Wood Rot

Can you repair wood rot?

When dry wood makes contact with moisture or condensation in unventilated areas, there is a good chance that wood decay will occur. Common sources include faulty plumbing, leaky downspouts and rain leaks. The decomposition of wood is not a sudden occurrence; rather, the damage is gradual and remains inconspicuous until the final stages.

Your first reaction might be to replace the wood. But, have you considered restoring the wood instead? Replacing wood can be an expensive and time-consuming project. Depending on how far the fungus has spread, it could be impossible to replace the wood.

One of the effects of wood decay is the growth of fungus, which spread quickly and destroys the wood. Cutting out rotted areas is one possibility. However, this process might not remove all of the infected areas. Unless the fungus is removed completely, the rotting will continue until floor break or doors fall.

At Hitch Property Constructions, we offer timber repairs work from simple timber repair to almost new structures, renovations, and extensions.

What Causes Dry Rot in Wood?

A certain species of fungus causes dry rot. Its spores land on wood, and with enough moisture, it thrives, despite the name. You may see white or grey growth on the wood and even a mushroom-like body if advanced. Other visible signs of dry rot include blistering, cracked or peeling paint, wood darker than surrounding areas, and green algae on the wood.

Window Sills and door sills are the building materials most often affected by dry rot, but it can grow into non-wood surfaces in contact with the ground, including plaster and mortar.

Repair Wood Rot

Should I Repair or Replace Dry Rot?

Certain amounts of dry rot can be repaired, but it is not recommended if the affected areas provide structural stability to your homes, such as with beams and joints, or even flooring for that matter. In those cases, you should replace the wood instead of repairing it.

Whether you repair or replace the wood, you must eliminate the conditions that allowed the rot to thrive in the first place or risk it coming back. Locate the cause of moisture buildup by checking for roof leaks, damaged gutters or downspouts, plumbing leaks or poor ventilation.

The First Decision: Remove Or Seal?

In order to restore rotting wood, you will usually need to remove the source of the rot. This means removing all the rotted wood with a claw hammer, a saw, a grinder, or some sandpaper. The rot is like a tumour, in the fact that you can only remove it by cutting it away. When you are dealing with rotted wood that has begun to crumble, you will have to remove the deadwood and replace it with some filler.

Sealing Without Wood Removal

If the rot is not that bad, you might choose to seal it in. After sanding, a small amount of wood rot can give some interesting colour patterns. Of course, this only works if you are talking about the early stages of wood rot, so this method isn’t always an option. If you choose to go this route, you have to sand the surface thoroughly, until you get to the bare wood. I would recommend the use of a power sander or an angle grinder with a sanding wheel to save time.

After you have done this, treat the wood with a wood hardener and maybe a wood sealer as well. By doing this, you will kill the fungi that cause the rot. Wood rot, in general, is caused by fungi that eat the wood from the inside. Since fungi require water to survive, this sealing process will kill the rot at its source.

Filler Methods

In most cases, you will need to use a filler of some kind. Start by taking the claw end of a hammer and raking away any wood that is crumbling and brittle. Don’t hit it too hard, as you don’t want to damage any of the unrotted wood. After you have gouged out the worst of the problem, you will need to sand away the rest.

From here, you have a number of options when it comes to filler material. Let’s go over those options one at a time.

Method One: Wood Filler

One of the more popular methods of replacing rotted wood is the use of wood filler. Also known as wood putty, this stuff is normally made from a mixture of wood fibres and glue. It makes a great tool when restoring rotted wood, as it has a consistency that is similar to clay. As such, you can mould it into any shape that you might want.

Wood filler is also generally easy to sand, making it even easier to adapt this substance to any surface. There are harder wood fillers that you can buy, but most of them are not suitable for load-bearing pieces of wood.

You wouldn’t want to use this stuff to repair the rafters of a house, or the leg of a chair, or anything else that is meant to bear a lot of weight relative to its size.

