Pete Bannister

Yes, I cant disagree with you! Giorgio Fiori excellent videos are food for thought though. Have you seen his demo load test on a side loaded alloy crab in a sinch configuration ?

That is a good point Wooden Hand re. the Singing Tree Quickie. Handy though it doubtless is, it looks as though there's little 'redundancy' in this application. I would think back-to-back screw gate crabs would be of at least equal, if not greater robustness ?

Have you seen the recent advice on rope washing? Teufelberger advice = 'Our tests reveal after eight washings with powder detergent the residual strength of a fiber ropes is 58%. In comparison, washing gel reduced tensile strength by 22%! After 8 washes SCRUBBA produces the best test results achieved with the least amount of tensile strength lost.' holy moly !

Plymarb I have an almost un-used one to sell. If you're intersted p.m. me cheers

yes..really good photos. thanks !

Dilz, not sure what you are looking at but all such resistance data (as Btggaz pointed out) are relative. So, yes you need to calibrate the 25% against other tests and then decide if the resistance is 'relatively' low or not. BTW my own experience is in the the use resistance drilling to detect decay in timber structures rather than trees. Although the tree is far more complex than most timber structures, the principles of resistance testing are much the same

Terry Hale has made a handful of mini-lectures. This one is particularly informative and if you're an Anorak like me, you could check out his others on the engineering principles of tree work

Well said that man! I'm amazed at the extent to which overtly racist comments are generally unchallenged on Arbtalk. that said, I'd endorse previous comments regarding buying 'dodgy' second hand gear. Dead right:thumbup1:

Hi Logrover, theres no statutory requirement in english law for public liabillity insurance in the circumstances you describe (or most others for that matter). There could be a contractual requirment for it though.

:sneaky2:""I have not investigated nor have I been entrusted to investigate ownership of the land, and your written (email) acceptance of this quote will imply that you have satisfied yourself that you have researched and obtained all necessary consents for us to carry out the work" Or any other other definition of 'willful blindness' might do!

Really nice little movie..maybe I’m getting cynical in my old age but am I the only one who thinks the producer is having a chuckle? The opening couple scenes give it a way a little Not sure about the LSD Kevin, you may be right: I thought I was looking at 'long-term Cannabis, Coke and no lack of Booze' syndrome there.

Now that's a really great photo. Well done.

Good luck with it Jamesd, Looks like Codlasher has set the bar high with his delux shed. You realise you're now under a moral obligation to send us the photos of your completed job. No pressure mate!

Kevin, In that particular case there was a body of water stewing away within thick masonry walls; so there was an unintended moisture source. However, the MVP membrane greatly restricted venting of the roof void that would otherwise have occurred naturally via the roof finishes. Its a common problem in refurbs. and conversion work were it may be difficult to provide compensatory ventilation at the eaves and ridge for example Codlasher, It not my roof thankfully! I investigate building defects professionally. The example in my photo is actually a ‘cold roof’ ie a traditional form with thermal insulation at ceiling level well below the roof. You might be surprised to know that most of the modern MVP membranes you see in the UK are specifically marketed for use in un-vented roofs, ‘cold roofs’ or ‘warm roofs’ . Many of them now have BBA certs for use in unvented construction. Crazy in my view but it stems from the concern to conserve heat energy in our buildings. Truth is that when a well-designed building remains in good condition an unvented roof may be fine..however, when a fault is introduced the lack of venting tends to result in a small local problem going exponential . The ‘warm roof’ has popular because its cheap to build. There’s no other good reason for using it in my view. The link you posted shows cold roofs’,’ warm roofs’ and ‘inverted roofs’. I think it might confuse the OP! Jamesd, The great advantage of vented air gaps is that it provides a ‘safety valve’ in the event of imperfect design, imperfect construction, or imperfect maintenance. Consider that the perfect building has yet to be built! Codlasher and I may share the view that ventilation is generally good for the health of the fabric but you have to decide if you can afford it! On the matter of thermal insulation; in broad terms, you get what you pay for. Do you need good heat retention in a shed? if its small it won’t cost much to heat for occasional use…depends want you intend to build it for. Anyways, the key point to consider is that when you introduce thermal insulation it generally increases the risk of interstitial condensation: so that needs to be addressed in the design.

