met

There is a 10 ft section of rotten sill plate on the top of the foundation. Do I need to replace it? Is it just possible to build the supporting wall using 2 x 6 lumber along the foundation in my basement to support joists that rest on the damaged part of the sill plate?
Thank you.

thekctermite

You should consider replacement for the following reasons...

• The sill plate is the attachment point for the wall sheathing, which is what provides wind load resistance for the home
• There may be point loads that need to be directly transferred to the foundation
• Wall anchorage will be lost until the mudsill is relaced
• There are a number of other structural issues that could be in play here

Pro Painter

Is there only a litle rot in a small part of the cross-section of the sill-plate? If you have adequate structural strength remaining, the penetrating epoxy wood-restoration products such as Smith's work well, and keep things from getting worse.

If there's major rot, then you need to look at the structural engineering aspects of the situation. An architect or structural engineer can probe the wood with an icepick, determine what remaining sound wood is there and whether it will carry the load, and advise on repairs.

met

Thank you for your response. There's major rot. I got $1600 estimate from contractor for the plate replacement. There is a water pipe along the plate that must be temporarily cutoff. The major problem is that the floor, which has to be jacked up, is covered with the ceramic tile that lies on the mortar and this work may cause the cracks in the mortar and lose tiles.
There is a light wooden frame wall along the foundation wall that was built to hold the fiberglass insulation. The top of this frame wall is almost at the same level as the top of the plate and there are shims between floor joists and top of the frame wall. So, currently this frame wall provides partial support to floor joists. I was thinking about reinforcing this existing frame wall with new one made of 2 x 6 posts and using shims to make a tight connection. I am not sure if this is an adequate solution instead of plate replacement.

AtlanticWBConst.

If the floor has sagged, then it needs to be jacked up.

If the plate is rotted, but there is minimal to no sag of the floor above it, then there is only a need to support it, during repair. You would not need to "jack it up" for the repair. You may not experience any, or, very little issues with the tile above.

Whatever the case, you should most definitely replace that rotted area.

Another point not mentioned yet, is that moist/rotted wood, also attracts carpenter ants and other pests.

__________________
- Build Well -

jimmy21

will rot spread? Like say you take away the moisture that was cuasing the rot, but one rotten board is still there, will it effect others?

Pro Painter

Fungi and bacteria cause the physical disintegration of wood, what we call "rot". The microscopic critters are literally eating the wood....as do termites, but these are smaller, perhaps only the size of a single wood fiber.

Fungi need four things to flourish and prosper: Air, Moisture, Warmth and Food.

Take away any one or more of those and rot is slowed or stopped.

Air...there will be always a very little amount of air, with its oxygen, diffusing through anything. Removing air to the greatest extent possible will slow things, but you can't seal the wood inside a glass or metal shell in a vacuum, so there will always be a little air.

Warmth...this is difficult to do anything about, as it depends on external weather and sun. Near freezing, we don't have much rot, and in very hot dryer climates we don't see much rot. There's not a lot of rot in Phoenix, Arizona or Taos, New Mexico.

Moisture...here we can do something. Providing ventilation helps the excess moisture in the wood to evaporate into the air. Dryer wood is less hospitable to fungal growth. Two pieces of wood in contact...here the fungi easily spread from one piece to the other, as there is little ventilation between those two pieces and the little critters can crawl or grow from one right onto and into the other.

Think of fungi as animals without skins, so there is no external membrane to keep the moisture inside their bodies. That's why they need a very humid atmosphere..about 85% relative humidity or above, and that's what you find inside a damp piece of wood. The wood is made of cellulose, that has the ability to "hold" chemically, enough water to provide the 15-40% moisture content inside the wood that makes fungi happy, and then they rapidly grow, eat the wood, and leave their spores, or eggs, everywhere.

When you dry out the wood, or, even better, dry it and take away its ability to hold that excess moisture, then the wood can't get damp enough to support fungal growth, and that's why the penetrating epoxy products work to restore the wood and keep the rot from starting up again. That kind of epoxy glues onto parts of the cellulose that would ordinarily hold the excess water, so the wood can't take up as much water and so it's a dryer environment and fungi and bacteria don't like dry wood.

Part of this kind of restoration process is stopping the source of water intrusion with good waterproofing design, proper drainage and flashing, and so forth. Excess water got in there to make an environment where rot could start, so there was something physically wrong in the first place. You need to find that and fix it.

Food...here also we can do something. There are poisons that can be put in the wood, that last for some long or short time, and kill some or most of the little critters that want to eat it. Pressure-treated wood nowadays has some copper compounds, which unfortunately corrode steel fasteners. That was the Law of Unintended Consequences, when CCA was taken off the market for use in Pressure-Treated Wood. There are borate compounds such as Tim-Bor (di-sodium octaborate), that are good, at fairly high levels, but are water-soluble and can leach away. Again, you need to protect the area from water intrusion. Besides the pesticides/preservatives/poisons, there are the epoxy products that say they just make the wood taste bad, so the little critters don't eat it. That seems to work; I was talking to a mold-abatement guy in Florida a few days ago who said he uses it and has never seen mold growing on it; maybe right up to it, but never on it.

So, if you take away their food one way or another, basically by telling them they should not or may not eat the wood, then you have successfully defended your wood against what are technically called Wood-Destroying Organisms.

Now, the spores of these things are in the air, everywhere, and any insect or animal carries them on their feet, and rainwater plucks them from the air and carries them everywhere. Paint and primers and restoration of the wood beforehand, all these things can help wood to last longer, but there is absolutely no substitute for keeping the water from getting inside the structure in the first place, and stopping it from getting in when you find it is happening.

jimmy21

i was just curious, I was thinking about it because we just replaced a giant window with a sliding glass door. All the siding up to the bottom of the window was buried in dirt. So of course the siding was really rotted bad. Along with a 2x10 that was on top of the bottom plate. The bottom plate had little spots that were barely rotten at all. And given that the bottom plate would have been a giant pain to replace we left it. But while it was out we went and bought some..... i think it was called copper napthnanate. We soaked everything we could in it. especially the small rot spots

i was just wondering if we had not used the wood treatment if it would have turned into something. And yes, of course we didn't bury the siding again

Pro Painter

Soaking everything with copper napthenate is a good way to keep what's there from getting worse for a long time, expecially since you removed the source of water intrusion. The bottom piece with those few rot spots is proof that some wood preservatives don't last forever. Copper napthenate is itself a liquid, and will slowly oxidize and diffuse away. It is very small molecules and they do indeed migrate away, and some bacteria and fungi seem to be able to eat it.

There is a very interesting paper at www.woodrestoration.com that talks about this whole technology of wood restoration, and contains an open standard for this kind of product that the entire industry can use. It may answer your question.