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Protective wood treatments

Protective wood treatments2019-12-17T09:50:04+00:00

Protective wood treatments for your log cabin

All log cabins and summerhouses need to be treated and maintained with a high quality waterproofing wood preservative to ensure they last a lifetime

A single coat of Cuprinol or Blackfriars, or Sadolin clear wood preservative should be applied both internally and externally  (including all faces and edges of doors and windows and their frames) and allowed to penetrate and dry for three days before treating with weather protector products.  The three day drying makes the use of these spirit based products suitable even when over-coated with water based stains such as Superdec.

For external treatments you can choose from many brands but we have found Sadolin or Sikkens to be excellent.  If you choose Sadolin, there are four systems which work well.

“Classic” as a first coat followed by “Extra” as a top coat – provides a semi gloss finish


“Onecoat” for both coats – also provides a semi gloss translucent finish


“Superdec” for both coats (water-based) – provides an opaque finish and is available in over 300 colours


“Classic” for both coats (better with three coats) – provides a matt finish

Other recommended products – Jotun/Butinox or Sikkens Novatech/Novatop

Whatever product you choose it must satisfy four criteria.

  • It must be a weather protector rather than a paint.
  • It must be a water-proofer (many preservatives do not have waterproofing abilities. This is also true of many varnishes.)
  • It must have at least a small pigment of colour, to provide a filter against the sun.
  • It must be of high quality, for joinery applications, e.g. front doors, windows, conservatories etc.

There are many lower quality stains available for sheds, fences, garden furniture etc. that really do not provide the correct weather proofing needed for a log cabin and/or need maintenance annually.  These are generally the lower priced products.  In our experience “Cuprinol Garden Shades” or “Ducks Back” have not performed well in log cabin applications.

It is always best practice to apply the treatments by brush and ensure that each coat is worked deep into all joints particularly at corners and between logs.  Do not brush too thin or apply over thick.  Ensure all faces and edges of doors and windows and their frames are also weather protected. Ensure exposed end grains of logs are thoroughly coated with three or four applications.

For the internal treatment, assuming you do not expect dampness being created in the cabin and also that you wish to retain the light pine appearance, simply apply the one coat of Cuprinol, Blackfriars or Sadolin clear wood preservative or similar all purpose preservative.

If there is likely to be moisture created within the cabin e.g. from cooking, many people breathing, gas heater, open garage doors and concrete floors, hot tubs etc.,  the internal faces of the walls and ceiling must also be waterproofed.  You could use Sadolin Extra Durable Clear Coat or Clear Polyurethane floor varnish. In all cases it is important to treat inside faces of doors and windows with the exterior weather protector stain to prevent differential moisture absorption that can cause warping of the doors or windows.

For floors we suggest Sadolin Polyurethane floor varnish in clear or oak finish.

All treatments are to be applied in accordance with the product instructions and maintenance coats are to be applied at intervals recommended by the product supplier.

It is sometimes necessary to add a silicon sealant to some joints in the cabin.  This is always needed for log end to end butt joints that occur in long walls and sometimes around door/window frames to wall joints and corner joints depending on weather conditions imposed. It is a simple case of running a bead of silicon water proof sealant into the joint to fill any gaps and provide a cover fillet.

However we recommend that the silicon is only applied after all other treatments are completed and the wood has dried and settled.  For this reason our installers are not in a position to apply the final sealants and responsibility for doing this lies with the customer.

To estimate quantities needed of wood treatment products.

For wood preservative (clear)

  • One coat to outside faces of exterior walls
  • One coat to inside faces of exterior walls
  • One coat to both faces of partition walls
  • One coat to underside of roof boards

Total length (in metres) of exterior walls divide by 4 = No. of litres

Total length (in metres) of partition walls divide by 4 = No. of litres

Ceiling area = width of cabin (in metres) x length of cabin (in metres) divide by 20 = No. of litres

Add all of the above = Total no. of litres (Round up to next whole 5 litre can)

For weather protecting stain (coloured)

Two coats to outside faces of exterior walls and all faces and edges of doors and windows

Total length in metres of exterior walls divide by 4 = No. of litres (Round up to next whole 5 litre can)

For log cabins that require Euro class B Spread of Flame (see our Building Regulations information) we recommend HR-Prof.

HR-Prof is a water based solution that is absorbed into the surface of the wood. It is easy to apply and has non-flammable properties which restrict ignition and spread of flame. It is applied first and can be fully over-coated with wood treatments as mentioned above.

For further details visit Fire Retardant UK Ltd

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