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How to use System Three Endrot Repair For Rotten Doors and Windows

Home » How to use System Three Endrot Repair For Rotten Doors and Windows

This post contains PR Products. If like me you live in an older home you will most likely have come across rotten wood. Windows, doors, frames, you name it! Age, lack of proper maintenance and the good old British weather all conspire together determined to reduce it to pulp. So what’s the answer? Some may go with replacements like UPVC but in my humble opinion you can’t beat wood. And you especially can’t beat old wood. With the proper care and maintenance it will more than outlive us mere mortals. But what do you do when you do find rot? Well this is where System Three comes in with Endrot repair and here’s how to use it for your rotten doors and windows.

Ok so first of all, before we actually get to the ‘how to’ part, let’s take a look at the Endrot Repair System itself. New in from the US it’s currently only stocked by London Decorators Merchants. It consists of three products. Rotfix, a two part epoxy liquid that sinks deep into the woods fibres to reinforce and waterproof it effectively making soft wood hard again. Then there’s Sculpwood Putty which enables you to rebuild missing parts that you’ve had to remove due to rot. And finally Sculpwood Paste for filling surface defects. Together they make a complete system to rebuild even the most rotten wood.

Today we’re going to take a step by step look at how to use the System Three on one of my very rotten sash windows. I’m always repairing them in some way or another! Whether it’s reglazing, replacing sash cords or fixing rot there’s always a job to be done on one of them. I’m not going to take you through the sash window removal today purely because I rather stupidly forgot to photograph it so that will be a post for Spring when it’s warm enough to tackle my next window. Today instead we’re going to focus on the repair itself.

System Three Rotfix, Sculpwood Putty and Sculpwood Paste

Disposable Gloves

A Hammer and a sharp Chisel

Old Paintbrush

Disposable Measuring Cups


Hot Air Gun And Scraper

Paint Remover – I used Kling Strip

Caulking Gun

First of all you need to see what you have to work with and this involves removing all the paint from the surface of the wood. Two points here! If the wood is old please test the paint for lead. You can buy lead testing kits quite cheaply. And if it is lead, please take the necessary precautions! It’s not something to be sniffed at, literally!

Secondly you need to decide on the best method to remove the paint. Either with paint remover or a hot air gun and scraper. In the case of a window paint removal may be better as a heat gun can easily crack the glass. Once the paint is removed it’s time to set to with your hammer and chisel. You need to remove all the old window putty, remove the glass (having labelled where it’s come from) and then every trace of rotten and/or flaky wood. As you can see above, there’s not much left of my window at this stage.

Now it’s time to seal the remaining wood with Rotfix. It’s a two part epoxy sealer, primer and consolidator designed for the restoration of rotting, deteriorated, dried out or spongy wood. It works by penetrating the fibres of the wood to create a sound, waterproof base for your repairs.

A two part system, you mix 2 parts A with one part B, mix thoroughly for a minute or so and then apply liberally with a paintbrush. Take note though not to use your favourite brush as it is going to end up in the bin! Rotfix seals wood permanently to prevent any further moisture penetration in the future ensuring your repair will last for years to come.

Now this is the really clever bit. This product is one of the most amazing I’ve ever tried! Sculpwood Putty is again a two part epoxy product but this time a kneadable version. It’s mouldable, lightweight, incredibly strong and sticks incredibly well to your rotten wood. It’s also (once dried) easily planed or shaped with a chisel and can be sanded as well as taking nails or screws and paint just like a normal piece of wood.

Once you’ve treated your rotten wood with Rotfix, now’s the time to start rebuilding all the bits you chiselled away. Firstly don a pair of disposable gloves and then open both pots of Sculpwood putty. And then carefully remove roughly the same amount from each pot. I created two separate balls so I could judge the amounts ensuring I had the same amount of each part. Now using your hands to knead the two parts together thoroughly so that you have one larger ball with a completely uniform colour.

There is a bit of technique to using the putty though. At first I tried to apply it with a filling knife like you would with other filler. Oh no, this really didn’t work. It just stuck to everything, my hands, the knife bits of wood! It was a mess and I was mildly panicked at this point I can tell you. Instead of applying with a knife in a smoothing sweeping action you need to pat the putty into shape. First make the rough shape applying with your fingers, almost like plasticine. And then use your filling knife flat side down to pat it into shape.

Don’t worry if it’s not perfect. The aim is to build up the rough shape and once dried you can shape it. I found around 3-4 hours was a bout the perfect amount of time to leave it before shaping. The putty has gone off enough to use a chisel but it hasn’t gone so hard that it takes all your determination and strength to carve. I used my chisel to shape the wood and then sanded it. I did have some low points at this point which I found were easy enough to build up by adding some more mixed together putty. And then once again I used my chisel to shape the putty once it had gone off before giving it another sand.

You should now have your rotten wood almost looking as good as new. But like me you may still have some surface imperfections. Some smaller gouges, nicks or scratches that need disguising and this is where the final step of System Three comes in. Again this is a two part product. It’s an easily spreadable waterproof paste that’s perfect for filling cracks and defects in not only rotten wood but damaged wood too. I for instance found it great for cracks in my old Victorian doors that I’ve recently refurbished.

Easy to use, just load the tube into a standard caulking gun and dispense the amount you need. You can buy a mixing nozzle but it’s not necessary. Mix the two components with a filling knife and then smooth over your wood before allowing it to dry and give it a sand. Et Voila! One manky old window that many on Instagram told me to throw away, repaired for a fraction of what it would have cost to replace! All that’s needed now is to reglaze, paint and put the sashes back in their frame.

So there you have ‘How to use System Three Endrot Repair For Rotten Doors and Windows’. Are you up for giving it a go? I honestly can’t rave about this product enough. It’s an absolute game changer! I even used it to mend a stair spindle that snapped it two 15 years ago and had kept just in case one day I’d find a way to fix it! Look at it now, safely back where it belongs!

Oh, and if you do have any questions please pop them in the comments below. I’m always happy to answer or help in any way I can xx

NB: Although ‘How to use System Three Endrot Repair For Rotten Doors and Windows’ contains PR Products, all words and thoughts are my own. This is an honest review of some pretty amazing products.