They'll all rapidly absorb liquid water and water as vapour, which is what you want. They can all act as a 'buffer' so you have to balance water absorption with desorption. Through ventilation is a good means of de-humidifying. Dry heating ( eg solar gain) is necessary if you are going to add water into the system by introducing damp gear.

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