Rotten Wood Repair Kits for Windows, Doors, Boats and Other Soft or Hard Wood Products

Rated 4.86 out of 5 based on 7 customer ratings
(7 customer reviews)

From: £96.00 £88.81

Rotten Wood Repair Kits are ideal for the restoration of Windows, Doors and Boats, anything made of wood with a rotten area is an ideal candidate for restoration with a repair kit.

These are premium repair kits, comprised of a pair of very high performance two part products. They may appear expensive, but the real cost of any repair is never the materials, and is always the time required to do the job properly (normally proper surface preparation). These kits can make a permanent waterproof repair.


Clear Penetrating Epoxy Sealer - CPES

Smiths Clear Penetrating Epoxy Sealer™ (CPES™) is a thin epoxy that will penetrate deeply into the surface of wood. It is the ultimate primer for wood to make paint or varnish stick. CPES restores strength to rotten wood and waterproofs all wood.


Smiths Fill-It Epoxy Filler - The flexible wood filler with epoxy strength

Fill-It Flexible Wood Filler is the perfect partner to Smiths CPES for restoring wood. It is the Epoxy Wood Filler that lasts offering a permanent and watertight solution. It will flex with wood and is so waterproof it can be used below the waterline.


Colouring Kit for Fill-It Epoxy Filler – optional

In stock


CPES Injection: 90ml Ear Syringe. – optional

The perfect tool for Smiths CPES Injection into holes drilled into deep sections of rotten timber.Get Smiths CPES into rotten wood with minimal mess.

Category: Timber


Rotten Wood Repair Kits are ideal for the restoration of Windows, Doors and Boats. Anything made of wood with a rotted area is an ideal candidate for restoration with a repair kit.

These are premium repair kits, comprised of a pair of very high performance two part products. They may appear expensive, but the real cost of any repair is never the materials, and is always the time required to do the job properly (normally proper surface preparation). These kits can make a permanent waterproof repair.

How will this repair my wood?

The CPES will consolidate rotten timber, penetrating deeply into the damaged rotted wood to consolidate and toughen it whilst stopping the rot completely. The Fill-It filler will bond strongly to the CPES saturated timber, offering a permanent flexible repair which is bonded to the underlying wood. Your rotten wood repair will be permanent – the rot will not return. The CPES seeks out all of the rotting wood, that which is clearly rotted, and the wood that has just started to rot underneath it. All of this will be saturated with CPES, and the rotted timber will rot no more.

The performance of these products at repairing rotten wood is evaluated at WoodRestoration.Com.

rotted wood repair six steps to restoration

Why is this better than other Rotten Wood Repair Products

This kit contains the worlds finest penetrating epoxy. It penetrates deeply and will find all rotten wood. You do not have to carve out all rot. You will not be left with wood that has started to rot underneath your repair, as CPES will seek that out too.

The filler is also a two part epoxy. It flexes with the wood, and mixed properly is so waterproof that it may be used below the waterline to repair boat hulls. It is an aggressive adhesive and will bond permanently to the CPES treated timber ensuring a permanent repair. It may be coloured to match the wood if required.

You will be left with a permanent repair to your rotted wood. The filler will be bonded permanently to stable epoxy saturated wood. The repair will last.

Most other products use an acrylic (a type of plastic: perspex is a common brand name of an acrylic plastic) base dissolved in a solvent as their wood hardener. It is a relatively cheap solution, which does not require mixing as it is a one part product. It’s performance does not compare to that of Clear Penetrating Epoxy Sealer, and the acrylic does not bond anywhere near as firmly to wood fibres as the wood derived resin in Smiths CPES.

Many of the competitors wood fillers use a polyester filler. Polyester fillers are easily identifiable by the relatively small amount of hardener used. They are similar in basis to the body fillers used for car repairs. Polyester fillers do not stick as well to wood as epoxy resins.

We will be conducting some real world testing of common wood repair products performance against CPES and Fill-It in the near future. Check back to see the results.

Will It Save Money?

The final finish, whether paint or varnish, will bond thoroughly to the CPES reducing maintenance costs and increasing durability. It is often far cheaper to repair rotting wood than replace the rotted wood with new, and these products will affect a permanent repair that will last.