I don’t think the maker's name was visible from within the roof Steve. I’ve seen quite a few similar examples of 'failures' throughout the UK over the last 15 years or so. They would all probably have occurred with any vapour permeable membrane because there's always a construction or maintenance defect encouraging the condensation. The fact is at whilst these membrane offer great benefits, they also eliminate the ventilation which happens via the gaps in cladding (e.g. slate, tiles, stones or shingles etc.). I’ve nothing against MVP membranes (having just spent over £100 per roll for top-end stuff on my own house) but folk often think that because they are called 'breathable' that they can forget about interstitial condensation risk in construction. They do so at their peril. In a temperate climate, condensation will occur at some point in the envelope of the building for much of the annual cycle. It’s not practical to stop it happening but traditional building techniques have evolved to help materials survive this condensation when it happens. Ventilation of a traditional ‘cold’ roof construction won’t stop condensation occurring but it will greatly speed up its re-evaporation after the event. If you are recovering an existing roof and need to keep water out of the building during the process, breather membranes are really helpful and a much cheaper option than a temporary roof

Jamesd, previous comments are correct; you don’t need a waterproof barrier behind well-designed timber cladding (unless its a partial rain-screen type cladding). The product you identify is probably not a good idea for your shed. A vapour permeable membrane ('breather membrane') will reduce air-filtration /draughts if heat gain or loss is your concern. As others indicate, that’s a better option. But even so called breather membranes are not always a good thing. Photo show condensation-related mould growth in a traditional roof construction where a high-quality 'breather membrane' has been used. You can see the grey mould and if you look carefully you'll see the condensate droplets too. Effective building is more about the way you use materials rather than the materials themselves.

Ah ...so that's what they've been up all this time in Guantanamo Bay

The truth is you can't always tell from macroscopic features. Even with a x10 hand lens its not always possible to distinguish your Acer from your Fagus! Have a look at this as a starter. Identifying Firewood in British Deciduous Woods

Here's the chart used in the HSE paper. I also attach a note on 'Blairs Formula' which although simplistic in certain situations is nevertheless very useful in my experience Blair's formula.pdf Log mass charts.pdf

More to the point it is a cracking looking tree, it? Was that deliberate? ho ho

If the zip line is too slack the 'curve' formed when loaded is steep, so you need pre-tension to get the right trajectory for the trolley ( eg petzl tandem) I tension our zip line into a grigri using a bit of m.a. to obtain the tension; then I leave it in place during use but I always tie off the slack end of the zip line very close behind the grigri, so that in the event of a failure of the grigri I dont end up with a catastrophe. If your lower anchor is a tree then a few turns and lock off at the base of the tree with a secured mule hitch is as good as anything. If you have plenty of ground clearance and dont mind speed, then less tension may work. Bear in mind that the vectors involved in zip lines when you pre-tension them can result in high loads at anchors. Ive always tested our run at home myself, before allowing children on it. Its not very high (in fact its not really high enough and impact with shrubs, sheds or the ground is the biggest potential hazard). If it was much higher, Id probably think about rigging a second parallel line above it as a safety and run the break line from the harness up to the safety line. The reason being, I often leave ours up for weeks or months on end but I reset everything and tension it up before each use. How long is your proposed run?

Ive always used static line with low stretch properties. Rope selection depends on duration and period of intended service. e.g. if you're leaving in place for a couple of years you might want a different rope that if its just for a weekend. I wouldn’t use a timber hitch to secure the zip line because of the risk of loosening during cyclic loading. You need a means of applying and adjusting tension but this should always be backed up by the main line, in the event of release of the tensioning rig. The line should be slackened off when not in use for long The safe means of run-out and breaking depends on the lie of the land. The list of things to consider goes on but have fun!

Hi biscoe, Good question; but 'No' is the simple answer. There's a huge amount of information on the mechanical properties of timber (because its such an important construction material for us humans). However, the variations in the properties of living wood are far too great to allow for meaningful simplification. Fractometers are generally used with reference to ‘pole’ structures or the stem of a tree. The data from fractometers is very limited and cant be safely applied to estimate the strength of a limb connection to a stem, for example cheers Pete

Woow. So they have gravity Stateside as well as here in the UK. Fun vid though!