Correcting cupping in wood siding

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Posted by: from Guelph
10/27/2012 at 1:46:50 PM

I am looking a purchase in Nova Scotia. The home is 20 years old and two sides (weather affected) have some serious cupping in the wood siding. Attempts by the seller to correct this by screwnailing has not worked.

Question is, can the underneath of the cupping be filled with a product that will prevent further cupping and stop and interior damage from occuring?

To replace the siding would be cost probibitive considering home values in the area.

Thanks very much for any assistance or comments.

Keith in Puslinch

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Date/Time10/27/2012 at 11:09:25 PM

Cupping is caused from the wood itself and comes from the grain direction of the wood fibers when it was first milled. Forcing it down will never work, obviously. More than likely it will not cup any more than it already has. There is no product that will stop cupping in this instance.

If replacement is not an option, then find an exterior caulking that is a similar color to the house and fill the underside of each board. It's not the best solution, but at least it will be weather tite.

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Date/Time10/31/2012 at 11:01:48 AM

Generally the cupping is caused by the protective coating breaking down and not attended to. It is too bad that people think of paint and stain as colour and not a protective coating that has a colourant in it.

As for the cupping, nothing can be done to cure it now.

As for filling, that would be a quick "possible" fix, but with the damage already being done, it is only a plug.

Check out how much it is going to cost to replace the affected areas. Have a qualified contractor give you an estimate. Also, not seeing the situation up close, the situation may be a simple one to fix. If the inspection proves that it should have something done, then it is up to you and the seller to come to terms with the problem. Obviously, he is aware of it, and somebody will have to pay for it, be it be him or yourself.

Not fixing it properly NOW, could cost you far more in the future.

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Date/Time11/1/2012 at 5:00:35 PM

Since you have mentioned that the previous owner had attempted to resolve the situation by screw/nailing but it was not successful leads me to believe that the problem is behind the siding.

I would carefully remove the siding (so that the siding can be reinstalled) then look at the cavity of the wall. The cause of the cupping must be found and corrected as something is happening to cause the cupping..

Sorry to say but if the present owner has tried to correct the situation but it was not successful then I feel that it may come down to the point that you must replace the siding or the area or pieces of the siding that is causing the cupping.

I understand that you must be carefull of the cost due to the home values but if it is not fixed then the purchaser will take that into account on the amount of their offer. So it is a loss either way but if it is fixed then it is not an item that the potential homeowner can use to lower the amount of their offer or even the end price.

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Medicraft Contracting in Kingston
Date/Time11/5/2012 at 2:10:07 PM

The simple answer is no. There is no way to "fix" cupped wood siding without replacing it. The damage is done and will probably continue to get worse. I have seen boards cup so badly they crack in half along their length.

The best bet is to get someone out to quote you on a price to replace the siding. Then ask for that much off the price of the house. Otherwise, you will be stuck with the whole bill five years down the road when the boards start splitting.

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Date/Time11/26/2012 at 11:21:34 AM

I'm a St. Catharines Home Inspector for Maple Trust Inspections in the Niagara Region, Ontario.

I think the other posters have given you some good advice on your home, but I would like to add one more thing.

Pay close attention to the interior finishes anywhere the exterior envelope has been compromised. Look for water staining, paint peeling, efflorescence and other signs of water penetration. If the siding is in such poor condition that it is no longer doing it's job, consider what the interior wall cavity might look like.

A home inspector with a good understanding of water penetration, a moisture meter and and infrared camera could be a great help to you before you get knee deep into things.

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