Rotten timber is a common issue, especially in older homes. Timber can rot indoors and outdoors, primarily due to moisture or time. You might notice rot in pipes, basements, door frames, decks, and fences. Instead of replacing all the timber, you can often save money by repairing the rotten wood.
Rotten timber is often caused by fungi, which thrive on moisture. If left untreated, fungi cause wood to rot and create structural damage. Addressing the rotted and unrotted wood during repairs is important for long-lasting results.
Here’s a step-by-step guide to fixing rotten timber with clear instructions.
Let’s get straight to the point.
Rotten timber, often caused by moisture and fungi, is common in basements, doors, decks, and fences. To fix it, assess the damage, remove the decayed wood, apply wood hardener, fill the gaps with epoxy or polyurethane filler, sand the area, and finish with primer and paint. For severe damage, remove the rotten sections and replace them with new timber secured using polyurethane glue. For small cracks, wood filler works well. Identifying and fixing the moisture source is important for long-lasting repairs.
Materials And Tools You’ll Need
Tools:
- Putty knife
- Utility knife
- Rasp or chisel
- Sandpaper (grit 100)
- Paintbrush
Materials:
- Wood filler (epoxy or polyurethane)
- Wood hardener
- Primer and paint (matching your timber)
- Gloves (for protection)
Steps In Fixing Rotten Timber
Step 1: Assess The Damage
Before jumping into repairs:
- Inspect the area.
- Determine the extent of the wood rot. If less than half of the timber is damaged, you can usually repair it without professional help.
- Find the source of moisture, such as leaking pipes or poor drainage, to prevent future damage.
Check For Water Entry Points
Look for spots where water can enter or gather, such as cracks, damp areas, or blocked gutters. Fixing these issues is vital to preventing further rot.
Step 2: Remove Rotten Wood
Carefully use a chisel or rasp to chip away the rotten wood. Be gentle to avoid damaging any solid timber around it. Remove all weak wood, ensuring you leave a clean surface.
Thoroughly Clean The Area
Clean the area after removing the rotten wood to remove mould, dirt, or debris.
Step 3: Apply Wood Hardener
Wood hardener is crucial for stabilising weakened timber. It seeps into the wood, strengthening it. Use a paintbrush to apply the wood hardener to the damaged area. Let it dry completely. This creates a moisture-resistant barrier.
Step 4: Fill The Gaps
Once the wood hardener is dry, it’s time to use wood filler. Epoxy or polyurethane fillers are best for this. Use a putty knife to spread the filler into the damaged sections. Be sure to smooth it out before it dries. Let it set overnight or for at least 24 hours.
Step 5: Sand The Repaired Area
After the filler has dried, use sandpaper to smooth the surface. The goal is to make the filled section level with the surrounding wood. Use a rag to clear away any dust or debris.
Step 6: Prime And Paint
Once the surface is smooth, apply a coat of primer. This helps the paint stick to the surface and ensures an even finish. After the primer dries, paint the area to match the surrounding wood. Depending on the product, you may need two or three coats of paint.
Pro Tip:
Use anti-fungal paint for outdoor areas or damp spaces to prevent future rot.
Fixing More Serious Wood Damage
Sometimes, you may need to repair wood that has sustained more damage. Here’s how to handle those situations:
Step 1: Remove The Decay
Use a screwdriver or thin chisel to scrape away the decayed wood. Rotten wood is usually softer and will come off easily, so don’t be fooled by paint—rot can hide underneath the surface. For larger sections, a chisel works well to gouge out the material.
Step 2: Soak The Area With Wood Preservative
Apply a wood preservative to the affected planks, ensuring it soaks in thoroughly. You may need to drill small holes into the wood to allow the preservative to penetrate deeper. This will protect the remaining wood from future damage.
Step 3: Fill Cracks With Epoxy Filler
Epoxy fillers are great for deep holes and cracks. Before applying the filler:
- Insert screws into the wood to help it bond.
- Use a putty knife to smooth the epoxy before it sets.
- Once it’s dry, sand the area for a smooth finish.
