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Metal & Glue Repairs #6727 03/29/06 07:15 AM
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Ken Hume Offline OP
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Hi,

I am preparing my final submission for a Masters Degree in Timber Building Conservation at Bournemouth University (Weald & Downland) and am currently seeking information on notable new or old timber buildings where metal bolts & plates and / or glues & resins have been employed to good or bad effect.

If you are located in the southern home counties in the UK then I would be prepared to give a free professional consultation to further this academic aim. International requests and advice by email only please.

Regards

Ken Hume


Looking back to see the way ahead !
Re: Metal & Glue Repairs #6728 04/02/06 02:08 AM
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northern hewer Offline
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Hi Ken:
Good luck on your master's, may it lead on to bigger and better things for you!

A few years ago I stumbled across a problem in an 1865 church attic. The bottom chord of the 45 foot truss had dry rotted off near the one end, and had dropped down.

The church council at that time obtained the service of a local engineer to come up with a solution. The solution was to splice in a new 12 by 14 section of timber, and use 3\4 inch thick steel plates and pressure rings along with 3\4 inch bolts to secure everything again. Of course the truss's chord was jacked up to the proper elevation before the repair was done.

No glue was used and the cuts were just butted together.

I believe it was a bit of overkill, but I realize that the bottom chord was doing alot of work. The truss was a bridge type of truss, and carried some of the load of the timberframed spire of the church.

I hope this might help,
NH

Re: Metal & Glue Repairs #6729 04/02/06 08:05 AM
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Ken Hume Offline OP
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Hi NH,

The problem that you describe is a classic and yes the solution described is not untypical.

Back in the days when the world was still portrayed in black and white in Timber Framers News (see No 15 - 1990) Jim Evans provided some words of caution regarding the use of bolted connections applied to wood especially where uneven bolt tightening could lead to localised wood failure. There is also the problem of joining a new piece of (green or semi seasoned) wood to a faily old (dry) piece of timber where shrinkage considerations in the new piece could result in an effective loosening of the bolts on the new side of the joint.

Freddie Charles in his book on Conservation of Timber Buildings expresses a disdain for hidden steel (flitch) plates but approves external (fish) plates because of the ability to inspect and maintain same.

Did you ever follow up on your referenced project and see what happened in reality ?

Thanks for keeping me in mind and "keep on hewing"

Ken Hume


Looking back to see the way ahead !
Re: Metal & Glue Repairs #6730 04/03/06 12:57 AM
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northern hewer Offline
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HI Ken:

I am going to continue to hew and teach others to hew as long as the Good Lord is willing.

I was an interested party, and asked to join the church council as they met with the engineering firm.

My preference was for a properly scarfed joint, one that had a step\cog built right into it, and wedged following guidelines that I had mentioned to them, ones that had stood the test of time, and described in an old joiner's manual.
The manual that I used over many years, written in 1867 was entitled "The Art and Science of Carpentry Made Easy" By William E Bell.

There were many excellent examples of joints that if constructed properly was as strong as the original timber.

This new end of the bottom chord timber was dovetailled into the wood timber plates that in turn sat on and were mortared in place on the stone walls.

Yes I was up a couple of times, and for the time being things look ok. But I expect that 50 or 60 years down the road will be a different story.

I enjoyed your knowledgeable reply, whoever hires you will get their money's worth!!.

NH


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