Dear Matt,
This question may not be exactly in the normal “general woodworking” category, but I would be grateful for your thoughts on my problem (see attached photo).
I recently had the house washed, and this revealed rotting areas on the ends of some barge boards. When these were made, some ten years ago, the board ends were capped with galvanized metal plates, which were then painted. Having removed the plate in the picture shown, I strongly suspect that the board ends were not adequately sealed first, and subsequently, moisture has been retained under the metal caps!
Apart from the visible defects, the obvious rot damage extends to the touch for at least 10cm back from the edge of the board in a patchy fashion, and in some places, the structure is only being held together by the paint! Using a syringe and large-bore needle, I tried injecting a liquid polymer product in an attempt to stabilise the wood, but this was both difficult and only partially successful. I am left wondering whether to ignore this rot (one affected board is about 8 metres off the ground and not easily accessible!) “for the moment” and accept the eyesore, or get radical. This would probably involve scaffolding and significant overall expense, considering the “localized” nature of the problems.
I would be interested in any comments about the situation, and in particular what techniques might be considered, if the rotted timber was to be “replaced”, without rebuilding the house…!
Yours sincerely,
Peter Charlesworth (New Zealand)
Replies
Peter,
I'll put in my two cents worth here, since I have a fair amount of experience dealing with these kinds of problems. My apologies, Matt, for intruding in a question sent to you.
The damage was caused by two related mistakes in the installation.
The first fault was capping the ends of the boards with metal, any moisture that worked behind the metal was immediately sponged up by the exposed unpainted end grain and, with no way to dry out, the metal and painted sealing against evaporation pretty well, the wood became permanently water logged and rot became inevitable. The board ends should never have been capped, they just should have been left exposed and painted, with an extra coat or two if needed to seal the end grain if it absorbed the first coats too readily.
The second detail that would have helped would have been to have a drip edge on the metal flashing that came out from under the roofing. A drip edge is a small, about 10 mm, lip that sticks out at a 45 degree angle from the bottom of the flashing that is wrapped over the edge of the roof. Any water that comes over the edge of the roof when it reaches the drip edge is forced to drip away from the metal rather than continuing down the side of the wood where it can cause trouble.
John White
Thanks John. This was out of my league so I'm glad you could step in!
Thanks very much John and Matt, and sorry for the delay in responding. I did not get the usual email notification that Matt had posted.
I was rather hoping that you might be able to suggest some options for definitive remedial action to address this problem. In particular, how could I approach partial replacement of the rotten segments of the barge boards. Any further thoughts would be greatly appreciated.
Regards,
Peter
Hi Peter,
Sorry to barge in on Matt, but a couple of ideas.
I know you tried to inject a consolidant. You will have limited success doing that.
One of the things you need to do is remove all the soft punky wood and let the surrounding area dry well. I have a feeling it went all the way through so doing this may remove a section in it's entirety.
If you can get most of it out and leave a little of the back in place this will be your foundation for a repair.
There are many epoxy companies that make a wood consolidant. You have to research what is available in your area. The consolident will be a brush-able liquid that will penetrate and harden the surface.
This is then built up with another epoxy that has some body to it. One I've used with great success is Abatron (here in the US). The product is called Wood Epox. Unlike brush able epoxy it has a dough like consistency. It has two parts A and B. They are mixed in a 1 - 1 ratio .
Mix a quantity and apply it to the surface. If it is a large and deep repair do it in stages as it generates a fair amount of heat as it cures. If doing it in stages I would place some dowels in the surface after application for the next coat to adhere to. When cured it can be painted to match.
This product is as light as a feather when cured yet it is structural. While a complete replacement of the board may be in order at some point this will certainly buy you some time.
The other option is to get up there, cut out the rotted area and replace it with a new board using a ship lap joint.
Either way it's work. I know it's not all that accessible either. Keep us posted.
Peter
Peter, thank you very much for those suggestions! I had been stuggling with the technical aspects of replacing the rotted sections with new board, but of course, the shiplap joint is the answer. I suspect that a combination of your methods might ultimately be necessary.
As you infer, my biggest problem is the general difficulty with access to these barge boards, and this might be enough to make me "carefully consider" the whole matter for quite a while longer.....! Perhaps I will have to wait until the whole house needs repainting, when scaffolding will definitely be required.
With kind regards,
Peter
Peter,
I've been slow to get back to you on this because there isn't a good simple solution. As intimidating as the job might appear I would seriously consider replacing the entire board, that is what I would do if it were my house.
I have done a fair amount of this work over the years, and it takes a lot of tedious work to cut away, reinforce, and then rebuild just the damaged end and after the work is done the seam between the original wood and the repair is almost always visible and generally gets more so as the wood ages.
John W.
John, thank you very much for your comments. I'm sure that you are quite correct....in an ideal world! However, the logistic and cost issues involved in completely replacing these boards (given that there are about a dozen potentially affected) are at the moment too daunting for me to contemplate..!
I greatly appreciate the considered advice, which gives me a good basis for further thought and action.
With best wishes for Christmas and the New Year,
Peter
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