Step 4: Protect With Epoxy Coating
You may need to apply epoxy liquid to the wood for large, damaged areas. This can be done using a brush or squeeze bottle, ensuring the liquid seeps deeply into the timber. This creates a robust, moisture-resistant barrier. Apply several coats if necessary while the previous one is still tacky.
Removing Severely Rotted Wood
Step 1: Cut Out The Rotten Timber
For sections with extensive rot, it’s best to cut out the damaged wood. Use a claw hammer to pull out rotten sections carefully, avoiding damaging any surrounding solid timber.
Step 2: Clean With A Router
To remove any remaining decayed wood, use a router with a V-shaped bit. This tool allows you to grind away the remaining rot while preserving the healthy wood. Continue until you’re left with clean, solid wood.
Replacing Large Sections Of Timber
Step 1: Measure And Cut A Replacement Piece
You’ll need to replace the timber for large holes or completely rotted sections. Measure the size of the hole and cut a piece of cedar wood to fit. Cedar is often used because of its natural resistance to decay.
Step 2: Secure The Patch With Polyurethane Glue
Moisten the surfaces where you’ll place the patch, which helps the polyurethane glue adhere better. Apply the glue to both the patch and the hole, then press the new wood firmly into place. Polyurethane glue expands slightly as it cures, filling any gaps.
Step 3: Sand And Finish The Patch
Once the glue has dried (usually around 6 hours), and the patch to ensure it is flush with the surrounding timber. This will make the repair nearly invisible once you’ve primed and painted the area.
Fixing Smaller Holes With Wood Filler
Wood filler is the best option if you only have a small hole or crack to fix. Here’s how to do it:
Step 1: Mix The Filler With Hardener
Squeeze out some wood filler and mix it with the provided hardener. Mix thoroughly until the filler turns a consistent colour.
Step 2: Apply The Filler
Using a putty knife, press the filler into the hole. Be sure to spread it beyond the hole’s edges to create a smooth, even surface. The filler dries quickly, so work efficiently.
Sanding And Finishing
After the filler has dried (usually within 30 minutes), use sandpaper to smooth it out. Start with coarse sandpaper and gradually move to a finer grit. This ensures that the surface is even and ready for painting or staining.
Conclusion
Fixing rotten timber is a practical and cost-effective way to extend the life of your home’s wood structures. Whether the rot is a small patch or a large section, addressing it early prevents more extensive damage and the need for expensive replacements.
By following these simple steps—assessing the damage, removing the decayed wood, applying wood hardener and filler, sanding, priming, and painting—you can restore the strength and appearance of your timber.
Techniques like epoxy filling and cutting out rotten sections are necessary for more severe damage, but even these methods can be tackled with the right tools and materials. Remember, the key to a long-lasting repair is to identify and resolve the source of moisture causing the rot in the first place.
With proper care, your timber can be revitalised and protected for years to come.
Whether you’re working on a door frame, deck, or fence, these repair techniques can help you save money and preserve the beauty and structure of your home. With patience and attention to detail, rotten wood can be restored, making your home look as good as new.
FAQs About Wood Rot
Can You Paint Over Rotted Wood?
Rotten wood is highly porous and must be sealed before painting. Before rotten wood can be painted, it must be treated with a wood hardener. The hardener absorbs into the rotted wood to provide a firm base for the paint.
What Happens If Dry Rot Is Left Untreated?
Dry rot is a dampness primarily found in aged homes and buildings. If left untreated, it can cause wooden structures to weaken and disturb the building’s foundation.
How Do You Fix Wet Rotted Wood?
Drill small holes into the rotten area to help the wood hardener penetrate deeper. It’s worth drilling holes in the area slightly beyond the rotten wood to ensure the rot doesn’t spread. Once you’ve removed the crumbling wood, use a wet rot wood hardener and apply it to the wood with a paintbrush.
Can A House Collapse From Dry Rot?
While dry rot can technically affect any wooden structure, it’s most commonly associated with homes and buildings. Left unchecked, dry rot can be catastrophic, leading to structural failures and collapses.
How Long Does It Take For Dry Rot To Spread?
Dry rot can spread up to 80 mm daily if it has optimal growth conditions. To achieve this intense growth, it needs temperatures between 66 and 70 degrees Fahrenheit. Unlike many other fungi, dry rot does not need much moisture to grow quickly.