All repair kits are supplied with CPES and Fill-It at a discount of 7.5% to purchasing them separately.

rotten wood repair kit epoxy resins fill-it cpes

Rotten Wood Repair Instructions:

  1. Remove any paint from the rotten wood repair area. It is recommended to remove paint from the entire piece if you can as the CPES will make any good wood very resistant to rot in the future, and will further make your paint or varnish finish last much longer
  2. Remove any rotted wood that is so rotten that it can be removed with your fingers. Retain anything firmer than this as CPES will harden rotted wood to the point where it will carry screws and filler without failure
  3. Allow the wood to dry out thoroughly before continuing with your rotting wood repair. Dry timber is much easier for the CPES to penetrate into
  4. Before applying CPES ensure that you can keep the work area dry until it has chemically cured
  5. Apply several coats of CPES (You will normally use Cold Weather formula for treating rotted wood, as it evaporates faster, but you may use Warm if you already have some, or need warm formula for another purpose as well) to the wood with rot, allow as much to be absorbed as the wood will take. One mixing can be used to apply three or four coats within one day if the solvent smell has dissipated. Keep mixed CPES covered between coats. Allow 24 hours to dry and partially set after the final coat. There should be no solvent smell and the surface should be firm to the touch. Large sections of rotted timber can take much longer for the solvents to evaporate, as they will absorb much more CPES into the rot. Moving air with fans can speed this process.
  6. Deep areas of rot can have holes drilled into them to assist getting CPES deep into the section of rotted timber. Our CPES injection syringe can be used to good effect on rotten timber joints in window frames and similar, allowing for application of CPES to a precise area that will consume a lot as the porous rotted end grain is restored.
  7. Once the rotting or rotten wood is saturated, the last coat will dry with a sheen, indicating that the wood will absorb no more
  8. Now mix and use the fill-it filler to restore the profile on any rotten areas removed in step 2. Colouring Kits are available if required and may be used to colour the filler to the colour of the damaged wood to allow varnish or clear finishes to be applied. Full details on Fill-It, including thorough mixing instructions can be found on the Fill-It Flexible Epoxy Filler.
  9. Allow the filler to set before any final finishing. Finish the Filler by carving or sanding.
  10. Apply a final sealing coat of CPES over the filler and wood. This will promote the adhesion of your paint or varnish top coat, reducing maintenance and extending life
  11. Your rotten wood repair should now be complete, and will just require finishing. The timber should now be very hard and highly resistant to further rot or water damage. The CPES dries as flexible as wood, and is also micro-porous, so the surface is very hard to damage yet will still allow the timber to breathe
  12. Apply the first top coat 24 hours after the final coat of CPES typically, The CPES should be dry to the touch, and not smell of solvents, but still be chemically curing. It will bond to the top coat, gluing it to the wood in a very permanent manner. As the restored wood will still breathe, micro-porous paints may be used to good effect

These are only very brief instructions, full instructions are included with each kit, and if you have specific problems, such as nail rot, we can advise you on how best to deal with those. Please contact us for assistance if this is the case.

What sizes of CPES and Fill-It do I need?

Fill-It Epoxy Filler

Fill-It Epoxy Filler does not shrink, so a void of 1 cubic centimetre is filled by 1ml of product. 1cu inch is 15 cubic centimetres, ml or cc’s.I include imperial measurements as I find it far easier to calculate volumes of cracks etc in inches. Examine your hole after you have removed any loose rotten timber as described.

You should always use two separate tools to remove part A and Part B from their containers, unless the entire volume of the container is to be used at once!

For estimation purposes our packages contain the following amounts:

PackageMilliLitres (cc)Cubic Inches
12 US Fl Oz35522
2 US Pint95058
1 US gallon3785231

Clear Penetrating Epoxy Sealer (CPES)

CPES use is very hard to accurately estimate. New softwood or ply will consume around 1 litre per 5 sq metres. Hardwood coverage may be up to 10 sq metres / litre.

If you are reading this you are very unlikely to be considering new wood coverage however. Treatment of rotten wood is normally done using cold weather formula as it evaporates faster.

Seriously decomposed rotted timber, soft to the point where you can push your finger through it, will consume up to 3 times the volume of the timber to harden it as far as it will go (to a rock hard piece of epoxy around some cellulose fibres). Less badly rotted wood will of course consume less. It’s nearly impossible to estimate accurately how much any piece of well rotted timber may consume without trying the CPES on the actual rotten wood, but if you estimate the same volume of CPES as obviously softened rotten timber that is as good a starting point as any.

The most accurate means of estimating the CPES requirements of your rotten wood is to trial it on an area. The aim is to saturate the rotted timber. We will take back unused product in saleable condition if you wish to buy enough to ensure you can get the job finished.

What About The Rest Of My Old Window Frame?