Many commercial wood filler products also contain latex, so you should always check the label to see what you are getting. Latex is very strong (far stronger than most wood), and is completely resistant to moisture and most other natural degradation. It also has a certain springiness that allows it to resist impact better than any other filler.

If you want to do some experimentation, you can make improvised wood putty at home. You will need sawdust (a lot of it!) and some glue. Of course, you can experiment with different types of glue, but the making of this substance is extremely simple. You mix two ingredients, so it isn’t complicated. The only trick is getting the consistency that you need. I recommend using very little glue at first and then gradually adding more until the desired consistency is reached. Once you have gotten your mix right, you can start experimenting with different additives.

A few ideas: Liquid latex, metal powders, wood hardener, silicone caulk, and epoxy hardener.

Method Two: Epoxy

Epoxy provides a very hard and tough solution for filling wood cavities. Some epoxies are almost as strong as steel (and a few that contain steel). It is also a very long-lasting repair and can be sanded and painted, much like putty. Epoxy also has the advantage of being very water-resistant.

Of course, there are some problems with this method as well. First of all, most people seem to agree that epoxy will be degraded by sunlight over time, which means you cannot use this for outdoor projects. Thankfully, there is a workaround for this problem. You can apply a UV-resistant primer and paint to the surface, and it should be fine. In most cases, you would probably want to paint the surface anyway, so this isn’t a huge problem. Epoxy is a little harder to use overall, and a little more expensive, but provides a pretty solid repair. Just remember that it needs to cure for at least 24 hours, or you will have a very difficult cleanup on your hands.

Method Three: Polyester Filler

Polyester wood fillers are another popular option. Most people seem to agree that this stuff is a little hard to use because it does not stick to the wood as well as some other fillers. Still, it is a very strong filler that can be used for more heavy-duty applications. It tends to dry very hard, making for a more durable surface. It is worth noting that polyester filler is often used on cars, and is more commonly known as Bondo.

Check out our range of timber repairs Melbourne at Hitch Property Constructions. 

Method Four: Wood Patching

You don’t always have to use a filler product when replacing rotten wood. In some cases, you might want to patch the missing area with another piece of wood.

This will be a lot easier if you use a saw to cut the area square. That way, you can use a square-ended piece of wood to fit neatly into the gap. In most cases, the square will be more like a rectangular cube, but let’s not start splitting hairs.

This method is pretty straightforward. You remove all of the old wood and then use a small saw (or maybe a grinder) to cut the gap into a squared-off area. You then cut a fresh piece of wood to the correct size and affix it with glue and long wood screws. Make sure you don’t use extremely thick wood screws, or you might end up splitting the wood. Remember, you are probably drilling into a weak spot, so take care and go slowly. For strength, the most important thing is to make sure there are no gaps between the new wood and the old wood. Any gaps will compromise the strength of the repair, so make sure those cuts are nice and straight.

How to Repair Rotted Trim with Epoxy

Remove Rot-Softened Wood

After clawing out the loose stuff with a hammer, Stahl removes all the rot-softened wood with a die grinder and core-box router bit. For an epoxy repair to be effective, the freshly exposed wood has to be sound and dry—less than 18 per cent moisture content. Stahl checks it with a moisture meter before proceeding.

Inject Borate Into Holes

The undisturbed area at the bottom right of the mullion is an old epoxy repair, around which the wood continued to rot. To ensure that won’t happen again, Stahl injects a borate wood preservative into holes drilled halfway into the wood. Sealed over with epoxy, the borate penetrates the wood, minimizing the chance of future decay.

On the exposed wood

A two-part epoxy primer brushed on the exposed wood ensures that the final repair will bond to the surface. After waiting about 15 minutes for the thin liquid to penetrate, Stahl wipes off the excess with a paper towel. The surface is now ready for a coat of the two-part epoxy filler.

Blend the Resin and Hardener

Stahl pumps the two components of the epoxy filler—resin and hardener—onto a plastic board, then blends them thoroughly with a plastic putty knife. Epoxy doesn’t stick to hard plastic surfaces, so the board and putty knife can be cleaned and reused.

