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We have a one-year old timberframe house in middle Maine. The porch timbers (white oak) have quite a bit of mildew. It was a long winter with a lot of snow and then a rainy spring. The wind blows from the west and north so that the front porch faces east and thus, the airflow is minimal. The timbers have only the original coat of oil. My builder has offered to sand the timbers but is not sure whether to use a bleach and in what proportions. Also, what would be the best suggestion for an oil sealer? I noted in another blog the recommendation to use a marine grade sealer.

Appreciate the assistance.

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Comment by Jake Lappan on September 25, 2009 at 8:13am
go to www.riverbendtf.com for some great front porch pictures.
Comment by James Lehr on September 24, 2009 at 4:53pm
I was wondering if you have any pictures of your home? My wife and I are considering timber framing our renovation project and we live in Norway, Maine. Are you closer to Augusta?
Comment by Chris Wood on July 30, 2009 at 6:46am
The 25% bleach to 75% water should be plenty strong enough. No matter what the finished stain or oil mix, make sure it isn't a "sealer" in the traditional sense. The wood has to be able to "breathe". Large timbers like White Oak aren't thoroughly dried and will continue to shrink and lose moisture. If you use a marine grade sealer, you'll have trouble. I like the Australian oil with UV. But any clear stuff will need re-applied every year or so.

You may also consider an additive called "Stay Clean I/E" that boosts the mold and mildew resistance on the top coat. Several stain suppliers carry this, or it can be ordered on line. Not 100% sure it blends well with linseed and/or tung oil though.

Comment by Jake Lappan on July 15, 2009 at 2:57pm
There a couple of items on the Thompsons water seal website that looked very promising (the waterproofers and Cleaners link above). Post some before and after picks when you are done with the cleaning.

Good Luck,

Comment by Bruce Harris on July 15, 2009 at 2:50pm
Jake: Appreciate the update and websites. I'll let you know how it works.



Comment by Jake Lappan on July 15, 2009 at 2:38pm
I got the steps from the web site mentioned above, but I would guess they are referencing a normal size spray bottle which would be around 16 ounces. It also mentions that you can increase the amount of bleach in the spray bottle up to a quarter cup if the mildew on the surface is heavy. The article also mentions that turpentine can also be used to remove mildew, but its use will destroy the finish on any part of the wood it touches. In addition to that I am not sure what it would do to what the timber is sitting on i.e. stone pier, wood deck, ect...so that would be a judgment call on your part.

In regards to the oil, chances are the oil that was used for the exterior timbers is the same for the interior timbers, but it has a higher linseed oil content that allows the oil to penetrate a little deeper and be a little stronger to against UV and moisture. I would use a clear deep penetrating sealer which is designed to repel water and stand up to UV. It does not have to be marine grades especially because there is going to be some continual up keep involved as the timbers move and check and it will be a little easier on the wallet.

Here are a couple of websites for some ideas

Wood Cleaner

Stain - Oil

Waterproofers and Cleaners

Comment by Bruce Harris on July 15, 2009 at 2:00pm
Jake: This is helpfiul, especially in terms of a "graduated response" to the problem. I was leery about my contractor using a belt sander to attack the problem!
Regarding " Mix a capfuil of bleach to cool water in the spray bottle," would that be one ounce to a 16 ounce bottle? Also, should the oil sealer be marine grade to make it last longer or just the oringinal oil sealer that was used on the timbers.


Comment by Jake Lappan on July 15, 2009 at 1:28pm
I got this info from http://www.ehow.com/how_4477911_remove-mildew-from-wood.html

Step 1
Wash the mildewed area with a sponge and soapy water. You do not have to use special wood soap. Rinse the area with clear water and allow to dry.

Step 2
Mix a capful of bleach to cool water in the spray bottle. Spray the affected area. Let dry. This will kill any mildew remaining on the wood. Let this dry and then wash again with soapy water and rinse. Look for any traces of remaining mildew after the wood dries. If necessary, repeat the process.

Step 3
Gently scrub the affected surface with steel wool if the above step did not work. The goal here is to remove the mildew without marring the surface of the wood to drastically. Remove as much of the mildew as possible and repeat Step 2.

Step 4
Using sandpaper is a last ditch effort to remove the mildew from the wood. Use fine grit sandpaper and remove the wood that has mildew damage. Keep the pressure even and remove only as much as necessary. Treat with the bleach water when finished and let dry.

Then after the mildew is gone I would seal the timbers with a good quality exterior oil sealer. Exterior timbers can look great but it takes continual maintenance to keep them that way especially during the first couple of years while they are drying out. You will need to make sure that you go back and re-oil where the timber checks are at, and at beam to post connection where some shrinkage will occur. In some time the moisture content will find its happy medium and the timber will stop shrinking and checking. Then you will only have to re-oil as required due to the sun.

Hope this helped.
Jake Lappan

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