While repairing a rotten section of any exterior wood item, if the entire exposed surface is cleaned back to bare wood (and dried if it is damp) it can be sealed with CPES whilst the repaired area is being restored. This treatment will seal the exterior surface of the wood permanently against the elements, particularly protecting end grain and vulnerable areas of the item. This finish will be breathable, allowing for micro-porous paints to be used to good effect. Furthermore the CPES will bond the final finish to the last coat of CPES very strongly, reducing future maintenance requirements if the final finish is applied whilst the CPES is chemically curing but after the solvents have evaporated.

Further Information for Our Rotten Timber Repair Kits

If you are unsure of which temperature CPES you require, click here.

For details of the use of CPES as a primer click here, wood hardener (consolidator) and rot restorer, see here.

To see how wood rots, and why the unique resins in Smiths CPES allows permanent rotten timber repairs, click here,

The rot doctor has just concluded some 5 year exposure testing of Smiths CPES, click here to view Rot Doctors 5 Year exposure test.

Additional information


Cold, Warm

Clear Penetrating Epoxy Sealer - CPES


Cold, Warm


0.95 Litre – 2 US Pint, 1.9 Litre – 2 US Quart, 7.6 Litre – 2 US Gallons

Smiths Fill-It Epoxy Filler - The flexible wood filler with epoxy strength


355ml – 12 US Ounces, 0.95 Litre – 2 US Pint, 3.8 Litre – 1 US gallon

7 reviews for Rotten Wood Repair Kits for Windows, Doors, Boats and Other Soft or Hard Wood Products

  1. Rated 5 out of 5

    Keith Jones

    Amazing Product. I purchased the small repair kit to repair the base of a load bearing strut support a small gable window that had partially rotted. These products are amazing, customer support is second to none, even on a Sunday. Followed they instructions to the letter and the repair is as good as the original. I was pondering whether to purchase because of the cost, but I can assure you this is well worth the money. The only other alternative was to remove the base of the strut and splice in a new piece which would have been difficult and expensive.

  2. Rated 4 out of 5


    Sealer & Filler. Only time will tell but if using these products on some early rot in my window frames cures the problem then 5 stars would be well deserved. th sealer/hardener was easy to apply & appeared to penetrate well. Unlike other epoxy based products it was slow to cure giving it time to penetrate deeply. The filler was quite easy to mix & apply even to vertical sections. Once again its slow cure allowed time to squeeze it into difficult timber sections. once set it is very hard but capable of being cut & sanded rather like a hardwood. So far I am very impressed & have recommended it to others including a local builder.

  3. Rated 5 out of 5

    andrew stephene

    so far so good. Only used a small amont so far but results excellent

  4. Rated 5 out of 5

    Jeremy Hamilton

    Wood filler. This is an excellent product – really helped us restore our ancient, but loved windows. Easy to work with – we would advise however that during a heat wave, you get less workable time than on a cooler cloudy day!

  5. Rated 5 out of 5

    masterworks (verified owner)

    I have used these products for over 20 years. I know the inventor personally as I had a warehouse next to his in Richmond, CA. I used to go into his shop to purchase and to discuss bonding mechanisms and restoration methods. I know the science behind these products is solid. I know they work. My review is about this company, Make Wood Good. I recently moved to Europe and thought it might be more difficult to get these products. Thank God I found Make Wood Good. I had a problem with the payment method at first, but the owner called me directly and fixed it right away on the phone and sent me the products quickly and professionally. What more do you want? Friendly service the way it should be is exactly what I received. I will purchase exclusively from this company as long as I am in Europe. If you find somebody solid and good… stick with them!!!

  6. Rated 5 out of 5

    gb (verified owner)

    Extremely good product. Won’t know too much about the clear epoxy for a few years, but hopefully it will do what it says in the tin. The filler itself is good in that the two colours ensure you mix it correctly. (best to use the provided gloves as it is a little sticky)
    Once set (and it needs a reasonable temperature as very cold days means it takes more than 24 hours) it can be carved and sanded. Leaves a super finish for painting.
    First impressions are; this product is really a very, very good one.
    One point is to ensure you calculate the volume you will need as it doesn’t really go too far. It will save you having to reorder all the time,

  7. Rated 5 out of 5


    I have used a small repair kit on an outdoor beam at the bottom of a rather flimsy construction of wooden slats which forms the ‘wall’ of a small conservatory.
    I followed the instructions as far as I could, although I was unable to remove the old paint in some places.
    I am very pleased with the result and the repair has survived the winter very well and no more leakage.
    The Product is exactly what it promised to be and I hope the repair will continue to last a long time.
    I would also like to say that you have been very helpful to me on the phone, thank you.

    Mariann Howell

    • Stephen Dakin (verified owner)

      Many thanks for your kind words Mariann. Good customer service is highly valued by us – hope you get many more years from the repair.

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