Sculpt the Epoxy

Using the same plastic putty knife, Stahl sculpts the viscous epoxy into shape. The mix remains workable for about 30 to 45 minutes (longer in cool weather and shorter when it’s hot).

Paint the Epoxy

Epoxy breaks down in sunlight, so it needs to be painted. The next day, after the repair hardens, Stahl sands it smooth, first with 80-grit paper, then 100-grit, then 220-grit. An acrylic primer is next, followed by two coats of 100-per cent acrylic paint.

How to Repair Wood Damaged by Dry Rot

If you are confident that the area with rotted wood is repairable, many products are available to strengthen and patch it.

Start by removing as much of the infected wood as possible with a wood chisel and wire brush.

If you cannot reach it all, inject an epoxy consolidant into the wood through drilled holes. It will reinforce the affected wood fibres and bond with unaffected surrounding areas. You can find this at most home improvement stores.

A wood-patching product can then complete the repair once the epoxy consolidant has cured. You apply the putty-like material to the rotted wood. Once it has cured, you can shape it to the desired form using a chisel and sandpaper.

Keep in mind that with repair, you run the risk of not getting all of the affected wood and allowing the fungus to spread deeper into the structure of your home. Only attempt repair if you have DIY experience with the work – otherwise, enlist the help of your professional handyman.

How to Replace Wood Damaged by Dry Rot

As noted with repair, only attempt replacement of rotted wood if you have sufficient experience. The work will involve:

  • Removing all rotted wood plus an additional three feet of surrounding wood to ensure no fungus remains
  • Removing all plaster, skirtings, panelling, linings and ceilings to ensure no fungus remains
  • Cleaning all surfaces, including steel and pipes, within five feet of the rotted wood or other material
  • Applying fungicide to all surfaces within five feet of the rotted area
  • Replacing with pressure-treated wood
  • Replastering or painting with a zinc oxychloride product to prevent the dry rot from returning

Throughout this project, all rotted materials will need to be removed from your home and disposed of appropriately. Again, as with repair, the goal is getting all of the affected wood and not allowing the fungus to spread deeper into the structure of your home.

Dry Rot vs. Wet Rot

Many homeowners also make the mistake of thinking dry rot is wet rot, which is caused by a different fungus. Wet rot looks wet, and it requires repair or replacement of the affected wood. To be on the safe side, enlist the help of a professional whenever you spot rot in your home.

We have a wide range of Melbourne timber repairs for your home renovations. Check out Hitch Property Constructions.

Preventing Wood Rot

Before you do any repairs or restoration, you might want to consider the use of an anti-rot treatment. Although a thorough sealing will generally kill the fungi that cause rot, a borate wood treatment will make sure that the job is done. It will also act as a termite repellent. If you want to make sure your wood has the longest life possible, this is a good thing to consider. It’s technically considered to be a pesticide, but it’s not a particularly toxic one.

In the end, a wood sealer is probably the best way to prevent wood rot before it happens.

Any piece of wood that is meant to last a long time should be treated with some sealer. The whole point is to isolate the wood from all external moisture, which will starve the fungi and preserve the wood for many years to come. Shellacs and other hard coatings are also good options, but a sealer has the advantage of being able to penetrate the surface of the wood. Also, good shellac is far from cheap.

For outdoor projects, two little tricks can help to preserve your wood from rot. First, make sure that any nails or screws are countersunk and plugged with a filler. Otherwise, those small recesses will collect water. Anywhere water collects, rot infests. For this same reason, outdoor wood should always have a sloped surface that won’t collect water.

Restoring partially-rotted wood is usually worth the time. If you know what you are doing, it won’t even take that much time whether you choose to use a filler, a wood patch, or just a sealer, most rotted wood can and should be salvaged. I hope that I have given you a good idea as to the principles and methods by which this is done.

Restoring wood and preserving it from further damage is a much simpler process than most would expect, so I recommend it for any wooden item that has value. Of course, no one can afford to seal and preserve every single piece of wood that they own, but you can certainly prioritize the important things and preserve them for years to come.

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