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Backer Board for Church Parts4/26
We made some rosette parts from mahogany to be placed on a church steeple. We glued up the parts in a way (Octagon) so the grain should not split along the grain.
The contractor has come back to us saying the surface he will install the pieces to is not flat and wants us to build a backboard to attach the rosettes to and then he will attach to the steeple.
Our question is - would you glue up the boards in a regular straight line fashion or in a octagon manner so they won't split. Maybe we are overthinking this as well.
Looking for some suggestions.
Azek or Extira for the backer.
I suggested both to them - they want to keep it wood.
Thanks for the suggestion
I would be inclined to bond the new parts on with a gap filling poly adhesive/sealant like 3m 5200 or PL white poly instead of the backer board.
The original parts were probably old growth Eastern White Pine. It survived up there forever with a few rusted finish nails to hold it on there.
Your parts look really good. I would do a really good prime job before handing them over to the contractor.
I assume the octagons are assembled with reinforced joints - splines, fingerjoints, mechanical fasteners or just staggered layers. That is the first step to longevity.
Secondly, the assemblies can be fastened to H Mahogany boards/panels with screws and washers from the back, set up to allow some movement. I am unsure of the sizes involved, but H Mahogany moves very little. The one photo shows multiple boards, probably T+G, where each is allowed to move a bit.
It would be beneficial to prime/paint the parts before assembly considering the location.
If the joints are not reinforced, then you must rely upon the backer for structural strength, and then expect the joints to open in time.
Your parts do look fine but I will add just a few thoughts for consideration.
Is the contractor going to do any prep work in the area the parts are going on? I can't imagine putting up those nice replacements on top of the disaster that the picture indicates. A combination of wood replacement and epoxy consolidation and filling of lesser voids should be included in the overall scheme.
Another issue to consider is relative to your product and that is the fact that mahogany is a tannin containing wood and it would have been ideal to glue everything together with an epoxy adhesive or saturate the piece in an epoxy sealer to prevent tannin bleed. The bleed will most likely occur where the paint film eventually breaks at the joints and water gets to the end grain and eventually creates a red/brown staining on the finish coat.
Don't be fooled into thinking the coat of primer and finish paint is enough to prevent the bleeding from happening in the no so distant future. Remember, this trim is EXPOSED to the elements and will take considerable wetting.
If the contractor can get the subsurface reasonable well prepared you can use a bedding compound as is used in the attachment of fittings to a wood boat deck.