Timber beam-end engineering repairs - Project 6
Part of a Crook Frame Truss, connection saddle T.R.S.
Click on any of the images for a larger view.
(Above) Detail of rot and infestation.
(Left) During the original inspection the lower part of the principal rafter was covered in a timber flitch plate. Upon removal of the plate it was found that four timber blocks which had been packed in the void where timber decay and infestation had eroded the lower part of the rafter. None of the blocks were fixed or connected to any structural component.
Tests were made to the principal timber to establish the extent of decay. Here a 150 mm long wood chisel is easily pushed into the wood.
Small inspection holes along the principal timber show the extent of Death Watch Beetle and areas of sound timber.
The rotted timber was carefully removed, which exposed the tenon of the arched springer.
Things starting to look pretty serious by now, supports were immediately installed.
(Left)
The main problem with this job was the fact that, originally, the principal rafter had a large running mortice that slotted over the tenon of the arched springer. Without taking the thatch off, I decided that the timber repair system (T.R.S.) should be manufactured in a saddle design, but split in two, so the two sections could be bonded together.
Here again, close work with David Moore from Property Repair Systems, who manufactured the T.R.S. and provided all the load calculations.
Work starts with the careful removal of the decayed timber.
This wood has definitely seen better days!
Once the decayed timber is removed the T.R.S. is installed into its position, the bar locations are set out.
Drilling up the end grain.
Once drilled out, the first section is fitted over the tenon and pushed up the principal rafter. First dry fit.
Not a bad fit. Note the location hole at the top of the T.R.S., this is to align the corresponding cover plate.
The other side of the beam. You can see that the T.R.S. is flush with the tenon face ready to accept the cover plate.
Here again, the cover plate is marked out for the bar locations.
And drilled out.
(Left) This is quite interesting. Hidden behind layers and layers of thatch that had dropped down into the cavity of the studding, we found the original decorations, pink flowers and green leaves. It was hand painted and probably goes back to the 17th century. Also note the horse hair plaster work.
